bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunochemical studies on fibrinogen
Authors: Gollwitzer R , Tanswell P , Lotter H , Henschen A , Timpl R 
Published: May 2019

The immunochemistry of fibrinogen has been subject of concise studies during the last years. Fibrinogen is a strong immunogen, based on a large variety of antigenic determinants located at different sites in the molecule. By using purified antibodies several of the surface and masked antigenic determinants on the individual chains and the large disulfide bonded CNBr-peptides were identified. According to these investigations the γ-chain is partially buried in the native molecule, whereas the antigenic determinants of a CNBr-peptide covering the C-terminal half of the α-chain are located on the surface of the protein. The structure of the antigenic determinants of this peptide which exhibits an extreme species variability has been more precisely defined in both bovine and human fibrinogen. A distinct structural variability was also observed for different antigenic determinants located m fibrinopeptides A and B.Supported by the Deutsche Forschungsgemeinschaft, SFB 51.
On The Release Function Of Adhering Platelets
Authors: Malmgren R , Larsson R , Olsson P , Tornling G , Unge G 
Published: May 2019

A method for measuring the continuous uptake and release of serotonin during 60 minutes by platelets adhering to a polymer surface is presented.Heparinized human blood with autologous 51Cr and 14C-serotonin labelled platelets is exposed to the polymer in Chandler loops rotated slowly for different periods. Initially the adhering platelets take up serotonin from non-adhering aggregating platelets by an active process and then slowly begin to release serotonin. Acetylsalicylic acid treated platelets adhere and take up serotonin to the same extent as untreated platelets, but do not undergo a release reaction.Coating of the polymer surface with fibrinogen prior to blood exposure or with fibrin (achieved by thrombin treatment of the fibrinogen adsorbate) does not affect the degree of adhesion and serotonin uptake, but inhibits the release reaction. When only fibrino-peptide A is split off with Defibrase from the fibrinogen layer the release function of the adhering platelets reappears.It is concluded that the release mechanism of adhering platelets is not only dependent of the functional state of the platelet itself, but also on the ultimate composition of the protein layer to which the platelets adhere.
Effects of Aspirin and Sulfinpyrazone on Thromboxane and Prostacyclin Synthesis in Rabbits
Authors: McDonald J , Cerskus A , Ali M 
Published: May 2019

Arachidonic acid (AA) or collagen were infused into rabbits causing intravascular platelet aggregation with thrombocytopenia, hypotension and death. Thromboxane and prostacyclin synthesis were measured by radioimmunoassay of plasma TXB2 and 6-keto-PGF1α. The effects of pretreatement with aspirin (ASA) or sulfinpyrazone(SPZ) were assessed.Death in drug-treated rabbits was always associated with elevations of plasma TXB2(1-40 ng/ml) and of 6-keto-PGF1α(1-20 ng/ml). Collagen produced only small elevations of plasma TXB2 compared to AA but protection by ASA correlated better with inhibition of TXB2 and 6-keto-PGF1α synthesis than with inhibition of aggregation. Low dose ASA produced less inhibition of prostacyclin synthesis than high dose ASA but was less effective in preventing thromboxane synthesis and death.
Ultramicroscopic and Coagulation-Fibrinolytic Findings Induced by Tissue Thromboplastin
Authors: Nagata H , Seya T , Oguma Y , Yamauchi M , Murakoshi T , Hasegawa H 
Published: May 2019

We have studied the ultrastructures of tissue thromboplastin (T.Tbp) to demonstrate how It changes during coagulation.[Materials and Methods] T.Tbp from lungs of rabbits was used for these studies. It was injected into ear veins of rabbits. Lungs were resected at several seconds, 10sec, 1 min, 5 min, 24 hrs or 48 hrs after the injection. They were examined by transmission electron microscope.[Results] Concentrically arranged membrane structures of the injected T.Tbp disappeared in extremely short time after the injection. 1 min after the injection, fibrin fibers were seen between single sheet of membrane and endothelial cells of capillaries. In the rabbit which had died suddenly after the injection of T.Tbp, multiple pulmonary thrombi made of fibrin and platelets were seen in capillaries. The endothelial cells of capillaries were destroyed and interstitial tissues were edematous.The hypercoagulable state was seen 10~30sec after the start of the injection, indicating the shortening of r of TEG. Then, it gradually returned the level before injection. Moreover, changes of the measurements of fibrinogen, antiplasmin and prekallikrein were also seen after the injection.
Association of Factor VIII Procoagulant Activity with Factor VIII Related Antigen
Authors: Armitage H 
Published: May 2019

