bluuebunny/crossref_metadata_2025 huggingface dataset:
Elevated Plasminogen Activator Inhibitor (PAI), a Cause of Thrombophilia? – A Study in 203 Patients with Familial or Sporadic Venous Thrombophilia
Authors: Engesser L , Brommer E J P , Kluft C , Briët E
Published: June 2018

Two hundred and three patients with venous thrombophilia were investigated in order to find out whether an elevated plasma concentration of plasminogen activator inhibitor (PAI) could be a cause of their tendency to thrombosis. The patients were studied in an asymptomatic period about 3 months after their last thromboembolic episode. PAI activity was found to be elevated in 19 patients (9%), and a corresponding elevation of PAI-1 antigen was observed.

In 16 out of the 19 patients with elevated PAI activity, followup could be performed after an additional asymptomatic period of about 1 year: in eight patients the elevation of PAI was transient and in eight it was persistent. Out of the eight patients with a persistent elevation of PAI, seven had a positive family history of thrombosis. Investigation of these families excluded a hereditary elevation of PAI activity in two families. In only two other families was elevated PAI activity also found among family members. The occurrence of elevated PAI activity, however, did not coincide with the occurrence of thrombosis in these individuals: except for the probands, all investigated family members who had a history of thrombosis had a normal PAI activity.

We therefore conclude that, at least in our material, familial thrombophilia can not be attributed to an inherited, persistent elevation of the blood level of PAI.
DDAVP Induces Systemic Release of Urokinase-Type Plasminogen Activator
Authors: Levi Marcel , ten Cate Jan W , Dooijewaard Gerard , Sturk Augueste , Brommer Emile J P , Agnelli Giancarlo
Published: June 2018

The desamino-d-arginine vasopressin (DDAVP) induced enhancement of endogenous fibrinolysis is generally attributed to the release of tissue-type plasminogen activator (t-PA) from the vessel wall.

The observation of concurrent release of urokinase-type plasminogen activator (u-PA), which eventually might cooperate in the enhanced fibrinolytic activity, has not been reported thusfar.

In a preliminary study in two healthy human volunteers we found a 1.8-fold increase of urokinase-antigen (UK-antigen) and a 1.7-fold increase of plasmin-activatable pro-urokinase (pro-UK) activity to DDAVP intravenously. The plasma-peak levels coincided with the maximal t-PA level. These responses following infusion of DDAVP were subsequently confirmed in a randomized double blind cross-over study in six human volunteers. We conclude that u-PA is released by DDAVP concurrently with t-PA and that it is presumably from the same origin as t-PA i.e. endothelial cells. u-PA and t-PA may therefore cooperate in the enhanced fibrinolytic activity upon DDAVP infusion.
Effect of Heparin and/or Antithrombin III on the Generation of Endotoxin-Induced Plasminogen Activator Inhibitor
Authors: Gómez C , Páramo J A , Colucci M , Rocha E
Published: June 2018

It has been experimentally shown that endotoxin induces a significant increase in the blood levels of a plasminogen activator inhibitor (PAI). We evaluated the effect of different doses of heparin (5 to 20IU kg−1 h−1), antithrombin III (10 to 40 U kg−1 h−1 and 240 U/kg as bolus) and of a combination of the two on: 1) the elevation of PAI activity, 2) fibrin deposition in kidneys and 3) mortality in rabbits infused with E. coli lipopoly-saccharide. Our results show that heparin plus AT III is able to significantly reduce the generation of endotoxin-induced PAI activity in rabbits' circulation. Low dose of heparin and a bolus injection of AT III both cause a decrease in the generation of PAI at 2 but not at 6 hours of endotoxin infusion. Moreover, fibrin deposits in kidneys of animals receiving heparin plus AT III or a bolus injection of AT III were significantly reduced as compared to control rabbits. The association between low levels of PAI and decreased fibrin deposits is strengthened by the significant correlation (p < 0.05) found between these two parameters. Finally, the plasma levels of PAI activity at 2 and 6 hours of endotoxin infusion in surviving animals were lower than those observed in animals that died within 2 hours after the end of treatment. We conclude that heparin plus AT III partially prevents the endotoxin-induced generation of PAI activity which seems to correlate with the reduced presence of fibrin deposits in kidneys and with a reduced mortality.
Coated Pits and Vesicles Transfer Plasma Components to Platelet Granules
Authors: Behnke O
Published: June 2018

Electron microscopy of mammalian blood platelets after contrast enhancement with tannic acid after an initial fixation in glutaraldehyde and osmium reveals numerous coated pits (c.p.) and vesicles (c.v.), indicating a process of receptor-mediated endocytosis. The c.p. may be located at any site of the plasma membrane or the canalicular, surface connected membrane system. C.v. fuse with platelet granules without losing their coat. Evidence for a continuous transfer of ambient fluid to granules via c. p. and c.v. was obtained by the use of fluid-phase markers.

