bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Differentiation of Acid Phosphatases of Human Blood Platelets
Authors: Kaulen H. D , Gross R 
Published: June 2018

SummaryThe Acid Phosphatase was tested in human platelets and in the rat liver mitochondrial-lysosomal fraction with p-nitrophenylphosphate and β-glycerophosphate as substrates. In the platelets the following differences were found between the hydrolysis of these two substrates, whereas in rat liver no such differences were observed. 1. The relative rates of hydrolysis and the pH optima for both substrates are different (pH 4.6 for the β-glycerophosphatase, pH 6.0 for the p-nitrophenylphosphatase in the platelets). 2. The p-nitrophenylphosphatase of the platelets is inhibited by p-chlormercuribenzoate and N-ethylmaleimide, but not by fluoride or L + tartrate, whereas the contrary is true for the platelet β-glycerophosphatase and the rat liver activities. 3. The platelet p-nitrophenylphosphatase is rapidly inactivated by preincubation at 40-45° C for 15 min, the other phosphatases are much more heat-resistant. 4. Sucrose density gradient centrifugation of platelet homgenates showed a separation of the two platelet phosphatase activities, the p-nitrophenylphosphatase with its maximum at lower densities than the β-glycerophosphatase.It is concluded that in human platelets there are at least two different Acid Phosphatases. The β-glycerophosphatase probably represents the lysosomal (as compared to the rat liver enzyme) phosphatase whereas the p-nitrophenylphosphatase of the platelets is a different enzyme whose subcellular localization and functions are as yet unknown.
The Human Blood Platelets as a Molecular Mosaic Its Role in Aggregation and Thrombus Formation
Authors: Mehrishi J. N 
Published: June 2018

SummaryOn the surface of human blood platelets various types of groups are present - sulphydryl groups, positively charged amino groups and at least three types of anionogenic groups. The numbers of these groups on a per cell basis have been calculated and then* relative contributions to the net charge determined. Two arrangements for the distribution of the groups in the cell periphery have been proposed. Such studies provide a molecular basis for many reactions taking place at the cell surface. The role of these groups in platelet aggregation and thrombus formation is discussed
Effects of Anti-Adhesive Agents on the Ultrastructure of Rabbit Blood Platelets in Vitro
Authors: Dougherty W. J , Bicher H. I 
Published: June 2018

SummaryThe in vitro effects of two anti-adhesive agents, designated as substances “86” and BLR-743, on the ultrastructure of rabbit blood platelets were examined. When compared with control platelet preparations, it was found that these agents, over a 10 min period, induced platelets to become spiny spheres. Vacuoles of the surface connected system inside platelets tended to enspherulate, also. No change in structure or location of form-maintaining structures such as microtubules were observed in treated platelets. Neither were changes observed in the structure or location of mitochondria. While the distribution within platelets of α-granules and vacuoles containing 5-hydroxytryptamine granules seemed to be little affected by treatement of platelets with these agents, 5-hydroxytryptamine granules were reduced in number and α-granules expressed variable degrees of electron density suggesting variable degrees of extraction of materials from these granules. It is concluded on the basis of the morphologic changes in platelets observed that the anti-adhesive agents have a primary action on the plasma membrane and other membrane bound structures of blood platelets.
Platelet Count and Platelet Stickiness in Rats
Authors: Grüner O. P. N , Endresen G. K. M 
Published: June 2018

SummaryIn rat, a transected tail vessel proved an adequate source of blood for platelet enumeration. When suspensions of rat blood in ammonium oxalate were rotated for 1 h a significant loss of platelets was observed. This platelet reduction rate (PRR), calculated as per cent of the pre-rotation count, showed individual constancy and inter-individual variance.
The Effect of Fibrinolysis Inhibitors on the Ellagic Acid Activation of Hageman Factor in the Dog
Authors: Girolami A , Fioretti D , Cella G , Pedrazzoli G , Bernardi R 
Published: June 2018

