bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fine Mapping of Monoclonal Antibody Epitopes on Human von Willebrand Factor Using a Recombinant Peptide Library
Authors: Ginsburg David , Bockenstedt Paula L , Allen Elizabeth A , Fox David A , Foster Paul A , Ruggeri Zaverio M , Zimmerman Theodore S , Montgomery Robert R , Bahou Wadie F , Johnson Timothy A , Yang Angela Y 
Published: July 2018

SummaryA recombinant human von Willebrand factor (vWF) cDNA fragment library was constructed in λgtll for the localization of anti-vWF monoclonal antibody epitopes. Twelve of 21 monoclonal antibodies screened identified epitopes expressed in λgtll as β-galactosidase fusion proteins. By sequence analysis, these antigenic determinants were localized to segments ranging from 17 to 105 amino acids in length. Four epitopes apparently shared by more than one antibody were identified, suggesting the presence of immuno-dominant epitopes within vWF. Monoclonal antibody C3, which blocks factor VIII (FVIII) binding to vWF, bound to the same epitope previously identified by a second monoclonal antibody which also blocks this function, suggesting that this region may be at or near the vWF/FVIII binding domain. Three antibodies recognize the same region within the vWF A2 repeat. Mutations near this region appear to be responsible for Type IIA von Willebrand’s disease. The co-localization of these antibodies suggests that this domain might be exposed on the surface of vWF, consistent with its apparent increased sensitivity to plasma proteases.
Partial Characterization of an Autoantibody Recognizing the Secondary Binding Site(s) of Thrombin in a Patient with Recurrent Spontaneous Arterial Thrombosis
Authors: Costa J M , Fiessinger J N , Capron L , Aiach M 
Published: July 2018

SummaryA patient with an 18 year history of recurrent arterial thrombosis and no evidence of atherosclerosis or embolism of cardiac origin presented with a prolonged thrombin clotting time when performed with human thrombin. The bovine thrombin clotting time was only slightly prolonged. During 30 months of follow-up, the thrombin time fluctuated, but remained prolonged. The patient has been treated with an oral anticoagulant for the past 8 years, with no thrombotic recurrence.The inhibitor activity was due to the presence of polyclonal IgGs which bound to thrombin-Sepharose. The influence of IgGs purified from the patient’s serum was compared to the influence of normal IgGs in several systems exploring the catalytic activity of thrombin and the binding of the enzyme to macromolecular substrates through secondary binding site(s). We found that the IgGs did not impair the catalytic activity toward small synthetic substrates, but inhibited the binding of thrombin to fibrinogen, thrombomodulin and heparin cofactor II. Such proteins are known to require a secondary binding site of thrombin to interact with the enzyme.The anti-thrombin antibody might have resulted from an abnormal generation of thrombin. This would be the consequence of the process favouring thrombosis. Alternatively, the autoantibody might have favoured thrombosis primarily, by impairing natural antithrombotic mechanisms triggered by thrombin.
Markers of Procoagulant Imbalance in Patients with Inherited Thrombophilic Syndromes
Authors: Mannucci P M , Tripodi A , Bottasso B , Baudo F , Finazzi G , Stefano V De , Palareti G , Manotti C , Mazzucconi M G , Castaman G 
Published: July 2018

SummaryIn 107 asymptomatic and untreated patients with inherited syndromes associated with thrombophilia (antithrombin III, protein C and protein S deficiencies), we compared in parallel two plasma peptides which reflect activation of the common coagulation pathway: the prothrombin fragment 1 + 2 (F1+2) and fibrinopeptide A (FPA). Both F1+2 and FPA were measured with simple, commercially available ELISA methods. High levels of F1+2 or FPA were found in about one fourth of the patients as a whole. When patients were divided according to the type of inherited thrombophilie syndrome, it appeared that F1+2 was more frequently elevated in protein C and protein S deficiencies than in antithrombin deficiency; and that, in general, it was no more frequently elevated than FPA. Although our data confirm the existence of a procoagulant imbalance in inherited thrombophilie syndromes due to defects of natural anticoagulant proteins, they do not confirm that such imbalance can be more frequently diagnosed by measuring F1+2 levels, particularly in patients with antithrombin deficiency.
Thrombomodulin Is a Cofactor for Thrombin Degradation of Recombinant Single-Chain Urokinase Plasminogen Activator "In Vitro" and in a Perfused Rabbit Heart Model
Authors: Molinari Antonio , Giorgetti Carla , Lansen Jacqueline , Vaghi Fabrizio , Orsini Gaetano , Faioni Elena Maria , Mannucci Pier Mannuccio 
Published: July 2018