It is proposed that the endocytic process may play a role in blood platelet activation.
Stability of Plasminogen Activator Inhibitor 1 (PAI-1)
Authors: Lindahl Tomas L , Sigurdardottir Olöf , Wiman Björn
Published: June 2018

The stability of PAI-activity has been studied at different conditions. The inactivation followed first order kinetics. Lowering the temperature and decreasing the pH both, increased the stability of PAI-1 dramatically. Addition of the PAI-1 binding protein, vitronectin, to reactivated PAI-1, about doubled the halflife of PAI-1 at all conditions studied. In the presence of chloramine T, the inactivation of reactivated PAI-1 was very rapid. In this case the protective effect of purified vitronectin, human plasma or fetal calf serum, but not of bovine serum albumin, was pronounced. The stability of the spontaneously active high Mr form of PAI-1 (partially purified or in plasma), constituting a complex between PAI-1 and vitronectin, was quite similar to reactivated PAI-1 in the presence of vitronectin. Addition of pure vitronectin, human plasma or fetal calf serum to such material had no further stabilizing effect. Reactivated PAI-1, which was inactivated by incubation at physiological conditions could again be fully reactivated, in contrast to chloramine T-oxidized PAI-1, which was irreversibly inactivated.
Stimulation of Plasmin Catalyzed Conversion of SingleChain to Two-Chain Urokinase-Type Plasminogen Activator by Sulfated Polysaccharides
Authors: Rydzewski Andrzej , Takada Yumiko , Takada Akikazu
Published: June 2018

Influence of heparin, chondroitin sulfate C and dextran sulfate (MW 3,500 and 7,000) on plasmin catalyzed conversion of singlechain (scu-PA) to two-chain (u-PA) urokinase-type plasminogen activator and generation of plasmin in mixtures of scu-PA and Glu-plasminogen (Glu-plg) was investigated. Conversion of scu-PA to u-PA catalyzed by plasmin was enhanced by chondroitin sulfate C and heparin, maximally by 10-fold and 3-fold, respectively. Sulfated polysaccharides potentiated generation of plasmin in mixtures of Glu-plg and scu-PA, as well as enhanced plasminogenolytic activity of u-PA. The possible role of these interactions is discussed.
A Second Plasma Inhibitor of Activated Protein C: α1-Antitrypsin
Authors: van der Meer Felix J M , van Tilburg Nico H , van Wijngaarden Aat , van der Linden Irma K , Briët Ernest , Bertina Rogier M
Published: June 2018

Inactivation of activated protein C (APC) in normal human plasma was studied in the absence and presence of heparin. In the absence of heparin APC inactivation followed pseudo-first order kinetics. In the presence of heparin the neutralization of APC was found to be biphasic. Up to 500 nM APC could be readily inactivated in normal plasma, indicating that the concentration of the APC inhibitor must be higher than previously assumed. Plasma deficient in the protein C inhibitor (PCI-I, as described by Suzuki and coworkers) and deficient in p2-glycoprotein I still possessed APC neutralizing capacity, presumably through the formation of complexes of APC with another plasma protein as was demonstrated by immunoblotting with anti-protein C antibodies. Together these data made us to conclude that a second inhibitor of APC (PCI-II) must be present in normal human plasma. This second inhibitor should be heparin independent, have a relatively high plasma concentration and form complexes with APC.

Subsequently, we purified this PCI-II by isolating APC-PCI-II complexes from plasma deficient of vitamin K dependent proteins, PCI-I and β2-glycoprotein-I, to which purified human APC had been added. Purified PCI-II has a molecular weight of 50,000 daltons and aminoacid analysis revealed that PCI-II is identical with α1-antitrypsin (α1-AT). The second order rate constant for the reaction between purified α1-AT and APC was found to be 269 M−1 min−1 in the absence of calcium and 602 M−1 min−1 in the presence of calcium.

Finally, the analysis of the kinetics of APC inactivation in the plasma of a patient congenitally deficient in α1-AT (3% α1-AT antigen) revealed that there probably is a third inhibitor of APC in plasma, different from PCI-I and from α1-AT.
Impaired Fibrinolytic Capacity and Tissue Plasminogen Activator Release in Patients with Restenosis after Percutaneous Transluminal Coronary Angioplasty (PTCA)
Authors: Kirschstein W , Simianer S , Dempfle C E , Keller H , Stegaru B , Rentrop P , Heene D L
Published: June 2018

To assess the role of the fibrinolytic system in the pathogenesis of restenosis after percutaneous transluminal coronary angioplasty (PTCA), we determined the components of this system in a retrospective study, including 16 patients with restenosis (gr. A) and 19 patients with long-term success (gr. B). In both groups at baseline fibrinolytic activity (FA) is unchanged, whereas tissue plasminogen activator antigen (tPA-Ag) is significantly increased (gr. A: 147.0%; gr. B: 139.8%; p <0.01). Fibrinolytic capacity (FC) and tPA-Ag release are significantly reduced in the restenosis group (FC: 46.5%, p <0.05; tPA-Ag release: 48.3%, p <0.01) compared to normal controls as well as to gr. B (FC: 84.3%, p <0.05; tPA-Ag release: 79.0%, p <0.05).

Relating to the contact activation system, F XII (79.5%, p <0.05) is significantly, and F XI (82.3%) is clearly reduced in gr. A. Protein C (PC) is significantly elevated in gr. B (117.5%, p <0.05). There is a negative correlation between plasminogen activator inhibitor (PAI 1) and HDL-cholesterol (r = 0.37, p <0.05).

It appears, that there is a typical pattern of defective fibrinolysis in patients with restenosis after PTCA and that this might be a pathogenetic factor in the development of restenosis.
The Effect of n-3 Fatty Acids on Lipids and Haemostasis in Patients with Type lla and Type IV Hyperlipidaemia
Authors: Berg Schmidt E , Ernst E , Varming K , Pedersen J O , Dyerberg J
Published: June 2018

Plasma lipids and haemostasis were investigated in 17 patients with hyperlipidaemia before and after 6 weeks supplementation with 6 g n-3 fatty acids. Nine of the patients had type IIa and 8 had type IV hyperlipidaemia. No effect on plasma cholesterol, LDL- or HDL-cholesterol were seen, but plasma triglycerides decreased after n-3 supplementation. Apolipoprotein B increased and apolipoprotein A1 decreased after the oil supplement. The bleeding time was prolonged, but platelet aggregation was unaltered by n-3 fatty acids. Protein C activity increased in type II a and decreased in type IV after the supplement. Fibrinolysis was markedly depressed while von Willebrand factor antigen was reduced after intake of n-3 fatty acids.
Haemostatic Effects of Ketorolac with and without Concomitant Heparin in Normal Volunteers
Authors: Spowart K , Greer I A , McLaren M , Lloyd J , Bullingham R E S , Forbes C D
Published: June 2018

