bluuebunny/crossref_metadata_2025_split huggingface dataset:
G4120, an Arg-Gly-Asp Containing Pentapeptide, Enhances Arterial Eversion Graft Recanalization with Recombinant Tissue-Type Plasminogen Activator in Dogs
Authors: Lu Hua Rong , Gold Herman K , Wu Zaomin , Yasuda Tsunehiro , Pauwels Patrick , Rapold Hansjörg J , Napier Mary , Bunting Stuart , Collen Désiré 
Published: July 2018

SummaryThe effects of G4120, a cyclic Arg-Gly-Asp (RGD) containing peptide which inhibits fibrinogen binding to the platelet receptor GPIIb/IIIa, on thrombolysis with recombinant tissue-type plasminogen activator (rt-PA) were investigated in a combined arterial and venous thrombosis model in heparinized dogs. The arterial thrombus model consisted of a 3 cm everted (inside-out) carotid arterial segment inserted into a transsected femoral artery which occludes within 30 min with platelet-rich material and which is resistant to recanalization with 0.5 mg/kg rt-PA. The venous thrombus was a 125I-fibrin labeled whole blood clot produced in the contralateral femoral vein.In 5 dogs given an intravenous bolus of 0.05 mg/kg G4120 followed by a continuous infusion of 0.05 mg/kg per hour for 3 h (group I), arterial occlusion persisted throughout a 4 h observation period and was still present at 24 h in all dogs; the extent of venous clot lysis after 120 min was 27 ± 7%. In 5 dogs given the same infusion of G4120 in combination with 0.5 mg/kg rt-PA over 60 min, recanalization of the arterial graft occurred in all dogs, within 13 ± 2 min and persisted throughout the observation period of 4 h (p = 0.01 versus G4120 or rt-PA alone); at 24 h, however, all grafts were occluded. Venous clot lysis in this group was 75 ± 8% (p = 0.002 versus G4120 alone andp NS versus rt-PA alone). Pathologic analysis revealed platelet-rich or mixed thrombus with platelet-rich and erythrocyte-rich zones. The last 6 dogs were given a reduced dose of G4120 consisting either of a 0.05 mg/kg bolus followed by an infusion of 0.05 mg/kg over 1 h in 3 dogs (group III) or of a single 0.05 mg/kg bolus in 3 dogs (group IV), both given in combination with 0.5 mg/kg rt-PA infused over 60 min. These protocols produced recanalization within 15 ± 2 and 34 ± 8 min, respectively, which was maintained throughout the 4 h observation period. Venous lysis in these groups was 63 ± 4 and 97 ± 1% respectively. Bleeding times prolonged from 1 to 2 min to >30 min with G4120, but returned towards baseline within 2 h after the end of the infusion. Platelet aggregation with ADP was completely inhibited with G4120 but partially recovered within 1 h after the end of the infusion. No fibrinogen breakdown was observed in association with the rt-PA infusion.Thus, G4120, a synthetic GPIIb/IIIa receptor antagonist, enhances and accelerates lysis of platelet-rich arterial thrombosis with rt-PA and prevents reocclusion during and within 3 h after the infusion. It may be useful for the conjunctive use with thrombolytic agents in patients with arterial thromboembolic disease.
The Effect of Intravenous Adenosine Diphosphate on the Number of Circulating Platelets in Experimental Animals: Inhibition by Prostaglandin E1, Dipyridamole, SH-869 and VK-774
Authors: Holmes Ian B. , Smith Gordon M. , Freuler Franz 
Published: July 2018