SummaryThrombin cleaves single-chain urokinase-type plasminogen activator (scu-PA) to a two-chain derivative (tcu-PA) fibrinolyti-cally inactive. This reaction was accelerated in vitro by purified rabbit lung thrombomodulin in equimolar complex with thrombin. Polyclonal antibodies to rabbit thrombomodulin prevented this effect.We also observed that heparin and other sulfated polysaccharides had an accelerating effect on thrombin cleavage of recombinant scu-PA. Their effect was concentration-dependent and then reversed at high levels. The effect of heparin and heparan sulfate was independent and synergic with respect to thrombomodulin. All observations except the effect of heparin, could be confirmed in a Langendorff isolated rabbit heart model. From competition experiments carried out with scu-PA derivatives and mutants, we postulate that the amino-terminal sequence of rscu-PA, containing the epidermal growth factor (EGF)-like and the kringle domains is involved in the cofactor effect of thrombomodulin on scu-PA inactivation by thrombin. We conclude that a regulatory mechanism of scu-PA inactivation is present at the cell surface.
Determinants of Induction of Increased Synthesis of Plasminogen Activator Inhibitor Type-1 in Human Endothelial Cells by t-PA
Authors: Fujii Satoshi , Sobel Burton E 
Published: July 2018

SummaryTissue-type plasminogen activator (t-PA) induces synthesis of a rapidly acting inhibitor, plasminogen activator inhibitor type-1 (PAI-1) in human umbilical vein endothelial cells (HUVEC) in culture. In vivo, an analogous process may induce negative feedback on the fibrinolytic system. To define specific determinants in the t-PA molecule contributing to the induction, PAI-1 synthesis was characterized in 35S-methionine labeled HUVEC in response to several molecular variants of t-PA. Catalytically active variants devoid of several specific structural domains in the A-chain retained the capacity to form complexes with PAI-1 and to induce increased concentrations of total PAI-1 (free and complexed) in conditioned media without depleting PAI-1 from the extracellular matrix. Surprisingly, a mutant t-PA with markedly reduced catalytic activity reflecting replacement of the active site serine with threonine (S478T) formed complexes with PAI-1 and induced increased PAI-1 synthesis as well. However, in contrast to wild-type t-PA and A-chain variants, it did not release 35S-methionine labeled PAI-1 from the extracellular matrix. Thus, its effects appeared to reflect increased secretion exclusively. Our results suggest that induction of PAI-1 synthesis in HUVEC by t-PA depends on its protease domain but that an active site serine is not a requirement.
Alternative Splicing Is Responsible for the Presence of Two Tissue Factor mRNA Species in LPS Stimulated Human Monocytes
Authors: Paul C , van der Logt E , Reitsma Pieter H , Bertina Rogier M 
Published: July 2018

SummaryAlthough normally absent from the surface of all circulating cell types, tissue factor (TF) can be induced to appear on circulating monocytes by stimulants like bacterial lipopolysaccharide (LPS) and phorbolesters. Northern analysis of RNA isolated from LPS stimulated human monocytes demonstrates the presence of 2.2 kb and 3.1 kb TF mRNA species. The 2.2 kb message codes for the TF protein. As demonstrated by Northern blot analysis with a variety of TF gene probes, the 3.1 kb message arises from an alternative splicing process which fails to remove 955 bp from intron 1. Because of a stop codon in intron 1 no TF protein is produced from the 3.1 kb transcript. This larger transcript should therefore not be taken into account when comparing TF gene transcription and TF protein levels.
Antithrombin Activity of Intact Human Platelets
Authors: Watanabe Kiyoake , Chao Francis C , Tullis James L 
Published: July 2018

