bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Platelets and Fibrin in Uteroplacental Arteries in Normal Human Pregancy
Authors: Sheppard B.I. , Bonnar J.
Published: May 2019

In normal human pregnancy the uteroplacental vessels undergo extensive morphological adaptations to provide an increasing blood flow to the placenta. These involve platelets and fibrin adjacent to trophoblast invasion of spiral arteries.

In early pregnancy, single layers of platelets or small thrombi are seen between trophoblast cells which form a pseudo-endothelium of the spiral arteries. In the media trophoblast cells and fibrin are present in an amorphous matrix which replaces the musculo-elastic component of the vessel. In late pregnancy these vascular changes extend into the myometrium, fibrin deposition is increased and mature mural thrombi are found.

The fibrin deposition in uteroplacental arteries, is a physiological phenoncma of pregnancy. Fibrin may provide the dynamic structural support required in these vessels expanding to accommodate an increasing blood flow. Fibrin also enables the immediate collapse of the vessel following placental separation. Mural thrombosis in the arterial supplyprobably accounts for areas of ischemia and small placental infarcts found in normal pregnancy. Because of the large placental reserve, this minor degree of spiral artery occlusion does not appear to effect adversely the fetus.
An Abnormal Fibrinogen (Copenhagen) Associated with Severe Thromboembolic Disease, but with Normal Adsorption of Plasminogen
Authors: Hansen Sandbjerg M. , Clemmensen I.
Published: May 2019

An autosomally inherited qualitative fibrinogen (F) defect is presented. The abnormal F was detected in the plasma of a 54 year old woman with severe arterial thrombotic disease. A decreased rate of fibrin formation of plasma, or purified F by thrombin or ancrod (Arvin (R ) ) was demonstrated. The plasma F concentration was normal, when estimated by clottability or immunologic technique. No F related material was present in the serum. The purified abnormal F was indistinguishable from normal F by Immunoelectrophoresis or SDS Polyacrylamide gel electrophoresis. The major defects detected were an abnormality of polymerization of fibrin monomers and a decreased rate of release of fibrinopeptide A. To evaluate a possible abnormality of the binding of plasminogen (P) to the abnormal fibrin, we examined the adsorption of partially degraded P (Lys-P), which has a higher affinity for fibrin than Glu-P. The adsorption was normal, but the study might be useful in the evaluation of dysfibrinogenemia associated with venous thrombosis.
Hypersensitivity of Platelets to Arachidonate /AA/ in Acute Myocardial infarction /MI/
Authors: Szczeklik A. , Łukasiewicz W. , Serwonska M. , Musiaŀ J.
Published: May 2019

We studied for 17 consecutive days platelet aggregation induced by AA and compared it with that induced by ADP in 20 patients with acute MI. Within 3-7 days following MI platelets required less AA to aggregate irreversibly in vitro. They also aggregated to greater extent 3 min after addition of 2 μM ADP, although the initial velocity /Vmax/ following ADP was not increased. Threshold AA concentrations causing irreversible aggregation correlated with the extent of aggregation induced by ADP, but not with ADP-Vmax. No uniform pattern of behaviour of circulating platelet aggregates was noted. These results suggest that platelet hypersensitivity in MI might be due to the activation of AA mechanisms. Use of anti-platelet drugs in MI might prevent these changes in platelet function limiting in this way the extension of MI.
The Value of Urinary β-Thromboglobulin Measurements in Clinical Situations
Authors: Dawes J. , Smith R.C. , Borsey D. , Aronstam D.
Published: May 2019

Plasma β-thromboglobulin (ß -TG) measurements are subject to occasional false high values arising during sampling and processing. In the normal individual urinary β-TG is maintained at a constant low level (0.14 ± 0.09 ng. ml-1), and elevations in this value reflect raised plasma concentrations. Plasma and urinary β-TG concentrations were measured in normal individuals, in 18 patients presenting with suspected deep venous thrombosis, and in 75 diabetic patients. Serial samples were also taken before and after 9 hip replacement operations. The results indicate that measurement of urinary β-TG concentration in patients may be a simpler and more reliable means of detecting platelet activation than assay of plasma samples. False positive results do not occur when urinary concentrations are measured, unless renal function is abnormal;grossly elevated values may even detect occult renal disease.
Platelet Function in Arterial Vascular Disease
Authors: Jones N.A.G. , Zahavi J. , Haas de H.A. , Clark S.E. , Leyton J. , Kakkar V.V.
Published: May 2019

Plasma β-thromboglobulin (βTG) has been measured in 56 patients (mean age 63.6 years) with peripheral vascular disease (PVD) and 53 (Mean age 77.7) with recent and chronic cerebro-vascular disease (CVD). They were compared to 202 healthy subjects, 56 of whom were age and sex matched. In 33 of the PVD patients, platelet production time (PPT) heparin neutralising activity (HNA) and platelet aggregation (PA) induced by ADP, collagen epinephrine and thrombin were also measured. HNA was significantly shorter (p ≤ 0.0005) and plasma βTG higher (p ≤ 0.0005) in the PVD patients compared to the controls. The abnormal βTG was apparent (Wilcoxon test) only in 23 advanced PVD patients. In addition PPT was significantly shorter in 14 advanced PVD patients. The rate and extent of platelet aggregation in the PVD and plasma βTG in the CVD patients did not differ significantly from controls. There was no correlation between the four tests in the patients, suggesting that the tests were measuring various aspects of platelet function. These result indicate that in-vivo platelet consumption as well as platelet “release reaction” are enhanced in advanced PVD patients and may reflect a pre-thrombotic state.
Characterization of Cryofibrinogen Isolated from Patients Plasma
Authors: Stathakis N.E. , Karamanolis D. , Koukoulis G.
Published: May 2019

