bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comparative Study Of Heparin And Heparin Fractions In Preventing Experimental Venous Thrombosis
Authors: Thomas D P , Barrowcliffe T W , Lindahl U , Thunberg L , Merton R E , Hiller K F , Eggleton C A 
Published: July 2018

We have compared the relative efficacy in preventing venous thrombosis of an ordinary mucosal heparin, a low molecular weight (LMW) heparin fraction and a decasaccharide fragment with high affinity for AT III. We examined the extent to which all three preparations impaired the formation of serum-induced stasis thrombi in New Zealand White rabbits. The LMW fraction, despite having an in vitro potency by APTT half that of ordinary heparin (but comparable anti-Xa activity) was as effective as heparin on a weight basis in preventing thrombosis.Two minutes after intravenous injection of 30 μg/kg of the LMW fraction the mean blood level by anti-Xa clotting assay was 0.12 i.u./ml (range 0.08-0.21), which was sufficient to prevent thrombosis. In contrast, the decasaccharide fragment, which had a specific activity in vitro by anti-Xa assays of 1000-1300 i.u./mg, but essentially no activity by APTT or thrombin time assays, prevented stasis thrombi only when given at a dose of 100 μg/kg, giving blood levels in excess of 0.3 i.u./ml by anti-Xa assays.It is concluded that in this experimental model a decasaccharide fragment, despite having a very high affinity for AT III, was less effective on a weight for weight basis than either ordinary heparin or a LMW fraction in preventing venous thrombosis. This suggests that while a sufficiently high anti-Xa activity can alone prevent venous thrombosis, the effectiveness of heparin as an antithrombotic drug does not depend solely on its AT III-binding capacity.
Antiheparin Antibody: Preparation And Use As A Functional Probe
Authors: Gitel S N , Medina V M , Wessler S 
Published: July 2018

Antiheparin antibodies were raised in 5 of 6 rabbits immunized sequentially with covalent complexes of ovalbumin-heparin and bovine IgG-heparin. Confirmation of the presence of heparin-specific antibodies in the antisera was based on:	(1) antisera precipitation of BSA-heparin but not BSA alone, (2) antisera inhibition of heparin anticoagulant activity without precipitating heparin, (3) antisera precipitation of heparin-heparin complexes, and (4) antibody removal from the antisera by heparin- Sepharose. The antisera had hemagglutination titers between 1:10,000 and 1:50,000 when tested against tanned red cells labeled with BSA-heparin complex; whereas no hemagglutination occurred with tanned erythrocytes tagged with BSA. Heparin-heparin oligomers, prepared by carbo- diimide coupling in aqueous solution and retaining anticoagulant activity, precipitated in the presence of the antiheparin antibodies. Data indicating that heparin has separate binding sites for antithrombin 111 and thrombin were obtained by quantitating the heparin oligomer- antibody precipitate in the presence and absence of these two purified, heparin-binding, coagulation proteins.
Factor VIII Complex In Non-Hemophilic Patients With Antibody To Factor VIII: C
Authors: Croissant M P , Allain J P 
Published: July 2018

An antibody to Factor VIII in non-hemophiliacs is a rare occurrence. The presence of low but detectable Factor VIII: C (VIII: C) and high Factor VIII antigen (VIIIR: Ag), together with high antibody levels, suggests a complex influence of anti- VIII: C on Factor VIII metabolism.We have studied Factor VIII complex in 16 non-hemophilic patients with anti-VIII: C. VIII: C, VIIIR: Ag and VIII: Rcof were measured by standard techniques and VIII: C antigen (VIII: CAg) by a liquid phase immunoradiometric assay using radio labelled anti-VIII:C Fab’ fragments purified from a hemophiliac.The plasma from all patients had low VIII: C (0.01 - 0.24 u/ml) and high VIIIR:Ag (1.4 - 8.8 u/ml) content. VIII:Rcof was approximately 50% of the VIIIR:Ag level. An increase in electrophoretically fast-moving VIIIR: Ag was observed in some casesVIII: CAg was tested in 13 patients. Two patterns of the dose response were observed. In most samples obtained from patients with low affinity anti-VIII:C whose VIII: CAg ranged from 0.19 - 2.45 u/ml, the dose response paralleled that of the control. In patients with high affinity antibodies the dose response curve was less steep than control, suggesting a competition between the patient’s antibody and the hemophilic anti-VIII: C Fab’ fragments for the VIII: C antigenic sitesThe Factor VTII complex was studied sequentially in 3 patients during immunosuppression. The results showed that : 1) when VIII: C normalizes, VIIIR: Ag levels and electrophoretic mobility progressively return to normal ; 2) levels of VIIIR: Ag are inversely correlated to the VIII: C irrespective of VIII: CAg levels ; 3) high VIII: CAg levels correspond to VIII:C-anti-VIII: C circulating immune complexes.In non-hemophilic patients low VIII: C, high VIII:CAg and high VIIIR: Ag indicate the presence of an anti-VIII: C inhibitor. Measurements of various components of Factor VIII in these patients are not only a means for monitoring the effect of therapy but also provide a rare opportunity to study the metabolism of Factor VIII in man.
Intraoperative Anticoagulation In Cardiovascular Surgery
Authors: Effeney D , Chin D , Goldstone J , Krupski W , Ellis R 
Published: July 2018

