bluuebunny/crossref_metadata_2025_split huggingface dataset:
Platelet Function in Surgical Stress
Authors: Naesh O , Friis J T , Hindberg I , Winther K 
Published: July 2018

SummaryTen patients for elective cholecystectomy were studied pre-, per- and postoperatively. All had neurolept anesthesia. Plasma concentrations of β-TG, TXB2 and 5-HT and intraplatelet 5-HT were measured. Aggregation to ADP was recorded.Serum cortisol concentration was used as index of the stress response, showing peroperative increase and postoperative decrease. Closely related to this we observed a significant increase in P-β-TG and P-TXB2 with postoperative normalization in 6 patients without complications. P-5-HT had a peak peropera-tively and remained elevated postoperatively. A negative correlation between P--5-HT and decreasing intraplatelet 5-HT postoperatively was observed.High postoperative levels of P--5-HT seem to be related to low arterial Po2 and pulmonary dysfunction. In 3 patients with complications a second increase in P-β-TG, P-TXB2 and partly in P--5-HT was found. Platelets were temporarily refractory to ADP immediately following surgery and showed increased aggregabil-ity postoperatively. We conclude that platelets are activated in surgical stress.
Multicenter Comparison of von Willebrand Factor Multimer Sizing Techniques
Authors: Mannucci P M , Abildgaard C F , Gralnick H R , Hill F G H , Hoyer L W , Lombardi R , Nilsson I M , Tuddenham E , Meyer D 
Published: July 2018

SummaryA multicenter study of various types of von Willebrand’s disease (vWD) was conducted in order to compare the different electrophoretic techniques used to evaluate von Willebrand factor multimers in plasma. Seven laboratories participated in the blind study of eight plasma samples from two healthy subjects and six vWD types and subtypes (la, lb, IIA, IIB, IIC and IID). From the results of the multimeric analysis of these samples, it appears that the differential diagnosis of vWD types and subtypes should be first approached by using a low-resolution electrophoretic technique, where each vWF multimer appears as a single band. Low-resolution techniques differentiate type I from type II, subtype la from lb and also subtype IIA from other type II subtypes. When type II subtypes other than IIA are identified with these techniques, samples should be rerun using high resolution techniques that resolve each of the fastest migrating multimers in at least three subbands, and permit the differentiation of subtypes IIB, IIC and IID.
Interactions Between Ethanol and Dietary Fat in Determining Human Platelet Function
Authors: Fenn Christopher G , Littleton John M 
Published: July 2018

SummaryPlatelet aggregation to collagen and ADP in vitro was assessed in the plasma of healthy human volunteers both before and after drinking 700 ml of white wine. This had no effect on platelet aggregation when compared with samples from the same individuals taken on a separate occasion without alcohol consumption. However, when alcohol was taken with a meal high in saturated fat, a significant inhibitory effect on platelet aggregation was observed when compared to the effect of the meal alone. There was no such interaction when the meal associated with alcohol ingestion contained mainly unsaturated fats. The fatty acid composition of plasma and platelet membranes from these volunteers showed a significantly increased proportion of saturated fats after the saturated fat meal. The concomitant ingestion of ethanol did not prevent this change. The concentration of alcohol in plasma achieved (c. 25 mM) may directly inhibit platelet aggregation when the platelet membrane content of saturated fats is high.
A Study of the Possible Role of Mesothelium as a Surface for Flowing Blood
Authors: Clarke J M F , Pittilo R M , Machin S J , Woolf N 
Published: July 2018