Ketorolac is a potent cyclo-oxygenase inhibitor used for the treatment of postoperative pain. It is known to have anti-platelet properties. The aim of this study was to determine the effect of ketorolac on haemostasis both alone and in combination with tow dose heparin in LZ healthy male volunteers. Each volunteer received the following drug combinations in a double blind, placebo controlled, cross over manner: ketorolac placebo/heparin placebo, ketorolac active/heparin placebo, ketorolac active/heparin active and ketorolac placebo/heparin active. Ketorolac significantly prolonged bleeding time, inhibited platelet aggregation to arachidonic acid and collagen and platelet thromboxane production. Heparin had no effect on bleeding time or platelet function, but significantly prolonged the kaolin cephalin clotting time and increased anti-Xa levels. Ketorolac had no effect on the kaolin cephalin clotting time or anti-Xa levels and no interaction was found between ketorolac and heparin in any of the investigations. The prolongation of bleeding time seen with ketorolac is unlikely, to be of any major clinical significance as almost all subjects remained within the normal range; however, it should be used with caution in subjects with haemostatic problems.
Heparin and Bleeding: An Association with Lipase Release
Authors: Barrowcliffe T W , Merton R E , Gray E , Thomas D P
Published: June 2018

The effects of four sulphated polysaccharides on bleeding time and lipase release in rabbits have been compared. Unfractionated heparin (UFH) and pentosan polysulphate both gave significant prolongation of bleeding times and high lipase release. Low molecular weight heparin had reduced effects on bleeding time and lipase release, while demialan sulphate had no influence on either parameter. There was a highly significant correlation (r = 0.97) between these two measurements.

These results suggest that the same structural featuresinfluence both the haemorrhagic and lipase-releasing properties of sulphated polysaccharides.
Factor VIII Procoagulant Protein Interacts with Phospholipid Vesicles Via its 80 kDa Light Chain
Authors: Kemball-Cook G , Edwards S J , Sewerin K , Anderson L O , Barrowcliffe T W
Published: June 2018

In a previous report, we detailed the fractionation of polyclonal human anti-Factor VIII :C into a component directed exclusively against the phospholipid-binding site on Factor VIII (PL-site antibody) and another directed at other sites (non-PL-site antibody). The location on the F.VIII molecule of its PL-binding site has now been studied by two different methods using this fractionated 125I-labelled anti-F.VIII: C Fab’.

The first method was modified from that of Weinstein et al. (Proc Natl Acad Sci USA 1981; 78: 5137-41), involving electrophoresis of F.VIII peptide-125I-Fab‘ A/F.VIII immunocomplexes in SDS-polyacrylamide gels. PL-site antibody reacted with F.VIII peptides of apparent Mr approximately 80 kDa and sometimes 160 kDa in plasma and concentrate, but not with larger peptides. Non-PL-site antibody, however, reacted with a range of peptides of apparent Mr 90 kDa to 280 kDa. In addition, when purified F.VIII containing heavy and light chains (HC + LC), and isolated LC peptides were analysed, PL-site antibody bound to LC peptides whereas non-PL-site antibody did not.

The second method used the antibody pools in immunoradiometric assays (IRMA’s) of purified F.VIII peptides. Both labels measured similar amounts of F.VIII: Ag in a sample of purified F.VIII containing both HC and LC; on assaying an HC preparation, however, PL-site label measured only 2% of F.VIII: Ag found by non-PL-site label, indicating that PL-binding sites are absent in HC preparations.

These results indicate that F.VIII binds to PL via its 80 kDa light chain.
Modifications of Extrinsic Pathway Inhibitor (EPI) and Factor Xa that Affect their Ability to Interact and to Inhibit Factor Vila/Tissue Factor: Evidence for a Two-Step Model of Inhibition
Authors: Warn-Cramer Bonnie J , Vijaya Mohan Rao L , Maki Steven L , Rapaport Samuel I
Published: June 2018

Inhibition of factor VIIa/tissue factor (TF) by extrinsic pathway inhibitor (EPI) requires the participation of factor Xa. Through this inhibition, factor Xa generated initially may feed back to suppress continuing generation of factor Xa via the extrinsic pathway during hemostasis. We have utilized chemical modifications of EPI and factor Xa to study the reactions responsible for inhibition. The data are consistent with a two-step model. First, EPI binds to factor Xa in a Ca2+ independent reaction in which the gla-domain of factor Xa does not participate. A functional active site on factor Xa and arginine residues on EPI are essential for this step. Then the factor Xa/EPI complex binds to factor VIIa/TF with resultant inhibition of its enzymatic activity. The gla-domain of factor Xa is essential for this step. Intact positively charged lysines on factor Xa may also be important
Coagulation Assays as Diagnostic Markers of Hepatocellular Carcinoma
Authors: Lefrère J J , Conard J , Mavier P , Bettan L , Beaugrand M , Gozin D , Lerable J , Dhumeaux D , Samama M
Published: June 2018