SummaryThe administration of 10 ml/kg b.w. of a 10−4 M ellagic acid solution to dogs primed with saline (control group) caused a marked shortening of the silicone clotting time and a mild shortening of the glass clotting time whereas no changes in the euglobulin lysis time were noted. The administration of the compound to dogs primed with Trasylol (10,000 K.I.U./kg b.w.) failed to cause any change in the clotting times but caused instead a sharp inhibition of fibrinolysis. The administration of ellagic acid to dogs primed with EACA (0.3 g/kg b.w.) caused a shortening of the silicone and glass clotting times similar to that observed in the control group whereas fibrinolysis was not significantly inhibited. These data indicate that Trasylol inhibits Hageman factor activation by ellagic acid whereas EACA has no effect.
Impaired Fibrinolysis in Sickle Cell Disease
Authors: Green D , Kwaan H. C , Ruiz G 
Published: June 2018

SummaryCoagulation studies were performed in 52 patients with sickle cell disease during asymptomatic periods and during episodes of crisis and infection. Platelet counts averaged 473,000, 469,000, and 461,000 per mm3 in these 3 groups, and factor VIII concentrations were elevated in all. Fibrinogen was increased to the same extent in both sickle cell and non-sickle cell patients with infection. Fibrinolytic activity, as measured by euglobulin lysis times and zones of lysis on fibrin plates, was markedly reduced during periods of infection in sickle cell patients but not in non-sickle patients. Impairment of fibrinolysis in most patients was not on the basis of overutilization or consumption, since no decrease in the levels of clotting factors or plasminogen was observed. It was suggested that generalized intravascular sickling in these patients may have caused widespread endothelial damage, resulting in decreased production of plasminogen activator.In addition, several sickle cell patients with infection were found to possess elevated levels of an inhibitor directed against urokinase.
The Influence of Inhibitors of Plasmin and Plasminogen Activation on the Streptokinase-Induced Fibrinolytic State
Authors: Spöttl F , Holzknecht F 
Published: June 2018

SummaryThe influence of the inhibitors of plasminogen activation by streptokinase, urokinase and tissue activator and of the two antiplasmins i.e. α1 antitrypsin and α2-macroglobulin, upon the formation and clearance of streptokinase-activator in vivo was investigated in 22 subjects. No influence of the above mentioned inhibitors on the formation of the streptokinase-activator could be found, whereas the clearance of the activator seems to be a function of the α2-macroglobulin level before streptokinase administration. The clearance rate of the streptokinase-activator differed significantly from the clearance rate of 131I labelled streptokinase caused by antigen-antibody complex formation [Fletcher et al. (10)], and was similar to the clearance rate of the histamine or nicotinic acid induced plasminogen activator. The possibility of a common clearing mechanism of fibrinolytic activators is discussed.The existence of 3 different inhibitors activities on plasminogen activation as tested in vitro i. e. inhibitor of streptokinase, urokinase and tissue activator, was demonstrated. These inhibitory activities are probably not the properties of 3 different serum proteins but rather the result of the action of α1antitrypsin and α2-macroglobulin. The degree of inhibition, however, of each of the 2 proteins on each of the 3 plasminogen activators (streptokinase, urokinase and tissue activator) seems to be different. This difference may be caused by a different inhibitory effect of α1 antitrypsin or α2-macroglobulin on each of the plasminogen activators.The plasmin formed after the streptokinase infusion is rapidly bound by the α2macroglobulin and this plasmin-antiplasmin complex is immediately removed from the blood, causing a decrease of the α2-macroglobulin level. This decrease of α2-macroglobulin is correlated with the initial level of α2-macroglobulin. This finding demonstrates the concentration depending formation of the plasmin-antiplasmin complex also in vivo.
Severe Hereditary Deficiency of Factor VII during Pregnancy
Authors: Seligsohn U , Peyser M. R , Toaff R , Shani M , Ramot B 
Published: June 2018

SummaryIn normal pregnant women factor VII level is increased. This may also be observed in women with hereditary partial factor VII deficiency.In a 38 year old woman with severe hereditary factor VII deficiency no change of the factor level was observed during pregnancy. The patient underwent two uneventful caesarian sections because of placenta praevia and transverse lie of the fetus.During the second caesarian section factor VII level was simultaneously determined in blood obtained from the antecubital and uterine veins and from the umbilical vein and artery. Factor VII levels in the umbilical vessels were similar and exceeded the levels observed in the mother’s vessels. In 3 control patients similar examinations were performed during caesarian sections but reversed ratios of factor VII levels were observed. These data seem to prove that factor VII does not cross the placenta.In the family study 2 siblings were found to have severe factor VII deficiency whereas several other members had either normal or partial deficient levels. The results obtained support again the assumption that factor VII deficiency is inherited by an autosomal gene that in the homozygous state is manifested by severe factor VII deficiency and in the heterozygous state by mild deficiency or normal factor VII levels.
Elevation of Factor VIII in Acute Fatal Liver Necrosis
Authors: Meili E. O , Straub P. W 
Published: June 2018

