bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect Of Removing Sialic Acid From Vascular Endothelium In Living Animals On Its Interaction With Circulating Platelets
Authors: Born G G V , Görög P , Schraufstätter Ingrid 
Published: July 2018

The non-adherence of platelets in the circulation has been attributed mainly to two mechanisms : electrostatic repulsion due to net excess negative surface changes on platelets and endothelial cells; and release of endothelial prostaglandin I2 (prostacyclin) which inhibits platelets. CUr experiments were intended to provide evidence on the relative contribution of these mechanisms.Rabbits were injected with 3H-S-hydroxytryptamine to label the circulating platelets. After about 2h, the rabbits were anaesthetised with nembutal. Both common carotid arteries were constricted in two places about 3 cm apart and perfused free of blood. One common carotid was perfused with saline as control and the other with neuraminidase (from Signa or Behring Werke : 0.5 u/ml saline) for 30 min. These conditions apparently brought about maximal release of sialic acid from the endothelial surface. The constrictions were removed from the arteries to restore the blood flow. After 10 min both carotids were removed. Separate segments were prepared for determinations of radioactivity and prostaglandin I2 and for microscopy.In seven experiments, the effects of neuraminidase was to increase the deposition of platelets, as measured by their radioactivity, about 4-fold (mean : range 2.0 - 7.3) above controls. Neuraminidase had no significant effect on prostaglandin I2 production, determined by bioassay and radioimmunoassay.It is concluded that diminution in electrostatic repulsion between circulating platelets and vascular endothelium by removal of sialic acids from, endothelial surface glycoproteins permits adherence of platelets irrespective of prostaglandin I2.
Analysis Of Chemical Heterogeneity And Purity Of Commercial Heparins
Authors: Hurst R , Lurie A , Settine J , Corum M 
Published: July 2018

The nature of chemical heterogeneity in commercial heparin was investigated, and a practical method of characterization and assay of pharmaceutical heparins was developed. One beef-lung (BL) and six hog-mucosal (HM) heparins were fractionated by sequential extraction of their hexadecyl- pyridinium complexes in 1-butanol by aqueous solutions containing successively increasing concentrations of NaCl. This system fractionates heparins larger than 10,000 daltons according to their anionic density. The fractions were characterized by molar ratios of carbohydrate constituents and by their anticoagulant potencies in the APTT test with human plasma. Galactosamine content and the amount of uronate extracted with less than 0.14 M NaCl provided a measure of non-heparin GAG and low-quality heparin. The molar ratios of carbohydrate constituents of equivalent fractions from different HM heparins were similar, and with the exception of one unbleached sample, had equivalent anticoagulant potencies which were linearly related to the square of the anionic density. The BL-heparin was clearly distinguishable from the HM-heparins in that its most abundant fractions were extracted at higher NaCl concentrations, and the systematic variation in anionic density seen with HM- heparins was not evident. The fractions were only about half as potent as the equivalent HM-heparin fractions.A simplified version of the extraction with a two-step partition fractionation was used to measure the percentages of non-heparin GAG and high-quality heparin respectively, and measurements of various molar ratios were used to both characterize the chemical properties of the heparin and its purity. Activation with silica in the APTT test yielded rectilinear semi logarithmic dilution plots whereas ellagic activation yielded curvilinear plots with lower sensitivity.
Detection And Regulation Of The Subunit Proteins Of Plasma Factor XIII
Authors: McDonagh J , Skrzynia C , Ikematsu S 
Published: July 2018

