bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Tryptic Fragments of von Willebrand Factor Involved in Binding to Thrombin-Activated Platelets with Fragments Involved in Ristocetin-Induced Binding and Binding to Collagen
Authors: Houdijk Wim P M , Girma Jen-pierre , van Mourik Jan A , Sixma Jan J , Meyer Dominique 
Published: July 2018

SummaryPreviously we have studied the binding domains on von Willebrand factor (vWF) involved in ristocetin-induced binding to platelets (ristocetin binding domain, RBD) and in the binding of vWF to collagen (collagen binding domain, CBD) using tryptic fragments of 125I-labelled vWF (21, 23). We have also reported on the RBD, CBD and the domain on vWF involved in the binding to thrombin activated platelets (thrombin binding domain, TBD) using vWF-fragments prepared by digestion with staphylococcal protease V8 (25).In the present study, we have digested 125I-vWF with TPCK-trypsin and we have performed at various times of digestion immuno-precipitation with Mab 9, the antibody inhibiting binding of vWF to thrombin activated platelets. The data were compared with the immunoprecipitation patterns simultaneously obtained with CLB-RAg 35 which inhibits binding of vWF in the presence of ristocetin and with CLB-RAg 201, which inhibits binding of vWF to collagen. At 90 min, Mab 9 and CLB-RAg 201 precipitated similar high molecular weight bands, whereas CLB-RAg 35 precipitated bands at 180 and 120 kDa. After 24 h, Mab 9 precipitated bands at 200, 155, 116 and 85 kDa; CLB-RAg 201 precipitated a band at 48 kDa and CLB-RAg 35 a band at 116 kDa. Two-dimensional electrophoresis demonstrated that the high molecular weight bands, precipitated by Mab 9 and CLB-RAg 201 at 90 min, were identical. The 116 kDa fragment recognized by CLB-RAg 35 had a different subunit composition than the 116 kDa fragment precipitated by Mab 9.These data indicate that there is an early split in the vWF subunit which yields a large fragment, containing the CBD and the TBD, and a smaller fragment with the RBD. Later, there is a split in the large fragment and the CBD and the TBD are separated. Comparison with data obtained with Staph protease V8 indicate that the CBD is located between the RBD and TBD.
Differential Detection of Single-Chain and Two-Chain Urokinase-Type Plasminogen Activator by a New Immunoadsorbent-Amidolytic Assay (IAA)
Authors: Corti Angelo , Luisa Nolli Maria , Cassani Giovanni 
Published: July 2018

SummaryA new immunoadsorbent-amidolytic assay (IAA) for the specific differential detection of two-chain urokinase-type plasminogen activator (tcu-PA) and its single-chain precursor (scu-PA) in cell culture supernatants has been developed. The assay combines the selectivity of immunoassays with the specificity of enzyme activity assays exploiting both the antigenic and enzymatic properties of the two proteins. tcu-PA and scu-PA are selectively immunoadsorbed on the wells of a microtiterplate coated with the monoclonal antibody 5B4 and tested for enzymatic activity before and after activation by plasmin treatment. Both proteins are determined with similar efficiency since overlapping dose-response curves were obtained in the range between 12.5-200 ng/ml. The assay has been used to determine tcu-PA and scu-PA in A431 human epidermoid carcinoma cell supernatants. The analytical recoveries for tcu-PA and scu-PA added to A431 cell supernatants were 95.2% and 96.9% respectively. The intra- and inter-assay variations (CV) were 5.5% and 9.0% for tcu-PA and 9.7% and 9.8% for scu-PA respectively.
Effect of the Calcium-Entry Blocking Agent Nifedipine on Activation of Human Platelets and Comparison with Verapamil
Authors: Han P , Boatwright C , Ardlie N G 
Published: July 2018

SummaryThe effects of the calcium-entry blocking agent nifedipine on the activation of human platelets by various agonists has been studied and compared with verapamil. Like verapamil, nifedipine inhibited platelet aggregation and secretion caused by collagen, the second phase of ADP-induced aggregation, and aggregation caused by the ionophore A23187. Both agents inhibited the formation of TXB2 from endogenous arachidonate, whereas only nifedipine inhibited platelet aggregation and decreased TXB2 formation caused by exogenous arachidonate without inhibiting uptake. These results indicate that both calcium-blocking agents may be inhibiting the release of arachidonate in platelets by phospholipases, and that nifedipine also inhibits the formation and action of thromboxane A2 in platelets. Epinephrine-induced aggregation was inhibited by low concentrations of verapamil while nifedipine only inhibited aggregation by epinephrine at much higher concentrations. It is suggested that low concentrations of verapamil inhibit epinephrine-induced aggregation by interacting with platelet α-adrenergic receptors, and that higher concentrations of both calcium-blocking agents inhibit platelet responses to other aggregating agents by preventing intracellular calcium mobilization.
Plasma Fibrinopeptide A and Beta-Thromboglobulin in Patients with Chest Pain
Authors: Douglas J T , Lowe G D O , Forbes C D , Prentice C R M 
Published: July 2018