The oryofibrinogen (CF) of 27 patients (15 with cancer, 9 with septicemia and 3 with thrombosis) was studied, after appropriate washing, by SDS-polyacrylamide gel electrophoresis and immunochemical methods. Analysis of the isolated CFS, as well as of the protein left after heat or thrombin defibrination, before and after reduction, in Polyacrylamide gels showed that CF is composed mainly of fibrin(ogen)(Ff) and cold-insoluble globulin (CIg). The Ff formed, in part, stabilized oligomers interlinked through γ-γ dimerizaticn. The degree of Ff proteolysis, as judged by measuring the a/γ+γ-γ ratio of the reduced samples was equal to or even lower than that of the fibrinogen of the initial plasma. The presence of Ff and CIg as the sole components of CF was confirmed by immunodiffusion experiments. The CIg:Ff molar ratio in the CF was 0.042.+0.018. The CIg and the Ff of the CF were strongly and linearly correlated with the plasma CIg levels (r=0.94 and 0.89 respectively). The amount of Ff depended also on the plasma fibrinogen levels, particularly when >500 mg/100ml.
Coagulation Studies in Argentine Hemorrhagic Fever
Authors: Molinas Felisa C. , Bracco de Maria M.E. , Maiztegui Julio I.
Published: May 2019

33 patients with Argentine hemorrhagic fever (AHF) grouped into mild (18 cases), moderate (9 cases) and severe (5 cases) clinical forms were studied from day 6th to day 22nd after the onset of Symptoms. The evolution profile of the coagulation factors wns similftr in all AHF patients regardless of the clinical form. PTTK was prolonged in the early stages (

78.0 ± 5.8 see on day 6th and

47.5 ± 1.9 sec on day 14th). However, the values of F VIII, F IX and F XI ranged in the lower normal limits. Quick time, factors II and VII-X remained within the normal range. In contrast F V activity was greatly enhanced (

257.5 ± 54.7% on day 10th). Congulation alterations tended to normalize after 14 days of evolution. Fibrinogen profiles differed in the three clinical forma. In the moderate and severe AHF groups fibrinogen increased to a mean of 532 ± 30.3 and 472 ± 40.9 mg% on day 12th of evolution. No fibrin monomers nor fibrinogen degradation products were detected. The clotting system abnormalities were observed cnincidentally to the described alterations of the complement system. The present results indicate that if activation took place there was no evidence of thrombin formation.
The Evaluation of Hemostasis in Patients with Hepatic Cirrhosis
Authors: Stein Sidney F. , Harker Laurence A.
Published: May 2019

The hemostatic defects in 36 patients with biopsy-proven hepatic cirrhosis have, been characterized kinetically using autologous 51Cr-thrombocytes (T), 131I-fibrinogen (F) and 125I-plasminogen (P). Mean concentrations (C) and survival times (S) of all three components were shortened significantly (see table), although the (ranges) were broad compared with the (values in normal subjects). FS was sometimes prolonged beyond normal values suggesting impaired hepatic catabolism.

Thrombocytopenia was due to a combination of shortened S and increased splenic pooling that overwhelmed the two fold increase in production. Conversely, increased F production largely compensated for the shortened FS. PC was greatly decreased because both PS and P production were reduced. The mechanisms of destruction appear to be independent for each component since there was no correlation among TS, FS and PS, (r < 0.0156) and heparin therapy in 8 patients prolonged FS (p <0.01 ) without affecting TS (p > 0.9). (* x 10-3)
Management of Hemostase in Acute Liver Failure
Authors: Stemberger A. , Vogel G. , Fritsche H.M. , Fischer M. , Bottermann P. , Blümel G.
Published: May 2019

In coma hepaticum perfusion with baboon liver in by-pass is a last remaining possibility. In order to maintain hemostase in the extra corporal circuit heparin was found to be necessary. This is of interest since clotting tests are prolonged and clotting factors like X,XIII and AT III are often based to zero values. AT III* was substituted with 250-500 AT III units every 3 hours resulting in 40-80 % of normal range and heparin was given in a dosage of 500-750 USPE hep./h resulting in 0.1-0.2 USPE hep./ml plasma. The therapy was monitored 4-8 times per day by chromogenic substrates. Further analysis of factor X, AT III heparin and hematocrit was performed in the arterial and venous part of the liver in by-pass. After blood passage there was a significant reduction of heparin; factor X,AT III and hematocrit showed constant values. With the controlled AT III substitution and minimal heparinization thrombus formation in the liver in bypass was never observed, hemostase was maintained, but the fate of the patients depended on liver regeneration.

* kindly provided by Behringwerke and Kabi.
Mechanisms of Human Blood VII Activation in Plasma During Contact Activation, Clotting and Exposure to Cold
Authors: Seligsohn U. , østerud B. , Brown S.F. , Griffin J.H. , Rapaport S.I.
Published: May 2019

Factor VII(VII) is activated, giving shorter clotting times with tissue factor, when plasma is exposed to kaolin, is clotted or exposed to cold. The mechanisms involved were studied. Incubation of plasma with kaolin resulted in: No activation in XII deficiency plasma (dp), partial activation (2.5 fold) in Prekallikrein (PK) dp and High Molecular Weight Kininogen (HMWK) dp, and 4.5-9 fold activation in normal or other dp. Clotting plasma by recalcification resulted in: No activation with XII dp, HMWK dp, XI dp and IX dp, and 4-5 fold activation with VIII dp, X dp and V dp. The mechanism of cold promoted activation of VII in plasma was studied by adding purified 125-XII or 125I-IX to plasma before storage at 4° and observing the extent of their proteolysis (a measure of activation) from their radioactivity profiles on reduced Polyacrylamide gels following electrophoresis in the presence of SDS. Significantly greater 125I-IX and 125I-XII proteolysis was observed in plasma from 4 subjects whose VII activated in the cold, than in plasma from 5 subjects whose VII was not activated in the cold. Addition of anti-IX antiserum inhibited 50% of the observed cold activation of VII. Thus, with kaolin XIIa was the principal activator of VII; after clotting IXa was the principal activator and in cold activation both XIIa and IXa played roles.
PGI2 Production and Effect of Aspirin on Endothelial Cells and Non-Endothelial Cells of the Vessel Wall
Authors: Buchanan H.R. , Dejana E. , Cazenave J-P , Mustard J.F. , Hirsh J.
Published: May 2019

