bluuebunny/crossref_metadata_2025 huggingface dataset:
Contribution of Platelets to the Cardiovascular Effects of ADP in the Rat
Authors: Dejana Elisabetta , Castelli Maria Grazia , De Gaetano Giovanni , Bonaccorsi Aurora
Published: July 2018

The contribution of platelets to the cardiovascular effects of ADP was investigated in rats in different experimental conditions. Following rapid i. v. bolus injections of ADP (from 0.001 to 0.03 mg/kg b. w.) only a dose-related fall in blood pressure could be detected. Increasing the dose of ADP (up to 1 mg/kg b. w.), platelet fall and changes in cardiac rhythm (bradycardia, A. V. blocks and ectopic beats) became evident. All these phenomena were rapidly reversed. Inhibition of platelet aggregation by a pyrimido-pyrimidine compound (SH 869) or thrombocytopenia induced by Busulfan or antiplatelet antiserum did not significantly protect the animals from the cardiovascular effects of ADP. The fall in blood pressure, however, was reduced. Adenosine, at equimolar concentrations, caused ECG changes similar to those induced by ADP with no platelet aggregation and a less pronounced blood pressure fall.

These results suggest that most of the cardiovascular modifications induced by rapid injection of ADP are largely independent of platelets. Platelets appeared to play a more important role when ADP was given for a longer period of time. A slow i. v. infusion of ADP (6 mg/kg b. w. for 10 min) was accompanied by platelet fall, cardiovascular collapse and ECG alterations typical of myocardial ischaemia. All these effects persisted throughout the ADP infusion but disappeared soon after its termination. They were almost completely inhibited in rats given SH 869 or made thrombocytopenic.

In conclusion, platelets seem to contribute to the cardiovascular effects of ADP only in certain experimental conditions. In others, the nucleotide’s direct effects seem more important.
Effect of 1-Methyl-2-Mercapto-5-(3-Pyridyl)-Imidazole (KC-6141) on Rabbit Platelet Aggregation in Vitro and Rat Platelet Retention
Authors: Umetsu Teruhiko , Kato Tadakatsu
Published: July 2018

Effect of l-methyl-2-mercapto-5-(3-pyridyl)-imidazole (KC-6141) on rabbit platelet aggregation in vitro and rat platelet retention were investigated.

In the in vitro study, KC-6141 inhibited ADP-induced aggregation by 27% at 5× 10−4M, being more active than dipyridamole but much less than adenosine. Inhibition of arachidonic acid-and collagen-induced aggregation by KC-6141 was more effective than that of ADP-induced one and its ED50 was 2.1×10−5 and 8×10−5M, respectively. KC-6141 was 10 and 4 times more potent than aspirin in arachidonic acid-and collagen-induced aggregation, respectively. The dose-response curve of KC-6141 was parallel to that of aspirin, suggesting it is an aspirin-like compound.

In the platelet retention study, a method for determining platelet retention in rats was devised so that platelet retention can be measured with a volume of blood as small as possible. By use of the method, effects of KC-6141, aspirin and dipyridamole were compared. When administered intraperitoneally at 100 mg/kg, KC-6141 indicated 54.8% inhibition of platelet retention, whereas aspirin and dipyridamole showed only 23.5 and 5.2% inhibition, respectively. On the oral administration at 200 mg/kg, KC-6141 inhibited by 60.8% and its ED50 was 125 mg/kg. The activity lasted over 32 hr.

The above results demonstrated that KC-6141 is a compound with more potent action on the platelet aggregation, as well as on the platelet retention than aspirin and dipyridamole – a known antithrombotic drug.
The Effect of Mitomycin C on Platelet Aggregation and Adenosine 3′, 5′-Monophosphate Metabolism
Authors: Hashimoto Shuichi , Shibata Sachiko , Kobayashi Bonro
Published: July 2018

The effect of Mitomycin C on aggregation, adenosine 3′, 5′-monophosphate (cyclic AMP) metabolism and reactions induced by thrombin was studied in rabbit platelets. Mitomycin C inhibited the platelet aggregation induced by adenosine diphosphate or thrombin. The level of radioactive cyclic AMP derived from 8-14C adenine or 8-14C adenosine increased after incubating intact platelets with Mitomycin G. Formation of radioactive adenosine triphosphate also increased though mitochondrial oxidation was not stimulated. Similar effect was observed also in rabbit liver. Mitomycin C failed to stimulate platelet adenyl cyclase but inhibited cyclic AMP phosphodiesterase in the absence of theophylline. In the platelets preincubated with Mitomycin C, thrombin-induced inhibition of adenyl cyclase, stimulation of membrane-bound cyclic AMP phosphodiesterase, and release of 250,000 dalton protein from platelet membranes were prevented. These results suggest that Mitomycin C will affect cellular membrane structure and function, and this extranuclear effect of Mitomycin C will lead to inhibition of aggregation in blood platelets.
Effect on Platelet Functions of Derivatives of Cyclic Nucleotides
Authors: Pareti F I , Carrera D , Mannucci L , Mannucci P M
Published: July 2018

Derivatives of cyclic nucleotides were evaluated for their ability to inhibit platelet aggregation and the release reaction. Derivatives substituted in position 8 (mainly 8-Br-cyclic GMP) were more active than 3’-5’ cyclic AMP, and their relative potency in inhibiting platelet aggregation and 14C-serotonin release was comparable to that of N62-0’-dibutyryl-cyclic AMP. Compounds substituted in position 6 or 2’-0 were not effective. The active compounds, which were also tested for their ability to stimulate platelet adenylate cyclase or to inhibit cyclic AMP phosphodiesterase, did not modify the intracellular levels of cyclic AMP. Since previous animal experiments have shown that these derivatives cause less side effects than cyclic AMP and its dibutyryl derivative in animals, it is suggested that modification of the cyclophosphate molecule might make it possible to find compounds active only on platelet function without interfering with other biological systems.
Ornithine Decarboxylase Activity in Cultured Endothelial Cells Stimulated by Serum, Thrombin and Serotonin
Authors: D’Amore P A , Hechtman H B , Shepro D
Published: July 2018

