bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biological Nature Of Platelet Inhibitors From Allium Cepa, Allium Sativum And Auricularia Polytrica
Authors: Makheja Amar N , Low Chow Eng , Bailey J 
Published: July 2018

Several lines of evidence indicate that extracts of onion (Allium cepa), garlic (Allium sativum) or Chinese black tree fungus (Auricularia polytrica) inhibit platelet aggregation both in-vitro and in-vivo.A systematic study showed that aqueous extracts of these vegetables produced a dose-dependent inhibition of ADP, arachidonic acid (AA) or collagen-induced platelet aggregation. Onion and garlic juices were extracted sequentially into petroleum ether and diethyl ether. The anti-platelet activity in the aqueous phases was completely inactivated by purified adenosine deaminase. The activity in the petroleum ether layer was further characterised by its effects on the metabolism of 14C-AA by platelets. This oily fraction of onion and garlic suppressed thromboxane synthesis completely and induced a redistribution in the products of the lipoxygenase pathway. Adenosine and allicin (found in the ether layer) inhibited aggregation without affecting AA metabolism. Preparative GC and GC/MS studies showed that the activity of the oily fraction was due principally to paraffinic polysulfides (PPS) of which dimethyl trisulfide was one of the most active. Authentic samples of dimethyl trisulfide duplicated the effects of onion and garlic oils on both aggregation and AA metabolism.
Stroke Prevention - Introductory Remarks
Authors: Barnett H J M 
Published: July 2018

A mass of experimental evidence indicates the benefit of platelet anti-aggregant therapy and suggests benefit to patients with thrombo-embolic disease. There are a number of varieties of threatening stroke with platelet-induced thrombogenesis related to ischemic events. The rationale for attempting to prevent stroke,with safe platelet anti- aggregants for which laboratory and animal studies are available,is sound. Several stroke-prevention trials have been conducted and it is appropriate to review the results and take stock of outstanding problems.The most obvious disappointment is that a substantial number of failures occur. Those with advanced disease and of the female sex lack responsiveness. It is an interesting speculation in that the failure of arteriosclerotic arterial walls to produce prostacyclin might be related to the poor response in advanced disease. The evidence that acetyl- salicylic-esterase is less active in females may be part of the explanation for the sex differential. The better prognosis enjoyed by women suffering from threatened stroke may play a role in explaining some of this therapeutic difference.Aspirin dosage may require some adjusting-either down or up. In favor of the former is the anti-thrombotic effect of 165 mg per day of ASA in dialysis patients. In favor of the latter is the benefit in women of a dose approaching 3 gm per day in preventing postoperative venous thrombosis.Drugs other than aspirin have failed yet to establish efficacy in threatened stroke. Sulfinpyrazone and dipyridamole alone have both been tested. Theoretical reasons exist for considering that ASA and persantine may prove synergistic but the evidence is based on in vitro observation. Trials are under way and conclusions from the studies of platelet physiology and biochemistry respecting their combined advantage is premature. “The great tragedy of Science - the slaying of a beautiful hypothesis by an ugly fact”, the words of Thomas Hurley, may apply here.
Von Willebrand Factor In Platelet Interaction With Subendothelium
Authors: Baumgartner H R , Tschopp T B , Meyer D , Turitto V T , Weiss H J 
Published: July 2018

Studies using citrated blood. A defect in adhesion of platelets from VWD patients to rabbit aorta subendothelium was first demonstrated in 1974 using our annular perfusion chamber. Later on we showed that the magnitude of the defect increased with the blood shear rate. Addition of void-volume fractions of cryoprecipitate chromatographed on Bio-gel A-15m to blood of patients corrected the adhesion defect. By treatment of normal human blood with homologous and heterologous antibodies to human FVIII/VWF a shear rate dependent adhesion defect was experimentally induced. Studies with reconstituted human blood by Sixma’s group confirmed the involvement of FVIII/VWF in platelet adhesion to subendothelium. Treatment of rabbit aorta subendothelium with antibodies to rabbit FVIII complex gave different results: an antiserum raised in goat inhibited adhesion, whereas an antiserum raised in guinea pig had no effect. The latter antiserum did, however, inhibit adhesion when added to rabbit blood. It is conceivable that the two antisera are predominantly directed towards different epitopes on FVIII/VWF.Studies avoiding anticoagulation. In these studies blood is directly drawn from a vein through the annular chamber at a controlled flow rate. In addition to a shear rate dependent inhibition of platelet adhesion to subendothelium a significant inhibition of maximum thrombus heights, thrombus growth and/or stability was observed at shear rates which were not associated with an adhesion defect. It is not yet clear whether this additional, defect is due to FVIII/VWF and/or VIII: C deficiency.
The Molecular Structure Of Fibrinogen And The Architecture Of The Fibrin Clot: A Model From Electron Microscopy
Authors: Weisel J W , Phillips G N , Stauffacher C V , Ford E , Cohen C 
Published: July 2018

