bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fibrinogen: Agreement of Experimental and Calculated Hydrodynamic Data with Electron-Microscopic Models
Authors: Serrallach Eugene N , Hofmann Victor E , Zulauf Martin , Binkert Thomas , Hofmann Robert , Känzig Werner , Straub P Werner , Schwyzer Robert 
Published: July 2018

SummaryThere is no general agreement on the size and shape of the fibrinogen molecule. We have studied the diffusion of the fibrinogen in solution by means of dynamic light scattering, nanosecond fluorescence depolarization and analytical ultracentrifugation. The results obtained under physiological concentration, pH an ionic strength are DT = 2.0 × 10-7 cm2sec-1, DR⊥ = 40’000 sec-1. Nanosecond fluorescence depolarization yielded DR// = 1.6 × 106 sec-1. Tentatively this value is interpreted as DR//, namely rotational diffusion about the major axis of the molecule. The sedimentation coefficient is 8.1 S. The hydrodynamic parameters derived from our measurements were compared with those calculated on the basis of the models proposed by Hall and Slayter, Hudry-Clergeon and Marguerie et al., Bachmann and Lederer, and Köppel.The agreement is poor even if the degree of hydration is varied within wide limits. However, satisfactory agreement can be achieved by assuming a flexible molecule of about 900 Å length corresponding to two end-to-end bound trinodular structures of the Hall and Slayter type, with a nodule diameter of about 45 Å. Experimental evidence indicates that the discrepancies between the different models might be due to different techniques of sample preparation leading to different conformations of the molecule.
Is the Antithrombotic Activity of “Antiplatelet” Drugs Based on Protection of Endothelium?
Authors: Hladovec Josef 
Published: July 2018

SummaryIn only five “antiplatelet” agents has the antithrombotic activity been confirmed both clinically and experimentally. These include acetylsalicylic acid, dipyridamole, clofibrate, hydroxychloroquine and sulfinpyrazone. Whereas only acetylsalicylic acid has a demonstrable effect on platelet aggregation in doses usually applied, the effects of all remaining drugs are more easily explained by their influence on the vessel wall. This assumption is supported by the finding that all five drugs possess a stabilizing effect on endothelium in doses corresponding closely to the clinical dose range. The method based on counting detached endothelial cells in blood after a standard stimulus was used to demonstrate this effect.
Ionophoretic Activities of Phospholipids on Human Platelets
Authors: Ikeda Yasuo , Kikuchi Masao , Toyama Keisuke , Watanabe Kiyoaki , Ando Yasuhiko 
Published: July 2018

SummaryThe effects of phospholipids on calcium uptake by human platelets were investigated utilizing 45CaCl2. Among the phospholipids tested, cardiolipin and phosphatidic acid exerted a significant increase of calcium uptake by platelets. Calcium uptake was dependent upon cardiolipin concentration and incubation time. These phospholipids enhanced platelet aggregation induced by ADP (2 μM) or epinephrine (0.5 μg/ml). Cardiolipin caused the significant release of serotonin from platelets in the absence of externally added calcium in the medium.These results may suggest that phospholipids activate platelets through their ionophoretic activities.
The Polymerase Chain Reaction with Sequence Specific Primers for the Detection of the Factor V Mutation Associated with Activated Protein C Resistance
Authors: Kirschbaum Nancy E , Foster Paul A 
Published: July 2018

SummaryThe prevalence of the Factor V (FV) mutation associated with activated protein C resistance (FV Leiden) and its significance as a genetic risk factor for venous thrombosis have necessitated the development of a simple, rapid, and accurate assay for its detection. The polymerase chain reaction with sequence specific primers (PCR-SSP) provides a powerful technique for the discrimination of alleles resulting from single base substitutions. PCR amplification was performed using a sense primer complementary to both FV alleles coupled with either of two antisense allele specific primers, one complementary to the normal FV allele and one complementary to the FV Leiden allele. PCR conditions were developed that favored amplification only in the case of perfect complementation between template DNA and allele specific primer. The FV genotype was assigned based on whether or not each allele specific primer set produced an amplified product. Assignment of genotypes correlated 100% with those determined by the method of PCR amplification followed by MnII digestion. PCR-SSP allows the rapid and accurate identification of carriers of the Factor V Leiden mutation by a simple PCR reaction without the need for the usual post-amplification specificity step.
Antithrombotic Action of Endogenous Porcine Protein C Activated with a Latent Porcine Thrombin Preparation
Authors: McBane Robert D , Wysokinski Waldemar E , Chesebro James H , Owen Whyte G 
Published: July 2018