Ornithine decarboxylase (ODC) activity, the rate-limiting step in the synthesis of polyamines, can be demonstrated in cultured, bovine, aortic endothelial cells (EC). Serum, serotonin and thrombin produce a rise in ODC activity. The serotonin-induced ODC activity is significantly blocked by imipramine (10-5 M) or Lilly 11 0140 (10-6M). Preincubation of EC with these blockers together almost completely depresses the 5-HT-stimulated ODC activity. These observations suggest a manner by which platelets may maintain EC structural and metabolic soundness.
Tissue Thromboplastin Activity of Isolated Human Monocytes
Authors: Prydz H , Allison A C
Published: July 2018

Certain agents that induce spreading of or increased content or release of lysosomal enzymes from human monocytes also induce a dramatic increase in tissue thromboplastin content of the cells. The increase is inhibited by cycloheximide and actinomycin D and does not appear in granulocyte, lymphocyte or platelet populations treated in the same way. The effect of several other substances on the development of monocyte tissue thromboplastin activity is reported.
Treatment of Congenital Factor VII Deficiency with a New Concentrate
Authors: Mariani G , Mannucci P M , Mazzucconi M G , Capitanio A
Published: July 2018

A new factor VII concentrate, made from ACD plasma by a process involving successive absorptions of cryoprecipitate supernatant on DEAE Sephadex and of the resulting supernatant on Al(OH)3, was administered to 10 patients with severe factor VII deficiency. 5 patients received only one dose for treatment of a single bleeding episode, the remaining 5 were given multiple infusions (47) for spontaneous hemorrhages or for the prevention of surgical bleeding. In vivo factor VII recovery ranged from 43 to 126% (average 88%) of the assayed in vitro activity of the concentrate. A dose of 0.5 u/kg was found to produce a 1% rise of the plasma factor VII levels. The mean half-life on injected factor VII as assessed in 7 kinetic studies was 205 min (range 168-234). Spontaneous bleeding was easily controlled by the concentrate and major surgical procedures (two tonsillectomies) could be performed without complications. 1 patient developed HBsAg positive hepatitis, but otherwise no serious side effects were observed. Factor VII concentrate reduces the risk of precipitating circulatory overload associated with the use of plasma and avoids the unnecessary rise of factor II, IX and X which follows prothrombin complex concentrates.
The Effects of an Increase in Endogenous Oestrogen on the Haemostatic Mechanism
Authors: Toy J L , Davies J A , Hancock K W , McNicol G P
Published: July 2018

The effects on the haemostatic mechanism of rises in circulating human oestrogen in a group of women being treated for infertility with pituitary hormones were studied. Despite large but brief rises in oestrogen levels no changes were found.
Platelet-Binding of the von Willebrand Factor
Authors: Green David , Muller Hendrik P
Published: July 2018

The aggregation of platelets by the antibiotic, ristocetin, requires a plasma cofactor (VIII:vWF) and one or more specific binding sites on the platelet membrane. The interaction between VIII:vWF and the platelet was examined using VIII:vWF labelled with 125 I. In the presence of ristocetin (1.5 mg/ml), from 70 to 90% of the 125 I-VIII:vWF became platelet- bound. By contrast, only 21% was bound with thrombin (2.5 u/ml), and 2.2% with buffer alone. Fractionation of the platelets revealed that peak radioactivity was present in the membrane fraction. Treatment of ristocetin-reacted platelets with either chymotrypsin, 100 ug/ml, or trypsin, 75 ug/ml, resulted in the partial release of the membrane-bound radioactivity. It is concluded that VIII:vWF binds to the platelet membrane in the presence of ristocetin.
Creatine Phosphate in Rat Blood Platelets
Authors: Shibata Sachiko
Published: July 2018

Creatine phosphate (CP) was found in rat platelets by an assay method devised to increase the specificity and sensitivity. In this method, radioactivity of [14 C] ATP was measured after the reaction of CP with [14 C]ADP in the presence of creatine kinase. The mean value of the CP content in rat platelets was 24.8 nmoles per 109 platelets. Since the molar ratio of CP and ATP was 1:2.6, it is probable that CP plays a role in the energy metabolism of rat platelets.
Subcutaneous Ancrod after Operation for Fractured Hip - a Dose-Ranging and Feasibility Study
Authors: Lowe G D O , Morrice J J , Fulton A , Forbes C D , Prentice C R M , Barbenel J C
Published: July 2018

We have conducted a dose-ranging and feasibility study of daily subcutaneous injections of ancrod (Arvin) as a potential antithrombotic method in 28 patients following operation for fractured neck of femur. Sustained, predictable fibrinogen depletion during the first post-operative week was induced by four different regimes. A total dose of 10 units/kg weight, given in divided doses starting on the day of operation, is suggested as a possible antithrombotic regime. Ancrod treatment produced a rise in fibrinogen/fibrin degradation products, prolongation of the thrombin clotting time, and a fall in plasminogen, plasma viscosity, blood viscosity and haematocrit-corrected blood viscosity. A rise in plasma fibrinogen and corrected blood viscosity were observed in 14 control patients. Plasma fibrinogen was correlated with plasma viscosity and corrected blood viscosity. No adverse effects of treatment occurred. Subcutaneous ancrod appears to be a simple, safe, and feasible potential antithrombotic method, and merits trials of efficacy in the prevention of post-operative thromboembolism.
Evidence that Calcium Regulates Platelet Function
Authors: Detwiler Thomas C , Charo Israel F , Feinman Richard D
Published: July 2018

It is generally believed that calcium ions play a key role in regulation of platelet function.

