bluuebunny/crossref_metadata_2025_split huggingface dataset:
Binding of 99mTc Plasminogen on Fibrin
Authors: Juhan-Vague I , Calas M F , Roux F , Juhan C , Durand-Dessemon F , de Laforte C , Serradimigni A 
Published: July 2018

SummaryBinding of plasminogen to fibrin was studied in vitro and in vivo using 99mTc Glu- and Lys-plasminogen.Binding of Glu-plasminogen on the clot was not observed in vitro, and in vivo in the dog.Conversely, the binding of Lys-plasminogen to fibrin displays a linear relationship to the concentration of Lys-plasminogen, up to doses exceeding equimolarity; thus suggesting the existence of several Lys-plasminogen binding sites on fibrin. Binding levels were identical, regardless of whether plasminogen was incubated in normal plasma or in plasma devoid of antiplasmin. In the dog, Lys-plasminogen bound specifically to the clot, however, clot sites could not be localized by scintigraphy in the dog or in man.
Inhibition of Human Platelet Functions by Verapamil
Authors: Ikeda Y , Kikuchi M , Toyama K , Watanabe K , Ando Y 
Published: July 2018

SummaryThe effects of verapamil, a coronary vasodilator, on platelet functions were studied.Platelet aggregation induced by ADP, epinephrine or collagen was inhibited by verapamil in vitro. Calcium ionophore A23187-induced platelet aggregation was also inhibited by verapamil in a concentration dependent manner. In washed platelets, verapamil caused a dose-dependent inhibition of serotonin release induced either by thrombin or A23187 in the absence of extracellular calcium. Addition of 1 mM CaCl2 with A23187 or thrombin partially overcame this inhibition. Addition of 1 mM CaCl2 in the absence of verapamil had no effect on thrombin- or A23187-induced secretion. When verapamil was administered to the healthy volunteers at the dosage commonly used, inhibition of platelet aggregation was observed 2 hrs after the drug ingestion. It is of great interest that verapamil potentiated the anti-aggregating activity of prostacyclin in vitro.Our results may suggest a potential role for verapamil in the treatment of thrombotic disorders.
Paris I Dysfibrinogenemia: A Point Mutation in Intron 8 Results in Insertion of a 15 Amino Acid Sequence in the Fibrinogen γ-Chain
Authors: Rosenberg Jonathan B , Newman Peter J , Mosesson Michael W , Guillin Marie-Claude , Amrani David L 
Published: July 2018

SummaryParis I dysfibrinogenemia results in the production of a fibrinogen molecule containing a functionally abnormal γ-chain. We determined the basis of the molecular defect using polymerase chain reaction (PCR) to amplify the γ-chain region of the Paris I subject’s genomic DNA. Comparative sequence analysis of cloned PCR segments of normal and Paris I genomic DNA revealed only an A→G point mutation occurring at nucleotide position 6588 within intron 8 of the Paris I γ-chain gene. We examined six normal individuals and found only normal sequence in this region, indicating that this change is not likely to represent a normal polymorphism. This nucleotide change leads to a 45 bp fragment being inserted between exons 8 and 9 in the mature γparis I chain mRNA, and encodes a 15 amino acid insert after γ350 [M-C-G-E-A-L-P-M-L-K-D-P-C-Y]. Alternative splicing of this region from intron 8 into the mature Paris I γ-chain mRNA also results after translation into a substitution of S for G at position γ351. Biochemical studies of 14C-iodoacetamide incorporation into disulfide-reduced Paris I and normal fibrinogen corroborated the molecular biologic predictions that two additional cysteine residues exist within the γpariS I chain. We conclude that the insertion of this amino acid sequence leads to a conformationallyaltered, and dysfunctional γ-chain in Paris I fibrinogen.
The Effects of Heparin and Annexin V on Fibrin Accretion after Injury in the Jugular Veins of Rabbits
Authors: Van Ryn-McKenna J , Merk H , Müller T H , Buchanan M R , Eisert W G 
Published: July 2018