Using the technique of coagulation in an agarose gel following rapid two dimensional Immunoelectrophoresis, the relationship of factor VIII procoagulant activity (VIIIC) with factor VIII related antigen (VIIIRA) was studied in plasma from patients with von Willebrand's disease and carriers of haemophilia. In each case, VIIIC was closely associated with both the fast and slow moving forms of factor VIIIRA as demonstrated by the formation of fibrin in the clotting gel in a similar position to the precipitin arc in the antibody containing gel.Mixtures of small molecular weight VIIIC with no detectable antigen and factor VIIIRA devoid of clotting activity, from either (a) haemophilic plasma, (b) Dithiothreitol treated haemophilic plasma, (c) normal serum or (d) von Willebrand serum were also studied using this technique. The samples of VIIIC and antigen were either electrophoresed in tandem or mixed in a test tube immediately prior to electrophoresis and an aliquot placed in a single well. Again fibrin formation occurred in the clotting gel in a similar position to the immune precipate. There was no peak of fibrin formation when the VIIIC was electrophoresed alone. All types of factor VIIIRA tested appeared to have an affinity for factor VIIIC and appeared to be capable of acting as a carrier protein.
A Hitherto Undescribed Naturally Occurring Plasma Antagonist of Activated Factor X Inhibitor (Antithrombin III)
Authors: Yin E. T. , Salsgiver W. J. , Tangen O. 
Published: May 2019

Circumstantial evidence suggested that normal human plasma contained a substance regulating the neutralization of F.Xa by F.Xa inhibitor(XaI), (Yin et.al.,Adv.Exper. Med. & Biol., 52 : 239, 1975, Plenum Press, N.Y.).This plasma component has now been isolated and partially purified in our laboratory, and tentatively designated as “Anti-XaI”.In experiments employing purified components, when Anti-XaI was incubated at 37°C with F.Xa, Xal and heparin for two minutes at pH7.5, the amount of F.Xa inhibited was inversely proportional to the Anti-XaI concentration. But, when the F.Xa was replaced by thrombin in the incubation mixture, the neutralization of thrombin clotting activity was undisturbed.Anti-XaI was found to be neither PF3 nor PF4.These and other data strongly suggest that the “Antithrombin III pathway” is more complex than currently believed to be. In circulating blood an equilibrium state must exist between Anti-XaI and XaI.Under certain conditions when the Anti-XaI activity is predominant the rate of F.Xa neutralization bv XaI then becomes slower than the activation of prothrombin to thrombin by F.Xa.
Amplification of Color Yield Obtained Using a Chromogenic Substrate for Determining Plasminogen Activator
Authors: Friedmaa Robert B. , Kwaan Hau C. , Szczecinski Marija 
Published: May 2019

A synthetic chromogenic substrate has recently been reported for use in the specific measurement of urokinase. This material (Chromozym UK, marketed by Pentapharm, Ltd., Basle) is a synthetic tripeptide linked through an amide bond to the chromogen para-nitroaniline (PNA). The release of free PNA can be monitored spectrophotometrically by measuring the increase of absorbance of light in the range of 380 to 410 nm. The present communication describes our efforts at enhancing the color yield of the assay as well as changing the absorption maximum to a wavelength which can more readily and accurately be measured on inexpensive laboratory spectrophotometers .Bratton and Marshall have developed a method which can be used for the determination of aromatic amines in biological systems. We have modified this method for use in semimicro applications and have adapted it to the measurement of free PNA in solution. After acidification of an aliquot of the enzyme digest with trichloroacetic acid (TCA), the liberated PNA is diazotized with sodium nitrite. Excess nitrous acid is removed with ammonium sulfamate, and the diazotized PNA is reacted with 1-naphthylethylenediamine reagent. The product has a magenta-red color with an absorption maximum of 545 nm. The substrate is not affected by exposure to TCA, and when fresh reagents are used, a low background is obtained. The color yield during actual enzyme assay is amplified twenty fold. Other coupling agents are also currently under investigation.
Methods for the Determination of Plasmin, Antiplasmin and Plasminogen by Means of the Substrate S-2251
Authors: Friberger P. , Knös M. , Gustavsson S. , Aurell L. , Claeson G. 
Published: May 2019