The optimal heparin dose during the occlusive phase of cardiovascular operations to prevent intraoperative thrombosis or excessive bleeding has not been determined Therefore, we studied the kinetics of heparin effect in 28 patients undergoing peripheral vascular and cardiac operations. The activated clotting time(ACT)was measured in seconds by an electronic clot timer. The maximum ACT after initial heparin administration and the time for decay of half the heparin effect (t 1/2) were determined.The data show that the anticoagulant effect of a given dose of heparin varies among patients. No correlation was found between the t 1/2 and the dosage of heparin given. Despite higher doses of heparin given to cardiac patients, the t 1/2 in cardiac and vascular patients were not significantly different.Four patients were given the same dose of heparin pre and intra-operatively in an effort to predict the intraoperative effect. The times to maximum effect were the same but t 1/2 intraoperatively was longer (p<.01).These results indicate: (1) maximum heparin effect occurs later than previously believed and is different for cardiac and peripheral vascular patients; (2) the recommendation to give more heparin based on the 5-minute ACT is not valid; (3) individual response to a standard dose of heparin is unpredictable, both in duration and maximum effect; and (4) intraoperative monitoring of heparin effect is practical and is the only way that any consistent specific end point of heparin can be achieved.
Lipoprotein Platelet Interaction: The Effect On Platelet Cholesterol Content And Platelet Function
Authors: Aviram M , Brook J G 
Published: July 2018

Intracellular cholesterol metabolism is regulated by membrane receptors which selectively bind plasma low density lipoproteins (LDL), the major extracellular source of cholesterol. Human platelets, unlike other cells, are unable to synthesize cholesterol, but bind LDL with specificity. We have shown that very low density lipoproteins (VLDL) and LDL, both of which contain apolipoprotein B compete with 125I-LDL for the platelet binding sites, while high density lipoproteins (HDL) is only able to compete to a limit extent and this by virtue of its apolipoprotein E content. Platelet uptake of both LDL and HDL is saturable at physiologic concentrations of these lipoproteins. The lipoproteins are internalized by the platelet but degradation occurs only to a limited extent. Incubation of LDL AND HDL with gel-filtered platelet results in significant changes in the platelet cholesterol content. IDL ( 1 mg protein/ml) increases cholesterol content by 15% whereas the same concentration of HDL causes a 5% reduction. In the presence of thrombin LDL enhances platelet aggregation by 300% whereas HDL decreases aggregation by 50%.We have thus shown that the lipoprotein platelet interaction alfects both platelet cholesterol content and also platelet aggregation. LDL and HDL have opposing effects and this again highlights their different roles in the atherogenic process.
Cohort Labelling Of Rat Platelets With 7 5Se-Methionine
Authors: Martin J F , Francis Prudence , Penington D G 
Published: July 2018

The origin of platelet density heterogeneity is in dispute. We examined whether this heterogeneity is age-related or whether platelets of differing density are initially produced from megakaryocytes. 75Se-methionine labels megakaryocyte protein and hence platelets produced after its intravenous injection. Rats were injected intravenously with 30 μCi of 75Se-methionine. On each of the succeeding 5 days blood was taken from groups of 5 rats following intravenous injection of Prostaglandin E1 (PGE1), and platelets isolated by velocity sedimentation into gradients of polyvinylpurrolidone coated colloidal silica (Percoll).The isolated platelets, which represented > 93% of the whole blood population and showed < .002% leukocyte contamination, were spun to equilibrium through continuous linear gradients of Percoll. Fractionation of these gradients yielded 15 density dependent platelet subpopulations, whose platelet count and density were measured.After three washes with cold isotonic saline containing PGE1, each fraction was also counted for platelet associated 75Se activity.The relationship of radioactivity to platelet count for each fraction for each day was measured by the mean index of concordance which was between 9.997 and 9.992 for days 1 to 5.On day 2, modal radioactivity and modal platelet counts were found at mean densities of 1.0674 g/ml and 1.0682 g/ml respectively.It is concluded that platelet density does not vary with platelet age.
Damage To Endothelial Cells In The Ear Artery Of Rabbits On An Atherogenic Diet
Authors: Silver M J , Sedar A W , Ingerman-Wojenski C M , Nissenbaum M , Klerfeld D , Kritchevsky D M 
Published: July 2018

