bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Cytotoxic Drugs on Platelet Functions and Coagulation in vitro.
Authors: Klener P , Kubisz P , Suranová J 
Published: July 2018

SummaryInfluence of melphalan on some platelet functions, plasmatic coagulation and fibrinolysis “in vitro” was investigated, using different concentrations of the drug (25, 50 and 250 μg/ml). The lowest concentration slightly inhibited adrenaline and/or collagen-induced platelet aggregation. Following the highest concentration of the drug, strong inhibition of aggregation was recorded, regardless of the inducer used. Melphalan was also shown to inhibit release of aggregating activity and release of platelet factor 4, as well as availibility of platelet factor 3 and platelet acid phosphatase. The intensity of inhibition depended on both, melphalan concentration and the time of preincubation. In contrast to this, adhesion of platelets to glass slide was not found to be influenced by melphalan. Similarly, melphalan did not induce (in any concentration) loss of LDH from platelet cytoplasma, while triton X-100 or freezing and thawing of platelets caused significant increase of LDH activity. From coagulation tests studied, only thrombin time and reptilase time was found to be moderately prolonged in the presence of melphalan.Authors assumed that melphalan acts as a specific inhibitor of release reaction and can induce an acquired thrombocytopathy. The platelet membrane is not damaged by the drug, as was confirmed by the investigation of LDH activity. Influence on coagulation indicates some antithrombin effect of the drug. Although presented results were obtained in vitro, analogous changes in vivo could be suspected. Thus, impairement of platelet functions might play a part in haemorrhagic complications accompanying, in some cases, melphalan therapy.
Induction of the Platelet Release Reaction by 1.3-Dimethyl-5-Aminoadamantane, a New Adamantane Derivative
Authors: Haacke Uta , Wesemann Wolfgang 
Published: July 2018

SummaryThe amantadine derivative 1.3-dimethyl-5-aminoadamantane, D 145, induces in high concentrations of 2–10 mM the release reaction. Adenine nucleotides and 5-hydroxytryptamine (5-HT) are liberated to the same extent and in the same ratio as found after thrombin-induced release. The time course of release is very slow; maximal release is reached in 15–20 min. The process is temperature-dependent and dependent on energy derived from glycolysis and oxidative phosphorylation. Extracellular Ca++ does not promote the release process. D 145, in accordance with the mother-substance amantadine, inhibits 5-HT uptake non-competitively, KI = 0.15 mM. In concentrations of 0.1–1 mM D 145 triggers only the liberation of 5-HT, adenine nucleotides are not liberated. The ADP induced platelet aggregation is completely inhibited after preincubation with a 1 mM solution of D 145.
Comparison between British Comparative Thromboplastin (BCT) and a Factor II-VII-X Determination Method (Simplastin A) Based on Fresh Plasma Samples from Dicoumarol-Treated Patients
Authors: Korsan-Bengtsen K , Johsen M , Pehrsson N.-G 
Published: July 2018

SummaryComparisons between British Comparative Thromboplastin (BCT) and a factor II-VII-X determination method – Simplastin A – have been carried out monthly during the time from December 1973 to March 1976. On each occasion fresh plasma from 20 dicoumarol-treated patients was analyzed with the two methods. It was found that the linear regression model is well suited for the comparison, that the BCT thromboplastin did not change significantly during the study, and that the method of comparing has a coefficient of variation of approximately 6–8 %. This means, for instance, that a ratio of 3.8 with BCT corresponds to a ratio of 3.5 ± 0.26 with Simplastin A. Thus in one period you may have ratio 3 and in another ratio 4 as the lower limit of the therapeutic range although you use the same thromboplastin and the same method. The importance of having a stable reference thromboplastin and an established method of comparing thromboplastins is stressed.
Immunoelectrophoretic Studies on the Kinetics of Plasmic Degradation of Human Fibrinogen
Authors: Braude Roberto , Altman Raúl , Rouvier Jorge , Aguilar Nélida 
Published: July 2018

SummaryIn vitro degradation of fibrinogen results in the appearance of an early fragment, different in its electrophoretic mobility to that of fragments X, Y, D and E.It reacts with antifibrinogen antiserum, does not react with anti-D antiserum and it is anti-genically related to fragment E.Compared with terminal fragment E, it migrates more slowly towards the anode, it appears earlier and in a greater concentration at the beginning, decreasing and disappearing during degradation.The antigen antibody crossed electrophoresis was used in these experiments, but to distinguish the fragments from already known X, Y or even fibrinogen, the applying of an intermediate gel with anti D was of great value.
The Stability of Glutardialdehyde-Stabilized 35-Heparinized Surfaces in Contact with Blood
Authors: Larsson R. L , Hjelte M.-B , Eriksson J. C , Lagergren H. R , Olsson P 
Published: July 2018

