bluuebunny/crossref_metadata_2025_split huggingface dataset:
Requirements for Aggregation of Washed Human Platelets Suspended in Buffered Salt Solutions
Authors: Harbury Christina B , Hershgold J. Edward , Schrier Stanley L 
Published: June 2018

SummaryWith the use of washed human platelets suspended in a buffered salt solution, we have studied the factors capable of acting directly at the platelet plasma membrane to produce aggregation as opposed to those which produce the platelet release reaction and secondary aggregation. Platelet aggregation was measured in an aggregometer and the release reaction followed by assays of the release products.Ca and fibrinogen will not independently induce aggregation in washed human platelets suspended in a buffered salt solution. However, in their absence ADP-, 5HT-and epinephrine-mediated aggregation will not proceed. Of particular interest was the finding that in the presence of Ca, threshold doses of thrombin will produce aggregation earlier if μg amounts of fibrinogen are added. Ca and fibrinogen therefore appear to be absolutely required for aggregation, whether the aggregation is produced by the addition or by the release of required components.If either ADP, 5HT or epinephrine is added singly to buffer-suspended platelets in the presence of Ca and fibrinogen, 10–20% aggregation is observed. The combination of either ADP-5HT, ADP-epinephrine or 5HT-epinephrine produces 60–70% aggregation. The addition of ADP, 5HT and epinephrine together produces 80–90% aggregation.No release reaction is produced by the addition of ADP or 5HT alone or in combination. A new finding in this study therefore is that 5HT and ADP can act directly at the platelet plasma membrane to produce extensive aggregation in the absence of any release reaction.Epinephrine does produce a small release reaction, and may therefore produce its enhancement of aggregation either by acting directly at the platelet plasma membrane or by the release of something other than Ca, fibrinogen, ADP, 5HT, or epinephrine.In this study using washed human platelets suspended in a buffered salt solution, no evidence was found for the requirement of a plasma protein other than fibrinogen in platelet aggregation.
Aggregation in Vitro of Immature Thrombocytes from Early Chick Embryos
Authors: Greenberg Judith H 
Published: June 2018

SummaryMammalian platelets and nonmammalian thrombocytes, although they perform a similar function, differ in morphology and in their response to thrombogenic agents. The present experiments extend the comparison between the two cell types to include the immature form of thrombocytes found in early chick embryos. Agents known to induce, or to inhibit, aggregation of platelets were tested for their effect on thrombocytes which were isolated from chick embryos of five days incubation age and which had been suspended in a tris-buffered saline solution containing EDTA. The degree of aggregation of thrombocytes was determined by phase microscopy after treatment with thrombin, trypsin, adenosine 5′-diphosphate (ADP), calcium chloride, or the sulfhydryl inhibitor N-ethylmaleimide. Approximately 450 trials were performed using 102 samples of blood, each sample being obtained by the pooling of the blood of five to six dozen embryos. The results demonstrate that thrombin and trypsin, in the presence of calcium ions, induce significant aggregation compared to that of untreated controls. Thrombin, in the absence of calcium ions, is ineffective in inducing aggregation, as is calcium chloride alone, or ADP in the presence or absence of calcium ions. Pretreatment of the thrombocytes with N-ethylmaleimide inhibited aggregation by thrombin in the presence of calcium chloride. It may be concluded that embryonic thrombocytes resemble platelets in their response to all the aggregating agents tested, with the exception of ADP, but resemble the thrombocytes of adult chickens in their failure to respond to ADP.
Progress in the Control of Oral Anticoagulation
Authors: Loeliger E. A 
Published: June 2018

SummaryIt should be realized that the quality of oral anticoagulation depends on thorough pharmacological knowledge of coumarin congeners, skilled clinical supervision of the patient and well-standardized laboratory control of patients’ blood. Results of the laboratory control should no longer be expressed in terms of conventional prolongation ratios or percentages only. Exact data as to laboratory standardization with reference plasmas and the results of translation into terms of reference thromboplastins have to be given.
The Shape of Blood Platelets
Authors: Murphy Martin J. 
Published: June 2018