This is based on 3 types of evidence.

1. Analogies with other cells. Calcium ions are known to trigger secretion and contraction in many cells, possibly reflecting a general role for calcium in all secretion and contraction.

2. Indirect evidence. Platelet aggregation and secretion are induced by divalent cation ionophores. The response to the ionophore A23187 is identical to that induced by other potent stimuli.

3. Direct evidence. Platelet activation can be blocked by drugs (e. g. certain local anesthetics) that block release of calcium ions from sarcoplasmic reticulum; the inhibition can be overcome by addition of extracellular calcium in the presence of a calcium ionophore. While this does not constitute definitive proof, the central role for calcium ions remains an attractive hypothesis that justifies attempts to further define calcium pools and fluxes in platelets.
Movement of Calcium Ions and their Role in the Activation of Platelets
Authors: Massini P , Käser-Glanzmann R , Lüscher E F
Published: July 2018

The increase of the cytoplasmic Ca-concentration plays a central role in the initiation of platelet activation. Four kinds of movements of Ca-ions are presumed to occur during this process: a) Ca-ions liberated from membranes induce the rapid shape change, b) Vesicular organelles release Ca-ions into the cytoplasm which initiate the release reaction, c) The storage organelles called dense bodies, secrete their contents including Ca-ions to the outside during the release reaction, d) At the same time a rearrangement of the plasma membrane occurs, resulting in an increase in its permeability for Ca-ions as well as in an increase in the number of Ca-binding sites.

Since most processes occurring during platelet activation are reversible, the platelet must be equipped with a mechanism which removes Ca-ions from the cytoplasm. A vesicular fraction obtained from homogenized platelets indeed accumulates Ca actively. This Ca- pump is stimulated by cyclic AMP and protein kinase; it may be involved in the recovery of platelets after activation.

It becomes increasingly clear that the various manifestations of platelet activation are triggered by a rise in the cytoplasmic Ca2+-concentration. The evidence for this and possible mechanisms involved are discussed in some detail in the contributions by Detwiler et al. and by Gerrard and White to this symposium. In this article we shall discuss four different types of mobilization of Ca-ions which occur in the course of the activation of platelets. In addition, at least one transport step involved in the removal of Ca2+ must occur during relaxation of activated platelets.
Dissociation of Factor VIII in the Presence of Proteolytic Inhibitors
Authors: Sussman Ira I , Weiss Harvey J
Published: July 2018

When gel filtration of factor VIII is performed with buffers of high ionic strength (1.0 M NaCl or 0.25 M CaCl2), the procoagulant activity elutes with proteins of relatively low molecular weight. It has been suggested that in the presence of proteolytic inhibitors, the procoagulant activity would appear at the void volume. To test this hypothesis, chromatography with buffers of high ionic strength was performed in the presence of benzamidine hydrochloride, soy bean trypsin inhibitor, heparin, DFP, and aprotinin. Under all of these conditions, the procoagulant activity continued to elute with proteins of low molecular weight. Similar findings were obtained after chromatographing cryoprecipitate prepared from the plasma of a normal subject who had received heparin. Thus, at present there is no direct evidence to suggest that proteolysis is involved in the dissociation of factor VIII by buffers of high ionic strength.
The Abnormal Factor IX of Hemophilia B+ Variants
Authors: Bertina Rogier M , Veltkamp Jan J
Published: July 2018

A rather large proportion of the hemophilia B patients can be characterized as hemophilia B+ because of the presence in their plasma of a protein which is immunologically identical with human factor IX. In a group of 33 hemophilia B patients we found 14 cases of hemophilia B+ belonging to 11 independent pedigrees. The variant factor IX molecules of these families have been compared with respect to the following properties: 1) factor IX activity and its dependence on phospholipid concentration; 2) factor IX antigen; 3) prolongation of prothrombin time with an ox brain thromboplastin; 4) electrophoretic mobility; 5) Ca2+ binding capacity; 6) affinity for binding to heparin and 7) susceptibility of the factor IX antigen to contact-induced activation. In the study of these parameters the use of a precipitating antibody against highly purified human factor IX showed to be of great value. According to our criteria at least 7 different factor IX variants were present in the 11 families with hemophilia B+ studied. Because of this rather high heterogeneity a suitable nomenclature for subclassification of hemophilia B+ variants is proposed.
The Binding of Calcium Ions to Bovine Factor X by Rate Dialysis
Authors: Yue Robert H , Gertler Menard M
Published: July 2018

The binding of Ca+2 to bovine factor X (molecular weight of 74,000) (Yue und Gertler 1977) was studied by the technique of rate dialysis and with the use of 45Ca+2. The binding data are consistent with a model of sequential mechanism. One mole of Ca+2 binds to the glycoprotein with a dissociation constant of 5.2 × 10-5 M and an additional 39 ± 4 moles of Ca+2 bind to this zymogen with a dissociation constant of 3.7 × 10-3M. The binding of the high affinity Ca+2 causes a functionally significant change in the zymogen, and (calcium) (factor X) complex is the real substrate in the activation process by the protease in Russell’s viper venom.
Identification of High Molecular Weight Derivatives of Plasmic Digests of Cross-Linked Human Fibrin
Authors: Regañon E , Vila V , Aznar J
Published: July 2018