SummaryHeparin can be bound to polymer surfaces by precipitation of an ionic heparin-amine complex which can be stabilized against dissolution by treatment with glutardialdehyde. The aim of this investigation was to study the degree and course of desorption of heparin from such a heparinized surface on contact with blood. This desorption must be considered when analysing the interaction between the heparinized surface and blood. Different heparinized surfaces were prepared by using 35S-labelled heparin, and the desorption of heparin on exposure in vitro to citrated plasma or heparinized blood as well as during exposure at in vivo conditions was quantified.During in vitro experiments, the glutardialdehyde stabilized surface became stable with no further desorption of heparin after an initial loss of about 3% of the initial surface-bound heparin. Under in vivo conditions, there was an initial loss of about 12%. There was no further loss from surfaces inserted into the circulation of the dog for seven days as compared to those inserted for one hour.
Potentiation by α and Inhibition by β-Adrenergic Stimulations of Rat Platelet Aggregation
Authors: Yu S. K , Latour J. G 
Published: July 2018

SummaryEpinephrine, known to potentiate and elicit aggregation of human platelets, was shown to inhibit thrombin-induced aggregation of rat platelets, delaying the onset of aggregation from 2 to 12 times. Incubation of rat platelet suspensions with propranolol (1.25–30 μM), inactive by itself, totally prevented the inhibitory effect of epinephrine and also permitted a potentiation effect to show up. On the contrary, phentolamine (1.25–30 μM) potentiated the inhibitory effect of epinephrine on rat platelets and unmasked an inhibitory effect on human platelets. Finally, isoproterenol (0.25–9 μM) produced a marked inhibition of aggregation induced by thrombin, ADP and collagen in the three species studied, but most particularly in the rat. From these results, we conclude that stimulation of the platelet adrenergic receptors may either result in promotion (α-stimulation) or inhibition (β-stimulation) of platelet aggregation. Furthermore, differences in the ratios or responses of α/β receptors may account for species variations in the platelet aggregation response to catecholamine challenge.
The Plasminogen Activator of the Arterial Wall
Authors: Donner L , Klener P , Roth Z 
Published: July 2018

SummaryThe plasminogen activator in 645 specimens of various human arteries – thoracic, abdominal aorta, carotic, pulmonary, renal, basilar, coronary – was studied using Todd’s histochemi-cal method. 92 cadavers were used, 1–18 hours post mortem from subjects aged from 272 days to 83 years. 45 specimens of pulmonary, renal and splenic arteries were obtained during surgery.The greatest fibrinolytic activity was within the adventitia. Intima occasionally showed very little fibrinolytic activity, or none at all.No statistically significant differences in plasminogen activator activity were found between the various arteries examined.A statistically significant increase in fibrinolysis in adventitia of atherosclerotic arteries was established. No correlation was found between the fibrinolytic activity of the arteries and their alkaline phosphatase content.Some properties of the plasminogen activator of the arterial vessel wall were evaluated. Influence of storage, inactivation with epsilonaminocaproic acid and extracted with potassium thiocyanate was studied.
Marathon Run II: Effects on Platelet Aggregation
Authors: Dimitriadou C , Dessypris A , Louizou C , Mandalaki T 
Published: July 2018

SummaryPlatelet count and aggregation were assessed in 9 Finnish amateur runners aged 34 to 48, and one 65-year old taking part in a non-competitive marathon race (42.2 km).After the run the mean value of platelet count showed a very significant rise (p <0.001). The platelets were markedly more sensitive to both ADP and collagen-induced aggregation. A highly significant increase (p <0.001) was noted for both the intensity and velocity of platelet aggregation.The finding of platelet hyperaggregability after prolonged strenuous exercise even in trained subjects is discussed. It is concluded that a thorough medical examination of the haemostatic balance is recommended before a marathon race.
Reduction of Mortality with Antithrombin III in Septicemic Rats: A Study of Klebsiella pneumoniae Induced Sepsis
Authors: Dickneite Gerhard , Pâques Eric-Paul 
Published: July 2018