SummaryThe number of circulating platelets was monitored in anaesthetized animals by a continuous flow technique, using a Technicon Autocounter®. Intravenous infusions of adenosine diphosphate (ADP) produced transient, dose-dependent falls in circulating platelet numbers in rabbits, dogs, rats, pigs and squirrel monkeys. The rat was the most sensitive of the species investigated.In the rabbit, the effect of a submaximal dose of ADP was inhibited in a dose-dependent manner by intravenous infusions of prostaglandin E1 (PGE1), dipyridamole, and two derivatives of dipyridamole (SH-869 and VK-774). The dose-response curves for PGEl, SH-869 and VK-774 were approximately parallel, whereas that for dipyridamole was considerably less steep. PGE1 was the most potent inhibitor, but the duration of action was very short. Dipyridamole and SH-869 produced inhibition of long duration. The duration of action of VK-774 was intermediate.All inhibitors produced marked and often long-lasting hypotension. The fact that no inhibition of ADP effects could be demonstrated with dibenzyline and hexamethonium, which also produced marked hypotension of long duration, indicated that inhibition of the ADP effect by the four antagonists studied was not due to changes in blood pressure.
In Vivo Labeling of Platelets with 75Se – Selenomethionine in Patients with Hepatic Cirrhosis and Thrombocytopenia.
Authors: Mayer Manfred , Herrmann Ilse , Kempgens Uwe , Queisser Wolfgang 
Published: July 2018

SummaryLabeling of platelets in vivo by 75Se – Selenomethionine (75Se-M) was performed in nine cases of hepatic cirrhosis and thrombocytopenia for evaluation of the kinetics of platelet maturation. Folic acid and vitamin B12 deficiency was excluded by pretreatment of the patients with these agents. The platelet maturation time – time between the injection of the isotope and maximum radioactivity of separated blood platelets – was shortened to 7.7±1.1 days (mean±SD) compared to the normal of 9.1±1.4 days. For explanation a disturbance of megakaryocyte maturation and/or platelet release from the bone marrow is suggested.
Soluble Fibrin Complexes: Separation as a Function of pH and Characterization
Authors: Benabid Y , Concord E , Suscillon M 
Published: July 2018

Summary1. The influence of the pH on the separation of high molecular weight derivatives obtained by a limited action of thrombin on fibrinogen was studied by agarose gel chromatography. When the pH of the elution buffer was 8.5, non crosslinked associations were easily separated in two peaks eluted prior to the fibrinogen peak: one contained a dimer, the other several high polymers. At pH 6.5, only the fibrinogen peak appeared: the fibrinogen molecule proteolysed by thrombin formed no stable associations at this pH and was eluted with the intact fibrinogen molecule. In the presence of factor XIII and Ca++, numerous associations were obtained which are independant of the pH.2. The polypeptide chain composition of the different species separated at pH 8.5 was studied by SDS-polyacrylamide gel electrophoresis. This technic showed Aα, Bβ and γ chains in the fibrinogen peak, whereas in the chromatographic fractions containing the dimer four bands corresponding to Aα, α, Bβ and γ chains were found. In the peak containing the high polymers, only the presence of α, Bβ and γ chains was demonstrated.3. These experimental results concerning the effect of pH on the formation of soluble complexes showed that the presence of fibrin monomers in fibrinogen solution was not sufficient to promote any associations. The formation of such derivatives is strongly dependent on the pH of the solution. This obviously can be explained by an influence of the pH either on the ionization of polymerisation sites and the intermolecular bonds between the complex units or on the unmasking of the polymerisation sites by a hypothetical pH induced conformational change of the fibrinogen molecule.
Soluble Fibrin Complexes in Early Fibrin Digests*
Authors: Nanninga Luddo B. 
Published: July 2018

SummaryEarly fibrin digests were analyzed in the ultracentrifuge and were found to contain compounds with molecular weights up to 3 x 106; these compounds are considered to be soluble fibrin complexes. Their similarity with intermediate polymers in inhibited clotting systems has been stressed. Their viscosity at low shear rates is extremely high; therefore, a rapid method to establish their presence in plasma would be the measurement of plasma and serum viscosity at low shear rates. Moreover, they shorten the clotting time (thrombin time) of fibrinogen considerably.
Controlled Trial of the Sequential Use of Streptokinase and Ancrod in the Treatment of Deep Vein Thrombosis of Lower Limb
Authors: Tibbutt D. A , Chesterman C. N , Williams E. W , Faulkner T , Sharp A. A 
Published: July 2018