SummaryWe compared the relative abilities of unfractionated heparin and annexin V to prevent fibrin accretion onto injured jugular veins in vivo. Heparin was used to accelerate the inhibition of thrombin by antithrombin III, and annexin V was used to inhibit the assembly of the prothrombinase complex on phospholipid surfaces, thereby blocking thrombin generation. Rabbit jugular veins were isolated in situ, a 2 cm segment was injured by perfusing it with air, and then blood flow was re-established. Five minutes later, each rabbit was injected with heparin (20 U/kg) or annexin V (0.3 mg/kg) and then with 125I-fibrinogen. The amount of 125I-fibrin accumulation onto each injured vessel wall segment was measured 4 h later. Each injured vessel was completely deendothelialized as a result of the air perfusion as demonstrated by electron microscopy. 125I-fibrin accretion onto the injured jugular veins was enhanced 2.4-fold as compared to the uninjured veins in sham-operated animals. Heparin treatment did not reduce fibrin accretion, whereas, annexin V treatment decreased fibrin accretion by 60%, p <0.05. This latter effect was achieved without sustained circulating anticoagulation. Additional experiments confirmed that the inhibitory effect of annexin V on fibrin accretion was associated with a surface specific effect, since more annexin V bound to the injured jugular vein segments as compared to the non-injured jugular veins. We conclude that, i) mild vessel wall injury (selective de-endothelialization) in veins results in a thrombogenic vessel wall; ii) the thrombogenecity of which is not inhibited by prophylactic doses of heparin; but iii) is inhibited by annexin V, which binds to injured vessel wall surface, and inhibits thrombin generation independently of antithrombin III.
An Antithrombin III Assay Based on Factor Xa Inhibition Provides a More Reliable Test to Identify Congenital Antithrombin III Deficiency Than an Assay Based on Thrombin Inhibition
Authors: Demers Christine , Henderson Penny , Blajchman Morris A , Wells Michael J , Mitchell Lesley , Johnston Marilyn , Ofosu Fred A , Fernandez-Rachubinski Franҫoise , Andrew Maureen , Hirsh Jack , Ginsberg Jeffrey S 
Published: July 2018

SummaryObjectives: To determine whether functional antithrombin III (AT-III) levels measured by a factor Xa inhibition (AT-III-Xa) assay identifies AT-III deficient individuals more reliably than functional AT-III levels measured by a thrombin inhibition (AT-III-IIa) assay.Study design: Cross-sectional study.Patient population: Sixty-seven members of a large family with type 2 AT-III deficiency.Intervention: DNA analysis was used as the reference diagnostic standard for AT-III status and subjects were classified as AT-III deficient or non deficient according to these results. Functional AT-III levels were measured in all subjects using: 1) a chromogenic substrate for thrombin and added human thrombin (AT-III-IIa), and 2) a chromogenic substrate for factor Xa and added bovine factor Xa (AT-III-Xa). Functional heparin cofactor II (HC-II) levels were measured using a commercially available kit. The proportions of 125I-α-thrombin complexed to AT-III and HC-II were measured by polyacrylamide gel electrophoresis and autoradiography.Results: Thirty-one (46%) individuals were classified as AT-III deficient and 36 (54%) as AT-III non deficient. AT-III-Xa assay measured a significantly lower mean AT-III value and a narrower range for individuals classified as AT-III deficient than the AT-III-IIa assay. Using the AT-III-IIa assay, six subjects had borderline AT-III levels compared to none with the AT-III-Xa assay. Thrombin inhibition by HC-II likely accounts for the AT-III-IIa assay giving higher values than the AT-III-Xa assay since 1) there was a significant correlation between the difference in AT-III-IIa and AT-III-Xa levels and HC-II levels, 2) the mean level of HC-II was significantly higher for individuals who had a positive difference between AT-III-IIa and AT-III-Xa levels compared to those who had a negative difference and 3) there was a significant correlation between the difference in AT-III-IIa and AT-III-Xa levels and the percentage of 125I-α-thrombin complexed to HC-II.Conclusion: The AT-III-Xa assay is a better discriminant between AT-III deficient and AT-III non deficient individuals than the AT-III-IIa assay.
Antithrombotic Activity of SR 46349, a Novel, Potent and Selective 5-HT2 Receptor Antagonist
Authors: Herbert J M , Bernat A , Barthelemy G , Dol F , Rinaldi M 
Published: July 2018

