bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Dextran on the Molecular Structure and Tensile Behaviour of Human Fibrin
Authors: Dhall T. Z , Bryce W. A. J , Dhall D. P 
Published: July 2018

SummaryCharacteristic changes induced by dextran during the conversion of fibrinogen to fibrin have previously been shown to be associated with profound alterations in morphology of fibrin. However, whether dextran is incorporated into the fibrin molecule and whether morphological changes are associated with alterations in mechanical behaviour of formed fibrin was unclear. The investigations described show that the fibrin made in the presence of dextran has a shortened syneresis time, a lowered modulus of elasticity, an increased elongation and diminished ultimate strength at break. The molecular composition of fibrin clots remains unaltered despite the altered mechanical properties and morphological changes. Furthermore, dextran is not incorporated into the fibrin structure in any appreciable quantity. It is suggested that these several effects of dextran on clot morphology, tensile behaviour and kinetics of fibrin formation arise from increased forces of attraction between fibrin molecules such that fibrin chains are held together by weak secondary cross-links rather than by stronger primary cross-links which are hidden within the thicker fibrin chain bundles.Recently Muzaffar et al. (1972 a, c) showed that the addition of small amounts of dextran in vitro to purified fibrinogen solution as well as platelet – poor plasma induces characteristic alterations in the kinetics of fibrin formation on account of accelerated polymerization of fibrin monomer. Further, fibrin made under such conditions was found to differ morphologically from control fibrin (Muzaffar et al. 1972 b) and to show an increased coarseness of individual fibrin fibre on electron microscopy together with an associated looseness of fibrin mesh. The degree of abnormality in fibrin morphology was found to be determined by the final dextran concentration. More significantly, dextran was demonstrated to induce similar changes in the kinetics of fibrin formation as well as in fibrin morphology of clots made from plasma after the infusion of clinical dextran fractions in pharmacological dosage in man. However, it is not clear whether dextran-induced structural alterations in fibrin are indicative ofbasic differences in its molecular composition nor whether these changes are associated with alterations in the mechanical strength of fibrin. Clearly these are fundamental questions with respect to the pharmacological effects of dextran in relationship to its clinically well documented antithrombotic activity (Lambie et al. 1970). We have investigated both these questions and report here our principal findings.
Chemorheological Studies of the Effect of Heparin on the Course of Coagulation
Authors: Overholser K. A , Baysinger C. B , Harris T. R , Deveau T 
Published: July 2018

SummaryThe influence of sodium heparin on viscoelastic change during coagulation was determined in vitro for whole blood samples from ten normal subjects at heparin concentrations ranging from 0 to 1.45 units/(ml whole blood). A four-parameter chemorheological model was used to describe the time course of coagulation as measured by the Weissenberg Rheogoniometer. One parameter compares closely with the whole blood activated partial thromboplastin time, while the other three may be related to the chemical kinetics of clotting.The chemorheological model and experimental techniques were then tested in a dog preparation. It was found that rheological measurements are more self-consistent than either thrombelastography or the activated partial thromboplastin time for the assay of in vivo heparin in two dogs.
Management of Hemophilia in Spain
Authors: Martin-Villar J , Ortega F , Magallon M 
Published: July 2018

SummaryResults are presented of a nation-wide inquiry into the management of hemophilia in Spain. It is calculated that there are 1,172 hemophilic patients in the country. A survey has been made of the therapeutic materials (prepared commercially or by hospitals) used in 1974 and their availability in the various hospitals of the Social Security Service. It is estimated that an average of 10,708 units of deficient factor were used per patient in this year. The number of patients on home therapy is 1.2% of the total. All cost of hemophilia treatment is covered by the Social Security. Comments are made on progress during the last five years.
Correlation between Baseline Plasminogen Activator Inhibitor Levels and Clinical Outcome during Therapy with Tissue Plasminogen Activator for Acute Myocardial Infarction
Authors: Sane David C , Stump David C , Topol Eric J , Sigmon Kristina N , Kereiakes Dean J , George Barry S , Mantell Susan J , Macy Elizabeth , Collen Désiré , Califf Robert M 
Published: July 2018