With the aim of improving the biological diagnosis of hepatocellular carcinoma (HCC), alpha-fetoprotein (AFP), des-gamma-carboxyprothrombin (DCP) and factor V levels were assayed in 119 patients with HCC and 60 cirrhotic patients without HCC. Among the patients with HCC, increased levels of AFP (>300 ng/ml) and of DCP (>15 mU/ml) vveie ubseived in 36% and 69% of the cases, respectively. None of the 60 patients without TTCC had increased AFP, and one had abnormal DCP; in this patient, DCP level returned to normal value after vitamin K1 injection. No significant correlation was found between increased AFP and DCP, thus indicating that the two tests complement each other for the diagnosis. A factor V level higher than expected from the reduced prothrombin time test of the patient was detected in 50% of patients with HCC and only 7% of those without HCC. No correlation was found between increased factor V and abnormal AFP or DCP The thrombin time, fibrinogen activity to antigen ratio, and polymerization index failed to differentiate between cirrhosis and HCC. We conclude that AFP, DCP and factor V may give complementary informations in the diagnosis of HCC, one of these markers at least being positive in 88% of the patients.
The Influence of Adrenaline on Gender Difference in Adenosine Diphosphate-Induced Aggregation of Platelets in the Rat
Authors: Oyekan A O , Botting J H
Published: June 2018

The role of adrenaline on the inhibitory effects of physiological levels of oestradiol on ADP-induced intravascular aggregation has been studied. Platelets from pro-oestrous female rats aggregated less than those from dioestrous and male rats. Following adrenalectomy, there was no longer any difference(s) in the aggregability of the platelets to ADP in any of the rats. Adrenaline infusion (20 mg kg−1 hr−1) restored platelet aggregation to preadrenalectomy levels in pro-oestrous rate. Measurement of spontaneous fibrinolytic activity of the plasma showed highest value in pro-oestrous rats. Adrenalectomy reduced, while adrenaline infusion increased the fibrinolytic activity. The results suggest that the inhibitory effects of oestradiol on intravascular aggregation are dependent on endogenous adrenaline possibly working through the fibrinolytic pathway.
Oxymetholone Therapy in Patients with Familial Antithrombin III Deficiency
Authors: Shibuya Akira , Ninomiya Haruhiko , Nakazawa Masaki , Nagasawa Toshiro , Yoda Yasuhiro , Abe Tsukasa
Published: June 2018

Three patients with familial antithrombin III (ATIII) deficiency, who also have histories of thromboembolism, were treated with oxymetholone in combination with warfarin. Thrombolysis was observed in one patient with acute thrombosis of inferior vena cava during the oxymetholone and warfarin therapy. No further thromboembolic episodes occurred in these patients after initiation of warfarin with or without oxymetholone. The levels of plasma ATIII, α1-antitrypsin, plasminogen and Cl-inactivator were significantly increased in all patients after the introduction of oxymetholone therapy. This suggests that oxymetholone augments anticoagulant and fibrinolytic activity. Hence we consider that oxymetholone in combination with warfarin may be possible thrombolytic therapy in patients with familial ATIII deficiency.
Abnormality of the N-Terminal Portion of von Willebrand Factor in Type IIA and IIC von Willebrand Disease
Authors: Takahashi Y , Kalafatis M , Girma J P , Meyer D
Published: June 2018

We have established a new analytical method which allows the characterization of von Willebrand factor (vWF) degradation fragments in minute amounts (10 μ1) of plasma, without the need for immunopurification of vWF. Plasma vWF was hydrolysed by S aureus V-8 protease (V-8 protease) and the cleaved fragments separated by SDS-agarose gel electrophoresis followed by staining with 125I-labeled polyclonal or monoclonal antibodies against vWF and autoradiography. Quantification of the amount of each product was estimated by counting the incorporated radioactivity following excision. V-8 protease limitedly hydrolysed vWF in normal as well as type I von Willebrand disease (vWD) plasma and produced two distinct fragments with identical electrophoretic and antigenic characteristics to those produced from purified vWF, i.e. a C-terminal SpII and a series of N-terminal Spill fragments (SpIIIa, b and c). The method was applied to further characterize the molecular abnormalities of vWF in eighteen patients with type II vWD. In seven individuals with type IIA and five patients with type IIC, Spill appeared significantly modified as compared to normal. In type IIA, there was a marked decrease or absence of SpIIIa and an increase of SpIIIb and c. In type IIC, SpIIIb was lacking. In three patients with type IIB and in three patients with type IID, there was no significant modification of Spill. In all cases, SpII was apparently not modified. In conclusion, the molecular abnormality of vWF in type IIA and IIC vWD appears to reside in Spill, the N-terminal portion of the vWF-subunit (residues 1 to 1,365).
A Study of the Effect of Ethamsylate (Dicynene) on the Bleeding Time, von Willebrand Factor Level and Fibrinolysis in Patients with von Willebrand’s Disease
Authors: Hutton Ronald A , Hales Mary , Kernoff Peter B A
Published: June 2018

Nine patients with clinically moderate or severe Type I von Willebrand’s disease were treated for 2 weeks with ethamsylate (2 g/day in four equal doses) and with a matched placebo in a randomised double-blind trial. Template bleeding time, von Willebrand factor activity (ristocetin co-factor) and antigen, euglobulin lysis time and type I tissue plasminogen activator inhibitor were determined before and at the end of each treatment period. None of these parameters showed any significant change attributable to ethamsylate. Thus, despite the fact that five patients thought subjectively that their bleeding symptoms improved during ethamsylate treatment compared to only one while on placebo, we obtained no evidence that the drug was of benefit to patients with von Willebrand’s disease
Interaction of Thrombin-Stimulated Platelets with Vitronectin (S-Protein of Complement) Substrate: Inhibition by a Monoclonal Antibody to Glycoprotein IIb-IIIa Complex
Authors: Thiagarajan Perumal , Kelly Kathleen
Published: June 2018