Male New Zealand rabbits were fed a diet containing 2% cholesterol, 6% peanut oil and 92% Purina Chow for periods between 6 and 9 weeks. Examination of the inner surface of the central ear artery by scanning electron microscopy (after perfusion in situ with Tyrode’s solution followed by 1% glutaraldehyde) revealed damage to the endothelium which appeared to be considerably worse at 9 weeks than at 6 weeks. At six weeks the damage included irregularly shaped cells, some breaks at intercellular junctions and occasional holes in the cells. At 9 weeks more severe damage was seen. This included many misshapen cells, cells with holes, and many cells lifting off from the vessel wall and beginning to expose sub-endothelial tissue. In 3 rabbits (respectively on the diet for 6,7 or 9 weeks) arrays of dark “spots” were seen in many cells. Such “spots” were never seen in endothelial cells of normal rabbits. After 1 ml of 0.83 mM sodium arachidonate (AA), instead of Tyrode’s solution, had been perfused through the arteries, further damage was seen. This damage included the lifting off of many cells and formation of many holes. Effluent from the arteries perfused with AA contained 6-keto-PGF1α and TxB2 (measured by specific radioimmunoassays) in amounts similar to those produced by arteries of rabbits fed a normal diet. These metabolites were not detected in effluents of arteries perfused with Tyrode’s solution.This report shows that an atherogenic diet may cause early morphological changes in a peripheral artery of the rabbit and suggests that widespread damage to arterial endothelium may result from atherogenic diets. Apparently, this damage does not impair the ability of the vessel wall to convert AA into prostacyclin. The rabbit ear artery system appears to be a simpler way to study the early changes in arterial endothelium during experimental atherosclerosis than studies on the aorta.
On The Mechanism Of Heparin-Induced Potentiation Of Platelet Aggregation
Authors: Yamamoto M , Watanabe K , Ando Y , Iri H , Fujiyama N , Furihata K , Yoshii Y , Sugiura K , Ikeda Y , Toyama K 
Published: July 2018

It has been suggested that heparin caused potentiation of aggregation induced by ADP or epinephrine. The exact mechanism of heparin-induced platelet activation, however, remained unknown. In this paper, we have investigated the role of anti-thrombin III ( AT ) in heparin-induced platelet activation using purified AT and AT depleted plasma. When ADP or epinephrine was added to citrated PRP one minute after addition of heparin ( 1 u/ml, porcine intestinal mucosal heparin, Sigma Co. USA ), marked enhancement of platelet aggregation was observed, compared with the degree of aggregation in the absence of heparin. However, in platelet suspensions prepared in modified Tyrode’s solution, heparin exhibited no potentiating effect on platelet aggregation induced by epinephrine or ADP. Potentiation of epinephrine- or ADP-induced platelet aggregation by heparin was demonstrated when purified AT was added to platelet suspensions at a concentration of 20 μg/ml. AT depleted plasma, which was prepared by immunosorption using matrix-bound antibodies to AT, retained no AT, while determination of α1-antitrypsinα2- macroglobulin and fibrinogen in AT depleted plasma produced values which corresponded to those of the original plasma when dilution factor was taken into account. The activities of coagulation factors were also comparable to those of the original plasma. Heparin exhibited potentiating effect on ADP- or epinephrine-induced aggregation of platelets in original plasma, but no effect in AT depleted plasma. When purified AT was added back to AT depleted plasma at a concentration of 20 μg/ml, potentiation of platelet aggregation by heparin was clearly demonstrated.Our results suggest that effect of heparin on platelet aggregation is also mediated by anti-thrombin III.
The Cyclic-Amp-Lowering Effect Of Pge2 And Of The PGH2 Analog, U46619
Authors: Martin B , Bonne C 
Published: July 2018