SummaryExperimental gram-negative sepsis was induced in the rat by Klebsiella pneumoniae. Although bacteria are susceptible to the treatment with the antibiotic Tobramycin, DIC could not be prevented. DIC was manifested by a leuko- and thrombocytopenia, decreases in fibrinogen and AT III and an increase of the aPTT. In this model the therapeutic treatment with human AT III was evaluated. To determine the optimal concentration of AT III a prestudy in a LPS induced DIC in the rat was performed. It was shown that a bolus i. v. injection of 500 U/kg improved survival and DIC, and was thus chosen for the Klebsiella sepsis model. The infectious load was adjusted to yield a mortality rate of 90-100% in the untreated Klebsiella group and a reduction to about 40-50% of the mortality rate by Tobramycin. It was found that AT III reduced mortality in the Klebsiella induced sepsis not only when given prophylactically but was effective even when administrated in a late stage of the DIC, i. e. 3 or 5 h post infection.
Therapeutic Effect of a Low Molecular Weight Dermatan Sulphate (Desmin 370) in Rat Venous Thrombosis - Evidence for an Anticoagulant-Independent Mechanism
Authors: Barbanti M , Calanni F , Milani M R , Marchi E , Semeraro N , Colucci M 
Published: July 2018

SummaryWe evaluated the capacity of a low molecular weight dermatan sulphate (D370) to prevent thrombus formation and to induce a reduction of a stabilized thrombus in a rat venous thrombosis model. Injection of D370, 10 min before induction of venous stasis (prevention model), prevented thrombus formation in a dose-dependent way (ED50: 2.3 mg/kg). When given to rats 6 h after induction of venous stasis (therapeutic model), D370 caused a time- and dose-dependent reduction in thrombus size (60% to 70% reduction 2 h after injection of 10 mg/kg). At comparable antithrombotic dosages (i.e. minimum dose giving complete inhibition of thrombus formation), heparin (0.5 mg/kg) only caused 40% reduction of a preformed thrombus while hirudin (1 mg/kg) was virtually ineffective (less than 10% reduction in weight). All three compounds inhibited 125I-fibrin(ogen) deposition on 6-h aged thrombi by more than 85%, suggesting that D370 and, to a lesser extent, heparin reduce thrombus size via mechanisms other than inhibition of thrombus accretion. The involvement of a fibrinolysis-mediated mechanism in the D370-induced effect is suggested by the following. EACA (1 g/kg), when given to thrombus-bearing control animals, did not influence thrombus weight. However, when administered before D370 treatment, it prevented the expected reduction in thrombus weight by more than 80%, without influencing the effect of D370 on 125I-fibrin(ogen) accumulation onto preexisting thrombi. D370 injection caused neither an enhancement of fibrinolytic activity nor a reduction of PAI in plasma. In vitro, D370 (200 μg/ml) was unable to potentiate the spontaneous or PA-induced lysis of 125I-fibrinogen labelled blood, plasma, or purified fibrin clots. It is suggested that prevention of thrombus formation by D370 is related mainly to inhibition of blood coagulation, whereas reduction of the weight of aged thrombi is primarily due to an anticoagulant-independent mechanism, most probably involving local enhancement of the fibrinolytic process. D370 may represent an alternative pharmacologic agent both in the prevention and in the therapy of venous thrombosis.
The Genetic Defect of Type I von Willebrand Disease “Vicenza” Is Linked to the von Willebrand Factor Gene
Authors: Randi Anna M , Sacchi Elisabetta , Castaman Gian Carlo , Rodeghiero Francesco , Mannucci Pier Mannuccio 
Published: July 2018

SummaryType I von Willebrand disease (vWD) Vicenza is a rare variant with autosomal dominant transmission, characterized by the presence of supranormal von Willebrand factor (vWF) multimers in plasma, similar to those normally found in endothelial cells and megakaryocytes. The patients have very low levels of plasma vWF contrasting with a mild bleeding tendency. The pathophysiology of this subtype is still unknown. The presence of supranormal multimers in the patients’ plasma could be due to a mutation in the vWF molecule which affects post-translational processing, or to a defect in the cells’ processing machinery, independent of the vWF molecule. In order to determne if type I vWD Vicenza is linked to the vWF gene, we studied six polymorphic systems identified within the vWF gene in two apparently unrelated families with type I vWD Vicenza. The results of this study indicate a linkage between vWF gene and the type I vWD Vicenza trait. This strongly suggests that type I vWD Vicenza is due to a mutation in one of the vWF alleles, which results in an abnormal vWF molecule that is processed to a lesser extent than normal vWF.
Pronounced Effects of the Combination of a New Thromboxane Antagonist (GR32191) and Heparin on Bleeding Time in Man
Authors: de Boer A , Kroon J M , Kroon C , van Vliet A , Schoemaker H C , Breimer D D , Donoghue S , Cohen A F 
Published: July 2018