SummaryEndogenously activated protein C is evaluated for antithrombotic activity in porcine carotid arteries subjected to mechanical trauma. Protein C is activated by intravenous administration of guanidinobenzoyl- thrombin, which binds to thrombomodulin and there deacylates to yield thrombin. The bound, transiently active thrombin yields a peak of anticoagulant activity between 5 and 10 min after infusion of the latent thrombin. Inhibition of thrombin binding in vivo by co-infusing an active-site-blocked thrombin preparation elicits acute and lethal systemic thrombosis. Nearly occlusive platelet thrombosis, which occurs within 30 min of crushing 1 cm segments of carotid arteries with a standard hemostat, is blocked by endogenous protein C activation initiated 2 min before the crush injury. It is concluded that activated protein C blocks thrombosis in deeply injured musculo-elastic arteries, and that activation of latent thrombin bound to thrombomodulin in vivo is a practical means for delivery of pharmacologically effective concentrations of activated protein C.
Kinetics of the Inhibition of Tissue Factor-Factor Vila by Tissue Factor Pathway Inhibitor
Authors: Lindhout Theo , Franssen Jo , Willems George 
Published: July 2018

SummaryTissue factor-factor VIIa catalysed activation of factor X and factor IX is inhibited by the complex of tissue factor pathway inhibitor (TFPI) and factor Xa. At present, no information is available as to what extent the kinetics of complex formation between TFPI and factor Xa during factor X activation contribute to the overall rate of inactivation of the factor X converting complex. We have determined the kinetic parameters of the individual reactions, i. e. factor X activation, formation of the TFPI-factor Xa complex, and inactivation of tissue factor-factor VIIa by the TFPI-factor Xa complex. We modelled the overall reaction by assuming a two-step reaction: factor Xa generated by tissue factor-factor VIIa forms a reversible complex with TFPI and in the second step this complex forms a reversible quaternary complex with tissue factor- factor VIIa. The validity of the model was demonstrated by analysis of factor Xa generation curves in the presence of TFPI. Independently determined constants for factor X activation (kcat= 12 s-1, Km = 70 nM) and inhibition of tissue factor-factor VIIa by TFPI-factor Xa complex (rate constant of inhibition of 1.1 × 108 M-1s-1) were used. The association rate constant of the formation of the TFPI-factor Xa complex was estimated by fitting the model to the data. The rate constants of association of the complex between factor Xa and the variants full length TFPI, TFPI 1-247 and TFPI1-61 were very close to the values determined independently in a kinetic study on the inhibition of factor Xa in the presence of phospholipids, namely 3.4 × 106 M-1s-1, 0.4 × 106 M-1s-1 and 0.3 × 106 M-1s-1, respectively. These results indicate that the factor Xa-dependent inhibition of tissue factor-factor VIIa-catalysed factor X activation by TFPI can be adequately described by the two-step reaction sequence. We found that phospholipids (25 mol % phosphat-idylserine/75 mol % phospatidylcholine) increased the rate constant of association with factor Xa for full length TFPI, but not for the C-ter- minus truncated TFPI. Our results further indicate that optimal inhibition of tissue factor-factor VIIa activity is obtained with full length TFPI because of the higher rate of TFPI-factor Xa complex formation.
Inherited Platelet δ-Storage Pool Disease in Dogs Causing Severe Bleeding: An Animal Model for a Specific ADP Deficiency
Authors: Callan Mary Beth , Bennett Joel S , Phillips Deborah K , Haskins Mark E , Hayden James E , Anderson Jamie G , Giger Urs 
Published: July 2018

SummaryThe nature of a disorder producing moderate to severe bleeding after minor trauma, venipuncture, and surgery was studied in 3 families of American cocker spaniel dogs. In the 5 affected dogs tested, platelet counts and measurements of plasma coagulant function and von Willcbrand factor were normal. However, bleeding times were prolonged in 4 of the 5 affected dogs tested, and platelet aggregation in response to ADP and collagen was consistently abnormal in 3, suggesting that the bleeding disorder was due to abnormal platelet function. Measurements of 14C-serotonin uptake and retention by the affected platelets were normal. However, their ADP content was decreased, while their ATP content was normal, resulting in a mean ATP/ADP ratio of 8.32, compared to a mean ratio of 1.9 in normal canine platelets. Electron microscopy revealed that the number and appearance of the dense granules in the affected platelets were indistinguishable from those of normal controls. These studies suggest that this bleeding disorder results from a deficient δ-granule storage pool of ADP; given the normal serotonin uptake and retention by affected platelets and the apparently normal number of dense granules, the ADP deficiency may be the consequence of a selective defect in δ-granule ADP transport. Additional studies of this unique platelet disorder will provide an opportunity to understand the mechanism of adenine nucleotide storage in platelet δ granules.
Interaction of Echicetin with a High Affinity Thrombin Binding Site on Platelet Glycoprotein GPIb
Authors: Peng Manling , Emig Frances A , Mao Ahua , Lu Weiqi , Kirby Edward P , Niewiarowski Stefan , Kowalska M Anna 
Published: July 2018