SummaryBaseline plasminogen activator inhibitor (PAI) levels were examined for their influence on the responses to thrombolysis with recombinant tissue plasminogen activator (rt-PA) administered for acute myocardial infarction during the Thrombolysis and Myocardial Infarction (TAMI)-I study. Baseline PAI activity was 19 ± 21 IU/ml (normal <5 IU/ml) and baseline PAI-1 antigen 54 ± 53 ng/ml (normal 27 ± 16 ng/ml), confirming previous findings of elevated PAI levels during acute myocardial infarction. Among clinical outcomes, lower PAI-1 antigen levels correlated weakly with greater patency at the 90 min angiogram. Thus, high baseline plasma PAI-1 levels may be detrimental to reperfusion with t-PA. There was no correlation with other major in-hospital clinical outcomes including reocclusion at the 7-10 day angiogram, survival to discharge, or bleeding. During the follow up period of 2.0 ± 0.4 years, no relationship between baseline PAI levels and post-discharge reinfarction was observed.
Synergism between Tissue-Type Plasminogen Activator and a Genetically Engineered Variant Lacking the Finger Domain, the Growth Factor Domain and the First Kringle Domain
Authors: Mattson C , Wikström K , Sterky C , Pohl G 
Published: July 2018

SummaryA modified variant of human tissue-type plasminogen activator (t-PA) lacking the finger domain (F), the growth factor domain (G) and the first kringle domain (K1), has an extended plasma half-life in vivo, compared to that of t-PA. When the variant (denoted K2P) was tested in vitro for its ability to lyse human plasma clots we found that the activity was characterized by a time lag phase and a sigmoidal dose-response curve. However, an attenuation of the lag phase in vitro was observed both when K2P was mixed with t-PA in a w/w ratio of 4 : 1 and when K2P was allowed to lyse a clot that had been pre-exposed to t-PA i.e. submitted to a limited plasmic digestion. Dosis that in vitro caused 50% lysis within 6 h were calculated from individual dose-response curves and were for K2P, t-PA and K2P/t-PA (4 : 1 w/w) 540 ng/ml, 360 ng/ml and 310 ng/ml, respectively. These results indicated a synergistic effect between K2P and t-PA. However, the data from individual dose-response curves showed that the effect of the K2P/t-PA mixture never was better than that of t-PA alone, and the synergistic effect in vitro is therefore considered to be of limited use. The thrombolytic activity in vivo was evaluated in a rabbit jugular vein thrombus model. Despite the lag phase observed in vitro, K2P was approximately 3 times as effective as t-PA in vivo (bolus injection). The thrombolytic effect of K2P was further potentiated when it was administred together with a small amount of t-PA (4 : 1 w/w). This potentiation in vivo was, in contrast to the effect in vitro, a useful synergistic effect as the dose-response curve for the K2P/t-PA mixture was steeper than that of t-PA and K2P alone. Doses that caused 50% lysis within 3 h were for t-PA, K2P and K2P/t-PA 1.28 mg/kg, 0.56 mg/kg and 0.35 mg/kg, respectively.
Effect of Picotamide on Platelet Aggregation and on Thromboxane A2 Production In Vivo
Authors: Minuz P , Lechi C , Arosio E , Guzzo P , Zannoni M , Lauciello C , Lechi A 
Published: July 2018

SummaryEffects of picotamide (900 mg in 3 oral administrations for 7 days) on ex vivo and in vivo platelet T×A2 production and on platelet aggregation wpre evaluated in 8 patients with peripheral arteriopathy and in 8 normal subjects. Picotamide significantly reduced ADP-induced platelet aggregation, but had no effect on
that induced by arachidonic acid or the thromboxane analogue U46619. Though ex vivo platelet T×A2 production (T×B2 concentration after arachidonic-acid-induced aggregation) was reduced from 946 ± 141 (mean ± SD) to 285 ± 91 ng/ml in controls and from 1515 ± 673 to 732 ± 420 ng/ml in patients with arteriopathy, there was no effect on urinary excretion of 2,3-dinor-T×B2 (in vivo indicator of platelet T×A2 production), or on in vivo PGI2 production (urinary excretion of 6-keto-PGF1α and 2,3-dinor-6-keto-PGF1α). In the same subjects, single-dose aspirin reduced ex vivo T×B2 production by at least 98% and 2,3-dinor-T×B2
excretion from 116.7 ± 61.4 to 32.6 ± 17.0 nglg creatinine in control subjects, and from 156.3 ± 66.1 to 59.1 ± 19.2 ng/g creatinine in patients with peripheral arteriopathy. Our data suggest that inhibition of platelet T×A2 production in vivo may not be picotamide’s main mechanism of action.
Immunocytochemical Study on Endothelial Markers with the Cerebral Vessel from a Patient with Familial Moyamoya Disease
Authors: Usuki Fusako , Ohtani Haruo , Okadome Toshihide , Shinmyozu Koichi , Maruyama Ikuro , Sakimoto Tetsuro , Atsuji Masayuki , Osame Mitsuhiro 
Published: July 2018