SummaryThe three dimensional structure of human blood platelets has been investigated using two different methods of tissue preparation. It has been demonstrated that freeze-drying preserves platelet structure to a greater degree than other methods which employ air drying.When platelets are prepared by conventional techniques their dendritic projections are uniformly found to be flattened and in contact with the substrate when viewed by scanning electron microscopy. When lyophilisation is used some of these fine cytoplasmic protuberances are found to be freely directed away from the substrate and may in fact elevate the entire platelet body or chromomere. The possible implications of this new observation are discussed in terms of platelet ultrastructure and their role in hemostasis.
Preparation of Modified Bovine Factor VIII with Enhanced Biological Activity Using Insoluble-trypsin Columns
Authors: Vogel Christine N. , Parfitt Henry E. , Kingdon Henry S. , Lundblad Roger L. 
Published: June 2018

SummaryCrude bovine Factor VIII preparations have been modified by passage over a column of trypsin-agarose. Factor VIII prepared without an early adsorption step utilizing either barium sulfate or aluminum hydroxide gel generated significant Factor Xa activity by passage over such a column and was unsuitable for further characterization. Factor VIII prepared using adsorption with barium sulfate contained no Factor Xa activity after passage over trypsin-agarose. This trypsin-modified material showed a decreased molecular size as judged by behavior on gel filtration and an increased rate of reaction with bovine Factor IXa.
Potentiation of the Anti-factor VIII Effect of Thrombin in Plasma by the Plasminolytic Derivatives of Fibrinogen and Fibrin
Authors: Chandra S , Triantaphyllopoulos D. C 
Published: June 2018

SummaryThe activity of factor VIII in mixtures of native plasma or blood with fibrinogen derivatives at concentrations high enough to inhibit prothrombin consumption, is greatly reduced. On the other hand the activity of factor VIII was found normal in similar mixtures of adsorbed native plasma with fibrinogen derivatives, where no generation of thrombin could have taken place. The fibrinogen derivatives increased significantly the inactivating effect of low concentrations of thrombin on the activity of factor VIII of mixtures of adsorbed oxalated plasma with the derivatives. The same inactivating effect was exerted by fibrinogen derivatives heated at 60° C for 15 minutes and by plasmin lysed fibrin. In contradistinction addition of intact fibrinogen or fibrinogen derivatives to heat-defibrinated plasma protected factor VIII from inactivation by thrombin. When both, intact fibrinogen and its derivatives, were added simultaneously at the same concentrations at which they were added singly, the protective effect was intermediate between that exerted by intact fibrinogen and fibrinogen derivatives alone. Under these conditions the fibrinogen derivatives appeared as if they potentiated the inactivating effect of thrombin. Probably by inhibiting the formation of structural fibrin they increased the amount of thrombin, which remained unadsorbed and free to inactivate factor VIII.
Detection of Carriers of Haemophilia
Authors: Ekert Henry , Helliger Holger , Muntz Robert H. 
Published: June 2018

SummaryProtein with antihaemophilic factor antigenicity (AHF-like protein) and the biological activity of antihaemophilic factor (AHF activity) was measured in 13 obligatory and 21 suspected carriers of haemophilia and 20 normals. The mean level of AHF-like protein was significantly higher in the obligatory and suspected carriers but there was a wide range of values. The ratio of AHF activity to AHF-like protein was significantly lowered. In 31 of 34 cases a diagnosis of the carrier status could be made by the use of this ratio. In 18 the AHF activity was within the normal range and in 15 of these the ratio could be used to diagnose the carrier status. The ratio was not diagnostic in 3 obligatory carriers. Estimation of the ratio of AHF activity to AHF-like protein is a valuable adjunct to genetic counselling in haemophilia.
Characterization of Clotting Factors Associated with Blood Platelets after Gel Filtration
Authors: Tangen Oddvar , Lestrup Eva B. , Berman Herbert J. 
Published: June 2018