The shape of the fibrinogen molecule and aspects of its packing to form fibrin have been derived from a study of electron microscope images of crystals and microcrystals. Using coordinated X-ray diffraction and electron microscopy, the length of the molecule was eastblished as 450Å. The molecules bond end-to-end to form filaments whose packing could be determined for several crystalline forms. A particularly useful aggregate in establishing the shape of the molecule was a “segment“ form of modified human fibrinogen that reveals direct information about the mass distribution. Computer simulations were carried out to refine the size and location of the globular domains. A single molecular model was derived to account for the substructure and packing in a variety of arrays seen in the electron microscope. The molecule can be seen in more detail than the tri-nodular Hall-Slayter model, and is made up of seven globular domains connected by rod-like regions.The molecular architecture of the fibrin clot has been a puzzle for several decades. A simple, half-staggered arrangement of trinodular molecules can account for the 225 Å repeat, but not the detailed features of the band pattern of the negatively stained fibrin in the electron microscope. We can now simulate the fibrin band pattern using the heptad model and a packing arrangement derived from one of the microcrystalline forms. The molecular arrangement in fibrin is complex: the 450 Å long molecules are half staggered and bonded end-to-end; they are also bent and tilted slightly. Further aspects of the structure and packing will be available from the X-ray crystallographic analysis of the hydrated molecule now in progress.
Relative Affinity Of Vascular And Tissue Piasminogen Activator To Fibrin And Fibrinogen
Authors: Kruithof E K O , Bachroann F 
Published: July 2018

Vascular and tissue plasminogen activator (VA and TA) induce lysis of preformed fibrin at concentrations which do not cause fibrinogenolysis. This phenomenon can be explained, in part, by the strong binding of VA and TA to fibrin. We have compared binding of TA to fibrinogen and to fibrin in various systems. Cn fibrinogen- and on fibrin-sepharose columns, the elution profile of TA was identical.In further experiments, we determined if fibrinogen decreases the binding of TA to fibrin. To a solution of TA, we added 2 µM of fibrin monomer and varying concentrations of fibrinogen (0-6 µM). In the absence of Ca++, addition of 6 µM of fibrinogen resulted in 30% inhibition of binding of TA to fibrin (expected if affinities were identical: 75%). When citrated plasma containing VA (collected after i.v. injection of DDAVP into volunteers) was clotted by the addition of thrombin, 1,3 U activator per ml of plasma could be extracted from the clot with 0,017 M acetic acid. When fibrin monomer (final concentration 2 µM) was added to the plasma and allowed to clot, about 0,9 U of VA per ml of plasma could be extracted from the fibrin. As the plasma contained 5,4 µM fibrinogen, the 30 percent inhibition of binding of VA to fibrin is similar to that of TA to fibrin by fibrinogen.The latter results demonstrate that the affinity of TA and VA to fibrin is at least five times higher than that to fibrinogen. The lack of difference in binding of TA to fibrin- and fibrinogen-sepharose indicates that the coupling of fibrinogen and/or fibrin to sepharose modifies their affinity characteristics for TA, or that fibrin polymerization itself increases the potential to bind TA.
The Effect Of Fibrinolysis In The Early Stage Of Acute Myocardial Infarction
Authors: Genth K , Frank J , Schaefer J , Korten V , Heene D 
Published: July 2018