The chromogenic peptide substrate H-D-Val-L-Leu-L-Lys-pNA (S-2251) has been chosen from a series of potent plasmin substrates. It is a highly specific and sensitive substrate towards plasmin (Km 2.5·10-4 mol/1, V 0.5·10-6 mol/min CTA-U) and its solubility in tris buffer (1·10-2 mol/1)is sufficient to obtain substrate saturation. Tris buffer pH 7.4 and I 0.15 serves as an optimal medium for the determination of plasmin. In this buffer, antiplasmins in plasma have been determined by using 0.05 CU of plasmin and 20 ul of plasma. At least two inhibitors have been found. One fast (<15 sec. incubation time) and the other(s)slow (5 min. incubation time).The substrate has also been used for plasminogen determinations after activation of 10 ul of plasma with UK (500 Ploug-U) or an excess (40 times) of SK. It was found that neither plasminogen free plasma (100% antiplasmin activity) nor an excess (>1000 times) of SBTI inhibited the substrate activity of the SK activated plasminogen. Optimal conditions for the SK-activated plasminogen was tris buffer pH 7.4, I 0.05. Km = 2.4.10-4 mol/1 for both purified plasminogen and plasma and V = 1.10-4 mol/min.CU or 3.10-6 mol/min-ml plasma.
Contribution of Platelets to the Cardiovascular Effects of ADP in the Rat
Authors: Dejana E. , Castelli M. G. , Gaetano G. de , Bonaccorsi A. 
Published: May 2019

The contribution of platelets to the cardiovascular effects of ADP was investigated in rats in different experimental conditions. Following rapid i. v. bolus injections of ADP(from 0.001 to 0.03 mg/kg b. w.) only a dose-related fall in blood pressure could be detected. Increasing the dose of ADP (up to 1 mg/kg b. w.), platelet fall and changes in cardiac rhythm (bradycardia, A. V. blocks and ectopic beats) became evident. All these phenomena were rapidly reversed. Inhibition of platelet aggregation by a pyrimido-pyrimidine compound (SH 869) or thrombocytopenia induced by Busulfan or antiplatelet antiserum did not significantly protect the animals from the cardiovascular effects of ADP. The fall in blood pressure, however, was reduced. Adenosine, at equimolar concentrations, caused ECG changes similar to those induced by ADP with no platelet aggregation and a less pronounced blood pressure fall. These results suggest that most of the cardiovascular modifications induced by rapid injection of ADP are largely independent of platelets. Platelets appeared to play a more important role when ADP was given for a longer period of time. A slow i. v. infusion of ADP (6 mg/kg b. w. for 10 min) was accompained by platelet fall, cardiovascular collapse and ECG alterations typical of myocardial ischaemia. All these effects persisted throughout the ADP infusion but disappeared soon after its termination. They were almost completely inhibited in rats given SH 869 or made thrombocytopenic .In conclusion, platelets seem to contribute to the cardiovascular effects of ADP only in certain experimental conditions. In others, the nucleotide’s direct effects seem more important.
Significant Alteration in the Stoichiometry of Factor VIII Inhibitor Interactions in the Presence of 0.25 M CaCl2
Authors: Harbury C. B. , Perry P. L. , Janszen M. E. 
Published: May 2019

The major aim of this study was to assess whether the hemophilic VIII antibody (Ab) interacted more readily with “monomeric” factor VIII than with undissociated VIII. Conditions were chosen so that multiplicity of neutralization would occur with low frequency, favoring one Ab molecule per VIII molecule. Remaining VIII (R8) was kept at 65% to 85% of original VIII activity. Ab units were calculated by units of VIII neutralized x 1/dilution of antisera. As R8 fell below 65%, the apparent potency of Ab units decreased. A 25-donor pool of lyophilized plasma was made up with H2O or 0.25 M CaCl2. Thus, within and between experiments, unknown but constant concentrations of VIII molecules and VIII antigens were present. Unknown but constant concentrations and types of Ab molecules from each of three inhibitor plasmas were used. Samples were incubated 2 hours @ 22° C. Controls remained stable for the duration. The two-stage factor VIII assay of Pool et al allowed sufficient dilution of CaCl2 for accurate assay.For 15 independent experiments,