SummaryEchicetin, a protein isolated from Echis carinatus snake venom, inhibited platelet aggregation and secretion induced by low concentrations of thrombin (<0.2 U/ml), by binding to platelet glycoprotein lb (GPIb). The inhibition was not observed when the platelets were stimulated with higher concentrations of thrombin (>0.2 U/ml). Echicetin competed with thrombin for binding to the high affinity site on GPIb. Thrombin also inhibited 50% of the binding of 125I-echicetin to the platelets.
The Effect of Fibrin Clots and Clot-Bound Thrombin on the Development of Platelet Procoagulant Activity
Authors: Kumar Rachana , Béguin Suzette , Hemker H Coenraad 
Published: July 2018

SummaryWe tested different types of clot for their ability to provoke procoagulant activity in platelets: normal clots from platelet poor plasma (des AABB- or fibrin II clots), similar clots in which the adsorbed thrombin has been inhibited by hirudin, and clots obtained by the action of two snake venom enzymes that release only fibrinopeptide A (des AA- or fibrin I clots). Analogous clots from fibrinogen solutions were also tested.In platelet rich plasma (PRP), where platelet coagulant phospholipids (PCP) are rate limiting for thrombin generation, the addition of any type of clot enhances the generation of thrombin thus it induces the appearance of PCP. Clots containing active adsorbed thrombin are the most potent ones in this respect. Lactate dehydrogenase (LDH) levels do not increase in the course of the thrombin generation so the platelets are not damaged in the process. Non-centrifugable PCP could be demonstrated to appear during the process, so the production of procoagulant phospholipid microparticles must be part of the mechanism. Membrane transbilayer phosphatidyl serine movement (flip-flop) can not be demonstrated in PRP as the activated platelets are caught in the emerging clot.In order to demonstrate flip-flop, we tried to investigate the influence of clots on washed platelets. However, contrary to platelets in a plasma milieu, isolated platelets are damaged by fibrin clots, especially in the presence of thrombin, as can be judged from the appearance of LDHWe conclude that, in PRP, clots induce the appearance of PCP from platelets by vesiculation, possibly accompanied by flip-flop and that thrombin accelerates the process but is not an absolute requirement
High Lipoprotein (a) Levels in Chronic Hemodialysis Patients are Closely Related to the Acute Phase Reaction
Authors: Kario Kazuomi , Matsuo Takefumi , Kobayashi Hiroko , Matsuo Miyako , Asada Reiko , Koide Masanobu 
Published: July 2018

SummaryTo study the mechanism underlying the high lipoprotein (a) [Lp(a)] level in uremic patients on chronic hemodialysis, we investigated the levels of Lp(a), acute phase reactants (C-reactive protein and sialic acid), and interleukin-6 (IL-6) in 54 dialysis patients. The mean [95% Cl] Lp(a) level was increased in the hemodialysis patients compared with the 30 controls (30 [25-36] vs. 18 [14-23] mg/dl, p <0.005). Among dialysis patients, 46% had an Lp(a) level >30 mg/dl, which was significantly higher than the percentage in the control group (17%). The levels of C-reactive protein, sialic acid, and IL-6 were also increased in dialysis subjects compared with controls (200 [134-299] vs. 37 [24-58] μg/dl, p <0.0001; 63 [59-66] vs. 54 [52-56] mg/dl, p <0.002; and 9.2 [7.8-11] vs. 5.5 [5.0-6.1]pg/ml, p <0.0005, respectively). The Lp(a) level was positively correlated with that of C-reactive protein (r = 0.415, p <0.002), sialic acid (r = 0.426, p <0.002), and IL-6 (r = 0.298, p<0.05) in the hemodialysis patients, but not in the controls or non-dialysis uremic patients. The Lp(a) level in the dialysis patients was also positively correlated with activation markers of coagulation (thrombin-antithrombin III complex and plasmin-α2-plasmin inhibitor complex, p <0.005). These results indicate that the Lp(a) level is closely related to the acute phase reaction and hypercoagulability in chronic hemodialysis patients.
Elimination of Acquired Factor VIII Antibodies by Extracorporal Antibody-based Immunoadsorption (Ig-Therasorb®)
Authors: Knöbl P , Derfler K , Korninger L , Kapiotis S , Jäger U , Maier-Dobersberger T , Hörl W , Lechner K , Pabinger I 
Published: July 2018