SummaryPlasma levels of β-thromboglobulin (BTG) and fibrinopeptide A (FPA), markers of platelet release and thrombin generation respectively, were measured in 48 patients within 3 days of admission to hospital for acute chest pain. Twenty-one patients had a confirmed myocardial infarction (MI); 15 had unstable angina without infarction; and 12 had chest pain due to noncardiac causes. FPA and BTG were also measured in 23 control hospital patients of similar age. Mean plasma BTG levels were not significantly different in the 4 groups. Mean plasma FPA levels were significantly higher in all 3 groups with acute chest pain when compared to the control subjects (p < 0.01), but there were no significant differences between the 3 groups. Increased FPA levels in patients with acute chest pain are not specific for myocardial infarction, nor for ischaemic chest pain.
Dissociation of Factor VIII Procoagulant Antigen VIII : CAg and Factor VIII Related Antigen VIIIR : Ag by EDTA - Influence of Divalent Cation on the Binding of VIII: CAg and VIIIR :Ag
Authors: Tran T H , Duckert F 
Published: July 2018

SummaryAssuming 1 U/ml in titrated plasma, the VIII: CAg concentration was found 1.66 U/ml in EDTA-plasma, 1.09 U/ml in heparinized plasma and 0.67 U/ml in serum. Addition of 10 mmol/1 EDTA to titrated and heparinized plasmas increased VIII: CAg 1.5fold. There was no increase of VIII: CAg in serum. Gel filtration of plasmas on different anticoagulants showed an elution of VIII: CAg in the void volume Vo and in the later fractions. The VIII: CAg amount detected in the internal volume increased following the series heparin < citrate < EDTA. Serum VIII: CAg was eluted at 2.2 Vo. Presence of EDTA in the elution buffer or incubation of plasma with EDTA prior to chromatography caused a displacement of practically all VIII: CAg amount in the internal volume with a peak at 2.2-2.3 Vo. VIIIR: Ag was exclusively detected in the void volume.Removal of divalent cation by chelation likely exposes more antigenic determinants of VIII: CAg, which are otherwise masked by steric hindrance due to VIIIR: Ag in citrated and heparinized milieu. Moreover gel filtration of plasma in the presence of EDTA completely dissociates VIII: CAg from VIIIR :Ag. The VIII: CAg fragment, having an estimated molecular weight of 70,000, might also be present in serum.
Determination of Factor XIII Activity and of Factor XIII Inhibitors Using an Ammonium-Sensitive Electrode
Authors: Hellstern P , Schilz K , von Blohn G , Wenzel E 
Published: July 2018

SummaryAn assay for rapid factor XIII activity measurement has been developed based on the determination of the ammonium released during fibrin stabilization. Factor XIII was activated by thrombin and calcium. Ammonium was measured by an ammonium-sensitive electrode. It was demonstrated that the assay procedure yields accurate and precise results and that factor XIII-catalyzed fibrin stabilization can be measured kinetically. The amount of ammonium released during the first 90 min of fibrin stabilization was found to be 7.8 ± 0.5 moles per mole fibrinogen, which is in agreement with the findings of other authors. In 15 normal subjects and in 15 patients suffering from diseases with suspected factor XIII deficiency there was a satisfactory correlation between the results obtained by the “ammonium-release-method”, Bohn’s method, and the immunological assay (r1 = 0.65; r2= 0.70; p<0.01). In 3 of 5 patients with paraproteinemias the values of factor XIII activity determined by the ammonium-release method were markedly lower than those estimated by the other methods. It could be shown that inhibitor mechanisms were responsible for these discrepancies.
New “Ex Vivo” Radioisotopic Method of Quantitation of Platelet Deposition – Studies in Four Animal Species
Authors: Badimon L , Fuster V , Chesebro J H , Dewanjee M K 
Published: July 2018