Highly cross-linked human fibrin was digested with plasmin and the nine main components (labelled initially 1 to 9) were detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The components of greater molecular weight, bands 1 and 2, which are identified with fragments Y dimer and Y-D (270,000 and 220,000) contain three subunits which are joined by disulphide bonds which originate from the α, β and γ-γ-chains of cross-linked fibrin. They show a reaction of partial identity against anti fibrinogen fragment D-sera and anti fibrinogen fragment E sera. Bands 3, 4 and 5 correspond to three species of fragment D-dimer and have molecular weights of 175,000,160,000 and 130,000. Each of these species differs in the size of the γ-γ-chain remnants, while all maintain the cross-link between the γ-γ-chains. The remnants of a and β-chains of cross-linked fibrin remain the same in all three species. The components of electrophoretic bands 6, 7 and 8 correspond to three fragments, each with a different molecular weight and with common antigenic components against anti fibrinogen fragment D-sera; these are called D6 (90,000), D7 (75,000) and D8 (65,000) and are formed by α- and β-chain remnants of equal molecular weight and by γ-chain remnants with a different molecular weight for each fragment. The last fragment to be identified, corresponding to electrophoretic band 9 (50,000 molecular weight) corresponds to fibrin fragment E. The present report is in agreement with previous studies of plasmin digestion of highly cross-linked fibrin, but differs from them in number of fragments D-dimer which appear during the digestion.
Alterations in the Coagulation and Fibrinolysis System in Pregnancy Labour and Puerperium, with Special Reference to a Possible Transitory State of Intravascular Coagulation during Labour
Authors: Gilabert J , Aznar J , Parrilla J J , Regañon E , Vila V , Estelles A
Published: July 2018

Various tests of hemostasis were carried out during pregnancy, labour and the puerperium in a group of 259 women. Determinations were carried out in the 1st, 2nd and 3rd trimesters, in the period of dilatation, the expulsion period, the period of expulsion of the placenta and the immediate postpartum period of labour and on each of the first 5 days of the puerperium. It was confirmed that during pregnancy there is an elevation of the fibrinogen degradation producs (FDP) levels with a proportional increase in the numbers of positive protamine sulfate and ethanol tests. The proportion of positive protamine sulfate and ethanol tests reaches a maximum in the expulsion of the placenta coinciding with the presence of soluble complexes heavier than fibrinogen as detected by polyacrylamide gel electrophoresis and by column chromatography.

All this indicates that there is a transitory intravascular coagulation produced during labour reaching its maximum at the time of birth and tending to become normalized in the first few days of the puerperium.
The Effects of a Combined Alpha- and Beta-Blocking Drug, Labetalol, on Some Aspects of Platelet Function
Authors: Lote Knut , Svenson Birgit J , Ånstad Unni , Nordøy Arne
Published: July 2018

The effects of the combined alpha- and beta-adrenoreceptor blocking agent labetalol on human blood platelets as estimated by platelet aggregation, platelet count, bleeding time and platelet factor 3 activity were studied in 5 patients. The drug reduced adrenaline - induced platelet aggregation in vitro. However, it did not influence the above platelet function test in therapeutic plasma concentrations in vivo.
In Vitro and In Vivo Effects of Adrenaline and Phentolamine on Platelet Function
Authors: Ponari Oreste , Civardi Emilio , Megha Alessandro , Pini Mario , Poti’ Raffaele , Dettori Anton Giulio
Published: July 2018

In vitro and in vivo effects of adrenaline (ADR) on platelet aggregation, on platelet factor 3 (PF3) availability and on platelet factor 4 (PF4) release were studied in man. Inhibitory action of an alpha-blocker, phentolamine (PHEN) was investigated in the same conditions.

The threshold concentration (TC) of ADR inducing the typical two-phase response in aggregation tests when added to platelet-rich plasma (PRP) varied in different pools of plasma, but always induced an evident PF4 release and increased PF3 availability. A further increase in both parameters was obtained with higher concentrations but without any significant dose/response correlation.

Adding PHEN alone to PRP did not induce platelet aggregation or modify PF4 release induced by stirring, but it reduced PF3 availability. On the other hand, PHEN prevented the effects of ADR in different platelet tests, at appropriate concentrations.

Intravenous infusion of ADR lowered the TC, and increased PF3 availability and PF4 release. In vivo administration of PHEN, in contrast, increased TC and reduced PF3 availability, while PF4 remained unchanged.
Effect of Treatment with Activated Prothrombin Complex Concentrate (FEIBA) on Factor VIII-Antibody Level
Authors: Lechner K , Nowotny Ch , Krinninger B , Zegner M , Deutsch E
Published: July 2018

The influence of treatment with an activated prothrombin complex preparation (FEIBA) on the antibody level was studied in 10 haemophiliacs with an antibody to factor VIII. The antibody level was observed to rise at least once in five patients, while in the remaining five patients no rise occurred. In all, 6 out of 31 treatments were followed by an anamnestic rise of the antibody level, corresponding to 19.4%. A rise of the inhibitor level following FEIBA treatment is likely to occur in patients who show a marked antibody rise after factor VIII treatment (good responders), but have a low antibody level at the time of treatment. High doses of FEIBA and simultaneous transfusion of red cells may also enhance the likelihood of an anamnestic response. Stimulation of antibody production is probably due to the presence of small amounts of factor VIII in this preparation.
Fibrinolysis in Grafted Arteries and Veins
Authors: Risberg Bo
Published: July 2018