SummaryAntithrombin activity has been identified in intact washed human platelets. An apparent activity was demonstrated at platelet concentrations above 0.31 × 109/ml, when platelet suspensions were incubated with 2.0 NIH units/ml of thrombin. Neither red cells nor white cells revealed antithrombin activity. No significant loss of the platelet antithrombin activity was observed after ten successive washings or after treatment of platelets with antibodies to antithrombin III or α2-macroglobulin. Almost the same amount of antithrombin activity as normal platelets was demonstrated in the platelets from an afibrinogenemic patient. Pre-treatment of platelets with trypsin, papain, and neuroaminidase reduced the activity significantly, whereas lipase was without effect. The platelet antithrombin reacted with thrombin in less than 3 seconds, and this rapid reaction of platelet antithrombin was different from that of plasma antithrombin III or fibrinogen. The thrombin-like clotting activity of ancrod was inhibited by fibrinogen but not platelets. Also, unlike plasma antithrombin III or fibrinogen, brief exposure to heat (56° C or 60° C) reduced considerable amounts of platelet antithrombin activity. These results suggest that platelets possess a specific antithrombin with different characteristics from other known antithrombins.
Patho-physiological Studies on Lactic Acid-induced Pulmonary Thrombosis in Rat
Authors: Tomikawa Munehiro 
Published: July 2018

SummaryThe roles of platelet aggregation and coagulo-fibrinolytic systems in thrombogenesis of lactic acid-induced pulmonary thrombosis in rat were studied using an anti-coagulant, platelet aggregation inhibitor, fibrinolytic or anti-fibrinolytic agents.In normal rat, heparin (2.5 mg/kg), acetylsalicylic acid (30 mg/kg) and tranexamic acid (100 mg/kg) suppressed specifically coagulation, platelet aggregation induced by collagen or thrombin and fibrinolysis respectively. Urokinase (10,000 units/kg) activated powerfully fibrinolytic system in addition to suppressing slightly platelet aggregation.The pretreatment with heparin, acetylsalicylic acid or urokinase markedly prevented the formation of thrombus initiated by the infusion of lactic acid at the doses used. Additive effect was also obtained by combined administration of these agents. On the other hand, it was interesting to note that tranexamic acid (100 mg/kg) did not affect the thrombus formation at all despite a potent anti-fibrinolytic effect of this agent.These results indicate that both platelet aggregation and enhancement of coagulation activity are important factors responsible for the formation of thrombi in DIC, while the fibrinolytic activity in blood seems not to be involved in it. On the basis of the findings, mechanism for triggering activation of coagulation and platelet aggregation is also discussed here.
The Comparative Ultrastructure of Fibrin Induced by Thrombin and by Staphylocoagulase
Authors: King M. J. S , Morris M. S , Tager M 
Published: July 2018

SummaryFibrin induced by the action of thrombin and by staphylocoagulase was studied by transmission electron microscopy.Periodic striations were consistently observed in the negatively stained preparations of both fibrins. When 4200 major periods in the thrombin fibrin system were measured the mean length was 228 Å. For 3666 major periods in the coagulase fibrin system the mean length was 223 Å. While the T test analysis of these values gave a value of 10, it is noteworthy that the differences are well within the scatter of periodicity reported in the literature for thrombin-induced fibrin.Gross inspection of the preparations indicated that the coagulase-induced fibrin had a knottier appearance and was accompanied by a greater amount of background debris than the thrombin-induced fibrin.
Plasma Fibrinolytic Activity Following Oral Anabolic Steroid Therapy
Authors: Walker I. D , Davidson J. F , Young P , Conkie J. A 
Published: July 2018

SummarySix anabolic steroids were assessed for their ability to enhance plasma fibrinolytic activity in males with ischaemic heart disease. Five 17α-alkylated steroids (Ethyloestrenol, Norethandrolone, Methandienone, Methylandrostenediol and Oxymetholone) were examined and all produced a significant increase in plasma plasminogen activator as measured by the euglobulin lysis time. The only non-17α-alkylated steroid studied (Methenolone acetate) failed to enhance fibrinolysis. The 17α-alkylated steroids studied all deserve more detailed evaluation of their long term effects on plasma fibrinolytic activity.
Local Treatment of Recent Arterial Thromboembolic Occlusions with Brinase
Authors: Nyman D , da Silva M. A , Widmer L. K , Duckert F 
Published: July 2018

