bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for the Regulation of Urokinase and Tissue Type Plasminogen Activators by the Serpin, Protein C Inhibitor, in Semen and Blood Plasma
Authors: España Francisco , Estellés Amparo , Fernández Pedro J , Gilabert Juan , Sánchez-Cuenca Jaime , Griffin John H 
Published: July 2018

SummarySince the serine protease inhibitor, protein C inhibitor (PCI), is present in seminal plasma at ≈3 μM, complexes of PCI with urokinase (uPA) and tissue type (tPA) plasminogen activator were quantitated using sandwich enzyme-linked immunosorbent assays (ELISA’s). Seminal plasma (N = 10) collected in the absence of extrinsic inhibitors had a mean of 25 ± 5 ng/ml uPA: PCI, 76 ± 23 ng/ml tPA: PCI, and 4 ± 2 ng/ml of tPA complexes with plasminogen activator inhibitor-1 (tPA:PAI-l). 93% of the uPA and 17% of the tPA antigen in seminal plasma was in complex with PCI and, when complexation was inhibited by collecting semen into an 1,10-phenanthrolinium solution, 33% of the uPA and 7% of the tPA was complexed to PCI. Urine (N = 10) contained 4 ± 1 ng/ml uPA:PCI. In purified system, complexation of uPA and tPA to PCI paralleled the inhibition of the enzymes. In vitro studies in blood and seminal plasma showed that heparin stimulated complexation of uPA and tPA with PCI, suggesting that negatively charged glycosaminoglycans in blood vessels and in the reproductive system may regulate PCI reactions with uPA and tPA. These results suggest that PCI is a physiologic regulator of uPA and tPA in male reproductive tissues and raises questions about a potential role of PCI in human fertility and in uPA-dependent cell invasiveness.
Requirement for Both D Domains of the Propolypeptide in von Willebrand Factor Muitimerization and Storage
Authors: Journet Agnès M , Saffaripour Simin , Wagner Denisa D 
Published: July 2018

SummaryBiosynthesis of the adhesive glycoprotein von Willebrand factor (vWf) by endothelial cells results in constitutive secretion of small multimers and storage of the largest multimers in rodshaped granules called Weibel-Palade bodies. This pattern is reproduced by expression of pro-vWf in heterologous cells with a regulated pathway of secretion, that store the recombinant protein in similar elongated granules. In these cells, deletion of the vWf prosequence prevents vWf storage. The prosequence, composed of two homologous domains (D1 and D2), actively participates in vWf multimer formation as well. We expressed deletion mutants lacking either the D1 domain (D2vWf) or the D2 domain (D1vWf) in various cell lines to analyze the relative importance of each domain in vWf muitimerization and storage. Both proteins were secreted efficiently without being retained in the endoplasmic reticulum. Despite this, neither multimerized past the dimer stage and they were not stored. We conclude that several segments of the prosequence are jointly involved in vWf muitimerization and storage.
Resistance to Activated Protein C in Nine Thrombophilic Families: Interference in a Protein S Functional Assay
Authors: Faioni E M , Franchi F , Asti D , Sacchi E , Bernardi F , Mannucci P M 
Published: July 2018

SummaryNine thrombophilic patients who had had previous diagnoses of functional protein S deficiency were reinvestigated. The functional protein S assays gave dose-response curves that were not parallel to those of the reference plasma. The same pattern was true for approximately half of the first-degree relatives of the propositi. When protein S was extracted from the plasma of the patients by immunoabsorption, it had a normal ratio of functional activity to immunologic concentration. Restriction fragment length polymorphism analysis, informative in one family, showed no linkage between the protein S gene marker and the abnormal behavior of the protein S functional assay. All the propositi and 23/36 first-degree relatives were resistant to the prolongation of activated partial thromboplastin time induced by activated protein C. Furthermore, there was striking concordance in all patients and relatives between the abnormal pattern of the protein S functional assay and resistance to activated protein C. We conclude that a plasma-based functional protein S assay is sensitive to activated protein C resistance and this may lead to spuriously low results in the assay. In agreement with the results of others, this study indicates that resistance to activated protein C is a frequent hemostatic defect in selected thrombophilic populations.
Characterisation of a Novel Series of Aprotinin-Derived Anticoagulants
Authors: Stassen Jean Marie , Lambeir Anne-Marie , Matthyssens Gaston , Ripka William C , Nyström Åke , Sixma Jan J , Vermylen Jos 
Published: July 2018