Platelets adhere to vitronectin substrate following activation with physiological concentrations of thrombin. Adhesion of activated platelets to vitronectin substrate is dependent upon the presence of divalent cations, the amount of vitronectin, and the duration of adhesion assay. The adhesion of platelets is inhibited by synthetic peptides containing the sequence of Arg-Gly-Asp. In addition, monoclonal antibodies to glycoprotein IIb-IIIa complex inhibit the adhesion of activated platelets to vitronectin substrate in a dose-dependent manner. These studies suggest that the glycoprotein IIb-IIIa complex on activated platelets may interact with vitronectin substrate through the Arg-Gly-Asp mechanism. Since vitronectin is present in the subendothelial matrix, it might be involved in platelet-vessel wall interactions
Interactions of Liposomes and Platelets
Authors: Reinish L W , Bally M B , Loughrey H C , Cullis P R
Published: June 2018

Rats were injected intravenously with liposomes of various compositions and sizes and blood platelet count measured. It was found that negatively-charged liposomal systems produced a transient reduction in platelet count in the first 5 minutes after injection which recovered by 60 minutes post-injection. This effect was most striking for multilamellar vesicles (MLV’s) containing phosphatidylglycerol (PG). Dose levels of 25 mg/kg of MLV’s containing 10 mole% PG caused the platelet count to drop from a control value of 1,086 ± 21 × 109/1 to 193 ± 14 × 109/1 by 2 minutes post-injection, an 82% decline. This thrombocytopenic effect was observed to diminish as vesicle size or vesicle dose was decreased. Positively-charged liposomes produced a less pronounced transient reduction in platelet count while neutral liposomes caused only a mild, transient platelet decline. This transient thrombocytopenic effect was not blocked by common anticoagulants and fibrinolytic agents but was pi evented by liposomal pretreatment. Radiolabeled platelet studies revealed that transient sequestration of platelets occurs in the liver and spleen 2 minutes after PG :EPC:CHOL MLV injection with a normalization of platelet distribution by 60 minutes post-injection. In vitro studies, using an automated blood counter suggest a transient association of liposomes and platelets occurring following injection. Liposomally-induced transient thrombocytopenia suggests a role for platelets in the biodistribution of liposomes.
An International Standard for Low Molecular Weight Heparin
Authors: Barrowcliffe T W , Curtis A D , Johnson E A , Thomas D P
Published: June 2018

An international collaborative study has been carried out with the aim of establishing an international standard for low molecular weight (LMW) heparin. Three preparations of LMW heparin were assayed against the International Standard for unfractionated heparin (UFH) by 25 laboratories in 13 countries, using nine different assay methods. The results confirmed previous findings of non-parallel assays, wide interlaboratory variability and differences between methods when LMW heparins are assayed against a UFH standard. Use of one of the LMW heparins as a standard for the other two gave parallel assays and much closer agreement between laboratories. The preparation in ampoules coded 85/600 was selected as likely to give the best agreement with the largest number of LMW heparins; potencies were assigned by taking the mean of all the anti-Xa assays, and the mean of the thrombin and APTT assays, to represent the two major groups of activities. Preparation 85/600 has been established by WHO as the 1st International Standard for LMW heparin, with potencies of 1,680 iu/ampoule by anti-Xa assays and 665 iu/ampoule by thrombin inhibition and APTT assays.
Impaired Fibrinolysis in Obstructive Jaundice - Evidence from Clinical and Experimental Studies
Authors: Colucci M , Altomare D F , Chetta G , Triggiani R , Cavallo L G , Semeraro N
Published: June 2018

Microvascular thrombosis is considered an important pathogenetic factor in renal failure associated with obstructive jaundice but the mechanisms leading to fibrin deposition are still unknown. The plasma levels of plasminogen activator inhibitor (PAI) in 29 patients with obstructive jaundice were found significantly increased as compared to 20 nonjaundiced patients. Fibrin autography of plasma supplemented with tissue plasminogen activator (t-PA) revealed that in icteric samples most of the added activator migrated with an apparent Mr of 100 kDa, corresponding to t-PA-PAI complex, whereas in control samples virtually all t-PA migrated as free enzyme. PAI activity detected in icteric samples is similar to the endothelial type PAI since it is neutralized by a monoclonal antibody against PAI-1.

Venous stasis in jaundiced patients was neither associated with an increase in blood fibrinolytic activity nor with a decrease in PAI activity. Immunologic assay showed that t-PA release was impaired in 3 out of 4 patients. In controls, venous occlusion induced an increase in both fibrinolytic activity and t-PA antigen and a reduction in PAI activity. Bile duct recanalization in jaundiced patients subjected to surgery was accompanied by a decrease in plasma PAI activity which paralleled the decrease in serum bilirubin levels. In nonjaundiced patients, surgical treatment did not cause significant changes in either parameter. Rabbits made icteric by bile duct ligation showed an early and progressive increase in plasma PAI activity indicating that obstructive jaundice itself causes the elevation of circulating PAI. It is concluded that obstructive jaundice is associated with a severe impairment of fibrinolysis which might contribute to microvascular thrombosis and renal failure.
Placental Transfer of Vitamin K1 and Its Implications in Fetal Hemostasis
Authors: Mandelbrot L , Guillaumont M , Leclercq M , Lefrère J J , Gozin D , Daffos F , Forestier F
Published: June 2018

Vitamin K status was evaluated using coagulation studies and/ or vitamin IQ assays in a total of 53 normal fetuses and 47 neonates. Second trimester fetal blood samples were obtained for prenatal diagnosis under ultrasound guidance. Endogenous vitamin K1 concentrations (determined by high performance liquid chromatography) were substantially lower than maternal levels. The mean maternal-fetal gradient was 14-fold at mid trimester and 18-fold at birth. Despite low vitamin K levels, descarboxy prothrombin, detected by a staphylocoagulase assay, was elevated in only a single fetus and a single neonate.