SummaryBrinase was administered intra-arterially in 16 patients with thrombotic or embolic arterial occlusions. Angiography could be performed before and after treatment in 13 patients. Thrombolysis was obtained in 3 of 9 patients with thrombotic and in 3 of 4 patients with embolic occlusions. In 3 patients severe local side effects occurred.
Fluid Mechanical Stress and the Platelet
Authors: Goldsmith Harry L , Yu Simmon S. K , Marlow Jean 
Published: July 2018

SummaryPlatelet thrombi in suspensions stirred in an aggregometer or subjected to shear flow in a Couette viscometer or circular tube can only form as a result of collisions between the cells. In whole blood, the presence of the red cells results in pronounced lateral displacements of the paths of the platelets through the vessel, which in turn increases the frequency of collisions between platelets and also makes possible platelet-wall interactions. In addition, blood cells in a suspension undergoing shear flow are subjected to fluid stresses which can result in their deformation. Such stresses may locally attain high values in the arterial circulation at bifurcations, sharp bends and stenoses where the flow is disturbed. Since platelet thrombi have been found downstream of sites of such geometry, the effects of high and variable shear stress on the platelet release reaction and aggregation were investigated. Washed platelets containing C14-serotonin in Tyrodes-albumin solution were subjected to oscillatory flow at 37° C and provided the time average wall velocity gradient was above 2,000 sec-1, the thrombin-induced release of serotonin was appreciably greater than in the corresponding controls incubated at rest. No measurable serotonin was released as a result of flow alone. This synergistic effect of oscillatory shear flow was also noted in the presence of inhibitors of the release reaction.
Effects of Vancomycin on Platelets, Plasma Proteins and Hepatitis B Surface Antigen
Authors: Coller Barry S , Lundberg W. B , Gralnick Harvey R 
Published: July 2018

SummaryThe antibiotic vancomycin shares many similarities with ristocetin, an agent noted for its effects on platelets and plasma fibrinogen. Vancomycin did not aggregate platelets as ristocetin, but platelets were incorporated into precipitates induced by vancomycin. Fibrinogen and factor VIII were precipitated from plasma at low concentrations of vancomycin. The precipitated fibrinogen remained clottable. Hepatitis B surface antigen was selectively precipitated from serum and could be recovered from the precipitate. Rabbits receiving bolus intravenous injections of high doses of vancomycin developed hypofibrinogenemia and thrombocytopenia within minutes and often went on to die. Studies with 125I-vancomycin revealed little stable binding of the antibiotic to platelets or fibrinogen. A relationship is suggested between the potent protein precipitating effects and phlebitis at the infusion site commonly associated with vancomycin therapy.
Hyperaggregability of Platelets in Thromboembolic Disorders
Authors: Yamazaki Hiroh , Takahashi Takeo , Sano Tadahiro 
Published: July 2018

SummaryPlatelet aggregability was measured using platelet rich plasma (PRP) collected from 197 clinical cases including 52 healthy volunteers. In 31 patients of acute stage of thrombosis (within 2 weeks from the onset), a significant enhancement of platelet aggregation measured 5 min after an addition of 3 and 10 μM ADP or 0.1 and 1 μg/ml of adrenaline to PRP (p < 0.05, compared to the healthy group). Also a significant enhancement of secondary aggregation induced by adrenaline was observed (p <0.05). The enhancement was especially marked in the response induced by adrenaline. Such an enhancement was not observed in patients in the recovery stage of thrombosis, hypertension, angina pectoris and other miscellaneous diseases. There was no difference in the parameters related to the velocity of aggregation or intensity of primary aggregation between the diseased and the healthy group. In response induced by collagen (bovine achules tendon, 0.3 and 1 mg/ml) any difference in the aggregation curve was not observed between the diseased and the healthy group. Such findings suggest a presence of an enhancement of ADP-release mechanism of platelets in acute thrombosis. Also a significance of adrenaline-induced platelet aggregation was proposed to detect platelet functions for analysis of mechanism of thromboembolic disorders.
The Position of Long-Term Stimulation of the Endogenous Fibrinolytic System: Present Achievements and Clinical Perspectives
Authors: Verstraete M 
Published: July 2018