SummaryThe immunocytochemical study of thrombomodulin (TM), a newly recognued anticoagulant endothelial surface protein, was performed with a surgical specimen of a superficial temporalartery (STA) obtained from a 29-year-old woman with familial moyamoya disease. The staining of TM showed positive immunoreactivity in smaller vessels in the surrounding connective tissue of the specimen, whereas negative in STA. Immunoelectronmicroscopically the luminal plasma membrane of endothelial cells was positive for TM. These staining pattern was the same as that in controls. She concurrently suffered from von Willebrand disease type I, and she had two cerebral hemorrhagic attacks. A quantitative defect of the von Willebrand factor in the endothelium was demonstrated immunocytochemically.
Continuous Quantitative Monitoring of Mural, Platelet-Dependent, Thrombus Kinetics in the Crushed Rat Femoral Vein
Authors: Stockmans F , Deckmyn H , Gruwez J , Vermylen J , Acland R 
Published: July 2018

SummaryA new in vivo method to study the size and dynamics of a growing mural thrombus was set up in the rat femoral vein. The method uses a standardized crush injury to induce a thrombus, and a newly developed transilluminator combined with digital analysis of video recordings. Thrombi in this model formed rapidly, reaching a maximum size 391 ± 35 sec following injury, after which they degraded with a half-life of 197 ± 31 sec. Histological examination indicated that the thrombi consisted mainly of platelets. The quantitative nature of the transillumination technique was demonstrated by simultaneous measurement of the incorporation of 111In labeled platelets into the thrombus. Thrombus formation, studied at 30 min interval in both femoral veins, showed satisfactory reproducibility overall and within a given animalWith this method we were able to induce a thrombus using a clinically relevant injury and to monitor continuously and reproducibly the kinetics of thrombus formation in a vessel of clinically and surgically relevant size
Effective Reversal of Warfarin-lnduced Excessive Anticoagulation with Low Dose Mtamin K1
Authors: Shetty H G M , Backhouse G , Bentley D P , Routledge P A 
Published: July 2018

SummaryReversal of the anticoagulant effect of warfarin in patients with no active haemorrhage can be achieved by administration of intravenous vitamin K1. Currently recommended doses of intravenous vitamin K1, for this purpose often result in subsequent difficulties in anticoagulation. We observed the response to low dose intravenous vitamin K1 in patients requiring reversal of anticoagulant therapy. Ten consecutive patients received L mg and 2l further patients received 0.5 mg of intravenous vitamin K1. In 50% of the patients who received 1 mg of vitamin K1 the INR (International Normalised Ratio) fell below 2 at 24 h whereas in patients who received 0.5 mg the INR fell below 5.5 in all subjects after 24 h and in none did it fall below 2.0. No patient had any thrombotic or haemorrhagic complications and no difficulty was encountered in re-establishing anticoagulant control after 24 h. We recommend 0.5 mg of vitamin K1 as an effective and convenient method of predictable and fine control of oral anticoagulant therapy.
Hereditary Cerebral Hemorrhage with Amyloidosis -Dutch Type: A Study of Fibrinolysis
Authors: Haan J , Kluft C , Leebeek F W G , de Bart A C W , Buruma O J S , Roos R A C 
Published: July 2018

SummaryIn view of reported associations between increased bleeding tendency and systemically decreased α2-antiplasmin in patients with systemic amyloid deposition we studied α2-antiplasmin, fibrinogen, C-reactive protein and blood levels of locally produced endothelial hemostasis factors in the acute and quiescent phase in 16 patients with hereditary cerebral hemorrhage with amyloidosis - Dutch type (HCHWA-D).None of the factors measured in the quiescent phase of the disease was abnormal. In the acute phase, shortly after a stroke, only factor VIII: Ag was evidently elevated. We concluded that systemic abnormalities in the part of the fibrinolysis system studied are not likely to be responsible for multifocal and recurrent cerebral hemorrhages in HCHWA-D. The role of an elevated factor VIII: Ag level in the acute phase is unclear.
The Mode of Action of CY216 and CY222 in Plasma
Authors: Béguin Suzette , Wielders Simone , Lormeau J C , Hemker H Coenraad 
Published: July 2018