= 53.4 ± 12 Ab u/ml and

= 25.8 ± 10 Ab u/mlFor 31 independent experiments,

= 437 ± 78 Ab u/ml and

= 174 ± 50 Ab u/mlFor 12 independent experiments,

= 80 ± 9 Ab u/ml and

= 32 ± 9 Ab u/mlThus, there was 2.07, 2.51, and 2.50 times more VIII neutralized in the 0.25 M CaCl2 vs. H2O incubation. Experiments were also run at 37° C, slightly increasing Ab u/ml for H2O; but the H2O control often lost significant activity. Possible explanations include: 1) the antibody is bivalent when VIII is monomeric; 2) Previously-hidden Vlll-neutralizing Antigen sites are revealed in the VIII monomeric form; or 3) antigen/antibody affinity is altered.
Immunological Evidence that Human Factor VIII is Composed of Two Linked Moieties
Authors: Koutts J. , Lavergne J.-M. , Meyer D. 
Published: May 2019

Whether the three measurable parameters of factor VIII (procoagulant activity, VIII:C; ristocetin cofactor activity, VIIIR:WF; and factor VIII related antigen, VIIIR:AG) reside on a single protein remains disputed. A solid phase immunoadsorption system, in which homologous antibodies to VIII:C arising in haemophiliacs were insolubilized onto Sepharose, was used to examine the action of such antibodies and the inter-relationship between VIII:C, VIIIR:WF and VIIIR:AG. Homologous antibodies were shown to bind specifically VIII:C and to induce a spontaneous separation of VIII:C from VIIIR:WF/VIIIR:AG. The bond between VIII:C and the homologous antibodies bound to Sepharose appeared to be very stable and could not be broken with the usual antigen-antibody dissociating agents. Following prolonged incubation with antibody-sepharose, concentrated VIIIR:WF/VIIIR:AG (20 u/ml), completely devoid of VIII:C and inhibitor-neutralizing activity, was obtained. The loss of VIII:C had no detectable effect on the molecular size, antigenicity or electrophoretic mobility of the original molecule. The concentrated VIIIR:WF/VIIIR:AG was used to absorb heterologous antisera raised against factor VIII. Specific heterologous antisera to VIII:C, no longer neutralizing VIIIR:WF nor precipitating with VIIIR:AG, were obtained. Immunization of rabbits with VIIIR:WF/VIIIR:AG resulted in antisera which potently neutralized VIIIR:WF and precipitated with VIIIR:AG but also weakly neutralized VIII:C. These antibodies, like 4 other heterologous antibodies to Factor VIII studied, did not neutralize VIII:C which had been dissociated from VIIIR:WF/VIIIR:AG.The results indicate that VIII:C and VIIIR:WF/VIIIR:AG are two different, but linked entities.
Fibrinolytic Activity of Hydatidiform Molar Tissue
Authors: Tsakok F. H. M. , Ratnam S. S. 
Published: May 2019

Intravascular coagulation has been previously suspected in hydatidiform molar pregnancy (McKay 1965) and isolated cases have been described (Egley 1974). Recently a comprehensive coagulation profile in 18 intact hydatidiform molar pregnancies has been reported (Tsakok 1976). These studies showed evidence of abnormal proteolysis with activation of the coagulation system and the fibrinolytic system in varying degrees. In the present work the fibrinolytic activity of fresh molar tissue from 16 patients was studied by the fibrin plate method (Nilsson 1962) and by histochemistry (Pandolfi 1972). The fibrinolytic activity was compared with fresh normal placental tissue.Marked fibrinolytic activity was found in the hydatidiform molar tissue as compared to none in the normal placenta. Increased fibrinolytic activity of hydatidiform mole may be the cause of early, prolonged and heavy uterine bleeding in such abnormal pregnancies. This may be due to local activation of the fibrinolytic system.
Defective Fibrinolytic Activity in Coronary Heart Disease
Authors: Walker Isobel D. , Davidson J. F. , Hutton I. 
Published: May 2019

The possibility of an association existing between defective fibrinolysis and the development of coronary heart disease (C.H.D.) has been examined.Using resuspended plasma euglobulin precipitates on fibrin plates, fibrinolytic activity (F.A.) was studied in 36 male patients with angiographic evidence of C.H.D. and in 16 male controls with normal coronary angiograms. Spontaneous plasma F. A. and “fibrinolytic potential”, as assessed by a 5 minute venous occlusion test, were measured in each subject at 0 hours (9 a.m.), at 5 hours (2 p.m.) and at 72 hours (9 a.m.).13 of the 36 patients had defective fibrinolysis compared with the controls. In only 7 of these 13 patients was a defect obvious in the 9 a.m. basal measurements of spontaneous F. A. but all 13 had a defect of diurnal rhythm as evidenced by an absent or significant reduction in the diurnal increase in F. A. at 2 p.m. All 13 had a defect of “fibrinolytic potential” as shown by an absent or impaired response to the challenge of the 5 minute venous occlusion tests. A marked increase in F. A. at 2 p.m. and a normal “fibrinolytic potential” were found in all 16 controls.By using a series of carefully timed resting and venous occlusion tests several aspects of F. A. can be studied and defects in diurnal rhythm and “fibrinolytic potential” demonstrated in 36% of patients with C. H.D.
Antiplasmin, the Fast-Reacting Plasmin Inhibitor of Human Plasma
Authors: Collen D. , Wiman B. 
Published: May 2019