We have studied prostacyclin (PGI2) production and its inhibition by aspirin (ASA) by endothelial cells (EC) and cells of the de-endothelialized vessel wall (non-endothelial cells (NEC)} in arteries (ART) and veins. Segments of ART and veins were obtained from rabbits 15 min, 1,3,6 or 20 hrs after ASA (100 mg/kg, IV). The EC were separated from the vessel wall as a complete monolayer using a cellulose acetate paper/cell adhesion method. PGI2 was quantitated by a thrombin-induced 14C-5HT release assay. ART EC produced 1.13 ± 0.12 ng PGI2/100 mm2 (2.15 ± 0.09 × 105 cells) (mean ± SE, n = 18). Vein EC produced 0.52 ± 0.06 ng PGI2/100 mm2 (1.34±0.08 × 105 cells). After ASA, PGI2 production was maximally inhibited in both ART and vein EC for 6 hrs and was almost restored to control levels by 20 hrs. ART and vein NEC produced 1.54±0.15 and 0.77 ± 0.08 ng PGI2/100 mm2 respectively. After ASA, ART NEC production was maximally inhibited for 6 hrs and was restored to 56% of control levels by 20 hrs. In contrast, PGI2 production by vein NEC was maximally inhibited for only 1 hr after ASA and was restored to control levels by 6 hrs. This data demonstrates that vessel wall cells other than EC produce PGI2 in both veins and ART and suggests that the turnover of cyclo-oxygenase in vein NEC is more rapid than EC and ART NEC PGI2 production by NEC may be an important source of PGI2, particularly when the vessel wall is transected or the EC are removed.
Effect of Indobufen (K 3920) A New Antiplatelet Agent After Oral Administration in Patients with Vascular Diseases
Authors: Coccheri S. , Fortunato G.C.
Published: May 2019

The antiaggregating effect of a new butyric acid derivative, indobufen (K 3920), was investigated in 30 patients with vascular diseases. A between-patient study was performed by administering 50 mg b.i.d. or 100 mg b.i.d. for 14 days to 2 groups of patients. A series of platelet function and clotting parameters were recorded at the end of the treatment period, both 2 and 24 h after the last administration.

A marked inhibition of platelet aggregation was observed in both groups, as shown from the significant changes in maximal amplitude, reaction time and slope of ADP- and collagen-induced aggregation wave.

Similar results were observed at the Breddin test in both groups of patients and at all experimental times.

Platelet adhesiveness was also reduced and circulating platelet aggregates were normalized in all patients who had abnormal basal values.

A shortening of euglobulin lysis time was observed 2 h but not 24 h after administration of both doses.

Tolerability was excellent.

Indobufen appears to be a promising drug for treatment of vascular diseases where platelet aggregation is involved.
Warfarin Versus Warfarin and Dipyridamole on the Incidence of Arterial Throms Embolism in Prosthetic Heart Valve Patients
Authors: Rajah S.M. , Sreeharan N. , Rao S. , Watson D.A.
Published: May 2019

The effect of Warfarin (W) was compared with a combination of Warfarin and Dipyridamole (W+D) on the incidence of arterial thrombo-embolism in patients with prosthetic heart valves in a prospective randomised study. Sixty-four and 53 patients were allocated to W and W+D. The two groups were comparable as regards age, sex, arrhythmias and site and type of valves. The dose of W was determined by regular monitoring of prothrombin ratio 0.9 - 3) and that of D by monitoring serum D levels to between 2 and 4 μmol/l. The mean period of follow-up was 26.98 months (range 1 to 36) for W and 22.02 months (range 1 to 36) for W+D. Six patients in W and 1 in W+D developed arterial thrombo-embolic episodes giving an incidence of 0.0035 per patient month for W and 0.0009 per patient month for W+D. An actuarial analysis of the yearly incidence of thrombo-embolism confirmed the superiority of W+D over W. Of the 6 failures in W, 5 were in sinus rhythm and 1 in atrial fibrillation and all had cerebral embolic episodes. The failure in W+D was a patient in atrial fibrillation who died suddenly 6 weeks after surgery and the post-mortem showed clots on both mitral and aortic prostheses.
COllagen-induced Platelet Behaviour
Authors: Taylor Patricia M. , Heptinstall S.
Published: May 2019

A comparison has been made of the extent to which collagen induces human platelets to aggregate (change in light absorbance) and to undergo the release reaction (release of 3H-serotonin) in heparinised platelet rich plasma which had been depleted of divalent cations by treating with Chelex 100 chelating resin (Ch.PRHP) and in Ch.PRHP to which different concentrations of CaCl2 or MgCl2 had been added.

Platelet aggregation required extracellular Ca++; Mg++ could only support aggregation when Ca++ was also present. The release reaction occurred via Ca++-dependent and Ca++-independent pathways. The divalent cation requirement for Ca++-dependent release was the same as for aggregation.

The extent to which platelets aggregated and were induced to undergo release varied with the concentration of extracellular Ca++ or Mg++. A plot of extent of aggregation or of release against concentration of Ca++ or Mg++ has an inverted ‘U’ shape. In any one experiment there was good correlation between extent of aggregation and of release.