SummaryPrevious investigations have indicated that interference with the initial level of the blood coagulation may lead to effective antithrombotic therapy. Recently a series of potential coagulation inhibitors derived from bovine pancreatic trypsin inhibitor (BPTI, aprotinin) was described. We have determined their inhibition constants, effects on coagulation assays, effects in an in vitro human thrombosis model and pharmacological profiles in hamsters. The aprotinin-derived analogues (4C2,7L22, 5L15, 6L15, 5L84) showed significantly increased inhibitory activity towards factor Xa, factor Vlla-tissue factor (TF) complex, factor XIa and plasma kallikrein or a combination of them, and a significantly decreased plasmin inhibition as compared to aprotinin. In the coagulation assays, 4C2 and 7L22 mainly inhibited factor Xa, 5L15 and 6L15 inhibited factor VIIa-TF complex and 5L84 inhibited factor Xa, factor VIIa-TF complex and the contact activation. In flow chamber experiments with human blood 7L22, 5L15, 6L15, 5L84 and rTAP significantly inhibited fibrin formation and platelet deposition on extracellular matrix from phorbol ester stimulated human endothelial cells both under high and low shear stress and in the presence of low molecular weight heparin. The pharmacological profiles of the aprotinin analogues and rTAP with a mean residence time of 64 to 140 min were not significantly different. Modification of an aprotinin analogue with PEG (5L15-PEG) resulted in a 10-fold decrease of the inhibition constant for the factor VIIa-TF complex and in a significant prolongation of the secondary half-life, while the initial half-life was unchanged.Thus the investigated aprotinin-derived coagulation inhibitors resulted in a series of combined coagulation inhibitors with a pharmacological behaviour, which justifies in vivo testing of their potential antithrombotic action, as reported in the accompanying paper.
Characterisation of a Novel Series of Aprotinin-derived Anticoagulants
Authors: Stassen Jean Marie , Lambeir Anne-Marie , Vreys Ingrid , Deckmyn Hans , Matthyssens Gaston , Nyström Åke , Vermylen Jos 
Published: July 2018

SummaryUpon vascular damage platelet activation and blood coagulation are initiated. Interference at the initial level of the activation of the coagulation cascade can result in effective inhibition of thrombus formation. The in vivo antithrombotic properties of a series of bovine pancreatic trypsin inhibitor mutants (BPTI, aprotinin) 4C2, 7L22, 5L15, 5L15-PEG, 6L15 and 5L84, as described in the accompanying paper, with a combined inhibitory activity on factor Xa, factor VIIa-tissue factor complex, factor XIa and plasma kallikrein were compared to rTAP, r-hirudin, heparin and enoxaparin in a platelet rich thrombosis model in hamsters.Platelet dependent thrombus deposition was quantified by dedicated image analysis after transillumination of the femoral vein to which a standardised vascular trauma was applied. After increasing intravenous bolus injections all tested agents, except for aprotinin, induced a dose dependent decrease of thrombus formation and a concomitant prolongation of the aPTT. From the linear correlation between these two parameters it was found that 5 out of the 6 tested aprotinin analogues, rTAP and r-hirudin completely inhibited thrombus formation at a therapeutical (2- to 3-fold) aPTT prolongation while 4C2, heparin and enoxaparin only inhibited thrombus formation for 40 to 50 percent at a 2-fold aPTT prolongation. Based on the calculated IC50 values for thrombus formation rTAP was found to be the most active compound in this model.It is concluded that acceptable interference at the initial level of the blood coagulation, e. g. within a therapeutical aPTT prolongation, can significantly inhibit platelet deposition at a site of vascular injury.
Secretion of Plasminogen Activators by Cultured Bovine Endothelial Cells: Partial Purification, Characterization and Evidence for Multiple Forms
Authors: Laug W E 
Published: July 2018