Summary1. During 1963–1967 we observed 9 patients with letal fulminant hepatitis and a usually massive elevation of plasma factor VIII activity in the presence of a severe depletion of all other coagulation factors.2. Patient plasma, diluted to 100% factor VIII activity was equally effective as normal plasma in correcting the haemophilia A defect in various systems.3. An artefact due to thrombin or other clotting intermediates has been excluded.4. The following observations suggest an increase of factor VIII protein and not only of factor VIII activity : No difference was found between normal and patient factor VIII in their behaviour during heating, pH alteration, adsorption, plasmin digestion, ammonium sulfate and euglobulin precipitation, and neutralization by a specific factor VIII inhibitor. In contrast, factor VIII artifically activated in vitro with thrombin, was inactivated more rapidly by heat and plasmin than untreated normal or patient factor VIII.5. The mechanism and possible causes for this factor VIII elevation are discussed. Factor VIII elevation is limited to the most severe cases and may therefore be of prognostic significance in liver dystrophy.
Studies on the Anticoagulant Action of Aprotinin (“Trasylol”)
Authors: Prentice C. R. M , McNicol G. P , Douglas A. S 
Published: June 2018

SummaryStudies were undertaken to localize the site of the anticoagulant action of Aprotinin (“Trasylol”). Contact activation studies using either kaolin or contact product eluted from celite demonstrated that Aprotinin had greatest inhibitory action against the interaction of a surface with the contact factors, but some inhibition of formed contact product was also noted. In addition, Aprotinin was found to have a slight anticoagulant action against activated factor IX prepared by incubation of contact product with a calcium phosphate eluate from serum. No inhibitory action in pharmacological doses was demonstrated against activated factor X or later stages in the coagulation sequence.It was concluded that Aprotinin is a relatively weak anticoagulant in doses liable to be obtained in vivo during therapeutic infusions.
Platelet Adhesiveness, Aggregation and Fibrinolysis after the Oral Administration of the Contraceptive “Lyndiol”
Authors: Farbiszewski R , Kurowska T 
Published: June 2018

SummaryThe adhesiveness and aggregation of platelets in plasma of women treated with “Lyndiol”, an anticonceptive agent, were investigated.An increase of adhesiveness and enhancement of platelet aggregation induced by ADP and thrombin was observed. The pathophysiological significance of the described changes is briefly discussed.
Protection from Hg-Inactivation of Factor XIII by Mercaptalbumin
Authors: Fantl P 
Published: June 2018

SummaryThe blood plasma factor XIII (fibrin stabilizing factor) is inactivated by mercuric ions and can be reactivated by serum - or plasma albumin of which the active component is mercaptalbumin. A relation between mercaptalbumin concentration and factor XIII activity is pointed out.
Functional and Steric Characteristics of Modified Thrombin Zymogen
Authors: Marciniak Ewa 
Published: June 2018

SummarySteric and functional changes of thrombin zymogen, due to the degrading action of thrombin, have been studied. A prothrombin complex of a high degree of activity was obrained from bovine plasma by adsorption on BaCO3. This preparation was further purified by ion exchange chromatography and converted with a small amount of thrombin into a modified form of zymogen. The difference between the unmodified and modified form, with respect to their reactivity, has been seen only in a biological type of activation with factor Xa-phospholipid-factor V-calcium complex. The modified form, when reacting as a concentrated substrate, or the diluted one, under conditions of the two-stage analysis, required several-fold higher concentrations of factor V. With factor Xa alone as activating enzyme, both forms of zymogen reacted in exactly the same manner. Gel filtration studies indicated a drastic change in shape or size of the altered zymogen molecule, as defined by Stokes radii.Factor X present in prothrombin complex preparations, by its frictional characteristic, obviously resembled the unmodified form of prothrombin. However, it was not affected by thrombin either in a functional way or in its molecular parameters. This indicates that, although present together in the same multiactivity preparation, factor X and thrombin zymogen do not form a molecular complex.
Mg++ - and Ca++-Induced Platelet Aggregation and ADP
Authors: Cronberg S , Caen J. P 
Published: June 2018