SummaryTreatment with streptokinase (‘Kabikinase’) was given to 26 patients with venographically confirmed deep vein thrombosis extending into the popliteal vein or above. Treatment was continued for 4 days and the patients were allocated randomly to oral anticoagulant therapy or a course of treatment with ancrod (‘Arvin’) for 6 days followed by oral anticoagulant therapy. The degree of thrombolysis as judged by further venographic examination at 10 days was not significantly different between the 2 groups. The majority of patients showed clinical improvement but there was no appreciable difference between the groups at 3 and 6 months. Haemorrhagic complications were a more serious problem during the period of treatment with ancrod than during the equivalent period in the control group.
Some Factors Influencing Metabolism and Distribution of Fibrinogen in Man and Rabbits
Authors: Chen Yi-Hsiang , Reeve E. B 
Published: July 2018

SummaryTo shed some light on the homeostatic regulation of plasma fibrinogen, metabolic studies were made in healthy females, and in normal, thyroidectomized, and thyroxine-treated rabbits. In females, compared with normal males, plasma fibrinogen concentration, plasma and interstitial fibrinogen decreased consequent to an increased fractional catabolic rate and a normal fibrinogen synthesis rate. The interstitial/plasma fibrinogen ratio remained unchanged. In normal rabbits, with increasing body weight fractional catabolic rate and catabolic rate decreased, while fibrinogen concentration and plasma fibrinogen remained constant owing to a simultaneous decrease in fibrinogen synthesis. In addition, fractional transcapillary transfer rate and transcapillary flux also decreased resulting in a shrinkage of interstitial fibrinogen. Thyroidectomy and thyroxine-injection markedly altered fibrinogen metabolism: thyroid hormone accelerated fibrinogen catabolism but also stimulated synthesis. The net result was an increase in plasma fibrinogen and fibrinogen concentration. The interstitial/plasma fibrinogen ratio decreased in thyroxine-treated, and increased in thyroidectomized animals. This study defines the variations of the fibrinogen system parameters in these physiologic and pathologic conditions, and illustrates some patterns of alterations in fibrinogen metabolism.
Properties of Washed Human Platelets
Authors: Kinlough-Rathbone Raelene L , Fraser Mustard J , Packham Marian A , Perry Dennis W , Reimers Hans-Joachim , Cazenave Jean-Pierre 
Published: July 2018

SummaryWe have shown previously that washed human platelets resuspended in Tyrode solution containing albumin and apyrase maintain their disc shape and their ability to aggregate upon the addition of low concentrations of ADP, providing fibrinogen is added to the suspending medium. We have now examined their responses to other aggregating and release-inducing agents. Collagen, arachidonate, thrombin, immune serum globulin, the ionophore A 23, 187 and phytohaemagglutinin from Phaseolus vulgaris caused aggregation and release of granule contents. The response to adrenaline was variable. Serotonin caused the platelets to change shape but no aggregation or release occurred. Addition of a small amount of plasma was necessary for ristocetin-induced aggregation. Polylysine caused immediate platelet-to-platelet adherence with little or no release of granule contents. Responses to collagen or thrombin were greater in a modified medium containing magnesium but no calcium; in this medium, aggregation caused by ADP or polylysine was followed by the release of granule contents whereas these agents caused aggregation without release in a medium with both calcium and magnesium. When protein was omitted from the suspending medium, platelet aggregation in response to ADP was variable. In this medium, collagen and thrombin caused more extensive release than in the albumin-containing medium. Aggregation by polylysine was accompanied by release and extensive lysis in the protein-free medium. Thus, the composition of the final resuspending medium has a major effect on the responses of washed human platelets to aggregating agents.
Enzymatic Properties of 5′-AMP Deaminase in Platelet Lysates
Authors: Holmsen H , Østvold A.-C , Pimentel M. A 
Published: July 2018