The fibrinolytic activity in autologous artery and vein grafts was studied in cats during a 4-month period. The fibrinolytic activity in the wall of an aortic segment interposed in the caval vein was increased in comparison to the normal aorta. In the corresponding segment of the caval vein interposed in the aorta, the fibrinolytic activity was reduced during the observation time. Thrombosed segments had a decreased activity. No changes were seen in sham operated animals. The plasminogen activator activity in the vessel wall was found to be influenced by the surrounding milieu.
Platelet Functions in Relation to Dietary Fats in Farmers from two Regions of France
Authors: Renaud S , Dumont E , Godsey F , Suplisson A , Thevenon C
Published: July 2018

To determine whether the long-term feeding of dietary fats affect platelet functions in man, platelet aggregation (to thrombin ADP, collagen, epinephrine) and clotting activity of platelet-rich plasma (PRP), platelet-poor plasma and of washed platelets, were studied in a mobile-laboratory in 44 healthy male farmers (40-45 years) from two French regions Var and Moselle, in relation to lipemia, glycemia, dietary nutriments, and platelet phospholipid composition. In the Moselle subjects, the platelet clotting activity of PRP and of washed platelets, the platelet aggregation to thrombin and ADP, were highly significantly (p <0.001) increased as compared to those of Var, but not the plasma cholesterol, which was identical in the two regions.

In Moselle, the intake of total calories, total lipids and saturated fats was higher than in the Var.

However, it was only with the saturated fat intake (mostly stearic acid) that the platelet clotting activity (p <0.01) and the platelet aggregation (p <0.001) were highly significantly correlated. The platelet clotting activity was also significantly (p <0.001) correlated with the fatty acid composition of the platelet phospholipid fractions phosphatidyl serine + phosphatidyl inositol.
Plasminogen Activator Inhibitor-1 Expression in Human Liver and Healthy or Atherosclerotic Vessel Walls
Authors: Chomiki N , Henry M , Alessi M C , Anfosso F , Juhan-Vague I
Published: July 2018

Individuals with elevated levels of plasminogen activator inhibitor type 1 are at risk of developing atherosclerosis. The mechanisms leading to increased plasma PAI-1 concentrations are not well understood. The link observed between increased PAI-1 levels and insulin resistance has lead workers to investigate the effects of insulin or triglyceride rich lipoproteins on PAI-1 production by cultured hepatocytes or endothelial cells. However, little is known about the contribution of these cells to PAI-1 production in vivo. We have studied the expression of PAI-1 in human liver sections as well as in vessel walls from different territories, by immunocytochemistry and in situ hybridization.

We have observed that normal liver endothelial cells expressed PAI-1 while parenchymal cells did not. However, this fact does not refute the role of parenchymal liver cells in pathological states.

In healthy vessels, PAI-1 mRNA and protein were detected primarily at the endothelium from the lumen as well as from the vasa vasorum. In normal arteries, smooth muscle cells were able to produce PAI-1 depending on the territory tested. In deeply altered vessels, PAI-1 expression was observed in neovessels scattering the lesions, in some intimal cells and in smooth muscle cells. Local increase PAI-1 mRNA described in atherosclerotic lesions could be due to the abundant neovascularization present in the lesion as well as a raised expression in smooth muscle cells. The increased PAI-1 in atherosclerosis could lead to fibrin deposit during plaque rupture contributing further to the development and progression of the lesion.
Effect of Concentration of Trisodium Citrate Anticoagulant on Calculation of the International Normalised Ratio and the International Sensitivity Index of Thromboplastin
Authors: Duncan E M , Casey C R , Duncan B M , Lloyd J V
Published: July 2018

The aim of this study was to determine whether the concentration of trisodium citrate used to anticoagulate blood has an effect on the INR of the sample and the ISI of the thromboplastin. Five thromboplastins including and Australian reference material were used to measure the prothrombin time of normal and patient samples collected into two concentrations of trisodium citrate - 109 mM and 129 mM. There was no effect of citrate concentration on the INRs determined with the reference material. However for the other four thromboplastins there was a significant difference between INRs for the two citrate groups. The prothrombin times of the samples collected into 129 mM were longer than those collected into 109 mM. This difference was only slight in normal plasma but more marked in patients receiving oral anticoagulants, causing the INRs for patient plasmas collected into 129 mM citrate to be higher then the corresponding samples collected into 109 mM citrate.

From orthogonal regression of log prothrombin times by the reference method against each thromboplastin, we found that the ISI for each thromboplastin was approximately 10% lower when determined with samples collected into 129 mM citrate than with samples collected into 109 mM. These results suggest that the concentration of trisodium citrate used for collection of blood samples can affect the calculation of the INR and the calibration of the ISI of thromboplastin. This was found both for commercial thromboplastins prepared by tissue extraction and for a recombinant tissue factor.
Inhibition of Thrombosis by a Selective Fibrinogen Receptor Antagonist without Effect on Bleeding Time
Authors: Tschopp Juerg F , Mazur Curt , Gould Kenneth , Connolly Raymond , Pierschbacher Michael D
Published: July 2018