SummaryAggregation of human and rabbit gel filtered platelets (GFP) has been studied in presence of Ca2+, activated factor X (Xa) and different plasma preparations. It was found that factor Xa by itself is not a platelet aggregating agent. However, the platelets aggregated immediately when platelet poor plasma (PPP) was added to a mixture of GFP, Ca2+ and factor Xa. Aggregation also occurred immediately when factor V-deficient plasma was substituted for PPP, but not when factor II-deficient plasma was used. In the absence of factor Xa, aggregation occurred on addition of factor V- or VIII-deficient plasma, but only after some delay. The platelet aggregation experiments and experiments with centrifugations and resuspensions of the platelets, clotting experiments, and gel filtration of platelet free plasma (PEP) led to the following conclusions : Factors II and X are totally removed from the platelets by gel filtration, factor V is closely associated with the platelet surface, and part of the factor VIII-activity in the plasma is eluted together with the GFP without being associated with the platelets. This factor VIII-activity belonged to an extremely large molecule or molecular complex with a Mw in the order of 2 - 5 · 107.
The Effect of Barbituric Acid Derivatives on Platelet Function in Vitro and in Vivo
Authors: Joist J. Heinz , Cazenave Jean-Pierre , Mustard J. Fraser 
Published: June 2018

SummarySodium pentobarbital (SPB) and three other barbituric acid derivatives were found to inhibit platelet function in vitro. SPB had no effect on the primary response to ADP of platelets in platelet-rich plasma (PRP) or washed platelets but inhibited secondary aggregation induced by ADP in human PRP. The drug inhibited both phases of aggregation induced by epinephrine. SPB suppressed aggregation and the release reaction induced by collagen or low concentrations of thrombin, and platelet adherence to collagen-coated glass tubes. The inhibition by SPB of platelet aggregation was readily reversible and isotopically labeled SPB did not become firmly bound to platelets. No inhibitory effect on platelet aggregation induced by ADP, collagen, or thrombin could be detected in PRP obtained from rabbits after induction of SPB-anesthesia.
Formation and Embolization of Thrombi after Electrical Stimulation
Authors: Spilker B. A , van Balken H 
Published: June 2018

SummaryCharacteristics of thrombi produced upon electrical stimulation of mesentery and brain vessels were studied in five species. Parameters for measuring drug effects were also evaluated to determine which were sensitive to platelet aggregation inhibitors. The current required to cause vasoconstriction in 50% of the rat mesentery arteries stimulated was increased by vasodilators, but not by inhibitors of platelet aggregation. The threshold of current necessary to cause thrombus formation was increased by Imipramine in both acute and chronic experiments and by aspirin and papaverine in chronic experiments. Since these were the only agents tested which inhibit platelet aggregation there appears to be a relationship between this property and the threshold of current necessary to cause thrombus formation. This parameter may possibly be used to differentiate between platelet aggregation inhibitors and streptokinase-like or heparin-like agents. Changes in mean embolization time under present conditions were not related to activity in inhibiting platelet aggregation.
A 3.5-Second Phenomenon in Haemostasis
Authors: Thilo D , Böhm E 
Published: June 2018

SummaryExperiments with injury of the abdominal rat skin were carried out to examine the haemostatic system mechanism in vivo after zero to 30 seconds bleeding time. In the bleeding area only a few platelet aggregates could be found with no primary platelet thrombus. After 3.5 second bleeding time the first fibrin strands have been observed at the site of injury. The hypothesis is put forward that there is a very fast reacting haemostatic mechanism which results in the fibrin formation already at 3.5 seconds.
Preferential Degradation of Soluble Fibrin Monomers in Streptokinase-activated Plasma
Authors: Konttinen Y. P , Lalla M.L.T , Turunen O 
Published: June 2018

SummaryDegradation of 125I-labelled fibrin monomers and 125I-fibrinogen in streptokinase-activated plasma was investigated. Release of the label proceeded at a much higher rate from soluble fibrin monomer complexes than from fibrinogen until ca. 70% of the label was recovered in the serum. It is concluded that the fibrinolytic system has an essentially higher affinity to monomers than to fibrinogen, but that the specificity of the monomers as substrate may be limited to the early steps of degradation. It is suggested that the preferential splitting of fibrin monomer complexes may be important in the body’s defence against pathological fibrin formations derived from paracoagulable fibrin.
Leucocytes and Thrombosis
Authors: Banks D.C , Mitchell J.R.A 
Published: June 2018

SummaryWhite cell loss from a rotating flask system is enhanced by noradrenaline, adrenaline, isoprenaline, 5HT and tendon extracts. Noradrenaline is the most active agent in this test of white cell behaviour and unlike the other materials its action is not blocked by an ADP-removing system.Adenosine inhibits both platelet loss and white cell loss, but concentrations can be found which selectively block the former.The implications of these findings for our understanding of the mechanism of polymorphonuclear leucocyte involvement in thrombus formation are discussed, but the role of white cells once they have become involved in thrombus formation has not yet been determined.
Quantitative Determination of Total Antithrombin III in Plasma
Authors: Yue Robert H. , Starr Toby , Gertler Menard M. 
Published: June 2018