It is suggested that collagen induces a Ca++-independent release reaction that leads to aggregation and that Ca++-dependent release is a result of the platelets aggregating.
The Interaction of Platelets with Individual Components of the Blood Vessel Wall
Authors: MacIntyre D.E. , Bailey A.J.
Published: May 2019

The aggregation of platelets by constituents (especially collagen) of the vessel wall is a basic event in haemostasis and perhaps in thrombosis and atherogenesis. Binding of platelets (without aggregation) in areas denuded of endothelium has also been seen. In this study, various constituents, identified in the vessel wall, have been isolated and their platelet reactivity examined. In particular, with the recognition of collagen polymorphism in the arterial wall, a number of different collagens have been examined. The results indicate that Types I nnd III collagens, as native-type fibrils, are both potent inducers of aggregation; both bind to platelets to aporox. the same degree. In contrast collagens Types IV and V, dialyzed against 0.02M Na2HPO4, or preincubated at 37° (procedures known to yield active fibrils with collagens I and III), failed to induce aggregation; little if any binding to platelets was detected. Disersions of lens capsule (containing Type IV in situ) were also inactive. However SLS-aggregates of these collagens did induce aggregation. These results emphasize that quaternary structure rather than specific type determines the ability of collagen to induce aggregation. They suggest the amorphous basement membrane collagens (IV and V) will not induce aggregation.

Elastin and its associated microfibrillar element failed to aggregate platelets; little binding of platelets to either was observed.

† Present address: Beth Israel Hospital, Boston, Mass., USA
Kinetics of Factor X Activation by Factor IXa the Effects of Phospholipid and Factor VIIIa
Authors: Dieyen G.V. , Rosing J. , Tans G. , Hemker H.C.
Published: May 2019

The kinetics of factor X activation by activated clotting factor IXa was measured either in the presence or absence of phospholipid, Ca-ions and factor VIIIa. This study was carried out with purified bovine clotting factors. The rate of factor Xa formation was measured using the chromogenic substrate S 2222. Both the Km for factor X and the Vmax of factor Xa formation were determined for different compositions of the factor X activating complex in order to get more insight in the role of phospholipid, Ca2+ and factor VIII in factor X activation. With factor IXa alone, the activation of factor X is a very inefficient process. The presence of phospholipids predominantly lowers the Km for factor X while in contrast factor VIIIa mainly increases the Vmax of factor Xa formation. The implications of these findings for the mechanism of, factor X activation in the intrinsic pathway will be discussed.
The Mechanism of Activation of Human Coagulation Factor X
Authors: Mertens K. , Bertina R.M.
Published: May 2019

During the coagulation process factor X is converted to a serine protease, factor Xa. The present study concerns the molecular events which occur during the activation of human factor X by Russell’s viper venom and by the purified proteins of the extrinsic and intrinsic activator. Conversion of factor X was detected by amidolytic assays and SDS/polyacrylamide-gel electrophoresis.

The results show that all activators convert factor X (MW 72,000) to an active form. In the presence of phospholipid the initially formed factor Xa (MW 54,000) complicates the further sequence of reactions by catalysing a) the conversion of factor Xa to a second active form (MW 50,000), b) the conversion of factor X to an inactive product (MW 59,000) by splitting off a peptide containing the active site serine, and c) the further degradation of the 50,000 and 59,000 components to a smaller component (MW 40,000).

Comparison of these data with those reported for bovine factor X suggests that the mechanism of activation of human factor X is more complicated. The inactivation of both factor Xa and factor X by product factor Xa might be considered as important regulatory principles.
Influence of Factor VIII-VON Willebrand Factor on Platelet Adhesion to Human Artery Subendothelium in Pulsatile and Non-Pulsatile Flow
Authors: Sakariassen K.S. , Bolhuis P.A. , Sixma J.J.
Published: May 2019

The influence of Factor VIII-Von Villebrand (F.VIII-VWF) on platelet adhesion to human post mortem artery subendothelium (SE) was studied in a perfusion chamber model according to Baumgartner, in pulsatile and non-pulsatile flow. Non-pulsatile flow was obtained by means of gravity while the perfusate was recirculated under similar conditions as in the pulsatile flow system. Platelet adhesion was greater in non-pulsatile flow than in pulsatile flow. A physiological amount of F.VIII-VWF increased the platelet adhesion approximately two-fold in both systems. When different concentrations of purified F.VIII-VWF were added to perfusates with this plasma factor, smaller concentrations corrected the adhesion in non-pulsatile flow than in pulsatile flow. Perfusates without F.VIII-VWF containing platelets suspended in red cells and plasma-cryosupernatant/Von Willebrand plasma/human albumin solution (HAS)or dextran solution resulted in the same amount of adhesion. When purified F.VIII-VWF was added to these perfusates, the adhesion increased to the level obtained in normal plasma and hemophilic plasma., Thus F.VIII-VWF is the only plasma protein necessary for normal platelet adhesion to SE. 125J-F.VIII-VWF was found to bind to SE before the F.VIII-VWR facilitated adhesion occurred. Binding of 125J-FVIU-VWF to SE was similar in pulsatile and non-pulsatile flow. However less bound 125J-FVIII-VWF was needed to increase platelet adhesion in non-pulsatile flow than in pulsatile flow.
Kinetics of Inhibition of ADP-Induced Platelet Aggregation by Dihomo-β-Linolenic Acid (DHLA).
Authors: Zuzel M. , Spencer A.
Published: May 2019