SummaryWe have developed a sensitive and quantitative method of “ex vivo” evaluation of platelet deposition on collagen strips, from rabbit Achilles tendon, superfused by flowing blood and applied it to four animal species, cat, rabbit, dog and pig. Autologous platelets were labeled with indium-111-tropolone, injected to the animal 24 hr before the superfusion and the number of deposited platelets was quantitated from the tendon gamma-radiation and the blood platelet count.We detected some platelet consumption with superfusion time when blood was reinfused entering the contralateral jugular vein after collagen contact but not if blood was discarded after the contact. Therefore, in order to have a more physiological animal model we decided to discard blood after superfusion of the tendon.In all species except for the cat there was a linear relationship between increase of platelet on the tendon and time of exposure to blood superfusion. The highest number of platelets deposited on the collagen was found in cats, the lowest in dogs.Ultrastructural analysis showed the platelets were deposited as aggregates after only 5 min of superfusion.
The Stability of Tissue Plasminogen Activator (t-PA)
Authors: Gaffney P J , Templeman J , Curtis A D , Campbell P J 
Published: July 2018

SummarySince tissue-type plasminogen activator (t-PA) derived from tissue culture and recombinant DNA procedures has been proposed for use in thrombolytic therapy in man, it is essential that
the t-PA molecule should display reasonable stability in a lyophilised state to facilitate its usefulness. In this study, four laboratories compared the potencies of three preparations of t-PA following storage at 4°, 20°, 37° and 45° C, using each t-PA stored at -20° C as a reference (100% activity) in each case. A pig heart extract of t-PA was the most stable, losing no activity when stored for 30 days at 37° C, while two melanoma cell tissue culture extracts varied in their storage behaviour. One was quite stable at 37° C (losing about 3% of its activity) while the other lost about 16%. Thus both the pig heart t-PA and one t-PA from melanoma cell culture proved suitable for the further development of reference standards for t-PA activity.
Anticoagulant Properties of Three Mucopolysaccharides Used in Rheumatology
Authors: Bauer F , Schulz P , Reber G , Bouvier C A 
Published: July 2018

SummaryThree mucopolysaccharides (MPS) used in the treatment of degenerative joint disease were compared to heparin to establish their relative potencies on 3 coagulation tests, the aPTT, the antifactor X a activity and the dilute thrombin time. One of the compounds, Arteparon®, was one fourth as potent as heparin on the aPTT, but had little or no influence on the 2 other tests. Further in vitro studies suggested that Arteparon® acted at a higher level than factor Xa generation in the intrinsic amplification system and that its effect was independent of antithrombin III. In vivo administration of Arteparon® confirmed its anticoagulant properties, which raises the question of the clinical use of this MPS.
Systemic Fibrinolytic Activity and Inhibitor Levels During Treatment of Deep Vein Thrombosis with Urokinase and Streptokinase
Authors: Theiss W , Asbeck F , Kriessmann A , Trübestein G , Knoch K , de Swart C A M , Marbet G A , van de Loo J C W 
Published: July 2018

SummaryIn a prospective, randomized trial 33 patients with deep vein thrombosis were treated either with 2,200 or 1,100 IU/kg/h urokinase or with 100,000 IU/h streptokinase for at least 6 days. While streptokinase was given continuously, urokinase was administered intermittently (12 hr urokinase alternating with 12 hr heparin).Urokinase treatment resulted in a dose-dependent fibrinolytic state with shortening of the euglobulin clot lysis time, easily demonstrable amidolytic activity and moderate decrease of plasminogen. At the end of each urokinase-free interval the fibrinolytic activity had mostly faded, but was reproducibly elicited again by each new urokinase administration. Streptokinase immediately evoked the customary, intense fibrinolytic state, which progressively tapered off as plasminogen fell to 1% of its pretreatment concentration. In all treatment groups α-2-antiplasmin dropped to approximately 40% of its initial value during the first 12 hr with a further decrease to about 20% after 6 days, α-2-macroglo- bulin fell only moderately with either urokinase regimen, whereas it decreased progressively to 45% under streptokinase.While the fibrinolytic activity decreased under streptokinase over the 6-day infusion period, it appeared to increase with each successive urokinase infusion particularly with 1100 IU/kg/h. Thus the final euglobulin clot lysis times and the final fibrinogen concentrations were similar in all three treatment groups on the sixth day.
The Effect of Two Low Doses of Aspirin on Whole Blood Thromboxane and Prostacyclin Generation in Healthy Subjects
Authors: Davì G , Custro N , Novo S , Mattina A , Strano A 
Published: July 2018

SummaryThe effects of two low doses of aspirin (20 mg and 100 mg) on prostacyclin and thromboxane formation during whole blood clotting were studied in 8 healthy volunteers.A single 100 mg aspirin dose caused more than 90% reduction of both serum TXB2 and 6-keto-PGF1α; a single 20 mg dose of aspirin inhibited serum TXB2 more than 6-keto-PGF1α but effects on these two products could not be completely dissociated.However, the effect of a single 20 mg aspirin dose on serum TXB2, was of much longer duration than its inhibitory effect on PGI2 synthesis during whole blood clotting.
Coagulant and Anticoagulant Actions of Australian Snake Venoms
Authors: Marshall Lorraine R , Herrmann Richard P 
Published: July 2018