SummaryEndothelial cells were obtained from the aortae of newborn calves and cloned. High plasminogen activator (PA) activity was detected in the supernatant medium and the cell lysates of confluent cultures. The PA activity in the growth medium increased steadily during 12 hrs of incubation, indicating active enzyme secretion by these cells. Sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis of the concentrated medium demonstrated the presence of four plasminogen activators with apparent molecular weights of 77,000 (±3000), 43,000 (±2000), 26,000 (±1500) and 14,500 (±1500) respectively. The 43,000, 26,000 and 14,500 molecular weight forms could be converted to radioactive derivates by active site labeling with 3H diisopropyl fluorophosphate (3H DFP) while the 77,000 Dalton form took up only traces of this radioactively labeled compound. The 43,000 molecular weight form was partially purified by means of salt precipitation and gel filtration. This enzyme preparation activated plasminogen by proteolytic cleavage with maximum activity at pH 7.5-8.5 and demonstrated a specific activity of 80,000 CTA (Committee on Thrombolytic Agents) units/mg protein when tested on 125I-fibrin in the presence of plasminogen. This PA was rapidly and irreversibly inhibited by diisopropyl fluorophosphate (DFP), suggesting that it was a serine protease. The partially purified enzyme was extremely labile at temperatures from 0-60° C, but could be stabilized by lowering the pH to 3 or by the addition of albumin.
Successful Treatment of Raynaud's Syndrome with Prostacyclin
Authors: Belch J J F , Newman P , Drury J K , Capell H , Leiberman P , James W B , Forbes C D , Prentice C R M 
Published: July 2018

SummaryThere is evidence to suggest that platelet activation occurs in Raynaud’s syndrome. We evaluated the effect of prostacyclin (PGI2) a potent antiplatelet and vasodilator agent in 5 female patients with Raynaud’s syndrome. Outpatient visits were made at weekly intervals for 4 weeks. At the first visit buffer solution (Wellcome Laboratories) was infused intravenously for 5 hrs, thereafter three five hr infusions of PGI2 at a peak dose of 10 ng/ Kg/min were given. Six weeks after the infusions patients were reviewed. Symptomatic improvement, including healing of ischaemic ulcers, occurred in 4 out of 5 patients. Thermography confirmed an increase in hand temperature after PCI2. Subjective and objective improvement has persisted for at least 6 weeks after the last treatment.
The Effect of the Phospholipase Inhibitor Mepacrine on Platelet Aggregation, the Platelet Release Reaction and Fibrinogen Binding to the Platelet Surface
Authors: Winocour P D , Kinlough-Rathbone R L , Mustard J F 
Published: July 2018

SummaryWe have examined whether inhibition by mepacrine of freeing of arachidonic acid from platelet phospholipids inhibits platelet aggregation to collagen, thrombin or ADP, and the release reaction induced by thrombin or collagen. Loss of arachidonic acid was monitored by measuring the amount of 14 C freed from platelets prelabelled with 14 C-arachidonic acid. Mepacrine inhibited 14 C loss by more than 80% but did not inhibit thrombin-induced platelet aggregation and had a small effect on release. ADP-induced platelet aggregation did not cause 14 C loss. Mepacrine inhibited ADP-induced platelet aggregation by inhibiting the association of fibrinogen with platelets during aggregation. The effect of mepacrine on fibrinogen binding could be considerably decreased by washing the platelets but the inhibition of 14 C loss persisted. Platelets pretreated with mepacrine and then washed show restoration of aggregation to collagen. Thus, mepacrine has two effects; 1. it inhibits phospholipases, 2. it inhibits fibrinogen binding. Freeing of arachidonic acid is not necessary for platelet aggregation or the release reaction.
Studies on Human Factor VIII and its Antibodies Using Radiolabelling and Affinity Chromatography
Authors: Kavanagh M L , Wood C N , Davidson J F 
Published: July 2018