SummaryTreatment of potent factor VIII antibodies is a difficult problem. In some cases a reduction ofthe antibody titer is necessary for effective treatment with human factor VIII concentrates. We describe a new method for extracorporal eliminationof factor VIII antibodies (antibody-based immunoadsorption). Blood is drawn from an antecubital vein, citrated, and plasma is separated with a rotating membrane. Plasma passes alternately through one of two columns filled with sepharose-coupled polyclonal sheep antibodies to human immunoglobulins (Ig-Therasorb00), whereas the other column is regenerated. Each cycle has a duration of 15 min. Three patients with high titer factor VIII antibodies (one hemophiliac and 2 with spontaneous antibodies; titers 29, 132, and 313 BU/ml, respectively) were treated. The average reduction of the antibody titer was 76.1 ± 17.2% per session. In each patient 4 sessions were necessary to reduce the antibody titer to < 1 BU/ml. The mean processed plasma volume was 6731 ± 640 ml and the mean duration of each session 3.9 ± 0.7 h. Serum IgG, IgA and IgM levels decreased by 75.3 ± 11.9%, 62.9 ± 19.1%, and 54.8 ± 23.8% respectively. The procedure was tolerated without any side effects. Thus, rapid elimination of factor VIII inhibitors can be achieved with antibody-based immunoadsorption, which can be lifesaving in some cases. This promising method should be evaluated in a larger number of patients.
Factor VIIa in Patients with C1-Inhibitor Deficiency
Authors: Nielsen Erik Waage , Morrissey James , Olsen Jan Ole , Østerud Bjarne 
Published: July 2018

SummaryIn hereditary angioedema (HAE), normal C1-inhibitor (CI-INH) is low and the contact system aetivated. Recently, the findings of a tissue factor mutant selectively deficient in promoting the conversion of FVII to FVIIa, but with retained cofactor for FVIIa, made it possible to examine reliably the pre-existing content of FVIIa in HAH patients. This was of interest as FXIIa (mainly inhibited by (CI-INH) is able to activate FVII directly. FVIIa in 21 remission HAH patients were within normal limits but nearly doubled as compared to their 23 normal siblings (p = 0.0017). Cold promoted activation of FVII (CPA) (common Clot assay) was displayed in plasma of all 5 untreated patients (CI-INH function <35%), but not in plasma of 2 patients treated prophylactically with danazol (CI-INH function about 40%). These results suggest that there is a minute, yet significant activation of FVII in patients with CI-INH deficiency.
In Vivo Recovery of Factor VIII Following Transfusion: A Survey of Recent Data and Publications to Assess the Influence of Standards Used for Potency Assignment
Authors: Prowse C V 
Published: July 2018

SummaryIn the therapy of factor VIII deficiency, experience has taught the value of achieving a target level of plasma coagulation factor VIII. There is a consensus that an empirical value of 2 iu/dl/iu/kg may be used to estimate recovery, and hence plasma levels, of factor VIII. This may be influenced by the methods used to assign label potency to the products and for assessment of patient post-infusion plasmas. To assess a possible influence of the standard used to assign product potency on in vivo recovery, a survey was undertaken of recent in vivo recovery studies. Analysis of submitted data, in combination with published studies over the last ten years, revealed a significant influence of the standard used to assign potency to products on the measured in vivo recovery. Furthermore, from limited data the potency determined in post-infusion patient plasmas was found not to be influenced by the use of one-stage or chromogenic assay methods.
Coagulation Activation and Tissue Necrosis in Meningococcal Septic Shock: Severely Reduced Protein C Levels Predict a High Mortality
Authors: Fijnvandraat Karin , Derkx Bert , Peters Marjolein , Bijlmer Rob , Sturk Augueste , Prins Martin H , Deventer Sander J H van , ten Cate Jan Wouter 
Published: July 2018