Membrane glycoprotein αIIbβ3 on platelets plays a pivotal role in hemostasis by mediating RGD-(arginine-glycine-aspartic acid)-dependent platelet adhesion and aggregation. Antagonists of αIIbβ3 ligand binding function, such as antibodies, snake venom peptides, or synthetic RGD-containing peptides can completely inhibit platelet aggregation in vitro and cause significant prolongation of bleeding times when injected into experimental animals. The in vitro and in vivo properties of an αIIbβ3 specific RGD-containing peptide 2G (G(Ten)GHRGDLRCA) were compared to two non-specific RGD-containing peptides IN (G(Pen)GRGDTPCA) and 2H (GRGDSPDG). All three peptides have similar IC50 values in human patelet aggregation (14-22 μM) and ELISA-based μIIbβ3 receptor assays (0.2–0.3 αM) but show different inhibitory activity (IC50 values) in the αv㯂5 (2G = 10 μM; IN = 0.06 μM; 2H = 0.05 μM) and receptor assays (2G = 8.3 μM; IN = 0.06 μM; 2H = 0.04). The αIIbβ3 specific peptide 2G had no effect on monolayers of human saphenous vein endothelial cells while IN and 2H caused many cells to detach and contract. Peptides 2G and IN inhibited ADP-stimulated ex vivo platelet aggregation in dogs in a dose dependent manner. When complete inhibition (>90%) of ex vivo platelet aggregation was achieved with either a 10 mg/kg bolus followed by a 16mg/kg/h infusion of 2G or with a 15 mg/kg bolus and 24 mg/kg/h infusion of IN, peptide IN caused a dose-dependent increase of the template bleeding time, while peptide 2G had no effect, even at doses up to 15 mg/kg bolus followed by 24 mg/kg/h infusion. The in vivo properties of peptides 2G and 2H were also examined in a baboon ex vivo shunt model for their ability to block platelet uptake and fibrinogen deposition on small caliber GORE-TEX® grafts and for their effect on the hemostatic system. Systemic administration of peptide 2G at 10 mg/kg bolus followed by 10 mg/kg/h infusion (or at a 2-fold lower dose) abolished platelet uptake and fibrinogen deposition on the graft surface without affecting the hemostasis and template bleeding time of the animal. By contrast, peptide 2H caused a 3-4-fold increase in bleeding time at a dose of 10 mg/kg. The results suggest that efficacy and the effect of specific aIIbp3antagonists on bleeding time can be separated and that selective aIIbP3 receptor blockade may be an efficient and safe approach to improve the patency and the success rate pf small caliber vascular grafts and to treat unwanted platelet-dependent thromboses. While peptide 2G may represent a unique class of antithrombotic agent, the clinical use of this type of molecule would require a significant enhancement in potency.
Immune Tolerance in Hemophilia-Principal Results from the International Registry
Authors: Mariani G , Ghirardini A , Bellocco R
Published: July 2018

40 Hemophilia Centers from the USA, Canada, Europe and Japan referred to the International Registry 204 patients with haemophilia A, treated by Immune Tolerance (IT) Protocols over the past two decades because of the presence of an inhibitor to FVIII. 82% of the patients were high responders, while IT was started with low levels of inhibitor (<10 BU) in most (57.3%) of the cases. 69 patients (33.8%) were given the highest FVIII dosage (≥200 IU/kg/day), 71 (34.8%) intermediate dosages (50 - <200) and 64 (31.4%) the lowest dosages (<50). Of 158 patients persevering with treatment long enough to judge the outcome thereof, 107 (67.7%) achieved tolerance, 12 (7,6%) had a partial response, while 39 (24.7%) did not respond. Multivariate logistic regression analysis showed that two variables were independently associated with the highest probability of success: the use of high dose protocols (≥100 IU/kg/day) (p <.0001) and the presence of low levels of inhibitor (<10 BU) at enrollment (p = .004). The Kaplan-Meier inhibitor-free survival curve showed that tolerance is longlasting: only 1 out of 107 patients relapsed and the longest documented tolerant patient has been inhibitor-free for 16 years. 129 hemophiliacs were HIV Ab-negative at enrollment; of the 118 HIV-screened after the treatment, 18 (13.9%) were found to be HIV Ab-positive. IT can indeed modify the natural history of inhibitors to FVIII in hemophilia.
On the Rôle of Human Serum Plasminogen Activator During „Spontaneous” Activation of the Fibrinolytic System
Authors: Doleschel W , Auerswald W
Published: July 2018

The rôle of human plasminogen activator was studied during the “spontaneous” activation of a human euglobulin preparation at 25° and 37° C. The lytic activity of the solutions undergoing incubation was tested both on heated and on normal bovine fibrin plates. Taking into account the at least two times higher sensitivity of heated fibrin towards plasmin than of normal one as used in this investigation the respective activator activities were calculated from the diverging lytic effects on the two different types of plates. While with incubation at 25° C only low activator concentrations and slow conversion of plasminogen could be observed, at 37° C the increasing activator activity, which reached its maximum after 60 hours, was accompanied by a correspondingly fast formation of plasmin.
Macroscopie Studies of Platelet Aggregation. Nature of an Aggregating Factor in Red Blood Cells and Platelets
Authors: Øllgaard E
Published: July 2018

In in-vitro experiments, it has been shown that red blood cells and platelets contain a factor which, on addition to a sample of platelet-containing plasma and subsequent rocking of the test tube, causes an aggregation of the platelets which is visible to the naked eye. In equal volumes, the concentration of this factor has been found to be about 5 times as high in platelets as in red cells. The factor is thermostabile, non-protein in nature, and exerts its action independently of the process of coagulation. It is assumed to be carbohydrate in nature. White cells and, to a less degree, plasma and serum seem to be able to destroy the aggregating factor by an enzymatic process.