SummaryMouse mesothelium has been examined as a surface for supporting blood flow. We have examined ten pieces of intact mesothelium and ten pieces of damaged mesothelium following 10 min exposure to flowing blood in a Baumgartner chamber. Scanning electron microscopy of the intact specimens demonstrated no adhering blood platelets, whereas the damaged specimens were found to be covered with large numbers of adhering platelets. In addition we have demonstrated that undamaged mesothelium does not appear to be morphologically altered after exposure to blood, and that undamaged mesothelium produces significantly more prostacyclin than damaged control. These findings suggest that mesothelial cells hold promise as a lining for prosthetic vascular implants.
Plasma Contact Activation and Decrease of Factor V Activity on Negatively-Charged Polyelectrolytes
Authors: Boffa M C , Dreyer B , Pusineri C 
Published: July 2018

SummaryThe effect of negatively-charged polymers, used in some artificial devices, on plasma clotting and kinin systems was studied in vitro using polyelectrolyte complexes.Contact activation was observed as an immediate, transient and surface-dependent phenomenon. After incubation of the plasma with the polymer a small decrease of factor XII activity was noticed, which corresponded to a greater reduction of prekallikrein activity and to a marked kinin release. No significant decrease of factor XII, prekallikrein, HMW kininogen could be detected immunologically. Only the initial contact of the plasma with the polyelectrolyte lead to activation, subsequently the surface became inert.Beside contact activation, factor V activity also decreased in the plasma. The decrease was surface and time-dependent. It was independent of contact factor activation, and appeared to be related to the sulfonated groups of the polymer. If purified factor V was used instead of plasma factor V, inactivation was immediate and not time-dependent suggesting a direct adsorption on the surface. A second incubation of the plasma-contacted polymer with fresh plasma resulted in a further loss of Factor V activity.
Medial Smooth Muscle Cell Proliferation in the Balloon Injured Rabbit Aorta: Effect of a Thiazole Compound with Platelet Inhibitory Activity
Authors: Schaub R G , Simmons C A 
Published: July 2018

SummaryTwenty-seven adult male New Zealand rabbits (3–4 kgs) were used in this study. Six rabbits received vehicle, 3 groups of 6 each received doses of 4,5-bis(p-methoxyphenyl)-2-(trifluoromethyl)- thiazole, (U-53,059), at 0.3 mg/kg, 3.0 mg/kg and 30.0 mg/kg/day respectively. Drug and vehicle doses were given orally each day starting 3 days before balloon injury and continuing for the entire 2 week time period. Three rabbits were used as nontreated sham controls. In the vehicle and U-53,059 treated groups aortae were denuded of endothelial cells by balloon catheter injury. Two weeks after injury platelet aggregation to collagen was measured and the aortae removed for analysis of surface characteristics by scanning electron microscopy and lesion size by morphometry. All doses of U-53,059 inhibited platelet aggregation. The 3.0 and 30.0 mg/kg groups had the greatest inhibitory effect. All balloon injured aortae had the same morphologic characteristics. All vessels had similar extent and intensity of Evan’s blue staining, similar areas of leukocyte/platelet adhesion, and a myointimal cell cover of transformed smooth muscle cells. The myointimal proliferative response was not inhibited at any of the drug doses studied.
Plasma and Platelet Fibrinogen Differ in γ Chain Content
Authors: Francis Charles W , Nachman Ralph L , Marder Victor J 
Published: July 2018

SummaryThe polypeptide chain composition of fibrinogen and cross- linked fibrin from normal platelets and plasma has been compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Fibrinogen was prepared from a lysate of normal human platelets by ethanol precipitation and by antifibrinogen immunoaffinity chromatography. While the Aα chains of platelet fibrinogen appeared to be somewhat degraded, the electrophoretic mobilities of purified platelet and plasma fibrinogen Bβ an γ chains were the same. Crosslinked fibrin was prepared from platelet and plasma fibrinogen and γ chain dimers identified by their electrophoretic mobility, incorporation of the lysine analog dansyl cadaverine during crosslinking, and by reaction with antifibrinogen antibody in Western blots. Platelet crosslinked fibrin had a different polypeptide chain composition than that of plasma crosslinked fibrin with absence of the γ50–γ57.5 dimer in the platelet fibrin. This finding indicates that the γ57.5 chain, which constitutes 5% of total normal plasma fibrinogen γ chains, is either absent or present in markedly reduced amounts in platelet fibrinogen.
Effect of 24 Hours of Normoglycaemia on Tissue-Type Plasminogen Activator Plasma Levels in Insulin Dependent Diabetes
Authors: Juhan-Vague I , Vague P , Poisson C , Aillaud M F , Mendez C , Collen D 
Published: July 2018