SummaryA relatively simple method has been developed to evaluate the total amount of antithrombin III in plasma. Since purified and stable bovine thrombin was readily prepared in our laboratory, it was selected to be used in our assay system. Purified α2-macroglobulin was found to inactivate thrombin following a pseudo first-order rate of reaction. However, purified antithrombin III inactivated thrombin following a bimolecular type of reaction. The second-order rate constant for antithrombin III and thrombin interaction was found to be 94 1/M/sec. under these conditions. A least-square straight line was drawn between 15 and 90 minute intervals and the intercept yielded the total amount of antithrombin III expressed NIH thrombin units. This assay system and the graphical analysis yielded the total amount of antithrombin III in plasma quantitatively. The results are reproducible.
Blood Coagulation Inhibitor in a Snake Plasma (Bothrops jararaca)
Authors: Nahas Linda , Betti Ferruccio , Kamiguti Aura S. , Sato Hissae 
Published: June 2018

SummaryExperiments with plasmas samples from the snake B. jararaca and X. merremii have shown that the two differ markedly with respect to their reaction to bovine thrombin. The plasma of X. merremii appears to react in a manner very similar to that of normal human plasma both using the thrombin clotting test and using the antithrombin III assay of Astrup and Darling (Biggs and Macfariane 1962). The plasma of B. jararaca on the other hand, contains, in addition to antithrombin III, an inhibitor which resembles mammalian heparin. This inhibitor prolongs the thrombin clotting time of human and X. merremii plasmas, is recorded by the antithrombin assay and is neutralized by protamine. The inhibitor is however, not identical with mammalian heparin since it is not adsorbed by BaSO4 and Al(OH)3 (which adsorb heparin) and it is heat labil whereas mammalian heparin is heat stable.
Evaluation of a New Preparation of Urokinase
Authors: Prentice C.R.M , Rogers K.M , McNicol G.P 
Published: June 2018

SummaryThe pharmacological effect of a new preparation of urokinase (Leo) has been studied, both in vitro and in six patients suffering from thrombo-embolic disorders. It was a non-toxic, effective fibrinolytic agent if given in sufficient dosage. A regimen consisting of an initial dose of 7,200 ploug units per kg body weight, followed by hourly maintenance therapy with 3,600 ploug units per kg intravenously, gave satisfactory evidence of whole body fibrinolytic activity. The preparation had minor but insignificant thromboplastic activity both when assayed in the laboratory and when given to patients.
The Filter Loop Technique as a Method of Measuring Platelet Aggregation in the Flowing Blood of the Rat; the Inhibitory Activity of 5-oxo-l-cyclopentene-l-heptanoic Acid (AY-16,804) on Platelet Aggregation
Authors: Muirhead Christopher R. 
Published: June 2018

SummaryThe filter loop technique which measures platelet aggregation in vivo in the flowing-blood of the rat was compared to the optical density technique of Born which is carried out in vitro with platelet rich plasma. Using these two experimental models the effect on platelet aggregation of three known inhibitors sulfinpyrazone, dipyridamole and prostaglandin E1, and a novel compound 5-oxo-l-cyclopentene-l-heptanoic acid (AY-16, 804) was determined.The effects on platelet aggregation of the known inhibitors were consistent with information in the literature. Prostaglandin E1 was the most potent inhibitor in both techniques; sulfinpyrazone inhibited aggregation in both models but was less potent than prostaglandin E1. AY-16, 804 exhibited activity in vitro and in vivo similar to that of sulfinpyrazone. Dipyridamole did not inhibit platelet aggregation in vivo and did not inhibit aggregation in vitro in concentrations at which it remained soluble.The filter loop technique is a suitable model for measuring platelet aggregation in the flowing blood of the rat. It is a relatively simple method of determining aggregation and easily adapted to other species.
The Migration of Human Platelets in Vitro
Authors: Nathan Paul 
Published: June 2018