Plasma factor XIII circulates as a noncovalently-associated, tetrameric zymogen (a2b2). The a subunit has the potential catalytic function, while the b subunit may act as a carrier protein plasma. In order to study the interactions between the two subunits, specific radioimmunoassays have been developed for each subunit. The assays are valid for measuring a and b protein concentrations in plasma and serum as well as in purified systems. The a assay detects all forms of the protein (zymogen, intermediate, enzyme). Factor XIII activity was measured by the monodansylcadaverine assay. These methods were used to correlate a and b protein concentrations with factor XIII activity in normal donors, in patients with factor XIII deficiency and their family members, and in patients with factor XIII inhibitors.The normal plasma concentration of each of the subunits of factor XIII is about 12 μg/ml, making the concentration of the zymogen complex to be 0.15 μM. All of the b protein is recovered in serum, while a variable amount of a protein (a*) is found in serum. a protein and factor XIII activity go in parallel in normal, factor XIII deficient, and heterozygous plasma samples. Deficient patients have <1% activity and <20 ng/ml a protein. Deficient patients have about 50% of the normal plasma b concentration, and heterozygotes have 50% a and 75% b protein. In three cases of spontaneous, autoimmune inhibitors against factor XIII, there was no detectable activity and b concentration was one-half normal. Following transfusion of two factor XIII deficient patients with a subunit, activity rose immediately to the expected levels, while b rose more slowly to 20% above the preinfusion level. All of these studies indicate that the circulating level of functional a subunit exerts a positive feedback effect on the concentration of b subunit in plasma.
Thrombocytosis And Platelet Activation In Alcoholics During Alcohol Withdrawal
Authors: Hutton R A , Fink R , Wilson D T , Marjot D H 
Published: July 2018

In order to further investigate the basis of the increased thrombotic risk reported in association with acute alcohol withdrawal, we have carried out platelet studies in a group of alcoholics admitted to a formal alcohol detoxification programme.All patients were alcoholaemic on admission but had taken no other platelet inhibiting medications for at least two weeks. Platelet counts, platelet aggregabi1ity, plasma betathromboglobulin (BTG) assays,platelet nucleotide levels and circulating platelet aggregates were measured sequentially over a 4-6 week period.On admission, platelet aggregabi1ity was impaired, compared to normal controls, particularly using ADP or adrenaline as agonists, but all other platelet studies were within normal limits.Compared to normal subjects, the treated group showed a statistically significant mean increase in platelet count, the level of circulating platelet aggregates, the plasma BTG level and in the aggregation response to ADP and adrenaline. There was also a small increase in the aggregation observed with collagen and Ristocetin and in the platelet nucleotide levels but these did not reach conventional statistical significance.The changes were not associated with any clinically overt thrombotic complications during the period of study,but may contribute to the increased incidence of thrombosis reported by others.
Role Of Lung Scanning In Diagnosis Of Pulmonary Embolism
Authors: Alderson P O 
Published: July 2018

There is general agreement that a normal perfusion lung scan essentially excludes the presence of pathologic pulmonary emboli (PE) and that the perfusion scan pattern helps guide subsequent pulmonary angiography. The perfusion scan alone is too nonspecific to aid evaluation of patients with suspected PE in other ways but combined ventilation-perfusion (V-P) imaging is often helpful. V-P imaging does not allow a definitive diagnosis of PE, but allows the probability of PE to be determined. If normal ventilation is present in two or more regions which demonstrate subsegmental, segmental or lobar perfusion defects, there is approximately a 90% chance that emboli are present. This is true even when a patient demonstrates a mixed pattern of V-P match and mismatch or when pulmonary infiltrates or other opacities are visible on the chest radiograph in other parts of the lung. If ventilation abnormalities are present in 50% or less of the lung fields and all perfusion defects are matched by ventilation abnormalities there is less than a 5% chance for PE.These data are derived from a recent study of 83 patients with suspected PE who underwent angiography and had V-P studies showing ventilation abnormalities and at least one area of V-P match. Angiography should thus be used selectively to evaluate patients with nondiagnostic lung scans (these account for 15-30% of most peopled experience), and to achieve definitive diagnoses in patients who are at special risk for anticoagulant therapy or who are to undergo surgical treatment of thromboembolism. V-P lung imaging is a safe, easily tolerated, low radiation dose exam which provides substantially greater confidence in the pre-angiographic diagnosis of PE than a standard clinical evaluation. For these reasons, V-P lung scanning can make significant contributions to management decisions in patients with suspected PE and alleviate the need for angiography in many instances.
Interaction Of Fibrin And Tissue Plasminogen Activator
Authors: Wallén P , Rånby M 
Published: July 2018