SummaryReports on platelet aggregation after addition of calcium or magnesium to EDTA- PRP or platelet suspensions were confirmed. An aggregating principle was found in the EDTA-plasma and the supernatant of the platelet suspensions. Aggregation by magnesium in a platelet suspension was inhibited by adenosine and phosphoenol- pyruvic acid and pyruvate kinase, which suggested that the active principle was identical with ADP. Degradation of ADP in EDTA plasma was blocked.It thus appears that aggregation induced by calcium or magnesium in EDTA-PRP and platelet suspension was due to accumulation of spontaneously liberated ADP, which was not degraded.
Mechanism of Action of Synthetic Fibrinolytic Compounds
Authors: Baumgarten W , Priester L. I , Stiller D. W , Duncan A. E William 
Published: June 2018

SummaryThe mechanism of dissolution of a preformed plasma clot was explored.Our experiments showed clearly that the purified fibrin clot, made by extensive washing of a plasma clot, was resistant to lysis and that the fibrinolytic potential of the active fibrinolytic compounds was related to the presence of other plasma proteins in addition to fibrinogen.The activation of the fibrinolytic precursors was reversible inasmuch as removal of the fibrinolytic compounds negated the fibrinolytic activity of the protein-fibrinolytic compound mixture.Antifibrinolytic compounds which had been shown to interfer with fibrinolysis by streptokinase-activated plasminogen inhibited dissolution of the preformed plasma clot by fibrinolytically active compounds.The fibrinolytic potential of fibrinolytic compounds was additive; however, no apparent synergism was observed.The implication of these results to the mechanism of synthetic fibrinolysis was discussed.
Thrombosis Prevention by Coagulation and Platelet Aggregation Inhibitors, in Hyperlipemic Rats
Authors: Renaud S , Lecompte F 
Published: June 2018

SummaryPhenylbutazone, oxyphenbutazone, and sulfinpyrazone were equally effective at the dosage of 100 mg/kg (per os) in inhibiting thrombin- and ADP-induced platelet aggregation in hyperlipemic rats, and in preventing the development of thrombosis initiated by the intravenous injection of an endotoxin. Despite a slight anticoagulant effect of these substances, their antithrombotic activity appears to be due mostly to inhibition of platelet aggregation.Thrombosis in hyperlipemic rats could also be prevented by a dicoumarol derivative, acenocoumarin, which only inhibits coagulation. Therefore, both platelet aggregation and fibrin formation appear to be essential for the occurrence of large thrombi under these conditions. Nevertheless, although acenocoumarin has no direct effect on platelet aggregation, it could indirectly affect this phenomenon by blocking the formation of thrombin, which is suspected of being the agent responsible for initiating thrombosis in hyperlipemic rats.Low doses of phenylbutazone and acenocoumarin, in condition, which when given alone were ineffective in inhibiting thrombosis, could decrease the severity of thrombosis by 33%. The substance GP45840, when added in vitro to platelet-rich plasma as well as given per os to hyperlipemic rats, was no more effective than sulfinpyrazone in inhibiting platelet aggregation. Nevertheless, this substance was significantly more efficient in reducing thrombosis than was sulfinpyrazone, apparently through some additional anticoagulant activity. The results of these experiments suggest that it could be beneficial to affect both coagulation and platelet aggregation in order to satisfactorily prevent thrombosis.
The Induction of the Release Reaction in Human Blood Platelets by Close Cell Contact
Authors: Massini P , Lüscher E. F 
Published: June 2018

SummaryWhen blood platelets are centrifuged at elevated pH they release serotonin. This reaction is similar to the release reaction which makes part of the complex called viscous metamorphosis. The experiments support the hypothesis that contact between platelets forms the stimulus which initiates the release reaction.
The Evaluation of a Method for Adenosine Diphosphate Induced Platelet Aggregation in the Guinea Pig
Authors: Mackenzie R. D , Henderson J. G , Steinbach J. M 
Published: June 2018