SummaryAn immuno-affinity chromatography method was used to isolate human factor VIII and its antibodies and the mechanism of the affinity system was investigated using iodine labelling.Rabbit antibodies to human factor VIII were insolubilised onto CNBr — activated Sepharose 2B which was used for the preparation of affinity columns. Both VIII:C and VIIIR:Ag were adsorbed onto such columns from factor VIII preparations. The subsequent application of immunoglobulin preparations containing human antibodies to factor VIII resulted in the adsorption of these antibodies onto the columns. Adsorbed material was eluted from the affinity columns with 0.2 M glycine - HCl, pH 2.3.When 125I-labelled factor VIII and 131I-labelled human antibodies to factor VIII were used in this affinity system, the eluted material could be separated into three fractions by gel filtration on Bio-Gel A 1.5 m. Fraction 1 occurred at the void volume position, fraction 3 at a position corresponding to the elution position of IgG and fraction 2 at an intermediate position. 131I-labelled material was present in all three peaks. 125I-labelled material was present mainly in peak 1, with a little in peak 2. The results support the view that VIIIR: Ag, which binds heterologous antibodies, is non-covalently linked to a smaller subunit, VIII.C, which binds homologous antibodies.
Haemostatic Clot Formation at Anastomosis of Synthetic Venous Graft in Defibrinogenated Dogs: A Scanning Electron Microscopic Study
Authors: Ishimaru S , Berglin E , Hansson H-A , Teger-Nilsson A-C , William-Olsson G 
Published: July 2018

SummaryA segment of the inferior vena cava was replaced by an expanded polytetrafluoroethylene graft in 13 dogs. Five of them served as a control group, while the other 8 were moderately or severely defibrinogenated with subcutaneous batroxobin. Plasma fibrinogen decreased to extremely low values throughout the experiment in the defibrinogenated dogs except in the moderately treated group in which it temporarily rose to 0.72-0.87 g/1 on the first postoperative day.Scanning electron microscopic observations of the haemostatic clot formed at the anastomoses of the graft revealed no significant morphological differences in platelet adhesion and/or aggregation between the three groups. These findings confirmed that platelets play a key role in primary haemostasis during defibrinogenation.The fibrin network was slightly diminished and only short fibrin filaments could be seen in the moderately and severely defibrinogenated groups respectively. These differences in composition of the clots are discussed in relation to their haemostatic capacity.
Multicenter Comparison of Five Functional and Two Immunological Assays for Protein C
Authors: Mannucci P M , Boyer C , Tripodi A , Viganò-D'Angelo S , Wolf M , Valsecchi C , D'Angelo A , Meyer D , Larrieu M J 
Published: July 2018

SummaryFive functional assays and two immunoassays for protein C (PC) were evaluated in parallel for the same plasma samples collected from healthy subjects, patients with congenital and acquired PC deficiencies or patients with conditions associated with high PC levels. For 7 patients starting warfarin therapy and for 15 patients during stabilized warfarin therapy, there were significant between-assay differences. For these groups immunoassays gave higher values than most functional assays and the latter also gave varied results, probably depending on their respective capacity for recognizing acarboxylated PC. On the other hand, there were no significant between-assay differences nor discrepancies between PC activity and antigen levels for healthy subjects (n = 39), patients with congenital PC deficiency (n = 10), myocardial infarction (n = 25), chronic liver disease (n = 19), disseminated intravascular coagulation (n = 35), in the post-operative period (n = 20) or in women taking oral contraceptives (n = 20). This comparison of PC assays indicates that PC levels measured by different functional or immunological assays are very close in the majority of clinical conditions, but not for patients on oral anticoagulants.
Evaluation of Monoclonal Antifibrin Antibodies by Their Binding to Human Blood Clots
Authors: Liau Chiau S , Haber Edgar , Matsueda Gary R 
Published: July 2018

SummaryThe primary goal of this study was to develop a method for evaluating fibrin-specific antibodies as thrombus detecting agents. The apparatus and assay conditions were chosen by testing antibody 64C5, which binds to the amino terminus of the fibrin beta chain, for its ability to bind to human blood clots. Using 125I-labeled antibody 64C5, the effects of antibody concentration, clot shape, clot mass, temperature, and flow rate were tested. Increased antibody binding was observed when antibody concentration, clot mass and temperature were increased. Under one set of conditions, six 125I-labeled monoclonal antifibrin antibodies (four specific for the beta chain, two specific for the alpha chain) were tested for their binding to retracted clots of human blood. Two radioiodinated antidigoxin antibodies were used as a control. Beta chain-specific antibody 59D8, which provided the highest level of binding to clot, bound 14-fold better than the control antidigoxin antibody. Neither alpha chain-specific antibody bound to clotted blood. To examine the in vivo relevance of the in vitro binding to clots, the uptake of antibody 64C5 was assessed for its binding to human fibrin clotted within the jugular vein of a rabbit. The correlation coefficient between in vitro and in vivo uptake as a function of clot weight was calculated to be 0.91. Thus, in vitro binding of monoclonal antifibrin antibodies to human blood clots was judged to be a realistic method for the comparison and selection of an ideal antifibrin antibody for detailed in vivo testing.
Randomized Double-Blind, Placebo Controlled Safety Study of a Low Molecular Weight Heparinoid in Patients Undergoing Transurethral Resection of the Prostate
Authors: ten Cate Hugo , Henny Ch Pieter , ten Cate Jan W , Büller Harry R , Dabhoiwala Nosjir F 
Published: July 2018