SummaryIn 35 consecutively admitted children (mean age: 4.3 years) with a clinical diagnosis of meningococcal septic shock (MSS), activation of the coagulation and fibrinolytic pathways was evaluated directly at admittance to the paediatric intensive care unit (ICU). The association of clinical signs and haemostatic abnormalities was assessed.All patients had signs of extensive activation of the coagulation system. The 28-day mortality was 26%. Protein C activity was strongly reduced, especially in non-survivors in whom it was significantly lower than in survivors (5% versus 23%; p <0.0001). There was a strong negative correlation between protein C activity and the mean size of the skin lesions (r = -0.71, p <0.001). These results suggest that an acquired protein C deficiency in MSS is related to the pathogenesis of purpura fulminans.Furthermore, no increase in C4b-binding protein (C4BP) and no decrease in the ratio free protein S/total protein S was observed, suggesting that a deficiency of free protein S as a result of increased C4BP does not play a pathogenetic role in meningococcal septic shock.
Antiparasitic Treatment of Patients with P. falciparum Malaria Reduces the Ability of Patient Serum to Induce Tissue Factor by Decreasing NF-κB Activation
Authors: Bierhaus A , Hemmer Ch J , Mackman N , Kutob R , Ziegler R , Dietrich M , Nawroth P P 
Published: July 2018

SummarySerum from patients with P. falciparum malaria at day 1 (pretherapy) induces tissue factor (TF) in cultured endothelial cells. TF induction depends on de novo transcription as shown in Nuclear Run On assays. Electrophoretic mobility shift assays demonstrated binding of AP-1 and NF- κB/Rel proteins to their recognition sites in the TF promotor. After therapy (day 28), stimulation of TF antigen by patient serum is reduced by 70%. When serum obtained before and after therapy was compared, a decrease of NF-κB activation was evident. Activation of NF-κB-like proteins was in part dependent on TNFα in patient serum, since a TNFα neutralizing antibody reduced induction of TF transcription and translation and induction of NF-κB-like proteins. Induction of TF activity was suppressed by pDTC, an inhibitor of NF-κB activation. When different promotor constructs of the TF gene were tested, induction was dependent upon the presence of the intact NF-κB-like binding site in the TF promotor. A mutant with deleted NF-κB, but intact AP-1 sites was not inducible. Mutation of the AP-1 sites did not prevent induction, but reduced inducibility by pretherapy serum. Therefore, NF-κB/Rel proteins are responsible for induction of TF transcription by pretherapy serum, but AP-1 is needed for highest inducibility. The effect of antiparasitic therapy on the induction of TF by serum from patients with complicated P. falciparum malaria is dependent on a therapy-mediated loss of activation of NF-κB-like proteins in post-treatment patient serum.
Coagulation Activation by MC28 Fibrosarcoma Cells Facilitates Lung Tumor Formation
Authors: Francis J L , Amirkhosravi M 
Published: July 2018

SummaryTumor cells interact with the hemostatic system in various ways and may thus influence malignant growth and spread. MC28 fibrosarcoma cells possess a potent procoagulant activity (PCA) and form lung tumors following intravenous injection. The aim of this work was to study the relationship between PCA, intravascular coagulation and lung seeding in the MC28 model. MC28 cells were injected into control, warfarinized and heparinized hooded Lister rats. Coagulation changes were monitored by thromboelastography (TEG) and Sonoclot™ analysis (SA), lung fibrin formation by light and electron microscopy, tumor seeding by macroscopic counting and tumor cell and platelet deposition in the lungs by radiolabelling. PCA was measured by chromogenic assay. MC28 PCA was characterized as a tissue factorfactor VIIa complex that probably arose during cell culture or disaggregation of solid tumors. Injection of tumor cells caused marked coagulopathy and was rapidly (within 30 min) followed by fibrin deposition in the lungs and accumulation of radiolabelled platelets. Heparin and warfarin significantly reduced lung seeding (p <0.001) and reduced retention of radiolabelled tumor cells in the pulmonary circulation (p <0.01). Inhibition of cellular PCA by prior treatment with con- canavalin A markedly reduced intravascular coagulation and lung seeding.We conclude that MC28 cells cause intravascular coagulation as a direct result of their procoagulant activity. The data suggest that tumor cells form complexes with platelets and fibrin which are retained in the lungs long enough for extravasation and seeding to occur.Anticoagulation reduces tumor cell-platelet-fibrin complex formation, decreasing the time spent in the lungs and thereby reduces seeding. Thus, the antitumor effect of warfarin, at least in the MC28 model, is due to its anticoagulant action.