The aggregation is reversible, since white cells as well as certain enzyme poisons and Na+ can reverse the process without any apparent change in the appearance of the platelets. The process observed thus actually seems to be a form of aggregation.
Heparin Resistance, Thromboplastin Generation and Glass Activation
Authors: Gormsen Johs
Published: July 2018

Simultaneous studies of the heparin resistance, thromboplastin generation, the partial thromboplastin time and recalcification time in normal control persons and in patients with increased heparin resistance, before and after activation with celite, appear to indicate that heparin resistance is very dependent to a factor or factor systems bound to celite.
Inhibition du Purpura Thrombopénique Immunologique par l’Acide ε-aminocaproïque
Authors: Salmon J
Published: July 2018

L’acide ε-aminocaproïque inhibe le purpura thrombopénique immunologique. La pathogénie de ce dernier, que ne peut expliquer la seule thrombopénie, relève vraisemblablement de phénomènes fibrinolytiques, sinon d’une protéolyse non spécifique.
Influence of Blood Platelets on Fibrinolysis
Authors: Holemans Rudolf , Gross Rudolf
Published: July 2018

1. Human blood platelets contain a considerable amount of proactivator activity but no plasminogen activator activity or plasminogen. In test systems, containing streptokinase, the lysis of bovine fibrin is enhanced, depending upon the amount of platelets present.

2. The platelet proactivator is completely destroyed by heating during 15 min at 70° C. Washing of platelets reduces their proactivator activity; however proactivator activity can still be found after ten washings.

3. Bovine platelets do not contain proactivator activity. The similarity in the content in proactivator activity in plasma and platelets of both species, as well as the decrease of proactivator activity by washing, strongly suggests that the proactivator activity of human platelets is adsorbed on the platelet surface from the plasma.

4. Both in human platelets and in bovine platelets, antifibrinolysin can be found. This factor is thermostable and is only slightly diminished by washing. The platelet antifibrinolysin seems for its larger part to be located in the platelets; only a small fraction may be adsorbed on their surface.

5. The platelet antifibrinolytic activity can, depending upon the platelet concentration, be easily determined in systems containing urokinase or plasmin. Also in streptokinase-activated systems, bovine blood platelets have an inhibiting effect; human blood platelets inhibit streptokinase-induced fibrinolysis when their proactivator activity has been destroyed by heating. When streptokinase and unheated human blood platelets are tested on bovine fibrin the inhibitor effect is completely masked by the presence of proactivator.

6. The clinical significance of these findings with regard to fibrinolysis occurring spontaneously or induced by streptokinase infusion, as well as their importance for the differentiation of proactivator and human plasminogen are discussed.
Effect of Surface and Hageman Factor on the Endogenous or Spontaneous Activation of the Fibrinolytic System
Authors: Iatridis Sotirios G. , Ferguson John H.
Published: July 2018

The effect of wettable surfaces and Hageman factor on the activation of the fibrinolytic system was investigated.

The fibrinolytic activity was estimated mainly by the euglobulin lysis test. Experiments were carried out with Normal and Hageman-deficient plasmas.

The euglobulin lysis time of both plasmas was greatly affected by varying the surface exposure. Normal euglobulin suspension incubated at 37° C, and tested at intervals, showed an increase of fibrinolytic activity. The evidence suggests that this activity is related to the generation of endogenous activator. The rate of generation was a function of surface. Hageman-deficient euglobulin suspension, under the same conditions, did not generate endogenous activator.

Evidence is presented to show that Hageman factor is different from proactivator and plasminogen.

It is concluded that wettable surfaces and Hageman factor may have a role in the endogenous (or spontaneous) activation of the fibrinolytic system.
Quantitative Determination of the Amino Acids and other Ninhydrin Positive Substances in Normal Human Platelets
Authors: Gross R , Gerok W
Published: July 2018

In normal human platelets twenty amino acids and additionally taurine, phosphoethanolamine and phosphoserine were determined on a quantitative basis, using elution chromatography on ion exchangers.

The highest molar share goes to taurine, glutamic acid, alanine, aspartic acid, proline and serine. The other amino acids can be found in free form only in a low concentration in platelets.

The connection of these results with other investigations on the metabolism is discussed.
Immunochemical Studies on Proteins Important in Blood Coagulation
Authors: Barnhart Marion I. , Erson G. F , Baker W. J
Published: July 2018

This report draws attention to the fact that only minute quantities of purified serum proteins (1 —15 μg/kg body weight) are required to stimulate antibody production. Injection of amounts greater than 1 mg/kg either is a waste or favors the production of non-specific antisera. Potent antisera can be produced in rabbits with a single intramuscular injection using either Al(OH)3 gel or Amphojel as an adjuvant.

A number of purified plasma protein preparations which appear homogenous by ultra centrifugation or biological activity studies actually contain several antigenic components and are immunologically heterogeneous, when checked with highly specific antisera.

Fibrinogen prepared by alcohol fractionation and tannic acid purification was found to be free of prothrombin, antihemophilic factor and Profibrinolysin. Both Immunoelectrophoresis and double diffusion in agar indicated a homogeneous preparation.

Fibrinogens prepared from human, canine and bovine plasmas exhibited a low species specificity.
Accolement des plaquettes aux structures conjonctives périvasculaires
Authors: Hugues Jean
Published: July 2018

Ce travail est consacré à l’accolement des thrombocytes au tissu conjonctif. Les particularités de ce phénomène sont étudiées de même, partiellement, que son mécanisme.