SummaryThree fractions of the low molecular weight heparin CY216 (fraxiparin, mean molecular weight [MMW] 5,090), with MMWs of respectively, 3,090, 4,400 and 7,910 were prepared by gel permeation chromatography. From CY222 (MMW 3,770) as well as from CY216 and its three fractions the material with high affinity to antithrombin III (AT III) was obtained by chromatography on immobilised AT III. The molecular weight distribution of each of the ten preparations thus obtained was determined by high performance liquid chromatography, while the content of AT III binding material was determined by stoichiometric titration of AT III, monitored by intrinsic fluorescence enhancement.We measured the effect of all heparins on the decay of endogenous thrombin in plasma and on the overall generation of thrombin in plasma, triggered via the extrinsic or via the intrinsic pathway. From these data we calculated the time course of prothrombin conversion, i. e. the course of factor Xa activity as expressed by prothrombinase activity.It was found that in platelet-poor plasma the anticoagulant properties of the heparins are largely dependent on their antithrombin action, which is determined by their content of high affinity material with a MW of 5,400 or higher. The specific antithrombin activity of all heparins, when expressed in terms of material with high affinity to antithrombin III (HAM) with a MW >5,400 is 13.0 min-1/(μg/ml) (range 10.5-15.9). The anticoagulant potency is not influenced by the presence of low-affinity material and hardly by material with MW <5,400.In platelet-rich plasma, however, the presence of non-AT III binding material enhances the inhibition, presumably by neutralising heparin binding material originating from activated platelets. The ultra low MW fractions (<3,400) show a similar activity in PPP and in PRP.
Characterization of Human Tissue-Type Plasminogen Activator with Monoclonal Antibodies: Mapping of Epitopes and Binding Sites for Fibrin and Lysine
Authors: Zacharias Ute , Fischer Bernhard , Noll Franz , Will Horst 
Published: July 2018

SummaryThe study defines interactions between human tissue-type plasminogen activator (t-PA) and 21 mouse monoclonal antibodies (mAb). Characterization includes epitope distribution, reactivity of different forms of t-PA with antibodies, and modification of t-PA function by antibody binding.Eighteen antibodies are directed against t-PA A-chain. These antibodies recognize four distinct epitopes (A, B, C, D) and one partially overlapping epitope (D’). The remaining three antibodies are directed against two different epitopes (E, F) on catalytically active t-PA B-chain. A-chain reactive antibodies do not bind to the reduced form of t-PA, while B-chain reactive antibodies bind to reduced and deglycosylated t-PA forms. The latter antibodies associate more tightly with sc t-PA than with tc t-PA and have a higher affinity for t-PA-PAI 1 complex as compared to free t-PA.The analysis of functional effects of antibodies reveals that antibodies directed against all above defined epitopes inhibit interactions between t-PA and fibrin: a) binding of t-PA to fibrin, b) fibrinolytic activity of t-PA, and c) fibrin activation of sc t-PA amidolytic activity. The observations support the assumption that several sites of t-PA are involved in fibrin binding and that fibrin-bound t-PA is closely surrounded by the fibrin mesh. Many antibodies quench also binding of t-PA to lysine-Sepharose. Experiments with free, non-fixed lysine confirm strong competition between lysine and mAb 16 and 18, directed against epitope A, and mAb 29, binding to epitope F. Weak inhibition is exerted on association of mAb 2, 21, and 25 to epitope D. Amidolytic activity is suppressed only by B-chain specific antibody 22.
Transport of Anti-Glycoprotein IIb/IIIa-Antibodies into the Alpha-Granules of Unstimulated Human Blood Platelets
Authors: Morgenstern Eberhard , Ruf Andreas , Patscheke Heinrich 
Published: July 2018