The influence of streptokinase (SK) on myocardial infarct size and left ventricular function after acute myocardial infarction was investigated. 21 patients with myocardial infarction received SK (SK-group), 27 patients underwent conventional therapy (C-group). In both groups therapy started within 8 hours after onset of chest pain. In the SK-group initially 250 000 IU were administered intravenously, followed by a maintenance dose of 100 000 IU/h, lasting 15 hours. Blood samples at 8 hours intervals were collected for 3 days for serial CPK-analysis to calculate infarct size (I=∫f(t)×dt×K×bw). M-mode echocardiography was taken before start of t her a py and after 15, 24, 48 and 72 hours. AOP and heart rate were recorded continuously. Infarct size was 47±12g in the SK-group and 84±25g in the C-group (p<0.05). The average time to peak blood CPK-activity was 24 hours in the SK-group and 40 hours in the C-group. Peak CPK-level was significantly higher (p<0.5) in the SK-group (841±160U/l) than in the C-group (532±13 8 U / l ) . In 16 patients of the SK-group short periods of ventricular tachycardia were recorded during the period of fibrinolysis. Before therapy all patients showed abnormal motion of the posterior left ventricular wall and/or the interventricular septum, detected by echocardiography. 14 patients showed after fibrinolysis an improved or normalized motion.The results indicate that early fibrinolysis may reopen the occluded coronary artery. Reperfusion of the ischemic perfusion area may salvage jeo pardized myocardium, therefore infarct size was reduced and ventricular function improved.
Fibrinolytic Therapy Of Subclavian-Axillary Vein Thrombosis With Urokinase
Authors: Zimmermann R , Mörl H , Harenberg J , Janssen E , Kuhn H M , Wahl P 
Published: July 2018

Acute vein thrombosis of the upper extremity occurs in consequence of trauma,stress,effort or spontaneously. The management was often performed conservatively,including anticoagulation and elevation of the involved arm. But the incidence of chronic residual edema,pain or disability in 6895 % of the cases suggests that active therapeutic procedures should be considered.In 18 cases with recent and older thrombosis of the suclavian and axillary veins fibrinolytic therapy was performed with urokinase in combination with heparin. Urokinase and heparin therapy was adjusted to attain an anticoagulant effect not exceeding that aimed at usually by heparin alone.7 of 11 patients with recently developed (8 days or less) thrombosis showed a complete recanalization of the venous system.2 cases demonstrated a partial success. In 2 patients no phlebogra- phic alteration could be stated. These 2 patients had received urokinase at the lowest maintenance dosage of only 970 and 1000 IU/kg/h,respectively. In addition 7 patients with thromboses more than 10 days old showed no alteration of the thrombotic occlusions. Relevant side effects were not observed.The therapeutic results unequivocally depended on the thrombus age,the dosage of urokinase applied and the duration of the fibrinolytic therapy. Under treatment with an median,initial maintenance dosage of urokinase 1300-2000 IU/kg/h in combination with heparin excellant therapeutic results could be attained. Our data suggest that the here presented therapeutic procedure has to be considered in serious cases of recently developed subclavian-axillary vein thrombosis.
A Monoclonal Anti Human Factor Ix Produced By A Mouse Hybridoma
Authors: Bertina R M , van der Linden I K , Muller H P , Derks J , Klein-Breteler E 
Published: July 2018

Spleen cells of a Balb-c mouse immunized with purified human FIX were fused with mouse myeloma cells (MOPC-21 derivative]. Among the fusion products one hybridoma was found producing an inhibitor of factor IX procoagulant activity. After sub- clonation (5 x) a stable hybridoma was obtained. In vitro cell culture of the hybridoma cells gives anti-FIX titers (Bethesda units] of about 0.8 units/ml. Injection of the hybridoma cells in pristane pretreated mice results in antiFIX titers of 600-1000 units/ml ascites. Analysis of the produced immunoglobulin demonstrated the presence of one main band after iso-electric focussing, which contained heavy chains both of IgG1 and IgG2B subclass.Monoclonal anti-factor IX was isolated from ascites liquid using affinity chromatography on protein-A-Sepharose. Using the purified antibody a radioimmunoassay was developed for the epitope on factor IX, against which this antibody is directed. The epitope is present both on FIX and activated FIXa; however, the affinity of the antibody for binding to FIXa is at least 10 times less. The antibody has no significant affinity for binding to the isolated heavy and light chain of FIXa.About 27 different genetic variants of factor IX [from haemophilia B patients were tested for the presence of this epitope. All FIX-variants possessed the epitope. At least 2 variants demonstrated a reduced affinity for binding to the antibody.
Radioimmunoassay Of Fragment E In Suspected Pulmonary Embolism
Authors: Duffy M J , Farrell R J , Duffy G J 
Published: July 2018