In the study of the effects on platelets of thromboxanes and prostaglandins (PG) large amounts of precursor fatty acids have frequently been added to platelet suspensions. In the case of DHLA, this results in a general inhibition of platelet reactions. We have employed kinetic analysis of the inhibition of ADP-induced primary platelet aggregation to estimate the potency, specificity and mode of action of DHLA on human platelets in citrated PRP. Platelet PG production was estimated from formation of malondialdehyde (MDA) and aspirin (ASA) was used to inhibit production-Inhibition of aggregation and MEA formation were dose-dependent and both were observed at DHLA concentrations of 0.1 mM and above. Inhibition of aggregation was of mixed type, consisting of an ASA-sensitive competitive component (K1 ≈ 0.2mM) and an ASA-insensitve component which was non-competitive and dominated inhibition at higher concentrations of DHLA. The KI (DHLA) of the non-competitive component varied from 0.4 to 1.5 mM with different batches of PRP. Other polyunsaturated fatty acids which are not PG precursors, did not cause competitive inhibition but were as potent as DHLA in the non-competitive inhibition of aggregation. The results show that a large part of the inhibition of platelet aggregation by DHLA in vitro is not due to its transformation into an inhibitor of platelet function in the PG production pathway.
Three Types of Hereditary Antiterombin III Deficiency
Authors: Nagy I. , Losonczy H.
Published: May 2019

The authors detected in the last seven years 15 patients with hereditary antithrombin III/AT III/ abnormality. All of them had typical clinical signs of recurrent arterious and venous thromboembolie. The abnormality inherited as an autosomal trait. Three types of the abnormality could be observed. In Type I both quantity and function of AT III were extremely decreased. In type II AT III is normal in quantity but abnormal in function. In Type III AT III is quantitatively normal and also its function seems normal as far as its basic activity is concerned /activity measured in absence of heparin/, but its abnormality becomes manifest in the presence of heparin in vitro/and also in vivo/. 5 of the patients belonged to Type I, 4 to Type II and 6 to Type III. In 60 examined family members of the 15 patients an abnormal AT III could be observed in 44, clinical signs in 23.

The examination of AT III activity in the presence of a given amount of heparin ia of great importance in recognition of the different types of antithrombin III abnormalities.
Fibrin Formation in Liver Cirrhosis: Acquired Dysfibrinogenaemia or Hampered Polymerisation?
Authors: Coccheri S. , Palareti G. , Poggi M. , Grauso F.
Published: May 2019

In 20 patients with liver cirrhosis and prolongation of thrombin (Th) and/or thrombin coagulase (ThC) times, fibrin polymerisation was followed at 350 nm after adjustment of fibrinogen concentration. The optical-density values at 10’ (OD 10) were grossly abnormal both with Th and with ThC, but no correlation was found between OD 10 and Th or ThC times. Polymerisation was re-tested after fibrinogen purification with 6 alanine and glycine. ThC time was generally shortened (p < 0.005) although in no case restored to normal. The OD 10 values improved (p < 0.001), but became normal in only a half of the cases, while remaining totally abnormal in 2 cases: PAA gel electrophoresis showed an abnormal band of very low m.w. fibrinogen in 2 out of 10 cases investigated. These results suggest that defective fibrin polymerisation in liver cirrhosis cannot be attributed only to acquired dysfibrinogenaemia. Other features like partially degraded fibrinogen and, especially, still unknown antipolymerizing factor(s)in plasma contribute to the disorder of iibrin formation.
Biochemical Comparison of Intermittent Streptokinase and Intermittent Streptokinase and Plasminogen Therapy
Authors: Barlow G.H. , Kakkar V.V. , Bentley P.G. , Chan P.S.F. , Jones N.A.G. , Mistry F.D.
Published: May 2019

A comparison has been made of some biochemical parameters during streptokinase and streptokinase combined with lys-plasminogen intermittent therapies using a twice a day dosing regimen. Results showed that while the fibrinogen levels, fibrinCogen) degradation products and total fibrinolytic activity appeared very similar there was a pronounced difference in the effect on anti-plasmin levels and on the amount of activator complex formed. With the combination therapy the anti-plasmin levels fell to zero and remained at zero throughout the therapy while the level returned daily to approximately 50% of normal with the streptokinase alone regimen. The amount of activator complex formed was much higher in the combination therapy and this could explain the lessened side effects observed in this type of therapy.
Rates and Mechanisms of Clot Lysis During Various Streptokinase (SK)-Plasminogen (PLGN) Treatments
Authors: Gaffney P.J. , Whitaker A.N.
Published: May 2019

Iodine labelled washed plasma clots were immersed alternately in SK solutions (7.5-4000 iu/ml) and lys-PLGN solutions (2.0 PLGN units/ml) and lysis rates were assessed by release of the 125I label. The composition of the lysates obtained during the SK → PLGN and PLGN → SK regimens was studied by detergent gel electrophoresis and by two-dimensional Immunoelectrophoresis. Lysis rates were also monitored in serum and plasma environments compared to buffered systems. Clots lysed completed in buffered PLGN during the SK → PLGN regimen while the PLGN → SK regimen yielded only partial lysis;the composition of the respective lysates suggested a more vigorous digestive procedure (free D dimer and fragment E present) during the SK → PLGN regimen. During the buffered PLGN → SK regimen the concentration of SK marginally affected lysis rates while a concentration of 125-250 iu/ml was found optimal during the SK → PLGN regimen. These data were confirmed when lysis was achieved in serum and plasma using an SK → PLGN regimen and suggested that the inhibitive effect of fibrin clot lysis was in the order:serum inhibitors, SK antibodies and fibrinogen. Lysis of clots in serum or plasma with either regimen always yielded only D dimer-E and its higher molecular weight complexes.
A Serotonin Induced Biphasic Aggregation By Platelets From Cats With The Chediakhigashi Syndrome
Authors: Meyers K.M. , Seachord C.I. , Prieur D. , Holmsen H.
Published: May 2019