SummaryA systematic study was made of the action on the plasma coagulation system of 20 Australian and Papuan Elapid and Hydrophiid snake venoms and compared with 4 Crotalid venoms and 1 Viper. The majority of Australian venoms were shown to be prothrombin activators with variable dependence on the presence of factor V phospholipid and calcium. None of these venoms had strong thrombin like activity in contrast to the Crotalid venoms which were powerfully thrombin like. The Crotalid venoms were also strongly fibrinolytic unlike the Elapid venoms which showed no or minimal evidence of fibrinolytic activity.Four Elapid venoms and 2 Crotalid venoms showed anticoagulant activity which contained neither antithrombin nor fibrinogenolytic activity and may act upon the prothrombin complex.
Rapid Quantitation of Plasma Heparin and Antithrombin III Levels for Cardiopulmonary Bypass Monitoring, Using Fluorometric Substrate Assays
Authors: Savidge G F , Kesteven P J , Al-Hasani S F , O’Brien P F 
Published: July 2018

SummaryPlamsa heparin and AT III levels were determined using recently developed fluorometric substrate techniques on serial samples taken from 9 unselected patients undergoing open-heart surgery on cardiopulmonary bypass. The fluorometric assay for AT III and established clotting and immunological methods showed a highly significant correlation (p <0.001). Heparin recovery was reduced in all cases, and plasma levels (fluorometric assay) demonstrated poor correlation to Whole Blood Activated Clotting Time (Hemochron) estimations. AT III levels were dramatically reduced during bypass, and in 3 cases reached levels below 0.08 iu/ml. Heparin reversal schedules based upon empirical dosage led to excessive protamine administration by a mean factor of 3.3, as assessed by in vitro neutralization of standardized heparin concentrations.
The Effect of Polyunsaturated Fatty Acids on Endothelial Cells and Their Production of Prostacyclin, Thromboxane and Platelet Inhibitory Activity
Authors: Brox Jan H , Nordøy Arne 
Published: July 2018

SummaryPrimary cultures of human endothelial cell monolayers were incubated with albumin-bound fatty acids of the ω-3 and ω-6 families for a maximum of 24 hrs, to investigate the production of 6-keto-PGF1α, TXB2 and platelet inhibitory activity (PIA). Arachidonic acid was a potent stimulator of all parameters. The release of 6-keto-PGF1α was significantly reduced by equimolar concentrations of linoleic, dihomogamma linolenic and eicosapentaenoic acids, but not by linolenic acid. PIA was not similarity affected.Dihomogamma linolenic add was also a weak stimulator of 6- keto-PGF1α and PIA, but reduced the content of both in the cells after 24 hrs. Eicosapentaenoic and docosahexaenoic acids both depressed 6-keto-PGF1α production but PIA was maintained after 24 hrs. Indomethacin always blocked 6-keto-PGF1α and PIA production. None of the effects correlated to release of 51CR from prelabelled cells.
A Sex Difference in the Effect of Aspirin on “Spontaneous” Platelet Aggregation in Whole Blood
Authors: Harrison M J G , Weisblatt E 
Published: July 2018

SummaryPlatelet aggregation can be measured in whole blood by monitoring the fall in single platelet count in an electronic platelet counter. The aggregation that occurs when whole blood is stirred in a small cuvette (“spontaneous aggregation”) or upon the addition of collagen has been studied in citrated whole blood from male and female volunteers. Aspirin 40 μg ml/1 inhibited aggregation induced by collagen in both sexes but spontaneous aggregation was only affected by aspirin in males. These results may help explain the sex difference apparent in the results of some clinical trials of aspirin as an antithrombotic agent.
Investigations of the Lupus-Like Inhibitor By-Passing Activity of Platelets
Authors: Howard Margaret A , Firkin Barry G 
Published: July 2018

SummaryPlasmas from ten patients with a lupus or lupus-like inhibitor were investigated. In each case the partial thromboplastin time with kaolin (PTTK) was prolonged and failed to correct on the addition of an equal volume of normal plasma. Activated control platelets corrected the inhibitory effect in the PTTK or thrombin generation time (TGT) in every instance. Activated autologous platelets were as effective as control platelets and may thus explain why bleeding is rarely associated with the lupus inhibitor. Experiments using platelets or plasma from patients congenitally deficient in a single clotting factor or normal washed platelets resuspended in deficient plasma indicated that the inhibitor bypassing activity is platelet and not plasma derived. Platelet fractionation studies suggested that this activity is localised at the platelet membrane.
Cyanide Prevents the Inhibition of Platelet Aggregation by Nitroprusside, Hydroxylamine and Azide
Authors: Schwerin Francis T , Rosenstein Robert , Smith Roger P 
Published: July 2018