Fibrin itself has a marked influence on fibrinolysis induced by tissue plasminogen activator (TA) indicating a specific interaction. The interaction between fibrin and TA is manifested in two ways, 1) a marked stimulating effect of fibrin on the activation of plasminogen; 2) physical ad- sorbtion of TA on fibrin. By measurement in a sensitive analytical system in which the generation of plasmin is followed by a chromogenic substrate it has been shown that TA is a rather poor activator of plasminogen. In the presence of fibrin the kinetics of the activation is dramatically changed. A stimulation up to 1000-fold is obtained at low plasminogen concentrations. As for activation of native plasminogen (Glu-plasminogen) there is a decrease of km (about 15-fold) as well as an increase of kc (about 80-fold). Fibrinogen has comparatively little effect on the activation rate (at the most 10-fold). The amidolytic activity of TA, using an activator sensitive substrate, is not influenced by fibrin indicating that the effect is not due to conformational changes in the active site region of TA.By varying the concentration of fibrin in the test system it has been demonstrated that the stimulation effect increases suddenly at a fibrin concentration of about 0.01μM. It was suggested that this value represents the dissociation constant of the TA-fibrin complex. However, the amount of fibrin necessary for the adsorbtion of TA in purification experiments indicates a significantly higher dissociation constant (about 0.4 μM). An important difference between the purification experiments and the studies on fibrin stimulation is that plasminogen (plasmin) is absent in the former studies. The formation of a triple complex between fibrin, plasminogen and TA may be the explanation for a more efficient binding of TA in the kinetic studies.
The Effect Of Coagulation On The Association Of VIII:CAg With VIIIR:Ag
Authors: van Mourik J A , Lantinga P H G , Hellings J A 
Published: July 2018

Solid-phase immunoradiometric assays specific for Factor VIII coagulant antigen (VIII:CAg) and Factor VIII related antigen (VIIIR:Ag) have been used to assay the immunoreactivity of these antigens in plasma and whole blood during coagulation at physiological calcium concentration. When non-anticoagulated plasma, prepared from blood immediately after venipuncture, was incubated at 37°C, the concentration of VIII:CAg and VIlIR:Ag did not change. However, when whole blood, collected withoutanticoagulant, was incubated, the concentration of VIII:CAg gradually decreased to 50% of the initial value whereas the concentration of VIIIR:Ag remained unchanged. Gelchromatographic analyses revealed that coagulation of plasma leads to progressive dissociation of VIII:CAg from the factor VIII:VWF complex. When plasma was chromatographed before the onset of coagulation, VIII:CAg was eluted at the void volume together with VIIIR:Ag whereas after coagulation of the plasma VIII:CAg devoid of VIIIR:Ag was eluted after the void volume. Similarly, when the supernatant plasma from blood was chromatographed before the onset of coagulation, VIII:CAg together with VIIIR:Ag was eluted at the void volume whereas during and after coagulation the amount of VIII:CAg associated with VIIIR:Ag gradually decreased. However, no concomitant increase of the concentration of dissociated VIII:CAg was noted under the latter conditions. It seems likely, therefore, that adherance of dissociated VIII:CAg to cellular constituents accounts for the loss of VIII:CAg during coagulation of blood. On the other hand, it can not be excluded that cellular enzymes, extruded during coagulation, affect the antibody-binding capacity of VIII:CAg.Further studies indicate that, at least in part, dissociation of the factor VIII:VWF complex during coagulation is mediated by thrombin.
Immunological Studies Of Human Factor XI
Authors: Bouma B N , Vlooswijk R A A , Griffin John H 
Published: July 2018