SummaryA simple procedure is described for measuring migration of human platelets in vitro. Migration increased with temperature reaching maximum values at approximately 30 °C. Addition of normal plasma to the incubation chambers increased migration in all tests and the increase reached twice the control values in 3 of 4 tests. The rate of migration in vitro was relatively rapid for the first 12 hrs. of incubation and then continued at a slower rate for at least an additional 12 hours.
Impairment of Human Platelet Aggregation and Serotonin Release Caused in Vitro by Echis Colorata Venom
Authors: Biran Haim , Dvilansky Alexander , Nathan Ilana , Livne Avinoam 
Published: June 2018

SummaryAggregation of washed human platelets, induced by either ADP, thrombin or collagen, was decreased by Echis colorata venom (EVC). With ADP as an inducer, the inhibition of aggregation was proportional to the venom concentration, starting from 0.27 μg/ml and attaining full inhibition with venom concentration of 9 μg/ml. Higher concentrations were required for comparable venom effects when collagen or thrombin were used as inducers. Based on serotonin release measurements and platelet counting, it is concluded that the ECV-diminished aggregation is not due to platelet lysis. Thrombin-dependent serotonin release was inhibited by the venom to an extent proportional to the log ECV concentration at a range of 0.27 to 90 μg/ml. ECV effeces on serotonin release are apparently independent on its effects on aggregation, since similar results were obtained either with or without EDTA.Endothelial damage and defibrination are already known to be associated with the bleeding tendency caused by ECV. The present data disclose a functional impairment of platelets as an additional antihemostatic effect of this venom.
Anticoagulant Factors from Viperidae Venoms
Authors: Boffa Marie Claire , Delori P , Soulier J. P 
Published: June 2018

SummaryTwo proteins presenting anticoagulant activities were isolated from Viperidae venoms : one from Vipera aspis, the other from Vipera berus. They interfere with the formation of prothrombinase. Their inhibitory effect results from a specific action of a complex which blocks the active sites of phospholipids. This complex is easily dissociated by antivenoms allowing normal clot formation.Berus inhibitor possesses a high phospholipase activity while aspis inhibitor is completely devoid of this activity. The anticoagulant action of these venom factors does not appear to be enzymatic.The affinity of both inhibitors for phospholipids seems similar though aspis inhibitor shows a more marked anticoagulant action which is neutralized by the addition of a greater amount of phospholipid.The study of these venom inhibitors confirms the fact that, in the absence of platelet phospholipids, clot formation is not possible.
Clinical Studies Concerning Factor XIII; with Special Reference to Hyperlipemia
Authors: Cucuianu Mircea P. , Vasile Vasile V. , Popescu Titus A. , Opincaru Augustin , Crîsnic Ion , Tapalagå Daniela 
Published: June 2018

SummaryFactor XIII, estimated according to the method of Heene, was found to be diminished in patients with cirrhosis of the liver, in acute renal failure and, to a lesser extent, postoperatively, owing probably to both a decreased synthesis and an accelerated utilization. When compared to values obtained in healthy, normal weight, normolipemic control subjects, the level of factor XIII was higher in hyperlipemic and especially in hypertriglyceridemic patients, whether clinical atherosclerosis was present or not. Low levels of factor XIII were usually accompanied by a decrease in serum pseudocholinesterase, while high values of this enzyme produced by the liver were noted in hypertriglyceridemic patients. The hypothesis of an enhanced synthesis of factor XIII by the liver, in subjects with endogenous hypertriglyceridemia is considered. It is also suggested that accelerated stabilization of fibrin might contribute to the fibrinolytic insufficiency of hyperlipemic patients and enhance certain atherogenic mechanisms.
Effects of Puff Adder Venom on the Coagulation Mechanism
Authors: Phillips Louise L. , Weiss H. J , Christy N. P 
Published: June 2018

SummaryStudies of the in vitro effects of puff adder venom (Bitis arietans) on the coagulation system of human plasma have suggested this venom activates factor XI. Incubation with the venom results in a prolongation of the partial thromboplastin times in glass which is associated with a depletion of factors V, VIII, and fibrinogen. The latter may be due to the proteolytic properties of the venom. Soluble fibrin monomer complexes are formed rapidly after addition of the venom to normal plasma. The venom also causes platelet aggregation which is not inhibited by heparin.