We have recently reported that PGE2 counteracted the anti-aggregating action of PGE1 and of other PG by inhibiting the adenylate cyclase system. But this effect is not due to the interference with anti-aggregating PG receptors. In this study, the mechanism of action of the c AMPlowering effect of PGE2 has been further investigated.Suspensions of aspirin-washed human platelets were incubated for 1 min at 37°C in the presence of papaverine (0.5mM) with PGE1 , PGE2, U46619, a chemical analog of PGH2, 13-azaprostanoic acid, a specific antagonist of TxA2, either alone or in various associations. The c AMP concentration was determined by protein binding assays in platelet extracts. PGE2 (l50nM) and U46619 (1μM) inhibited the rise in c AMP induced by PGE1 (30nM) On the other hand, when 13-azaprostanoic acid (507#x03BC;M) was added to the incubate, the inhibitory effects of these compounds were suppressed.These results support the conclusion that TxA2 and U46619 act on a unique receptor which triggers the c AMP-lowering effect and suggest that PGE2 antagonizes the anti-aggregating PG through interaction with this receptor.
Influence Of Fibrin And Fibrinogen On The Activation Of Plasminogen By Urokinase
Authors: Takada Y , Takada A 
Published: July 2018

Human plasma was clotted with thrombin or Ca++ in the presence of urokinase (UK), and the activity of plasmin was measured by hydrolysis of S-2251. As a control, the hydrolysis of S-2251 was measured without the addition of thrombin (in the absence of clot). The hydrolysis of S-2251 was higher in the clot than in the plasma. When euglobulin solution was clotted by thrombin in the presence of UK, the hydrolysis of S-2251 was higher in the presence than in the absence of clot. Thus the increased hydrolysis of S-2251 in the clot after the addition of UK was not due to the interaction of plasmin with inhibitors (∝2AP or∝2M) in the presence of clot, but plasminogen (plg) seems to be better activated by UK in the presence of fibrin. When purified Glu-plg was used, Glu-plg was better activated by UK in the presence of fibrin than fibrinogen. The addition of AP to the mixture of Glu-plg and UK resulted in complete inhibition of plasmin activity but the presence of fibrin partially prevented its inactivation by ∝2AP. When Glu-plg was incubated with plasmin,resuiting Lys-plg was far better activated by UK than Glu-plg, but the presence of fibrin slightly enhanced its activation rate. When fibrinogen or fibrin was degraded by plasmin, early FDP enhanced the activation more than early FgDP. Early FgDP still better activates Glu-plg than fibrinogen. Extensive degradation products (D and E) resulted in less activation of Glu-plg than in the absence of these products. The addition of these degradation products to already activated plasmin had no effect on the enzymatic activity of plasmin.In conclusion, Glu-plg was better activated by UK when clot was formed. Binding of Glu-plg with fibrin through lysine binding sites protected it from inactivation by AP. Early degradation also resulted in better activation of Glu-plg, but extensive degradation resulted in less activation which may be an important feedback mechanism of fibrinolysis.
Ultrasonic Vibration For Boosting Fibrinolytic Effect Of Urokinase
Authors: Tachibana Shunro 
Published: July 2018

Boosting effect of ultrasonic vibration on fibrinolytic activity of urokinase has been investigated. Fibrinolysis was studied grouply in (1) experimental fibrin clot with urokinase, (2) clot with urokinase preceded exposure of clot to ultrasonic waves, (3) clot exposed to ultrasonic waves and (4) clot with saline solution. Scanning electro microscopic examinations were made on the clots in each four series. Fibrinolysis was not evident in the clots (3) and (4), though fine cracks were seen in the clots (3). The four hour rate of fibrinolysis was 50% in the clots (1) where as 100% in clots (2).Procedures (1)(2)(3) and (4) were also emplyed in the Chandler’s Loop Technique clot of four hour rotation. The rate of fibrinolysis was 50% in the clot (1) when 60 IU of the urokinase was used, where as 86% in the clot (2) , which scanning electro microscopically gave a feature of decreased fiber structure. Fibrinolysis was accere- rated by ultrasonic vibration in the clot with certain amount of urokinase added, breaking up of the clot being reached in shorter time than the series without ultrasonic wave application.Ultrasonic vibration mechanically might cause microstream in the clot architecture, which could help urokinase contact directly with the fiber net. Scanning electro microscopic examinations revealed morphological representation of enhanced fibrinolysis by ultrasonic vibration. It was suggested that physical ultrasonic vibration could be applied to boost a chemical fibrinolytic effect of urokinase.
On The Mechanism Of Plasminogen Activator Release By Ddavp: Animal Studies
Authors: Boulton F E , Prowse C V , Cash J D 
Published: July 2018