After maternal oral supplementation with vitamin K1, cord vitamin K1 levels were boosted 30-fold at mid trimester and 60 fold at term, demonstrating placental transfer. However, these levels were substantially lower than corresponding supplemented maternal levels. Despite elevated vitamin K1 concentrations, supplemented fetuses and neonates showed no increase in total or coagulant prothrombin activity. These results suggest that the low prothrombin levels found during intrauterine life are not due to vitamin K deficiency.
Altered Fibrinolysis in DVT: Influence of Site of Sampling
Authors: Han P , Koay E S C , Tsakok M , Aw T C , Wong L Y , Pradhan M
Published: June 2018

Alteration of the fibrinolytic system is considered to be important in the development of deep venous thrombosis (DVT). Using specific assays for tissue plasminogen activator (t-PA) activity, t-PA inhibitor (PAI) and t-PA antigen, we measured these activities in 16 women who developed DVT during their pregnancies. A group of 24 healthy females of comparable age was studied as controls. PAI was increased in 87% of these patients compared to the healthy controls. In some of these patients a defect in release of t-PA from vascular endothelium was found as well. The site at which blood was sampled for analysis appeared to be an important criterion in the ex vivo assessment of functional t-PA reserve and PAI levels, though relatively less so for the latter measurement. The unaffected lower limbs, relative to the unaffected upper limbs, showed an increase in PAI and a demonstrable decrease in t-PA release, both representing increased risk factors for rethrombosis. The affected lower limbs showed similar but more accentuated changes in these parameters.
Influence of Polymorphonuclear Leukocytes on the Metabolism of Arachidonate in Human Platelets
Authors: Oudinet Jean-Paul , Sraer Josée , Bens Marcelle , Ardaillou Raymond
Published: June 2018

The effect of the association of purified polymorphonuclear leukocytes (PMNL) with platelets on arachidonic acid (AA) metabolism was studied in the presence of various concentrations of this fatty acid. Both thromboxane B2 (TXB2) and 12-hydroxyeicosatetraenoic acid (12-HETE) were measured. In the presence of tracer doses of AA, addition of increasing amounts of PMNL to platelets inhibited in a concentration-dependent manner their 12-HETE and TXB2 production. This inhibition was not due to diversion of AA metabolism towards other pathways since, apart a negligible amount of 12,20-diHETE, no other product could be detected. Inhibition of piatelet-TXB2 synthesis by PMNL persisted at increasing concentrations of AA below 16 μM. Above this concentration, TXB2 production by platelets incubated alone diminished progressively. Addition of PMNL blunted in part this inhibitory effect and even resulted, above 16 μM AA, in an increased production of TXB2. In contrast with what was observed for TXB2 formation, the inhibition of 12-HETE synthesis persisted when PMNL and platelets were coincubated in the presence of high doses of AA (163 μM). At this concentration, 15-HETE generation became apparent for each cell type incubated separately and was markedly enhanced in the coincubation studies. The present investigation demonstrates that the presence of PMNL modifies the metabolism of arachidonate by human platelets. Moreover, this cell-cell interaction markedly depends on the concentration of substrate. PMNL in excess may attenuate synthesis by platelets of their toxic products.
Regulation of Plasminogen Activator Inhibitor-1 mRNA in Human Endothelial Cells
Authors: Berg E A van den , Sprengers E D , Jaye M , Burgess W , Maciag T , Hinsbergh V W M van
Published: June 2018

The plasminogen activator inhibitor (PAI-1) from endothelial cells is a potentially important regulator of plasminogen activator activity. Cultured human endothelial cells increase their PAI-1 production upon stimulation with LPS and TNF, agents that are known to cause an increase in PAI-1 levels in vivo.

We isolated a PAI-1 cDNA probe, and by RNA hybridization analysis studied the regulation of PAI-1 mRNA synthesis in human endothelial artery cells. Freshly isolated endothelial cells do not contain detectable amounts of PAI-1 mRNA, but after adherence and incubation for 18 h in growth medium produce considerable amounts of PAI-1 activity and contain PAI-1 mRNA levels comparable to those found in subcultured cells. When subcultured endothelial cells are incubated for 6 h with LPS or TNF, both species of PAI-1 mRNA increase 10 to 20 fold, while PAI-1 activity in the growth medium increases only 1.5 to 2 fold. Stimulation of endothelial cells in the presence of cycloheximide (CHX) results in superinduction of mainly the 3.0 kb PAI-1 mRNA. The 3' end of this mRNA contains a 60 bp AT-rich sequence, that resembles 3' sequences present in a number of other genes superinducible with CHX.
Circulating Osteocalcin During Oral Anticoagulant Therapy
Authors: Haarlem L J M van , Knapen M H J , Hamulyák K , Vermeer C
Published: June 2018

In this paper we present the following observations:

1) In sheep vitamin K-antagonists like phenprocoumon induce a decrease of the serum levels of osteocalcin (bone Gla-protein) and of the affinity of the circulating osteocalcin for hydroxyapatite.

2) In sheep vitamin K counteracts the effect of phen-procoumon on the blood coagulation system, but not that on the osteocalcin production.

3) In human subjects vitamin K-antagonists also lead to decreased levels of serum osteocalcin and a low affinity of the protein for hydroxyapatite.