SummaryMetabolic ATP is converted to hypoxanthine during platelet secretion, metabolic shock and slowly in the resting state. This conversion involves deamination of 5′-AMP to 5′-IMP which has been studied by incubating 5′-AMP (3–40 μM) with human platelet lysates and quantifying the metabolites formed. Deamination occurred only when EDTA was present or endogenous ATP absent, showing that 5’-AMP deaminase (EC 3.5.4.6) was the only enzyme attacking AMP. EDTA stimulated AMP deamination, probably by removal of endogenous heavy metals which were powerful inhibitors of deamination. The experiments were therefore performed with EDTA. 5′-AMP deaminase was soluble, and had optimal activity at pH 6.5; however, the rate of AMP deamination was highly dependent on the type of buffer used. Km was 0.92 × 10–3M and Vmax was 0.26 μmoles/min x mg protein. The deamination required presence of monovalent cation with Li+ = Na+ >K+ >NH4
+, a sequence distinctly different from that seen with erythrocyte and muscle deaminase. 50 mM Na+ gave maximal activity with [math]. Tris+ and K+ were competitive inhibitors with respect to Na+, a feature not reported for the enzyme from other tissues. Above 60 mM K+ there was no effect by Na+ (0–100 mM). PPi, GTP, ITP, CTP and UTP gave greater inhibition than Pi and phospho-esters. Unlike AMP deaminase from other tissues, the platelet enzyme was insensitive to fluoride. ATP counteracted Pi and GTP inhibition and activated with or without Na+; ATP-and Na+-activation were additive. The activity increased as the adenylate energy charge was lowered, but was linearly related to the AMP concentration, thus in sharp contrast to deaminase from the liver. It is suggested that in the intact platelet AMP deamination is regulated chiefly through variations in the AMP level and not likely through variations in the ATP/Pi ratio.
A Simple and Practical Method for Isolation of an Early Plasmin Degradation Product of Human Fibrinogen
Authors: Takagi Kimiteru , Kawai Tadashi 
Published: July 2018

SummaryOne of the earliest plasmin degradation products of human fibrinogen, so-called fragment A, was isolated by a simple method.This peptide has a molecular weight of approximately 22,500, migrating electrophoretically at beta-area, and its amino acid composition shows a very high content of glycine, serine, threonine and proline, and a markedly low content of hydrophobic amino acids. This fragment does not react against anti-fibrinogen; however, the anti-serum of this fragment reacts strongly with fibrinogen.
Use of 125I-Fibrinogen Kinetic Data to Detect Disseminated Intravascular Coagulation and Deposition of Fibrin in Patients with Metastatic Cancer
Authors: Robson Elean B , Murawski Gail F , Bettigole Richard E 
Published: July 2018

SummaryA technique using computerized data handling for following the fate of 125I-fibrinogen through various physiological compartments is presented. Its use in detecting fibrin build up in patients with metastatic tumors and cancer-caused DIC is explained. An increase in j3u (fractional catabolic rate as seen in the urine data) throughout the course of a study was found to be an important indicator of extravascular fibrin build up.
Interlaboratory Oral Anticoagulant Quality Assessment by the Netherlands Federation of Thrombosis Services
Authors: van Dijk-Wierda C. A , Hermans J , Loeliger E. A , Roos J 
Published: July 2018

SummaryThe 50 laboratories of the Netherlands Federation of Thrombosis Services, covering a population of 9 million and responsible for the laboratory control of approximately 150,000 patients under oral anticoagulation, have participated since 1974 in a voluntary external and internal quality control program. The external program comprises a monthly distribution to the member laboratories of a series of artificially prepared control blood samples, two of which are identical. The overall variation of the coagulation times found were 10% (CV) in 1974 and 8% (CV) in 1975. Performance improved rather abruptly at the beginning of 1975, after the application of a tight methodological standardization and improvement by the manufacturer of the thromboplastin preparation (Thrombotest) used by the great majority of the laboratories involved. The main source of variation was found to be random error in the Thrombotest determination, approximating 6%. Interbatch variation of Thrombotest and inter-aliquot variation of control blood samples both do amount to approximately 3% (CV). In terms of rabbit tissue thromboplastins, which have a lower sensitivity than Thrombotest (i. e., a flatter slope of the correlation between the PT and the anticoagulant effect), the total variation in the performance of the Dutch laboratories is 2.2-5.6% (CV), which is unusually low. The main reason for this is the fact that the laboratories can rely not only on the services of the manufacturer but also on a central information office and a reference laboratory responsible for the preparation of the control blood as well as the standardization (calibration) of thromboplastin.
Studies on the Tissue Thromboplastin During the Coagulation-Fibrinolytic Process – Ultrastructural Changes
Authors: Hasegawa Hiroshi , Nagata Hiroshi , Murao Makoto 
Published: July 2018