SummarySR 46349 (trans-4-[(3Z)3-(2-dimethylaminoethyl)oxyimino-3(2-fluorophenyl)propen-1-yl] phenol, hemifumarate) is the first member of a newly-developed 5-HT2 antagonist series. SR 46349 potently inhibited serotonin-induced aggregation of rabbit and human platelets (IC50 = 1 and 3.9 nM respectively) but had no effect on the action of other platelet aggregating agents. SR 46349 was 118 and 25 times more potent than ketanserin against 5-HT + epinephrine-induced aggregation of rabbit and human platelets respectively.A single per os administration of SR 46349 (1 mg/kg) resulted in a strong inhibition of 5-HT + epinephrine-induced platelet aggregation in the rabbit as measured ex vivo (67% inhibition, 6 h after the administration). Intravenous or oral administration of SR 46346 inhibited in a dose-dependent manner venous thrombosis induced by ligature of the jugular vein of rabbits whose blood was made hypercoagulable by i.v. administration of tissue thromboplastin. The doses of SR 46349 which inhibited 50% of thrombus formation were 1.5 ± 0.8 mg/kg and 17 ± 0.5 mg/kg after i.v. or oral administration respectively. When given i.v. to rabbits, SR 46349 exhibited a dose-dependent antithrombotic effect in an arterio-venous shunt model. Significant increase of the bleeding time was observed after the i.v. administration of 5 mg/kg of SR 46349 (3-fold increase). In dogs, SR 46349 inhibited cyclic coronary artery blood flow variations, complete abolition of CFVs being achieved after the i.v. administration of 0.5 mg/kg.In conclusion, SR 46349 is a highly potent, selective antagonist of serotonin in vitro and is to be considered as a potent, orally active antithrombotic agent.
Retinoic Acid Enhances Fibrinolytic Activity In-Vivo by Enhancing Tissue Type Plasminogen Activator (t-PA) Activity and Inhibits Venous Thrombosis
Authors: van Giezen J J J , Boon G d I A , Jansen J W C M , Bouma B N 
Published: July 2018

SummaryWe studied the profibrinolytic effect and the anti-thrombotic potential of retinoic acid in-vivo. Male Wistar rats were treated with retinoic acid either acutely or twice daily for a period of 5 consecutive days in a dose range of 0.01 to 3.0 mg/kg. Fibrinolytic activity was measured ex-vivo using the diluted blood clot lysis test and net t-PA activity in tissue extracts was measured in a spectrophotometric rate assay. Clot lysis was dose dependently increased by retinoic acid up to about 170% (relative to vehicle treated rats) at a dose of 3 mg/kg. No tachyphylaxis could be detected. Ex-vivo measured fibrinolytic activity after single administration of 1 mg/kg of retinoic acid peaked at 3 h after ingestion. Even after 18 h a significantly higher clot lysis rate was measured. Lysis of blood clots from vehicle and retinoic acid treated rats could be completely blocked by addition of tranexamic acid or antibodies against rat t-PA before clot formation. t-PA activity in plasma was slightly increased after retinoic acid treatment; no effects were measured on plasma PAI-1, u-PA, plasminogen, and α2-antiplasmin levels. t-PA activity in lung and kidney was marginally enhanced by retinoic acid but in heart and aortic tissue extracts t-PA activity was increased by about 50%. We confirmed this potential anti-thrombotic property in an in-vivo venous thrombosis model. A reduced clot size was observed after retinoic acid administration (35% reduction at a dose of 1 mg/kg). We could not detect any effect on ex-vivo measured platelet aggregation, bleeding time, prothrombin time, thrombin time, partial thromboplastin time or plasma fibrinogen level, indicating that there were no effects on platelet aggregation or blood coagulation. We conclude that retinoic acid enhanced fibrinolytic activity in-vivo by selectively enhancing t-PA activity and that retinoic acid is a potential anti-thrombotic agent in-vivo.
Production of Cryoprecipitate of Intermediate Purity in a Closed System Thaw-Siphon Process
Authors: Mason Ernest C , Pepper Duncan S , Griffin Brenda 
Published: July 2018

SummaryThe thaw-siphon procedure for routine production of cryoprecipitate is described briefly, and also its extension to a reproducible procedure for production of cryoprecipitates of intermediate purity. For the latter, the average yield of factor VIII is 60% of that in the prefrozon plasma and approximately 30% is present in the supernatant plasma. The product contains 0.53 units of VIII:C per mg of total protein (of which about 70% is clottable). The mean value of the ratio VIII:C/VIII:RAG is about 0.7. The yield and purity of the product compare favourably with those reported for intermediate purity factor VIII concentrates produced by large-scale plasma fractionation laboratories. The procedure offers an alternative pathway to the production of factor VIII concentrate of intermediate purity and can be operated in any blood bank with a minimum of equipment.
Studies on the Specific Fibrinolytic Effect of Human Extrinsic (Tissue-Type) Plasminogen Activator in Human Blood and in Various Animal Species in Vitro
Authors: Korninger C , Collen D 
Published: July 2018