In pentobarbitone anaesthetised dogs, IV infusion of 1-desamino-8-D-arginine vasopressin (DDAVP) over 15 minutes produced a dramatic increase in plasma plasminogen activator (PA) levels, as measured by the euglobulin lysis time. However, 70 ug/Kg of DDAVP were required, compared with circa O.4 ug/Kg for a similar response in unanaesthetised human subjects. Factor VIII levels increased only slightly in dogs even at these relatively high doses.Infusion of 7.0 ug/Kg DDAVP into the femoral artery of dogs had no discernible effects on the PA level of ipsilateral femoral venous blood - similar to findings previously reported for humans. In contrast, infusion of this dose into the carotid artery of dogs produced a marked rise of PA in jugular venous and systemic blood.Fifty mls of jugular venous effluent were collected immediately after DDAVP infusion to carotid artery, the plasma separated, stored frozen, and subsequently infused intravenously to another dog. PA levels rose moderately.It is suggested that DDAVP acts on some cephalic receptor - possibly in the hypothalmus - from which a humoral factor is released which in turn releases PA from a peripheral storage site. The high doses of DDAVP required in these studies, and the relative lack of fVIII response, suggests that barbitone anaesthesia may interfere with this mechanism.
Therapeutic Implications Of Heparin Metabolism In Newborns
Authors: McDonald M M , Hathaway W E , Reeve E B 
Published: July 2018

While thrombotic complications are relatively frequent in the sick newborn, therapeutic heparinization is often difficult to achieve. The clearance of one bolus dose of heparin has been found to be more rapid in the newborn (T% of 35.5 min. in babies 33-36 weeks gestation vs. 63.3 min. in the normal adult). Decreased levels of antithrombin III (AT-III) in the newborn (20-50% of normal adult) may explain the relatively short T1/2; however, an adult with congenital AT-III deficiency (50% level) was found to have a prolonged plasma heparin T1/2 of 106 min. The function of fetal AT-III was studied by isolating the protein from cord blood of nine term and preterm babies by heparin affinity chromatography. Evaluation by SDS-PAGE, immunoelectrophoresis, heparin cofactor specific activity, progressive neutralization of thrombin and Xa at 37°C, pH related antithrombin kinetics and thrombin neutralization relative to heparin concentration revealed a fetal protein with structure and function indistinguishable from that isolated from normal adults.Clinical use of heparin included the evaluation of the Laidlaw (LL) micro whole blood clotting time. The mean LL time of 79 newborns was 96.2 sec. (SD=23). The LL time was not related to gestational age (24-42 weeks) nor to size (600-3980 g). Nine babies were heparinized for three days to six weeks for major vessel thromboses. Heparin infusion rates were compared with heparin levels achieved, LL clotting time prolongations and AT-III levels. The newborns required heparin infusion rates of 25 to 40 U/kg/hour to achieve plasma heparin levels of 0.3-0.5 U/ml. The prolongation of the LL correlated with the heparin level achieved. In these nine babies, AT-III levels did not decrease during the course of heparin therapy.These studies suggest that the newborn has an increased heparin requirement for anticoagulation not completely explained by a low level of a normal antithrombin III.
A Sensitive Heparin-Protamine Competitive Binding Assay
Authors: Dawes J , Pepper D S 
Published: July 2018

Using protamine-agarose beads, with 125I- heparin as a tracer, we have developed a sensitive competitive binding assay with very wide applications. We are able to measure the concentrations of heparin and heparan sulphate in protease-treated biological fluids down to 40 ng. ml-1. Chondroitin and dermatan sulphates do not interfere with the assay, which can also be used to:(1) measure other acidic polysaccharides e.g. dextran sulphate, semisynthetic heparin analogues, and carrageenans.(2) assay proteins which bind to heparin, such as platelet factor 4, antithrombin III and protamine.(3) screen polymers and solid phases as potential binding materials for these molecules.(4) compare a series of polymers e.g. assess the degree of sulphation of heparins, or the affinity of basic polymers for heparin.Solid phase polyelectrolytes such as Dowex are potentially more robust substitutes for protamine- agarose, being resistant to proteases.