SummaryA method is described for the in vivo measurement of ADP-induced platelet aggregation in the guinea pig. This method uses the property of the lungs to remove platelet aggregates from the circulation. ADP is infused into the jugular vein and blood samples are removed from the carotid artery for determination of platelet concentration.In order to find a practical concentration of ADP and infusion time, the effects of several concentrations and infusion time on platelet count versus time were determined. A dose of 0.2 mg/kg ADP infused over 1 min was found to produce an approximately 50% drop in platelet count with a return to the original level at about 30 min. The analysis of the platelet response to ADP can be made quantitative by measurement of the total response, that is, the total decrease of platelet count from start of infusion to the return to preinfusion values.Prostaglandin E1 was tested and found to inhibit the total aggregation response with this method.
Platelet Reactions and Immune Processes
Authors: Jobin F , Lapointe F , Gagnon F 
Published: June 2018

SummaryWe have studied the effect of IgG, IgA, IgM, lambda light chains, Fc fragments, heat-aggregated gammaglobulin, albumin and fibrinogen on the interaction of latex, Kaolin, celite or bentonite particles with human platelet-rich plasma.1. Marked enhancement of platelet aggregating activity was produced by preincubating these particles with IgG at an appropriate concentration. Excess IgG abolished this platelet aggregating property.2. Platelet aggregation could also be induced by betamethasone acetate particles. The latter and IgG-coated latex, Kaolin or bentonite particles were inhibited by chymotrypsin substrates and inhibitors.3. Heat-aggregated IgG produced platelet aggregation in platelet-rich plasma only when adsorbed onto (Kaolin) particles.4. Results obtained with fibrinogen-coated Kaolin suggest that the particles thus acquired a slightly increased platelet clumping activity.5. The other proteins studied failed to enhance the platelet aggregating activity of Kaolin particles, and could even inhibit the formation of IgG-coated Kaolin particles able to readily aggregate platelets.
Aspirin Inhibition of In Vivo Effects of Intestinal Alkaline Phosphatase on Platelets
Authors: Iatridis P. G , Iatridis S. G , Ferguson J. H 
Published: June 2018

SummaryIntravenous injections of 10 mg/kg purified intestinal alkaline phosphatase (AlPh) into (I) normal (non-aspirinized) rabbits and (II) aspirinized rabbits, show that aspirin inhibits significantly the AlPh effects on platelet aggregation and adhesion. Since aspirin does not change the assayable injected AlPh activity or its electrophoretic distribution, and whereas aspirin inhibits the platelet ADP release, it is very possible that the effects of AlPh on platelets are due to platelet ADP release by AlPh.Aspirin also inhibits the hypercoagulable effect of the injected AlPh. If aspirin acetylates the platelet membrane by its acetyl group, this could compete with HF (Hageman factor) which is a sialoglycoprotein, and could thus prevent the activation of HF on the surface of platelets.
Retention of Plasminogen Activator and Acid Phosphatase in Lysosomes of Lipemic Rats
Authors: Beard E. L 
Published: June 2018

SummaryThe effect of chronic lipemia on lysosomal permeability was investigated. Rats were fed either 40% butter, 40% corn oil, atherogenic, thrombogenic or normal diet for 9 months. Prior to sacrifice, half of each diet group was injected with acid phosphatase to increase lysosomal lability. Blood and liver lysosome isolated were assayed for lysosomal enzyme levels. Only lysosomes from rats fed the normal diet responded to acid phosphatase injections by releasing increased quantities of plasminogen activator and acid phosphatase from liver lysosomes into the blood. It was concluded that chronic hypercholesterolemia and elevated blood phospholipid levels increased the integrity of lysosomal membranes and interfered with release of the hydrolytic enzymes retained by them.
Factor X
Authors: Prydz H , Gladhaug Å 
Published: June 2018

SummaryA monospecific antiserum against factor X was prepared in rabbits. The antiserum precipitated factor X in human plasma and serum and monkey serum. The antiserum was used to :1. demonstrate the presence of factor X precursor in blood from patients under anticoagulant therapy,2. produce an artificial factor X deficiency substrate useful for testing factor X,3. study the species specificity of factor X from various common laboratory mammals.