La fixation sans délai des plaquettes au tissu conjonctif périvasculaire joue vraisemblablement un rôle important dans les premiers stades dé l’hémostase.
The Measurement of Fibrinolytic Activity with I131-labelled Clots. I. The Methods
Authors: Wit C. Dudok de , Krijnen H. W , den Ottolander G. J. H
Published: July 2018

The technical details of a method for the measurement of fibrinolytic activity with I131-labelled clots are described. The advantages of this modification of the method of Alkjaersig are discussed.
Procedures for the Quantitative Determination of Autoprothrombin C
Authors: Cole Edmond R , Marciniak Ewa , Seegers Walter H
Published: July 2018

Two quantitative procedures for autoprothrombin C are described. In one of these purified prothrombin is used as a substrate, and the activity of autoprothrombin C can be measured even if thrombin is in the preparation. In this procedure a reaction mixture is used wherein the thrombin titer which develops in 20 minutes is proportional to the autoprothrombin C in the reaction mixture. A unit is defined as the amount which will generate 70 units of thrombin in the standardized reaction mixture. In the other method thrombin interferes with the result, because a standard bovine plasma sample is recalcified and the clotting time is noted. Autoprothrombin C shortens the clotting time, and the extent of this is a quantitative measure of autoprothrombin C activity.
Molecular and Genetic Analysis of Two Patients with Bernard-Soulier Syndrome – Identification of New Mutations in Glycoprotein Ibα Gene
Authors: Kanaji Taisuke , Okamura Takashi , Kuroiwa Mika , Noda Masaaki , Fujimura Kingo L , Kuramoto Atsushi , Sano Masayuki , Nakano Shuji , Niho Yoshiyuki
Published: July 2018

We investigated two unrelated patients with Bernard-Soulier syndrome (BSS) by performing molecular and genetic analysis.

A flow cytometric and immunoblotting analysis showed GP Ibα to be absent from the platelet membrane of both patients. Other glycoproteins that formed GP Ib/IX/V complex were present on the platelets, but in decreased amounts. Therefore, GP Ibα gene from both cases was sequenced after PCR amplification and subcloning. We identified a homozygous mutation of a dinucleotide deletion within the TGTG repeat at cDNA number 972 to 975 in GP Ibα gene from Case 1. In Case 2, compound heterozygosity was demonstrated in GP Ibα gene; an insertion of a single base (T) at cDNA number 1,418 in one allele, and a deletion of a single base (A) within the 7-adenine repeat at cDNA number 1,438 to 1,444 in another allele. The three new mutations in both patients appeared to cause a frameshift, which created a new termination codon shortly thereafter, and thus lead to a GP Ibα deficiency on the platelet membrane. Truncated mutant proteins could be detected in the plasma and platelets of Case 2, but not of Case 1. According to these findings, it is thus supposed that the properties and conformation of additional COOH-terminal peptides, which were supposedly synthesized as results of the mutations, may have an important role on the processing of mutant GP Ibα in megakaryocytes and platelets.
Prospective Evaluation of the Prevalence of Haemostasis Abnormalities in Unexplained Primary Early Recurrent Miscarriages
Authors: Gris Jean-Christophe , Ripart-Neveu Sylvie , Maugard Claude , Tailland Marie-Laure , Brun Sophie , Courtieu Christophe , Biron Christine , Hoffet Méderic , Hédon Bernard , Marés Pierre
Published: July 2018

The prevalence of haemostasis abnormalities was evaluated in 500 consecutive women with unexplained primary recurrent miscarriages. Two matched reference groups with no antecedent of miscarriage were studied: 100 healthy mothers and 50 childless women.

In the prospective part of the study, we found 9.4% of the patients (95% C.I.: 6.8-12%) with an isolated factor XII deficiency, 7.4% of the patients (5.0-9.8%) with primary antiphopholipid antibodies, 47% of the patients (42.6-51.4%) with an insufficient response to the venous occlusion test and an isolated hypofibri- nolysis was found in 42.6% (38.2-47%) of the patients (reference groups: respectively 0/150, 3/150, 2/150, 2/150, pclO’3). Willebrand disease, fibrinogen deficiency, antithrombin, protein C or protein S deficiencies were not more frequent in recurrent aborters than in members of the reference groups. In the retrospective part of the study, cases of plasma resistance to activated protein C were not abnormally frequent.

Patients had higher Willebrand factor antigen (vWF), tissue-type plasminogen activator antigen (t-PA), plasminogen activator inhibitor activity (PAI) and D-dimers (D-Di) than the reference women. Values of vWF, t-PA, PAI and D-Di were altogether correlated but were not related to C-reactive protein concentrations. Among patients, those with an antiphospholipid syndrome and those with an insufficient response to the venous occlusion test had higher vWF, t-PA, PAI and D-Di values than the patients with none of the haemostasis-related abnormalities.

Thus, factor XII deficiency and hypofibrinolysis (mainly high PAI) are the most frequent haemostasis-related abnormalities found in unexplained primary recurrent aborters. In patients with antiphospholipid antibodies or hypofibrinolysis, there is a non-inflammatory ongoing chronic elevation of markers of endothelial stimulation associated with coagulation activation. This should allow to define subgroups of patients for future therapeutic trials.
Habutobin Splits the Arg16-Gly17 Bond in the Aa Chain of Rabbit Fibrinogen
Authors: Kinjoh Kiyohiko , Kosugi Tadayoshi , Nakamura Mariko , Hanashiro Kazuhiko , Sunagawa Masanori , Tokeshi Yoshihiro , Eguchi Yukinori
Published: July 2018

We reported previously that habutobin, a thrombin-like enzyme from Trimeresurus flavoviridis venom, clotted only rabbit fibrinogen, whereas human, monkey, bovine, dog, rat and guinea-pig fibrinogens were unaffected. In the present study, we investigated the cleavage site of the rabbit Aα chain by habutobin. The fibrinopeptide released by habutobin was identical to the fibrinopeptide A released by thrombin, and its amino acid sequence corresponded to Aα 1-16 of rabbit fibrinogen. It was clarified therefore that habutobin cleaves the Arg16-Gly17 bond in the Aa chain of rabbit fibrinogen.