Recently a new plasmin inhibitor was discovered in human plasma by three different groups (Eur. J. Biochem. 69, 209, 1976; J. Biol. Chem. 251, 5956, 1976; Biochem. J. 159, 545, 1976). This inhibitor is responsible for the fast-reacting plasmin-neutraIizing activity of human plasma and forms a very stable 1:1 molar complex with plasmin, which is devoid of protease and esterase activity. The concentration of antiplasmin in human plasma is approximately I μM (2/3 that of plasminogen).We have purified the inhibitor by affinity chromatography on insolubilized plasminogen, followed by DEAE-Sephadex and concanavalin A chromatography. It is a glycoprotein with a mol . wt. of 67,000 (SDS-gel electrophoresis), a carbohydrate content of 14%, and amino terminal sequence Asn-Gln-Glu-Gly (Wiman and Collen, submitted).The inhibitor interacts strongly with the light chain of plasmin (probably through reaction with the active site serine), and weakly with the heavy chain (probably through interaction with the lysine-binding site), suggesting that antiplasmin not only functions as an inhibitor of plasmin, but also interferes with the interaction between plasm in (ogen) and fibrin.
In Vivo Studies with a New Antiaggregating Drug EMD 26644, A Mercapto-Oxazolyl-Carbon-Acid Derivative
Authors: Krzywanek H. J. , Pietsch U. , Breddin K. 
Published: May 2019

The inhibitory effect of EMD 26644 on platelet function has been studied with the following methods: spontaneous aggregation (PAT III), ADP-, collagen-and epinephrire-induced aggregation, primary shape change of thrombocytes at 37°C incubation temperature and platelet spreading.Duke’s bleeding time, platelet count and some coagulation parameters like partial thromboplastin time, Quick’s test, fibrinogen, thrombin time and factor VII-assay as well as platelet spreading were unchanged throughout the test period.An aspirin like inhibitory effect on platelet aggregation and primary shape change was observed 48 – 72 hrs. after the ingestion of a single dose of 250 mg EMD, which lasted for 2–3 weeks. A prolonged antiaggregating effect was achieved by the continuous oral administration of 25 – 50 mg EMD for a period of 2 – 3 months. No potentiation of the antiaggregating effect was seen, if ASA was given in addition to EMD 26644.In comparison with aspirin the new compound seems to have some advantages: the same antiplatelet properties are achieved with a much lower dose and no side effects have been reported so far. Clinical studies will have to confirm whether EMD 26644 is an effective antithrombotic agent.
Alterations in The Trans-Membrane Potential of Human Blood Platelets in Response to Aggregating Stimuliow
Authors: Horne W. C. , Larsen N. E. , Simons E. R. 
Published: May 2019

It has been suggested that the mechanism of response of platelets to aggregating stimuli is analogous to the stimulus-response coupling mechanisms of muscle and secretory cells. Because the coupling mechanisms of both types of systems involve changes in the trans-membrane potential of the stimulated cell, we have examined the membrane potential of human platelets to determine if the potential changes in response to aggregating agents. The membrane potential of gel-filtered platelets was monitored using a fluorescent cyanine dye. Aggregation was prevented to minimize artifacts due to changes in light scattering. The effects of ADP, thrombin, and collagen on the potential were examined. In response to ADP, the membrane rapidly became more negatively polarized. The response was concentration dependent, the minimum response occurring with 3x10-5M ADP. The response to thrombin was more complex. Low concentrations (0.01 U/ml) produced a change similar to that caused by ADP. Higher concentration (1–10 U/ml) led to a rapid decrease in the polarization of the membrane. When pre-formed collagen fibrils were added, in the presence of creatine Phosphokinase to destroy released ADP, no changein the potential was observed.Thus the platelet membrane potential changes in response to aggregating stimuli, supporting the hypothesis that stimulus of platelet aggregation is analogous to other stimulus-response coupling mechanisms. The change in potential is not a necessary step in the coupling mechanism. The different responses to specific agents indicate that the agents may trigger aggregation through different mechanisms.