4) These two variables reached steady-state levels within 24 h after the start of oral anticoagulant treatment and - at continu-ation of the therapy - they remained low for at least several years.
Cytofluorometric Identification of Plasmin-Sensitive Factor XIIIa Binding to Platelets
Authors: Kreager Julie A , Devine Dana V , Greenberg Charles S
Published: June 2018

We have investigated the binding of blood coagulation factor XIIIa to thrombin-stimulated platelets using cytofluorometric analysis. Washed thrombin-stimulated platelets bound exoge-nously added factor XIIIa in a calcium-dependent reaction. The expression of endogenous platelet factor XIII was also detected on the surface of thrombin-stimulated platelets. When fluorescence analysis was performed based on particle size, factor XIIIa bound to the surface of greater than 95% of particles which contained more than one platelet, but only 50% of single platelets. The binding of factor XIIIa to thrombin-stimulated platelets was inhibited by plasmin. Plasmin also inhibited thrombin-dependent expression of the factor XIIIa binding site on platelets. Experiments in which thrombin-stimulated platelets were incubated with factor XIIIa in the presence of 125I-dimethyl-casein or 3H-putrescine demonstrated that platelets bear both glutamyl and lysyl substrates for factor XIIIa. Thrombin increased the expression of factor XIIIa substrates by platelets. Plasmin inhibited both the expression of factor XIIIa substrates and degraded them. The binding of factor XIIIa to thrombin-stimulated platelets and the availability of factor XIIIa substrates on the platelet surface could provide a mechanism by which factor XIIIa stabilizes the hemostatic plug by promoting crosslinking reactions between platelet membrane proteins and adhesive glycoproteins. In contrast, plasmin inhibition of factor XIIIa binding and crosslinking could disrupt hemostasis.
Antithrombin III Avranches, a New Variant with Defective Serine-Protease Inhibition - Comparison with Antithrombin III Charleville
Authors: Aiach M , Roncato M , Chadeuf G , Dezellus P , Capron L , Fiessinger J N
Published: June 2018

A decreased plasma antithrombin activity in presence or in absence of heparin was discovered in a 47-year-old patient presenting with recurrent venous thromboembolism. The immunoreactive material (AT ΠΙ-IR) was normal. The same biological abnormalities were found in two relatives of the patient, leading to the diagnosis of hereditary qualitative AT III deficiency.

The propositus’ AT III was coeluted with normal AT III from an heparin-sepharose column. An additional step of ion-exchange chromatography on a Mono Q column using a FPLC system (Pharmacia, St-Quentin en Yvelines, France) allowed the purification of a protein which was homogenous in SDS-10% polyacrylamide electrophoresis gel (PAGE). AT III purified from propositus’ plasma, normal plasma and the plasma of the patient known to have an AT III variant with defective protease binding (AT III Charleville) were compared. The specific activities measured as heparin cofactor anti thrombin or factor Xa inhibition in absence of heparin were decreased to half the normal value.

Kinetic studies confirmed a decreased rate of thrombin inhibi-tion for both abnormal AT III preparations. SDS-PAGE experi-ments performed in purified system and immunoblots obtained from plasma showed that the two variants have different behaviour: in the case of AT III Charleville thrombin induced an apparent 5 Δ increase in molecular mass, probably due to a conformational change. AT III Avranches did not form stoechiometric complexes with thrombin, but was unmodified by the protease.
Blood Flow and Thrombosis
Authors: Goldsmith Harry L.
Published: June 2018

Platelet thrombi have been observed at bifurcations, constrictions and stenoses in the arterial tree where flow separation with accompanying vortex formation can occur. Hence, studies of the flow behavior of human blood cells in models of à vessel obstruction and a sudden expansion of a vessel lumen were carried out. These showed that the particles were subjected to first high, and then much lower shear stresses as they entered the vortices where the environment appeared favorable for the formation of aggregates.

The effects of high and variable shear stress on the release reaction and aggregation of platelets were therefore studied using cells labeled with C14-Serotonin suspended in Tyrodes-albumin undergoing oscillatory tube flow for 20 min at 37° C. There was no significant release of serotonin due to flow alone, but the thrombin-induced release of C14-activity was appreciably greater in suspensions subjected to shear rates > 2000 sec-1 than in control suspensions which had been incubated at rest. The synergistic effects of the shear flow were also noted in the presence of adrenaline, which increased the release reaction, and when [Ca++] was raised above the physiological level or acetyl salicylic acid added, which inhibited the release of serotonin.
The Hemostatic Effect of Bovine Peptide-B from Fibrinogen
Authors: OSBAHR A. J
Published: June 2018

Bovine peptide-B from fibrinogen was active in the hemostasis of rat tail arterioles. The time of bleeding exhibits an inverse log proportionality to the concentration of bovine peptide-B. The peptide produced a 10-fold decrease in the time of bleeding at the highest concentration tested. Prolonged incubation of the peptide with the system was unnecessary and it appeared to participate immediately as a hemostatic agent.

These findings suggest that hemostasis was due to vasoconstriction since coagulation time remained constant as the bleeding time decreased with increasing concentration of peptide-B. Bovine peptide-B is interpreted as a physiological substance which probably acts on some smooth muscle receptor.
Effects of Alpha and Beta Receptor Stimulating and Blocking Agents on Experimental Disseminated Intravascular Coagulation
Authors: Moriau M , Noel H , Masure R
Published: June 2018

In this experimental study on rabbits, we compare the haemostatic and histological changes observed in animals with disseminated intravascular coagulation (DIC) induced by thrombin perfusion (100 u/kg/hr during 3 hours) with or without preventive administration of alpha and beta receptor stimulating or blocking agents.