Platelets from cats with the Chediak-Higashi syndrome (CHS) have an intrinsic platelet defect similar to storage pool deficiency in man and there is a virtual absence of secretable serotonin and ADP. Serotonin-induced platelet aggregation responses were monitored in four cats with the CHS. Low serotonin concentrations (0.5 ug/ml) induced a monophasic reversible aggregation response. When the concentration was increased (1-2 μg/mlj a biphasic aggregation response was observed and at higher concentrations (4-8 μg/ml) a monophasic irreversible aggregation wave was observed. The concentration dependent aggregation responses can be progressively inhibited with increasing concentrations of the serotonin antagonists, SQ-10,631 and cyproheptadine. The secondary aggregation wave is inhibited by both aspirin and indomethacin. Arachidonate (0.5mM) induces a monophasic irreversible CHS olatelet aggregation resoonse which is also inhibited aspirin and indomethacin. These findings suggests that the secondary aggregation wave is due to an arachidonate metabolite formed in response to serotoninWhile the metabolite has not been directly identified serotonin induces formation of thromboxane B2 (TxB2) by CHS cat platelets and in all but one animal increasing Serotonin increased TxB2 formation. In addition, the cat whose platelets exhibited the weakest serotonm-induced aggregation response produced the smallest amount of TxB2.
Effects of Dipyridamole and Aspirin on Platelet camp Levels and Prostaglandin Biosynthesis in vivo in Patients with Diabetes Mellitus
Authors: Best L.C. , McGuire M.B. , Ward J.D. , Holland T. , Preston F. E. , Segal D.S. , Russell R.G.G.
Published: May 2019

Platelets from diabetics with microvascular complications were shown to have lowered aggregation thresholds to ADP, epinephrine and collagen. They also produced more malonyl dialdehyde (MDA) than normal controls. In eight diabetic subjects, administration of dipyridamole (100mg tds)raised platelet aggregation thresholds and increased cyclic AMP levels, presumably as a result of inhibition of phosphodiesterase activity. It also caused a slight reduction of MDA production. This latter effect could be due to the rise in cyclic AMP, although we have found an apparently direct inhibitory effect to dipyridamole on MDA and thromboxane B2 production by intact platelets and platelet microsomes in vitro. On withdrawal of the drug, platelet cyclic AMP and MDA levels and aggregation thresholds returned toward pre-treatment levels. The administration of aspirin (120) plus dipyridamole markedly inhibited platelet aggregation, particularly in response to arachidonic acid and collagen and strongly inhibited MDA production. However, the rise in platelet cyclic AMP levels produced by dipyridamole alone was not present when aspirin and dipyridamole were given together, Aspirin may influence platelet cyclic AMP metabolism directly or by inhibiting prostacyclin formation. Thus, under appropriate conditions, basal platelet cyclic AMP may provide an index of PGI2 production in vivo.
Modulation by Dipyridamole of the Arachidonic Acid Metabolic Pathway in Platelets an in vivo and in vitro Study
Authors: Serneri Neri G.G. , Gensini G. F. , Abbate R. , Favilla S. , Laureano R.
Published: May 2019

Dipyridamole is a useful antiplatelet agent in specific clinical conditions, but its effects on TxEL production by platelets are now being debated, Resting platelets from patients with 1.5-2 fig/ml serum dipyridamole (spectrofluorimetric assay). administered by venous infusion or by oral route, showed an increased concentration (m.v. +60% P<0.001) of cAMP (radiometric assay). After stimulation with thrombin (5U/ml) platelets produced a significantly decreased amount of TxB(m.v. -60%, F< 0.001) (radioimmunoassay with antibody kindly supplied by Doctor J.B. Smith, Philadelphia). However also after stimulation with arachidonic acid (A.A.) 1 mM TxB production was decreased(m.v. -50%, P<0.001). The incubation of control platelets with different concentrations of dipyridamole (0.5, 1 and 2 μg/ml) for 20 min at 37°C resulted in an increase of cAMP and in a decrease of TxB, production after stimulation with thrombin and with A.A.. These results indicate that dipyridamole is endowed with direct antiaggrega= ting activity caused by a decreased production of TxB2. This in tum seems due to an inhibitory modulating effect of cAMP on arachidonic acid cyclo-oxygenation. However our findings do not rule out an inhibitory effect also on phospholipase A2.
Increase of Circulating PGI2 and PGI2 Released by Vessel Wall after Dipyridamole
Authors: Masotti G. , Poggesi L. , Galanti G. , Serneri Neri G.G.
Published: May 2019

PGI2 present in circulating blood is produced by the lungs (Grygiewski et al. 1978) and in humans can be also produced by vessel wall after 3 min. ischemia (Neri Serneri et al. 1978). We studied the effects of Dipyridamole (Dp) on circulating PGIand on its release by vessel wall induced by ischemia. PGI2 was assayed by Vane superfusion technique. Dp in acute infusion such to deliver a 1, 5-2 ug/ml serum concentration (spectrofluorimetric determination) provoked in (spatients an increase in circulating PGI2 (between 30% and 500%); in 2 patients the appearance of PGI2 previously undetectable; and no changes in the last 2 patients. Also PGI2 production by vessel wall after ischemia was increased by Dp in fiout of 8 patients but at a lesser extent (increase of PGIg output between 1% and 40). The effects of Dp were prevented by pre treatment with indomcthacin, Our results indicate that antiaggrcgating activity of Dp in vivo is connected not only with its effects on platelets, but also to enhanced production of PGI2 not necessarily due to an increased level of intracellular cAMP.
Dipyridamole (D) Reduces the Effectiveness of Prostaglandin (PG) I2. PGD2 and PGE1 as Inhibitors of Platelet Aggregation in Human Platelet-Rich Plasma (PRP)
Authors: Minno Di G. , Gaetano de G. , Silver M.J.
Published: May 2019