SummaryPotential pharmacokinetic and pharmacodynamic interactions between two oral doses of GR32191 (40 and 80 mg), a new thromboxane antagonist, and heparin (5,000 IU bolus + 1,000 IU/h for 3 h) were studied in eighteen healthy male volunteers using two separate double-blind, randomised, placebo-controlled, cross-over studies.Mean (range) bleeding time values were 8.4 min (7.5–9.7) during heparin/placebo, 12.1 min (9.2–18.6) (GR32191/placebo) and 16.3 min (11.5–21.4) (GR32191/heparin) in the 40 mg study, while these values were 8.7 min (5.5–15.5), 16.0 min (9.3 – >36.0) and 23.8 min (10.7 – >36.0), respectively in the 80 mg study. Compared to screening values, the combination of 80 mg of GR 32191 and heparin had a greater effect on the bleeding time than the sum of the prolongations after the separate treatments (p = 0.05). In the 40 mg study this was not the case. Pharmacokinetics of heparin (as assessed by plasma anti-Xa and antithrombin activity) and GR32191 were unaltered during coadministration of the two drugs. GR32191 did not influence the effects of heparin on APTT. Heparin slightly diminished the inhibition of collagen induced platelet aggregation by 80 mg of GR32191 and the U-46619 (thromboxane A2-mimetic) induced platelet aggregation remained unchanged. Overall fibrinolytic activity (as evaluated by the fibrin plate test) was similar during all three treatments in the study with 80 mg.The combination of 80 mg of GR32191 and heparin caused a prolongation of the bleeding time which was more than expected on the basis of their individual effects.
The Influence of Infusions of 1-Desamino-8-D-Arginine Vasopressin (DDAVP) In Vivo on Thrombin Generation In Vitro
Authors: Ibbotson S H , Davies J A , Grant P J 
Published: July 2018

SummaryTo investigate the effect of increasing FVIII:C in-vivo on coagulation ex-vivo, DDAVP was infused over 15 min in 10 volunteers and in-vitro thrombin generation measured. FVIII:C rose from 0.42 and 0.43 IU/ml before DDAVP to 1.38, 1.73 and 1.78 IU/ml at 15, 30 and 60 min respectively (p <0.001).A computer-assisted thrombin generation test was performed in defibrinated plasma using chromogenic substrate, S2238. Time to reach 50% maximal thrombin activity (T50/s) and lag phase of thrombin generation (lag/s) were measured. Lag shortened from 75 and 60 s before to 45 s during and after infusion (p <0.001). T50 shortened from 78.5 and 76.0 to 62.5, 60.0 and 58.5 s at times 15 (p <0.01), 30 (p <0.001) and 60 (p <0.001) min. FVIII:C correlated inversely with lag and T50 (r = –0.847, p <0.001, r = –0.826, p <0.001, n = 10) respectively.These findings show that acute elevations of FVIII:C in-vivo accelerate in-vitro thrombin production. This work suggests that elevated FVIII:C levels in-vivo may be important in thrombo-occlusive disease.
The Effect of Thrombin Inhibitors on Tissue Plasminogen Activator Induced Thrombolysis in a Rat Model
Authors: Klement Petr , Borm Anita , Hirsh Jack , Maraganore John , Wilson Gregory , Weitz Jeffrey 
Published: July 2018

SummarySuccessful coronary thrombolysis depends on rapidly restoring blood flow and maintaining patency of the infarct-related artery. Although widely used as an adjunct to lytic therapy, heparin is limited in its ability to produce these effects. Since the limitations of heparin may reflect its inability to inactivate clot-bound thrombin, we developed a rat model of tissue plasminogen activator (t-PA) induced thrombolysis to compare doses of heparin, hirudin, hirulog (a synthetic hirudin-derived peptide), and D-Phe-Pro-ArgCH2Cl (PPACK) that produced a 4-fold prolongation of the baseline activated partial thromboplastin time (APTT) with saline in terms of their ability to accelerate thrombolysis and to prevent reocclusion. A thrombus rich in red cells and fibrin was formed in the distal aorta by applying an external constrictor after denuding the endothelium with a balloon catheter. Thrombolysis was induced with t-PA (1 mg/kg bolus, followed by 1 mg kg–1 h–1 over 30 min) and the rats were then randomized to receive a concomitant 80 min infusion of a thrombin inhibitor or saline. By continuously monitoring blood flow and pre- and post-stenotic blood pressures, the time to clot lysis, and the number of reocclusions were determined. Compared to saline, heparin had no significant effect on these variables. In contrast, hirudin, hirulog, and PPACK significantly (p <0.01) increased the percentage of the time that the vessel remained patent from 63.9 ± 7.7 to 90.7 ± 2.2, 94.0 ± 0.9, and 94.7 ± 1.0%, respectively by significantly (p <0.01) decreasing the number of reocclusions. The superiority of the antithrombin III-independent inhibitors over heparin supports the hypothesis that the limited effectiveness of heparin in this setting reflects its inability to inactivate clot-bound thrombin. Compared to saline, hirulog and PPACK also significantly (p <0.02) accelerated the time to thrombolysis from 10.5 ± 2.3 to 4.4 ± 0.6, and 4.2 ± 0.8 min, respectively, whereas heparin and hirudin did not. The ability of the lower molecular weight inhibitors of thrombin to accelerate lysis may reflect their greater accessibility to clot-bound thrombin. These findings raise the possibility that the antithrombin III-independent inhibitors of thrombin may not be equally effective as adjuncts to thrombolytic therapy with t-PA.
Inhibition of Fibrinolytic Activity In-Vivo by Dexamethasone Is Counterbalanced by an Inhibition of Platelet Aggregation
Authors: van Giezen J J J , Jansen J W C M 
Published: July 2018