SummaryHuman extrinsic (tissue-type) plasminogen activator (EPA) was highly purified from the culture fluid of a human melanoma cell line, both as a one-chain or as a two-chain molecule. Its specific fibrinolytic effect on human whole blood clots or plasma clots with different degrees of fibrin crosslinking was evaluated in an in vitro system, composed of a 125I-fibrin labeled clot, hanging in circulating human plasma. After infusion of EPA (30 IU per ml over 3 hrs), non-crosslinked clots lysed more extensively (75-100 percent in 5 hrs) than totally-crosslinked clots (50-65 percent), and no difference was found between one-chain or two-chain EPA. The extent of lysis of totally-crosslinked human or animal plasma clots hanging in autologous plasma induced by EPA varied markedly from one species to the other. When 90 IU of EPA were infused over 3 hrs, crosslinked human plasma clots dissolved for over 95 percent within 5 hrs. Under comparable conditions, the degree of lysis was 80 percent in primate plasma (cynomolgus fascicularis), 60 percent in cat and rabbit plasma, 30 percent in dog plasma and only 10 percent in rat plasma. Systemic activation of the fibrinolytic system in the circulating plasmas was minor and dose-dependent in all species, but complete fibrinogen breakdown was not observed in any species following infusion of up to 90 IU EPA per ml plasma.It is concluded that the human system is more susceptible to EPA induced fibrinolysis than the other animal systems which were investigated, and that even totally-crosslinked clots can be lysed after infusion of EPA.
Arachidonic Acid-Induced Chemiluminescence of Human Platelets: Contribution of the Prostaglandin and Lipoxygenase Pathways
Authors: Wörner P 
Published: July 2018

SummaryTwo signals of chemiluminescence are observed when platelets are exposed to arachidonic acid in the presence of luminol. Three groups of agents interfere with these luminescence responses. Inhibitors of cyclooxygenase, known to augment the turnover of arachidonic acid by lipoxygenase, inhibit the first and enhance the second signal of luminescence.Sodium azide, diamide, NEM, and the endoperoxide analogues U 44069 and U 46619 interfere with the second luminescence signal but not with the first one nor with the generation of MDA. These agents may represent selective inhibitors of the lipoxygenase pathway.Phenidone, nordihydroguaiaretic acid, quercetin, silybin, phenylthiazolyl-thiourea, and aminotriazole inhibit both luminescence signals promoted by arachidonic acid.Measurement of luminescence may provide a tool to follow the time course of arachidonic-acid turnover by prostaglandin synthetase and lipoxygenase in whole cells.
The Effect of Cod Liver Oil and Corn Oil on Platelets and Vessel Wall in Man
Authors: Brox Jan H , Killie Jan-Eirik , Gunnes Sigurd , Nordøy Arne 
Published: July 2018

SummaryTen healthy male subjects on an ordinary diet were given daily dietary supplement of 25 ml cod liver oil (CLO) or corn oil (CO) for periods of 6 weeks in a crossover study. Significant changes were observed in the plasma total fatty acid composition. The main platelet phospholipids fractions were also significantly altered, particularly by CLO with an increase of the eicosapentaenoic acid (EPA): arachidonic acid (AA) ratio. Both supplements reduced collagen induced platelet aggregation and TXB2 production, with CLO as the most potent one. No spontaneous release of an antiaggregatory substance or 6-keto-PcF1α from vein tissues were found, and the total urinary excretion of prostaglandin metabolites (E and F series) remained unchanged.
Studies of Phospholipid Reagents Used in Coagulation II: Factors Influencing Their Sensitivity to Heparin
Authors: Barrowcliffe T W , Gray Elaine 
Published: July 2018

SummaryThis study demonstrates the many technical variables which exist in the use of APTT reagents to detect and measure heparin. With the same phospholipid reagent different activation regimes produced significant differences in heparin sensitivity. The concentration of phospholipid was also an important influence; decreasing concentration led to increasing sensitivity, and the highest sensitivity was given by omitting the phospholipid altogether. Other factors which influenced the sensitivity to heparin were buffering of the reagents and the presence of oxidation products in the phospholipid. The results emphasize the need for standardisation of at least some of these variables if the APTT is to be used to determine the therapeutic range of heparin.
Activated Factor IX Complex in Treatment of Surgical Cases of Hemophilia A with Inhibitors
Authors: Hanna Wahid T , Madigan Robert R , Miles Marian A , Lange Robert D 
Published: July 2018