Human Factor XI was purified from normal plasma, using ionic exchange chromatography on DEAE-sephadex at pH 8.3, and SP-sephadex at pH 5.3., followed by an affinity chromatography column of insolubilized high M.W. kininogen. Factor XI adhered to this column and was step eluted with 0.5 M NaCl. This rapid method gives highly purified Factor XI with yields of 15-20%. Antibodies were raised in goats against purified Factor XI. A trace of a contaminating antibody was removed by absorption with a Factor XI-depleted γ-globulin fraction. When tested by double immunodiffusion, one precipitin line was observed against normal plasma, which showed a reaction of identity with the line obtained against purified Factor XI. No line was observed against plasma of a patient with Factor XI deficiency. The antiserum specifically inhibited the Factor XI clotting activity of normal plasma.Factor XI, which is a γ-globulin (pI ∼ 9) that does not migrate during immunoelectrophoresis (IEP), forms reversibly complexes with high MW kininogen, an a-globulin. Complex formation under conditions of IEP at pH 8.4 was shown in purified mixtures by crossed IEP using anti Factor XI and by rocket IEP. Rocket IEP showed no Factor XI antigen in Factor XI deficient plasma. Factor XI antigen in normal plasma was increased by addition of high MW kininogen, suggesting that part of the Factor XI present in normal plasma is not complexed to high MW kininogen. These results show that IEP studies of Factor XI and high MW kininogen are influenced by complex formation.
Influence of operative trauma on F XII and Inhibitor of plasminogen activator
Authors: Hedner U , Bergqvist D 
Published: July 2018

A parallel decrease of factor XII and an inhibitor of plasminogen activator (PA inhibitor) earlier described by Hedner (1973, 1980) was observed in a small series of patients postoperatively (Hedner 1978). In order to further investigate this, 52 patients (29 males and 23 females) were studied in connection with vascular surgery. The following parameters were analysed: factor XII (clotting and imm.chem.assays), PA inhibitor, α2-antiplasmin (α2AP), α2-macroglobulin (α2M) and CT-inactivator (CT-INA)(rocket technique) and factor IX (clotting assay). A significant parallel decrease to about 50 % of factor XII measured with both methods reaching its minimum on day 4-5 postop as well as of the PA inhib was seen. This decrease was found in all patient groups except those operated upon because of varicose veins. These latter patients all left the hospital already on the 2nd or 3rd postop day. No concomitant decrease of α2AP, α2M, CT-INA was seen. The observed lowering of f XII and PA inhib on day 4-5 did not depend on changes in haematocrit associated with the operation.The findings of a parallel decrease of f XII and the PA inhib shown to inhibit f Xlla (Hedner and Martinsson 1978) may indicate that an activation of f XII followed by consumption of this factor as well as of the inhibitor to f Xlla occurs during or after surgery. Whether the f XII dependent fibrinolysis is of importance in the defence against deep venous thrombosis is still debatable. It is, however, striking that low levels of f XIIa occurs postop at a time when most proteins show an increased synthesis rate because of stimulation by the acute phase reaction. Furthermore inhibitors against the activation phase is known to be associated with thrombotic disease (Hedner and Nilsson 1976).
Detection Of Hypercoagulable State By Measuring Mechanical Impedance Of Clotting Whole Blood
Authors: Sugiura K , Handa M , Yoshii Y , Ikeda Y , Toyama K , Ono F , Watanabe K , Ando Y 
Published: July 2018

The transition of mechanical impedance of clotting whole blood was determined by Sonoclot(Scienco Inc. U.S.A.) in 22 normal individuals, 14 patients with arterial thrombosis and 20 patients with venous thrombosis. Sonoclot primarily senses loss modulus and records entire coagulation process continuously. Peak g represents the maximum mechanical impedance of clot and slope i represents the rate of gelling process. Sixty-five per cent of cases with venous thrombosis and 36 % of cases with arterial thrombosis showed abnormally high values either in g or in i. In venous thrombosis, there were positive correlations between hematocrit and i, and between fibrinogen and g (r=0.6, p<0.01)In arterial thrombosis, there were positive correlations between platelet count and g (r=0.6, p<0.05) and negative correlations between fibrinogen and g and also between fibrinogen and i (r=-0.6, p<0.05). In normal individuals, no significant correlations were noted between any two of these parameters.Our results suggest that analysis of clotting process from the biophysical aspect is important to demonstrate hypercoagulable state and that mechanical impedance can be a common indicator of hypercoagulable state.
Extracellular Calcium And Platelets
Authors: Taylor P M , Heptinstall S 
Published: July 2018