Previous investigators have reported that radioimmunoassay of fragment E (FgE) can distinguish between symptomatic deep venous thrombosis and other conditions giving a similar clinical picture. Elevated serum FgE levels have been reported in pulmonary embolism, but these have not been compared with non-thromboembolic lung disorders. In this study serum FgE was measured in 44 patients undergoing lung scans for suspected pulmonary embolism and in 12 patients with pneumonia.Serum FgE levels greater than 250 ng/ml were found in 2/22 patients with normal lung scans, in 9/12 with pulmonary embolism (PE), in 3/6 with chronic obstructive airways disease (COAD), in none of 4 patients with congestive cardiac failure (CCF) and in 5/12 with pneumonia. Mean serum FgE levels in the above groups.In this series, serum FgE did not discriminate between pulmonary embolism and non-thromboembolic lung diseases. Radioimmunoassay of FgE may have some value in screening for thromboembolism but it is not sufficiently specific tobe used as an indication for anticoagulant or thrombolytic therapy.
CA2+ Affects Platelet-Subendothelium Interaction Independent Of F VIII-Vwf
Authors: Sakariassen K S , Sixma J J , Bolhuis P A 
Published: July 2018

The effects of Ca2+ in the presence or absence of F VIII-VWF on blood platelet adherence to subendothelium of human arteries were investigated in an annular perfusion chamber according to Baumgartner, using a non-pulsatile perfusion system. The perfusates consisted of citrated blood or reconstituted fluids with washed red blood cells, 51Cr-labelled platelets, and the appropriate plasma replacements. F VIIIVWF was purified from cryoprecipitate by Sepharose CL-4B chromatography and radio-labelled with 125I by the lactoperoxidase tecjiijtique. Platelet adherence was measured by registration of 51Cr count or by morphometry. Free Ca2+ was assayed with a calcium electrode, with a minimum detection limit of 10 µM. A close correlation was observed between the Ca2+ concentration and the haematocrit in normal blood anticoagulated with l/lO vol 110mM Na3-citrate. The plasma concentration of citrate and Ca2+ had mean values of l8 mM and 65 yM respectively. Perfusion for 7 min at a vessel wall shear rate of 1000 s-1 with this blood, produced a monolayer of adherent platelets and only occasionally small platelet aggregates on the subendothelium2+but no thrombi > 5 µM in height. At plasma citrate and Ca2+ concentrations of respectively 40 mM and 25 µM the platelet spreading on the subendothelius^ was impaired. At a citrate concentration of l60 mM and a Ca2+ concentration below the detection limit, the initial contact between platelets and subendothelium was abolished. In perfusion fluids in which plasma was substituted by a human albumin solution (HAS), the adherence at Ca2+ concentrations above 10 µM was higher in the presence of F VIII-VWF than in its absence. However, at a Ca concentration below 10 pM induced by addition of citrate (160 mM in HAS), the adherence yith and without F VIII-VWF was abolished. The binding of 125I F VIII-VWF to the subendothelium was unchanged at levels below 10 µM Ca2+.These data indicate that the various steps of pikelet interaction with subendothelium require specific Ca2+ concentrations. The effect of F VIII-VWF is independent of this.
Platelet-Vessel Wall Interactions In Experimentally Induced Hypercholesterolemia
Authors: Tremoli E , Aqradi E , Socini A , Petroni A , Galli C 
Published: July 2018