Both alpha and beta receptor stimulating agents enhance the disorders induced by thrombin alone, while alpha or beta blocking agents reduce them.

This favourable action is still more pronounced with the combination of these two last types of drugs.

The modifications observed appear to be related to changes in platelet function.
Effect of Induced Chronic Intravascular Coagulation on Plasminogen Activator in Dogs
Authors: Sun Nora C. J. , Bowie E. J Walter , Titus Jack L. , Owen Charles A.
Published: June 2018

Plasminogen activator activity in blood vessels of various organs was determined in three untreated (control) male dogs and in two male dogs that received a continuous infusion of canine brain thromboplastic emulsion for 2 weeks. Activator was measured by the speed and degree of lysis of fibrin films that were overlaid with slices of tissue. Depletion of vascular plasminogen activator occurred in the vena cava of treated dogs at the site of the tip of the catheter, which was surrounded by a clot. A decrease of activator was found in most organs and particularly in certain endocrine organs (thyroid, pituitary, and testis). Of organs that normally contained the most activator, the greatest depletion was found in the skin, lung, and penis. The wide variation of plasminogen activator activity in organs of normal dogs is described.
Electronic Platelet Counting after Isopycnic Differential Centrifugation A Simple Rapid and Accurate Method
Authors: De Bruyere M , Bellenot CL , Sokal G
Published: June 2018

A semi-automatized platelet counting procedure with the use of a Coulter Counter is described. Its originality consists in providing an electronic method of counting of the platelets after a differential centrifugation of the blood sample previously diluted with a hypertonic NaCl solution (density 1.053) which is isopycnic to platelet density. This procedure allows elimination of red and white cells without loss of platelets in the supernatant. The final platelet number can be calculated without further corrections.

The method is quick and does not require specially skilled technicians. A single technician can perform 40 counts in one hour. The reproductibility of the method is excellent and the coefficient of variation 2,4 %.

The accuracy and feasibility of the method is also sustained by two years’ experience in an haematological routine laboratory.
Erythrocytes and Blood Coagulation
Authors: Surgenor Douglas MacN.
Published: June 2018

The action of intact and hemolyzed red cells in in vitro clotting systems is analyzed against the background of the clinical manifestations of red cell procoagulants in incompatible transfusions and hemolytic anemias in man and in experimental animals. It is suggested that the nature of the lesion in the stroma may be of importance in determining the biological effects.
A Prospective Comparison of Four Methods for the Diagnosis of Deep Vein Thrombosis
Authors: Wu Kenneth K. , Hoak John C. , Barnes Robert W.
Published: June 2018

A simultaneous prospective study was undertaken to compare the accuracy, usefulness and limitations of four methods (125I-fibrinogen test, Doppler ultrasound technique, impedance phlebography and venography) for the diagnosis of acute and recurrent thrombophlebitis. We found that impedance phlebography was unreliable with an accuracy of 50% for the diagnosis of acute thrombophlebitis. The other three methods were reliable and had good correlation. Discrepancies among these methods were noted in recurrent thrombophlebitis. To determine whether the recurrence of symptomatology in these patients was due to an active process, the 125I-fibrinogen test was extremely useful since it detected acute thrombotic activity. As expected, both the Doppler technique and venography were insensitive for this purpose. We conclude that in evaluating patients with recurrent thrombophlebitis, it is important to perform an 125I-fibrinogen test which helps to avoid unnecessary anticoagulation.
Reversible and Irreversible Alterations of Human Plasminogen Indicated by Changes in Susceptibility to Plasminogen Activators and in Response to ∈-Aminocaproic Acid
Authors: Thorsen Sixtus , Kok Preben , Astrup Tage
Published: June 2018

Increasing concentrations of EACA produce a biphasic pattern of inhibition and enhancement of urokinase-induced lysis of bovine fibrin containing bovine plasminogen, while the inhibition of fibrinolysis induced by a porcine tissue plasminogen activator increases uniformly. The biphasic EACA pattern is also observed with human plasminogen in fibrinolytic and caseinolytic assays of urokinase. The biphasic EACA pattern produced with urokinase is related to the presence of a genuine form of plasminogen. The enhancement phase is caused by an increased rate of plasminogen activation in the presence of EACA. A brief treatment of genuine plasminogen with acid at ionic strength 0.15 results in an enhanced susceptibility to plasminogen activators and in a partial abolishment of the biphasic response. These acid-induced alterations of plasminogen seem to be reversed by acid dialysis at low ionic strength. Other preparations of plasminogen with enhanced susceptibility to activators have lost the ability to produce a biphasic pattern of inhibition and enhancement of urokinase-induced plasminogen activation in the presence of EACA and this ability does not return after acid dialysis at low ionic strength. EACA inhibits all plasmin preparations, whether prepared from genuine or altered forms of plasminogen, in the same uniform manner.

Our results show that different forms of plasminogen can be identified by differences in the susceptibilities to activators, by their response to EACA, and by the reversibility or irreversibility of the alterations.
Kinin-like Activities of the Synthetic Low Molecular Weight Fragment of Fibrinogen Degradation Products
Authors: Takaki Akira , Yamaguchi Tsuyoshi , Ohsato Keiichi
Published: June 2018

Some biological properties of a synthetic peptide based on an anticoagulant peptide obtained from fibrinogen degradation products by the action of plasmin are reported. This peptide produced smooth muscle contraction without the presence of bradykinin. The contraction caused by this peptide was not modified by atropin (10-6 g/ml), hyoscine (10-6 g/ml) and tetrodotoxin (2xl0-7 g/ml). A hypotensive effect was observed following the intravenous injection of the peptide into an anesthetized rat indicating that this peptide has an action similar to that of bradykinin though less potent.