SummaryThree patients with severe hemophilia A with inhibitors to factor VIII were treated with activated factor IX complex. Bleeiling was controlled adequately during surgical procedures involving each of the three. Partial thromboplastin times showed a variable shortening and prothrombin times were significantly shortened to values less than normal. Hemostasis was substantiated by the use of epsilon aminocaproic acid. Neither anamnestic responses nor thrombotic complications were observed. A transient hypertension developed in two patients shortly after infusion with the activated factor IX complex.
Stability of Prostacyclin in Human Plasma and Whole Blood: Studies on the Protective Effect of Albumin
Authors: Orchard M A , Robinson C 
Published: July 2018

SummaryThe biological half-life of prostacyclin in Krebs solution, human cell-free plasma or whole blood was measured by bracket assay on ADP-induced platelet aggregation. At 37°C, pH 7.4, plasma and blood reduced the rate of loss of antiaggregatory activity compared with Krebs solution. The protective effect of plasma was greater than that of whole blood. This effect could be partially mimicked by the addition of human or bovine serum albumin to the Krebs solution. The stabilisation afforded by human serum albumin was dependent on the fatty acid content of the albumin, although this was less important for bovine serum albumin.
Turnover of Human Extrinsic (Tissue-Type) Plasminogen Activator in Rabbits
Authors: Korninger C , Stassen J M , Collen D 
Published: July 2018

SummaryThe turnover of highly purified human extrinsic plasminogen activator (EPA) (one- and two-chain form) was studied in rabbits. Following intravenous injection, EPA-activity declined rapidly. The disappearance rate of EPA from the plasma could adequately be described by a single exponential term with a t ½ of approximately 2 min for both the one-chain and two-chain forms of EPA.The clearance and organ distribution of EPA was studied by using 125I-labeled preparations. Following intravenous injection of 125I-1abeled EPA the radioactivity disappeared rapidly from the plasma also with a t ½ of approximately 2 min down to a level of 15 to 20 percent, followed by a small rise of blood radioactivity. Gel filtration of serial samples revealed that the secondary increase of the radioactivity was due to the reappearance of radioactive breakdown products in the blood. Measurement of the organ distribution of 125I at different time intervals revealed that EPA was rapidly accumulated in the liver, followed by a release of degradation products in the blood.Experimental hepatectomy markedly prolonged the half-life of EPA in the blood. Blocking the active site histidine of EPA had no effect on the half-life of EPA in blood nor on the gel filtration patterns of 125I in serial plasma samples.It is concluded that human EPA is rapidly removed from the blood of rabbits by clearance and degradation in the liver. Recognition by the liver does not require a functional active site in the enzyme. Neutralization in plasma by protease inhibitors does not represent a significant pathway of EPA inactivation in vivo.
Factor IX Alloantibodies Shorten the Bovine Thromboplastin Coagulation Time of Normal Human Plasma
Authors: Ørstavik Karen Helene 
Published: July 2018

SummaryWe have previously demonstrated that neutralization of factor IX in normal plasma by heterologous antisera shortens the one stage prothrombin time determined with bovine thromboplastin. In this study, a similar effect of homologous antibodies was demonstrated. Addition of plasma from two patients with hemophilia B- and an acquired inhibitor to factor IX gave a shortening of the prothrombin time of plasma from normal persons, compared to the prothrombin time determined after addition of control plasma from a patient with hemophilia B- and no inhibitor. Addition of inhibitor plasma had a similar effect on the prothrombin time of plasma from four patients with hemophilia B+ and one patient with hemophilia Br, but had no effect on the prothrombin time of plasma from ten patients with hemophilia B-. Complexes between factor IX and the human inhibitor could be demonstrated both before and after the coagulation with bovine thromboplastin. These complexes were demonstrated as a factor IX antigen with a reduced electrophoretic mobility in crossed immunoelectrophoresis against a rabbit antiserum to factor IX. The results demonstrate that normal factor IX loses the ability to act as an inhibitor in the coagulation with bovine thromboplastin after having formed a soluble complex with a homologous antibody, although the factor IX molecules still have antigenic determinants which are free to react with the rabbit antibodies.
Studies of a Fibrinolytic Enzyme from the Larvae of Lonomia achelous (Cramer) Using Chromogenic Peptide Substrates
Authors: Arocha-Piñango C L , Pepper D S 
Published: July 2018

SummaryA fibrinolytic agent purified from the haemolymph, hair secretion and whole body extract of Lonomia achelous (Cramer)cleaves various chromogenic peptide substrates. The best substrate were found to be pyro-Glu-Gly-Arg-pNA (S-2444) followed by D-Pro-Phe-Arg-pNA (S-2302) and Bz-Ile-Glu-(or) Gly-Arg-pNA (S-2222) designed for urokinase, plasma kallikrein and factor Xa, respectively. Using substrate S-2251 we also found a plasminogen activator.