A simple method was developed to study platelet-vesseln wall interactions based on the perfusion of platelet rich plasma (PRP) through isolated segments obtained from the aorta of the same animal. The inhibition of aggregation of the perfused PRP, indicating prostacyclin (PGI2)-like material production by aortic wall, was quantified. The effect was not present when normal PRP was perfused through the vessels obtained from aspirin-treated animals. This experimental model was used in the study of platelet-vessel wall interaction in normal (N) and hypercholesterolemic (HC) rabbits (one month on a high cholesterol -2% W/W - diet).In the HC animals increased aggregating response coupled with reduced platelet sensitivity to the inhibitory effect of exogenous PGI2 was observed. When PRP of the two groups of animals was perfused through their own aortas, the inhibition of aggregation was significantly lower in HC samples, suggesting ever lower aortic production or lower sensitivity to the inhibitory effect of PGI2-like material in treated animals. In addition a lower inhibition of platelet aggregation occurred after perfusion of PRP from HC animals through aortas of N rabbits, indicating a decreased platelet sensitivity to the inhibitory effect of PGI2-like material released.It appears that in experimental HC rabbits, platelet aggregation and their sensitivity to the antiaggregatory effect of PGI2 are significantly affected. In our experimen tal conditions, production of PGI2-like material in the aorta is not reduced, but the overall outcome of plateletvessel wall interaction is a reduced inhibition of platelet aggregatory response.
A New, Rapid And Sensitive Determination Of Fibrinopeptide- A (FPA) By A High Affinity Antibody To FPA Antiserum
Authors: Stehle G , Harenberg J , Schmidtgayk H , Zimmermann R 
Published: July 2018

The clinical relevance of the determination of FPA is not yet fully recognized because of the still time consuming radioimmunological techniques. Shortening of the incubation times allways lead to a critical loss of the sensitivity of the assay. We present now a modification which provides highly sensitive and reproducable results within 2hrs.The ethanolic extraction of FPA from plasma was shortened to 20 min including centrifugation. Samples were analysed in triplicates and evaporated at 50°C on microtiter plates. The addition of 0.2μl normal rabbit serum (NRS) lead to a 20% increase of the reaction rate of the FPA antiserum to FPA. A second antibody with high affinity to rabbit immunglobulin i.e. the FPA antiserum improved the maximal binding to 35% after an incubation period of only 10 min. 35-40000 cpm tracer FPA were added to each sample. FPA antiserum, second antibody and NRS were preincubated for 1-24 hrs and then added together with the tracer to the samples. Thus a sensitive standard curve was obtained between 0.16 and 160 ng/ml (12000-600 cpm). The correlation coefficient of this modification to our previously described method was r=0.96 (n=60) The variation coefficient could be improved substantially to 3.1 for low, 4.0 for medium and 4.5% for high FPA. Normal FPA were measured between 0.16 and 2.5 ng/ml (mean 1.4 ng/ml, n=32).The presented modification of the radioimmunological determination of FPA overcomes the difficulties of previously described methods and provides acurate results within 2 hrs.
Effect Of Heparin On The Thrombin-Antithrombin Reaction Product
Authors: Danishefsky Isidore , Bender Michael S 
Published: July 2018

The characteristics of the primary complex (C-l) formed between thrombin and antithrombin in the absence and presence of heparin, were investigated. Each of the complexes were isolated by gel-filtration of the reaction mixture on Sephadex G-100.Analyses by SDS-polyacrylamide gel electrophoresis showed that thrombin causes the successive degradation of both complexes to lower molecular weight products C-2 and C-3, respectively. C-l that was formed in the absence of heparin also undergoes spontaneous direct degradation at pH 7.5, to a complex that is similar to C-3. Additionally, this C-l dissociates very slowly to release thrombin, as demonstrated by its action on a synthetic substrate. Treatment of C-l with 1M NH2OH results in its breakdown to thrombin and antithrombin. The complex formed in the presence of heparin differs from the one formed without heparin, in that it does not exhibit any measurable dissociation and does not undergo breakdown to the C-3-type product. Moreover, whereas C-l formed in the absence of heparin is decomposed completely by 1M NH2OH, the complex formed in the presence of heparin undergoes only partial breakdown even with 2M NH2OH. Addition of heparin to C-l originally produced in the absence of heparin, has no effect on its properties.The results thus indicate that heparin influences the mode of binding between thrombin and antithrombin as well as the rate of their interaction.