To gain more information on the role of extracellular Ca in platelet behaviour, the movement of 45Ca between plasma and platelets has been studied. Ttoo experimental procedures have been used: platelets were either studied in plasma that contained near-physiological levels of divalent cations or were studied in divalent cation-depleted plasma.There was a continuous movement of Ca from plasma into platelets when the latter were suspended in plasma that contained near-physiological levels of divalent cations. The iptake was linear with time (2.0 to 2.5 ng ion Ca/109 platelets/60 mins) and was faster at 37°C than at 25°C. The amount of Ca taken up by the platelets increased as the extracellular Ca level was increased and was markedly inhibited by Mg. Sr did not affect the uptake. EGTA displaced only a small amount of the Ca that associated with the plater lets which indicated that Ca was taken up into an intracellular pool rather than sinply bound to the platelet surface. The relevance of this movement of Ca into the cells to platelet behaviour has not been established.Studies using platelets suspended in divalent cation- depleted plasma shewed that extracellular Ca was in equilibrium with Ca bound at or near the platelet surface. The binding of Ca was time-dependent but saturable (0.30 to 0.50 ng ion Ca/109 platelets/30 mins), and the majority was readily displaced by EGTA. The amount of Ca bound to the cells increased as the extracellular Ca level was increased but was little affected by an excess of either Mg or Sr. Mare Ca bound to platelets when they were incubated at 25°C than at 37°C. This was because platelets lost their ability to bind Ca when they were incubated at 37°C in divalent cation-depleted plasma. This phenomenon was time-dependent and irreversible and was paralleled by a loss in the ability of the platelets to aggregate. These Ca binding sites would seem to be relevant to the aggregation process.
The Role Of Membrane-Bound Tubulin In Platelet Functions
Authors: Ikeda Y , Handa M , Yoshii Y , Imai M , Sugiura K , Toyama K , Watanabe K , Ando Y 
Published: July 2018

Evidence has been presented which suggests the existence of tubulin, subunit protein of microtubules, as an integral part of plasma membrane of certain cells. We have investigated whether tubulin is also a constituent of platelet plasma membrane or not, and, if so, what the functional significance is? Platelet membranes isolated by glycerol lysis technique according to the method of Barber and Jamieson retained colchicine-binding activity, 6.2 ± 1.4 n mol colchicine per 100 mg platelet membranes. Colchicine-binding activity of platelet membranes was not decreased after membranes were washed 3 times, indicating that colchicinebinding activity of membranes is not due to contamination of loosely bound cytoplasmic soluble tubulin. On SDS-poly- acrylamide gel electrophoresis, platelet membranes revealed Coomassie blue stained band of molecular weight 55,000, which comigrated with purified cytoplasmic tubulin isolated from human platelets by two successive cycles of temperature -dependent polymerization depolymerization as described previously(Ikeda & Steiner, J. Biol. Chem. 251:6135, 1976). Monospecific antibody against platelet tubulin was prepared in rabbits by injecting soluble tubulin at weekly intervals for 4 weeks. Platelets preincubated with anti-tubulin F(ab’)2 fragment showed reduced platelet aggregation and shape change induced by collagen, but not by ADP or epinephrine. Collagen-induced release of 14C-serotonin was also inhibited by anti-tubulin F(ab’)2 fragment while ADP- or epinephrine-induced serotonin release was not inhibited(collagen 2μg/ml:45.6% of control, ADP 10μM:92.0% of control, epinephrine 4μg/ml: 98.0% of control).Our results suggest that membrane-associated tubulin may play important roles in collagen-platelet interactions.