SummaryIn preparation for an efficacy study, the effect of the low molecular weight heparinoid Org 10172 on postoperative blood loss was assessed in a randomized double-blind, placebo controlled study in patients undergoing transurethral resection of the prostate (TURP). Org 10172 and placebo were given twice daily as i.v. injection for three postoperative days starting one hour preoperatively. Three doses of Org 10172 (800, 1600, and 2400 anti-Xa units b.d.) were evaluated against placebo in three consecutive patient blocks respectively. Each block consisted of 20 patients, 15 receiving Org 10172 and 5 patients placebo. The study was discontinued after 9 patients of the third block had completed the protocol because of excessive urinary blood loss. Data analysis showed a dose-dependent increase in postoperative haemoglobin loss, this was not significant for the 800 anti-Xa units b. d. dosage but was significant in those patients treated with 1600 (p <0.05) and 2400 anti-Xa units b.d. (p <0.01).It was concluded that the heparinoid Org 10172 caused a dose dependent increase in urinary blood loss following TURP.
Immunoaffinity Purification of Factor VIII Complex
Authors: Hornsey V S , Griffin B D , Pepper D S , Micklem L R , Prowse C V 
Published: July 2018

SummaryMurine monoclonal antibodies to human von Willebrand factor (vWf) were immobilised on Sephacryl S-1000. Various solutes were screened for their ability to elute 125 I-vWf from the immobilised antibodies. The most effective solutions were then tested to determine which allowed retention of factor VIII procoagulant activity (VIII: C) and activity of vWf measured by platelet aggregation in the presence of ristocetin (Ristocetin cofactor activity R.cof.). Finally, F VIII complex was purified from both plasma and cryoprecipitate by immunoaffinity chromatography under the selected conditions. The product had a specific activity of 45 units of VIII: C per mg of protein and 60 units of R. cof. per mg representing a 4000-fold purification from plasma. The fibrinogen and fibroneetin content were each less than 4% of the total protein with vWf accounting for 60% of the total protein in the final product. Multimer analysis of the product showed a similar pattern to normal plasma and contamination by murine monoclonal antibody was less than 300 ng per mg of protein. A novel product is thus obtained containing both clinically relevant VIII :C and R. cof. in a single vial whilst using only one specific monoclonal antibody.
Laboratory Screening of Inherited Thrombotic Syndromes
Authors: Mannucci Pier Mannuccio , Tripodi Armando 
Published: July 2018

SummaryThe prevalence of inherited thrombotic syndromes in the general population (1 in 2,500/5,000) appears to be higher than that of inherited bleeding disorders. The problems of their laboratory diagnosis are reviewed and a screening procedure is proposed. The most important candidates for screening are patients with unexplained venous thromboembolism at ages of less than 40-45 years, particularly when thrombotic episodes are recurrent. Screening must start from the exclusion of common acquired causes of thrombophilia. A negative family history does not exclude inherited thrombophilia, because the defects have a low penetrance and fresh mutations may have occurred in the propositi. Laboratory screening is based on a two-step procedure. The first step is aimed at detecting, preferably with specific functional assays. the most frequent and well established causes of inherited thrombophilia, i.e. deficiencies or dysfunctions of antithrombin III, protein C, protein S, plasminogen and fibrinogen. The tests included in the second step of the screening are aimed at detecting the less common or less well established causes of inherited thrombophitia (low heparin cofactor II, defective release of tissue plasminogen activator, and high plasminogen activator inhibitor). The simplest, more reliable and specific assay methods to be used in laboratory practice are recommended.