SummaryThe redistribution of the antibody-glycoprotein (GP) IIb/IIIa complex was investigated with the immuno-gold labeling technique in order to trace its transport in resting platelets. Washed platelets were incubated in the presence of aspirin and a prostacyclin analogue (iloprost) with three different monoclonal antibodies (Gi3, J15 and P2) against GPIIb/IIIa. The examination of ultrathin serial sections showed that the surface labeling was internalized into the surface connected membrane system (SCS). Labels were found within the alpha-granules after 40 min and the number of labels increased during longer incubation periods (max. 120 min). The transport possibly involved coated membranes. The alpha-granules were neither found to be altered during this process nor were any morphological signs of platelet activation detectable. The anti-GPIIb/IIIa complex remained membrane-associated during the transfer. These observations indicate that the membrane-GPIIb/IIIa complex was stable and transported from the surface into the alpha-granules of resting platelets. Since this transport was not influenced by iloprost or by aspirin it may be interpreted as constitutive endocytosis.
Effect of Calcium Channel Blockers on Platelet GPIIb-IIIa as a Calcium Channel in Liposomes: Comparison with Effects on the Intact Platelet
Authors: Rybak Mary Ellen M , Renzulli Lori A 
Published: July 2018

SummaryThe platelet membrane glycoprotein IIb-IIIa complex is essential for platelet aggregation and functions as a fibrinogen receptor on the activated platelet. When incorporated into phospholipid vesicles, this glycoprotein complex can function as an apparent calcium channel which facilitates the transit of calcium across a phospholipid barrier. In order to further evaluate this calcium channel, the effect of calcium channel blockers of the dihydropyridine (nifedipine and nicardipine), arylalkylamine (verapamil) and benzothiazipine (diltiazem) classes were evaluated on GPIIb-Illa liposomes with encapsulated fura-2 (a fluorescent calcium indicator). Nicardipine, verapamil, and nifedipine significantly inhibited calcium influx into GPIIb-IIIa liposomes; however, this required 190 μM, 400 μM, and 140 μM drug, respectively. These concentrations are 10-1,000 fold greater than those clinically obtainable. In contrast, diltiazem at concentrations >220 μM and amiloride at concentrations >800 μM showed no inhibitory effects. When aspirinized platelets were activated with 30 μg/ml bovine fibrillar collagen, both nicardipine and diltiazem produced a decrease in both the initial rise and maximum cytoplasmic calcium concentration. Parallel experiments were performed to assess the effects of verapamil, nicardipine, and diltiazem on platelet aggregation in platelet rich plasma. Nicardipine, 190-380 μM, induced a prolongation of the lag phase, but no effect on the final degree of platelet aggregation to collagen. Similar inhibition of platelet aggregation was seen with diltiazem and verapamil although the effect of diltiazem was less pronounced particularly at higher concentrations of collagen. No effect was seen on aggregation with 32 μM ADP which is release independent, or on the primary wave of low dose ADP induced platelet aggregation. Verapamil (200 μM) and nicardipine (>190 μM) partially inhibited the secondary wave of 3.2 μM ADP aggregation. In contrast, diltiazem (400 μM) had limited effect on ADP induced aggregation. Similarly, both nicardipine and verapamil markedly inhibited platelet aggregation to 6 μM epinephrine; however, diltiazem had no effect. These data demonstrate that the GPIIb-IIIa calcium channel is selectively inhibited by different classes of calcium channel blockers. This inhibition requires concentrations much higher than that to inhibit classic voltage gated calcium channels and may be by a different mechanism. Further evaluation will determine whether this differential inhibition of the GPIIb-IIIa calcium channel is related to differences observed in platelet aggregation.
Neutralization of the Antiheparin Activity of Platelet Factor 4 by a Monoclonal Antibody
Authors: Saggin Leopoldo , Cazzola Flavia , Corona Giuseppe , Salvatico Emanuela , Cella Giuseppe , Prosdocimi Marco 
Published: July 2018

SummaryWe have produced a panel of monoclonal antibodies (mAbs) against rabbit platelet factor 4 (PF4). Two of these mAbs have been characterized in this study. In particular the antibody called 10B2, which also recognizes the human molecule, is able to block PF4’s ability to neutralize heparin in a modified Heparin-Factor Xa chromogenic assay. The inhibition appears to be more than 95% at 1:1 mAb/PF4 molar ratio both for purified rabbit and human PF4. Similar results were obtained using supernatants from stimulated human platelets (90% of inhibition at 1:1 mAb/ PF4 molar ratio) or using Fab fragments from 10B2. Studies to determine the antigenic determinant against which 10B2 is directed, show that this is an assembled epitope which involves disulfide bonds of the PF4.