The effectiveness and the mechanism of action of D as an anti-thrombotic agent has been controversial. It has been proposed that D works by potentiating the inhibitory activity of "circulating" PGE2 on platelet aggregation by inhibiting platelet phosphodiesterase activity. To determine whether such potentiation exists in normal humans we studied inhibition of aggregation by the PGs in PRP before and 90 mln after the ingestion of D (100 mg). As expected, we found that the threshold aggregating concentrations of ADP, collagen and arachidonic acid (AA) were unchanged after the ingestion of D. Unexpectedly, the threshold inhibitory concentration of each PG was greater after ingestion of D than before. The mean elevations for PGI2 were 8.8 nM (p<0.05) vs ADP; 9.1 nM(p<0 01) ys collagen; 9.2 nM (p<0.001) vs AA; for FCD2 14.5 nM (p<0.05) vs AA; for PGE, 69 0 nM (p<0.05) vs collagen and 25.9 nM (p<0.05) vs AA. The elevations for PGD2 vs ADP and collagen and for PGE1 vs ADP were not significant. These data do not support the hypothesis that D aces as an anti-thrombotic agent by potentiating the inhibition of platelet aggregation by “circulating” PGIZ. The findings show that ingestion of D Interferes with the inhibitory effect of the PGs and suggest that other mechanisms of action ot D should be investigated.(Supported by the Italian CNR and NIH).
Detection of Activated Platelets and the Evaluation of Anti Platelet Drugs
Authors: Tsukada T. , Ito T.
Published: May 2019

Usefulness of examinations such as the assay of plasma beta-thromboglobulin(BTG) plasma platelet factor 4 or platelet survival is stressed for the detection of activated platelets in vivo. To determine whether changes of platelet nucleotide contents is useful indicator detecting the presence of activated platelets, platelet nucleotide contents were measured by high pressure liquid chromatography simultaneously with plasma ETC in diabetics with various vascular complications. Only 40/84 cases demonstrated both normal nucleotides(ATP 4±0.2 (SEM), ADP 2.6±0.2, GTP 0.4±0.04 μ moles/1011 plts.) and normal BTG levels( less than 50 ng/ml). 6/15 cases with elevated BTG showed decrease in nucleotides (ATP 1.5±0.4, ADP 1±0.1, CTP 0.2±0.04). 29/69 patients with normal plasma BTG demonstrated significant decrease of nucleotides (ATP 2±0.2, ADP 1.2±0.1, GTP 0.3±0.03). These abnormal nucleotide contents and/or BTG levels have returned to normal range within one month after daily administration of 750 mg aspirin and 150 mg dipyridamole. Without anti-platelet therapy, these abnormal values have continued for several months.

Simultaneous measurement of platelet nucleotide and plasma BTG is an excellent indicator detecting the activated platelets in vivo and demonstrating the effectiveness of antl-platelet drugs.
A New Approach to the Study of Platelet Proteins: Crossed Immuni-electrophoresis in the Presence of Detergent
Authors: Hagen I. , Bjerrum O. J. , Solum N.O.
Published: May 2019

Crossed immunoelectrophoresis o f human platelet proteins solubilized in 1% Triton X-100 against rabbit whole platelet antibodies revealed more than 20 immun precipi tates. Identification o f albumin (No.6), factor VIII, (No.9) and fibrin ogen(No.24) was done with the respective monospecific antibodies The topographical arrangement of the membr an eproteins was examined with extracts from lactoperoxidase(125I)-iodinated platelets as antigens, and with antibodies absorbed with a suspension of whole platelets. Four radioactive precipitates (No.16, l7, 20, 23) were observed, indicating a surface exposure of the corresp o nding proteins in the membrane. This was confirmed by the use of absorbed antibodies. Six glycoproteins(No.S, 8,9,16,l7,23) (were identified by crossed affino-immunoelectrophoresis using four different lectins, and four sialoglycoprote in s(No.9,15,16, 20) by their reduced electrophoretic migration after neuraminidase-treatment. Charge shift crossed immunoelectrophores is and crossed hydrophobic intera ction immunoelectrophoresis revealed that all the membrane prote ins were amiphilic. The present methods represent a new approach to the study of the stru cture and function of platelet proteins.
Effects of Trans and CIS Isomers of Oleic and Linoleic Acids on Platelets and Endothelial Cells
Authors: Rastogi B. , Lowery C. , Nordøy A.
Published: May 2019

The role of trans isomers of fatty acids in the development of coronary heart disease has been questioned. Hwang and Kinsella (l) indicated that feeding of trans linoleate to rats caused decreased serum prostaglandins. We report the effect of trans isomers of oleic and linoleic acids on platelet aggregation (PA). No significant differences were observed in collagen- and ADP-induced PA in platelet rich plasma preincubated with the various fatty acids bound to albumin for 90 min. When the albumin bound fatty acids were incubated with primary cultures of human endothelial cells (ECM) and PRP for a similar periode of time, significant differences in PA were observed with ADP but not with collagen. PA was higher for the trans isomer than for the cis isomer of linoleic acid. This difference disappeared when the ECM were preincubated for 15 minutes with indomethacin. We suggest that endothelial cells could synthesize prostacyclin (PGI2) from cis isomer of linoleic acid but not from the trans isomer.
Platelet Activation Pathways of Domestic Animals
Authors: Meyers K.M. , Holmsen H. , Seachord C.I. , Smith J.B.
Published: May 2019