SummaryThere is reasonable evidence in favour of the assumption made by several investigators that patients with thrombosis of arteries or veins, or cutaneous vasculitis have, very often, a low spontaneous fibrinolytic activity. The use of long-term activators of blood fibrinolytic activity such as diguanides and anabolic steroids was shown to increase the activators to normal levels in the above mentioned and other conditions. In many instances, but not all, this induced increase of fibrinolytic activity resulted in an improved clinical condition and prevention of venous thrombosis. At the present time, there are indications that new and more powerful compounds will cause a sustained stimulation of the fibrinolytic potential and be useful for the prevention of thrombotic disorders. Some of these compounds, which have been investigated only partly at the clinical level, appear to approach the requirements of a useful oral fibrinolytic agent and it is hoped that from these observations further improvements in this range of drugs will be made.
Determination of Human Fibrinopeptide A by Radioimmunoassay in Purified Systems and in the Blood
Authors: Budzynski A. Z , Marder V. J 
Published: July 2018

SummaryThe formation of fibrin clots or circulating soluble fibrin is accompanied by the appearance of fibrinopeptides. Measurement of the fibrinopeptide concentration in plasma can provide important information on the rate of conversion of fibrinogen to fibrin by thrombin. This rate varies under different physiologic and pathologic conditions. Fibrinopeptide A is a better molecular marker of the conversion than fibrinopeptide B since it is the first peptide to be cleaved by thrombin. A radioimmunoassay technique has been developed for the quantitative determination of human fibrinopeptide A. The procedure detects human fibrinopeptide A at a concentration of approximately 0.05 ng/ml. The fibrinopeptide A concentration in plasma of normal persons was found to be approximately 0.5 ng/ml. The variation of fibrinopeptide A content in normal persons may reflect its rapid formation and catabolism. A significantly increased concentration of this peptide was found in a patient during defibrination therapy with a purified enzyme from the venom of Agkistrodon rho-dostoma and in patients suffering from retinal vascular occlusions.
Mini-Dose Heparin
Authors: Wessler Stanford 
Published: July 2018

SummaryMini-dose heparin has demonstrated a significant decrease in postoperative deep venous thrombosis as manifested by 125I fibrinogen venous limb scans. Whether a similar benefit in lethal pulmonary emboli can be demonstrated is currently under active investigation in England and the Continent. If this European multicenter trial yields a positive result, a safe method for the primary prevention of postoperative pulmonary emboli will have been established. Such a result would encourage evaluation of mini-dose heparin for the prophylaxis of venous thromboembolism among patients with acute myocardial infarction and perhaps for arterial thrombosis complicating coronary arterial bypass surgery.The late Carl V. Moore, when told of the original Kakkar trial and the rationale behind it, said “well, if it doesn’t work, it ought to!” That may be the way many sympathetic investigators, myself included, feel about mini-dose heparin, but in the end everyone knows that the decisions will be based on hard data.
Calculation of Predictive Odds for Possible Carriers of Haemophilia
Authors: Prentice C. R. M , Forbes C. D , Morrice Sandra , McLaren A. D 
Published: July 2018

SummaryBetting odds for possible carriers of haemophilia have been calculated using data derived from normal and known carrier populations. For each possible carrier the concentration of factor VIII-related antigen and factor VIII biological activity was measured and used to determine the probability of the individual being a carrier. The calculations indicated that, of the 32 possible carriers, 11 were likely to be normal (odds of more than 5:1) while 11 were likely to be haemophilia carriers (again odds of more than 5:1).
Evans Blue: A Specific Inhibitor of Factor VIII-Induced Platelet Agglutination
Authors: Kirby E. P 
Published: July 2018

SummaryLow concentrations of Evans Blue ( < 1 μM) inhibit the agglutination of formalin-treated platelets by bovine Factor VIII or by human Factor VIII in the presence of the antibiotic ristocetin. Evans Blue is a specific inhibitor of this reaction and acts by inhibiting the binding of Factor VIII to the platelet surface.