SummaryAn electron-microscopical study was made on morphological changes in which T-Tbp would undergo during clotting and fibrinolytic process. Morphological appearance of concentrically arranged membrane structure in T-Tbp remained nearly intact during blood coagulation process. T-Tbp, which existed in the sediments following dissolution of fibrin clot by the application of UK, showed an appearance of fine granules adhering to the surface of aggregates of particles through SEM. Through TEM, T-Tbp in the sediments was found to have retained its concentrically arranged membrane structures in most places, while, in some other places the appearance of fused membranes, smaller single vesicles and long sheets of membranes, and the formation of “blebs” etc. were observed. Various morphological changes caused by fibrinolytic substances accompanied the loss in coagulation activities.Our results showed that coagulation activities of T-Tbp must be completely dependent upon the presence of the membrane structures.
Cytokine Regulation of the Synthesis of Plasminogen Activator Inhibitor-2 by Human Vascular Endothelial Cells
Authors: Zoellner Hans , Wojta Johann , Gallicchio Marisa , McGrath Katherine , Hamilton John A 
Published: July 2018

SummaryPlasminogen activators are inhibited by plasminogen activator inhibitors-1 (PAI-1) and -2 (PAI-2). We describe the synthesis of PAI-2 by human vascular endothelial cells (EC) cultured from umbilical vein, saphenous vein and foreskin microvasculature in response to interleukin-1α (IL־1α) and tumour necrosis factor α (TNFα) and compare it with that of PAI-1. Both PAI-2 and PAI-1 were quantitated by ELIS As. PAI-2 was cell-associated while PAI-1 was secreted by EC. IL-lα and TNFα increased the synthesis of PAI-2 and PAI-1 by EC in a dose-dependent manner. IL-1α was a stronger stimulus for PAI-2 synthesis than TNFα, while both cytokines were equally effective for PAI-1. Northern blot analysis revealed similar changes in mRNA levels to those in antigen levels. PAI-2 synthesis by cytokine-stimulated EC may be important in thrombus formation and inflammation.
Anticoagulant Activity of Hirulog™, a Direct Thrombin Inhibitor, in Humans
Authors: Fox Irving , Dawson Adrian , Loynds Peter , Eisner Jane , Findlen Kathleen , Levin Elizabeth , Hanson Don , Mant Tim , Wagner John , Maraganore John 
Published: July 2018

SummaryHirulog™ (BG8967) is a direct thrombin inhibitor built by rational design using the protein hirudin as a model (Maraganore et al. [1990]; Biochemistry 29: 7095–101). In order to evaluate the therapeutic potential for hirulog in the management of thrombotic disease, the tolerability and anticoagulant activity of the agent were examined in a study of human volunteers.In a randomized, placebo-controlled study (n = 54), the intravenous infusion of hirulog over 15 min showed a rapid, dose-dependent prolongation of activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). There was a corresponding dose-dependent increase in plasma hirulog levels. The peptide was rapidly cleared with a half-life of 36 min and a total body clearance rate for the peptide of 0.43 1 kg−1 h−1. Similar activity was observed following subcutaneous injection but with sustained pharmacodynamic and pharmacokinetic behavior. There was a significant correlation between pharmacokinetic and pharmacodynamic variables for both intravenous (r = 0.8, p <0.001) and subcutaneous administration (r = 0.7, p = 0.002).To evaluate the possible interactions of aspirin on the tolerability and anticoagulant activity of intravenous hirulog, a cross-over design was employed in eight subjects. Aspirin administration did not modify the peptide’s activity. At the administered dose of 0.6 mg kg−1 h−1 for 2 h, hirulog infusion prolonged APTT from 230 to 260% baseline. The infusion of hirulog in subjects who had received aspirin was not associated with any significant changes in the template bleeding time.The final phase of the study examined the activity and tolerability of hirulog in ten subjects during prolonged intravenous infusions for up to 24 h. The peptide (0.3 mg kg−1 h−1) exhibited sustained anticoagulant activity with no evidence for a cumulative effect. During hirulog infusion, APTT was prolonged from 210 to 250% baseline.In all phases of the study, hirulog administration was generally well-tolerated.Our observations show that hirulog is an active antithrombin agent with excellent tolerability in humans. As a direct thrombin inhibitor, hirulog provides a novel approach for the management of thrombotic disease.