SummarySodium cyanide (CN-) in concentrations of 10 uM or more prevented the inhibition of epinephrine (2.5 uM) and of ADP (4.0 uM) induced primary and secondary aggregation brought about by 10 uM sodium nitroprusside (SNP). Cyanide alone in the same concentration had no effect on platelet aggregation induced by epinephrine or ADP. Even when the addition of CN- was delayed for as long as 9 min after epinephrine and SNP, it immediately reversed the SNP block and initiated a bimodal wave of aggregation. The effect of CN- on SNP inhibition of platelet aggregation appears to be competitive and reversible. Although they are less potent inhibitors of platelet aggregation than SNP, the effects of hydroxylamine (HA) and azide were also prevented by SNP. In our hands, sodium nitrite did not inhibit platelet aggregation consistently. The inhibitory effects of glyceryl trinitrate, papaverine and nitric oxide hemoglobin on platelet aggregation were not prevented by CN-. These interactions probably have no significance in vivo, but they indicate that SNP, HA and azide act on platelets and on vascular smooth muscle by similar or identical biochemical mechanisms. They also suggest that there are at least two sub-classes of so-called nitric oxide vasodilators. The effect of CN- may be mediated through an inhibition of the formation of nitric oxide from SNP, HA and azide.
The Human Plasmin-Derived Light (B) Chain·Streptokinase Complex: A Second-Generation Thrombolytic Agent
Authors: Robbins K C , Summaria L , Wohl R C , Bell W R 
Published: July 2018

SummarySpecific assay methods for the human plasmin-derived light (B) chain · streptokinase (B·SK) complex, in terms of both streptokinase (SK) and urokinase (UK) International Units, are described. The kinetic properties of various SK activator complexes with plasminogen, Val 442-plasmin, and the plasmin-derived light (B) chain were compared to SK in terms of their catalytic efficiencies and Lineweaver-Burk plots. Similar kinetic data, and Lineweaver-Burk plots, are described for both highly purified high-molecular weight UK and low-molecular weight UK, including different clinical UK preparations. The B·SK complex has the highest catalytic efficiency of all the activator species studied. The Lineweaver-Burk plots of each of the various activator species are “fingerprints” of the enzymatic character of the activator. The B-SK complex is more like UK than SK, as an activator, in activating non-human plasminogen species. The biological halflife of the B·SK complex, in a dog model, was determined to be about 4 hr which is longer than the biological half-life(s) of SK in the same animal model, namely 0.6 hr (47%) and 2.8 hr (53%). This new second-generation activator complex may prove to be a useful thrombolytic agent in the treatment of thromboembolic diseases.
Intra-Coronary Thrombolysis with Streptokinase or Lys-Plasminogen/Urokinase in Acute Myocardial Infarction: Effects on Recanalization and Blood Fibrinolysis
Authors: de Prost D , Guerot C , Laffay N , Horellou M H , Samama M 
Published: July 2018

SummaryForty-two patients with total occlusion of a coronary vessel were treated with intracoronary fibrinolytic agents. Four therapeutic protocols were compared: group I received streptokinase (SK) as a continuous infusion; group II and III received SK as a bolus at different doses and group IV received lysplasminogen (Pg) plus urokinase (UK); maximal doses were 350,000 IU of SK and 250,000 IU of UK plus 75 μK of Pg. Thrombolysis was assessed by coronary angiography. Coagulation studies were performed prior to, 15 min and 6 hr after the end of the thrombolytic treatment. Recanalization was achieved in 27 of the 31 SK-treated patients (87%) and in 7 of the 11 Pg-UK- treated patients (63.6%). The recanalization frequency was the same in the three SK-treated groups, even though when SK was administered as a bolus, the dose was significantly less than when administered on a continuous infusion. Although systemic fibrinolysis occurred in all 4 groups of patients, this effect was less pronounced in the UK-treated patients than in the three SK- treated groups. This study also shows that recanalization can be achieved with a dose of SK lower than the anti-SK antibody level. Haemorrhagic side effects were minimal in all patients studied. Severe defibrination is usually considered a risk of haemorrhage. These preliminary results suggest that bolus injection of SK or the use of UK plus lys-Pg can reduce the level of defibrination and thus the haemorrhagic risk.