Platelets secrete substances (ADP/5-HT) which are located in platelet dense granules and activate platelets. Platelets are also activated by compounds formed from arachidonate (thromboxanes/prostaglandins). The contribution of the dense granule pathway and the arachidonate pathway depends upon the amount of substance formed or secreted arid the sensitivity of platelets to these substances. A comparative study involving platelets from cattle, horses, pigs, cats, dogs, rabbits and mink was undertaken to evaluate the former. To assess the dense granule pathway platelets were incubated with 14C-adenine to label the metabolic adenine nucleotide pool and the platelets gel filtered. The gelfiltered platelets were treated with thrombin to induce maximal secretion and content and secretion of ATP, ADP, S-HT, Ca2+ and Mg2+ determined. Platelets from horses, cows, dogs, pigs and rabbits secreted (expressed as per 10” platelets) approximately 0.5 μMoles while mink and cat platelets secreted between 1.0 and 1.5 μMoles of ADP. Serotonin secretion varied from approximately 1.2 μMoles in cat platelets to about 0.3 μMoles in the horse. To evaluate the arachidonate pathway arachidonate- and thrombin-induced malondialdehyde (MOA) formation and thrombin-induced thromboxane B2(TxB2) formation was measured. In response to arachidonate there were high MDA producers (cat and dog), medium MDA producers (horse and mink), and low MDA producers (pig and cow). Dog platelets produced large amounts, horses medium amounts and mink, pigs and cows low amounts of MDA and TxB2 in response to thrombin.
Pharmacological Studies with Platelets and Cultured Vascular Cells
Authors: Gordon J.L. , Pearson J.D.
Published: May 2019

Suspensions of cultured porcine aortic smooth muscle cells (SMC) induce platelet aggregation, which is decreased by pretreating SMC with collagenase. In contrast, porcine aortic endothelial cells (EC) usually inhibit platelet aggregation. Radioimmunoassay of the culture medium demonstrates that both cell types secrete prostaglandins (PG); EC mainly PGI2 and SMC mostly PGE2. EC PG production is stimulated by cell-free plasma and inhibited by aspirin (IC50 ≃ 100μM) or sulphinpyrazone (IC50 = 50-100μM). Aspirin pretreated EC can induce platelet aggregation directly which is inhibited by 2-azido-AMP, an ADP analogue. [3H]-adenine and adenosine are incorporated into EC or SMC nucleotides, mainly ATP. EC and SMC possess a high affinity (Km < 1μM) system for adenine uptake. In contrast only EC have a high affinity (Km = 3μM) adenosine transport system, potently blocked by dipyridamole (IC50 < 0. 1μM at 10μM adenosine); EC and SMC have a lower affinity adenosine uptake site (Km = 250μM for EC, > 1mM for SMC) preferentially blocked by adenine (IC50 > 10μM at 10μM adenosine for both cell types) but not by dipyridamole. Treating EC or SMC with trypsin or thrombin stimulates the release of significant amounts of the cells’ ATP (measured by prelabelling or by luciferase assay) without detectable LDH release or vital dye uptake. This ATP is rapidly (t½ < 5 min) converted to ADP by an ectoATPase (Km ≃ 450μM for EC, 125μM for SMC), and subsequently to AMP and adenosine by other ectonucleotidases.
Ex Vivo Effects of Acetylsalicylic Acid, Sulfinpyrazone and Dipyridamole on Platelet Adhesion and Thrombus Formation in Flowing Native and Anticoagulated Blood
Authors: Baumgartner H. R.
Published: May 2019

Potential platelet inhibitors are usually tested ex vivo by investigating platelet function in vitro after drug ingestion and subsequent blood collection into citrate. The purpose of the present study was to determine whether and how citrate anticoagulation interferes with possible drug actions in rabbits. Platelet adhesion and thrombus formation on subendothelium were compared after perfusion at 1300 sec-1 wall shear rate of native blood and of blood anticoagulated with citrate, heparin or heparin plus citrate.

Results. 15 mM citrate in plasma caused significant reduction of aggregation, thrombus volume and thrombus height; adhesion was concomitantly increased. Heparin (500 U/kg) had no effect on adhesion and thrombus dimensions. Treatment of rabbits with acetylsalicylic acid or sulfinpyrazone (2x100 µmol/kg) caused a significant reduction of thrombus volume and thrombus height in the presence of citrate. However, no drug effects were observed after perfusion of native or heparinized blood of the same rabbits. Equimolar doses of dipyridamole were always without effect.

Conclusion. Low citrate concentrations (1) inhibit thrombus growth, (2) enhance thrombus breakdown,(3) secondarily increase adhesion and (4) strongly enhance a possible inhibitory effect of acetylsalicylic acid and sulfinpyrazone on thrombus growth and/or breakdown.
Post-Operative Deep Vein Thrombosis:Prophylaxis in High Risk Patients
Authors: Clayton J. K. , Crandon A.J. , Peel K. R. , McNicol G.P.
Published: May 2019

The prophylactic use of subcutaneous low-dose heparin or dextran 70 to reduce the incidence of post-operative deep vein thrombosis may increase bleeding during and after surgery and the general use of prophylactic measures also involves the unnecessary treatment of a large number of patients. In 1976 we demonstrated (Clayton, J.K. et al. Brit. med. J., 1976, 2, 910) that by using two simple laboratory tests and three pieces of clinical information, it was possible to design a prognostic index which when reapplied to the population from whom it had been derived gave good prediction of those at risk of developing post-operative deep vein thrombosis. We then applied this same prognostic index prospectively to a new group of patients, with again a good predection of patients who are at risk to post-operative deep vein thrombosis. We have subsequently used the prognostic index to restrict prophylaxis to high risk patients having gynaecological surgery. In the high risk group of patients, the incidence of postoperative deep vein thrombosis is about 56%. With low-dose subcutaneous heparin prophylaxis given only to patients predicted as being in this high risk group, the incidence of deep vein thrombosis was reduced to 6%. The possibility of identifying high risk patients should encourage the greater use of prophylactic measures and will also facilitate the comparison, with an economy of effort, of different methods of prophylaxis of venous thrombosis. A similar approach to the much larger and more difficult problem of arterial thrombo-embolic disease may also be worthwhile.