SummaryDexamethasone decreases the fibrinolytic activity in cultured medium of several cell types by an induction of PAI-1 synthesis. As a result of this enhanced PAI-1 synthesis a prothrombotic state is expected in patients treated with dexamethasone. However, such a prothrombotic state is not reported as a major adverse effect. We have studied the effects of dexamethasone (dose range: 0.1–3.0 mg/kg) on the fibrinolytic system of rats after a 5 day pretreatment period. It appeared that dexamethasone dose dependently decreased the fibrinolytic activity (a dose of 1 mg/kg showed a reduction of about 40%). This reduced fibrinolytic activity could be functionally translated into an increased thrombus size as measured with a venous thrombosis model: thrombus size was increased by 50% with 1 mg/kg dexamethasone. No effects could be measured on the coagulation system, but it appeared that ex-vivo measured platelet aggregation was dose dependently inhibited by dexamethasone treatment. This effect resulted in-vivo in prolonged obstruction times as measured with a modified aorta-loop model. These results indicate that the expected prothrombotic state due to a diminished fibrinolytic activity caused by dexamethasone is counterbalanced by an inhibition of platelet aggregation.
Defect of Platelet Aggregation and Adhesion Induced by Autoantibodies Against Platelet Glycoprotein IIIa
Authors: Balduini Carlo L , Bertolino Giampiera , Noris Patrizia , Piovella Franco , Sinigaglia Fabiola , Bellotti Vittorio , Samaden Anna , Torti Mauro , Mazzini Giuliano 
Published: July 2018

SummaryA young patient developed chronic idiopathic thrombocytopenic purpura. Prednisone therapy normalized platelet number, but bleeding symptoms did not disappear. Platelet function was severely impaired, since platelet aggregation, ATP release and adhesion to collagen and subendothelial matrix were significantly reduced. Plasma and purified immunoglobulins of the patient reproduced the functional defects in normal platelets. Immunoblotting revealed that patient’s plasma contained an antibody reacting with a component of platelets with the same electrophoretic mobility of glycoproteins IIIa of normal platelets. Moreover, patient’s plasma inhibited the binding of an anti-GPIIb/IIIa monoclonal antibody to platelet surface. Additional immunosuppressive therapy with prednisone and azathioprine normalized platelet function and induced the disappearance of bleeding symptoms.
Studies of Fibrinogen Binding to Platelets by Flow Cytometry: An Improved Method for Studies of Platelet Activation
Authors: Lindahl Tomas L , Festin Roger , Larsson Anders 
Published: July 2018

SummaryPlatelet function is dependent upon membrane receptors and their interaction with other proteins. Platelet activation appears to cause a structural change of the glycoprotein IIb/IIIa complex that exposes the fibrinogen binding site, which subsequently binds fibrinogen. Fluorescence-activated flow cytometry (FACS) is an efficient method for studying membrane proteins. Flow cytometry gives single-cell data, allowing the detection of only a small proportion of labelled platelets in whole blood without any washing steps. One problem with this method is that the labelled antibodies and the antigen, if present in plasma, form an immune complex, which may cause false positive reactions due to interaction between mammalian IgG and Fcγ receptors on the platelets.We show that immune complexes with chicken IgG do not activate human platelets. We have developed a method for measuring platelet-bound fibrinogen in whole blood and platelet-rich plasma utilising fluorescein isothiocyanate (FITC)-conjugated chicken antibodies directed towards human fibrinogen. As low as 1% activated platelets could be detected without interference from Fc-interactions.