SummaryWe have previously demonstrated that a short period of normoglycaemia obtained through an artificial pancreas in uncontrolled insulin-dependent diabetics improves parameters of the functional microangiopathy such as erythrocyte deformability and platelet aggregation. Because recently an immunoradiometric assay for tissue plasminogen activator (t-PA) was developed we measured t-PA levels in 18 uncontrolled insulin-dependent diabetics before and after 24 hr of normoglycaemia induced by insulin to look for a modification of endothelial cells function. After 24 hr of strict control, plasma free insulin levels rose significantly, total t-PA R-Ag, its active fibrin binding fraction and euglobulin fibrinolytic activity were significantly decreased. These results suggest a responsibility for insulin in the decrease in t-PA blood level and could explain at least partially the relation between hyperinsulinism, thrombosis and atherogenesis.
Platelet Aggregation Caused by Dithiothreitol
Authors: Zucker M B , Masiello N C 
Published: July 2018

SummaryMacIntyre et al. showed that over 1 mM dithiothreitol (DTT) aggregates blood platelets in the presence of fibrinogen; aggregation is not inhibited by prostaglandin E1. We confirmed their data and found that 70 mM 2-mercaptoethanol was also active. DTT- induced aggregation was not associated with platelet shape change or secretion of dense granule contents, was not inhibited by tetracaine or metabolic inhibitors, was prevented at pH 6.5, and prevented, reversed, or arrested by EDTA, depending on when the EDTA was added. DTT did not cause aggregation of thrombasthenic, EDTA-treated, or cold (0° C) platelets, which also failed to aggregate with ADP. Platelets stimulated with DTT bound 125I-labeled fibrinogen. Thus DTT appears to “expose” the fibrinogen receptors. SDS gel electrophoresis of platelet fractions prepared by use of Triton X-114 showed that aggregating concentrations of DTT reduced proteins of apparent Mr 69,000 and 52,000 (probably platelet albumin) and, to a variable extent, glycoproteins Ib, IIb and III. Exposure of unlabeled or 125I- labeled platelets to ADP had no discernible effect on the electrophoretic patterns.
A New Platelet Aggregating Material (PAM) in an Experimentally Induced Rat Fibrosarcoma
Authors: Mohanty D , Hilgard P 
Published: July 2018

SummaryThe present work concerns our studies to search for factor(s) which may influence the hemostatic process in or around metastasis of tumours. We studied the platelet aggregating property of a methyl cholanthrene induced experimental tumour. Platelet aggregating material was found to be different from the known aggregating agents like thrombin, ADP, collagen, thromboxane A2 and trypsin. It depends on a critical level of calcium for its action. PAM is a high molecular weight substance which contains sialic acid. It is trypsin and plasmin insensitive. The activity of this substance is not being destroyed by phospholipase-C. Metabolic study indicates that PAM acts by mitochondrial energy metabolic pathway of the platelets.
Effects of Human Antithrombin III on Mortality and Blood Coagulation Induced in Rabbits by Endotoxin
Authors: Triantaphyllopoulos D C 
Published: July 2018

SummaryTwenty-one rabbits were infused with 20μg/kg/hr of E. coli endotoxin for 6 hr. Eight of the animals were preinjected immediately before the infusion of endotoxin, with a bolus dose of human AT III calculated to increase the antithrombin content of the plasma by about 4 units/ml. All eight animals which were preinjected with AT III survived, while 5 of the 13 control rabbits infused with endotoxin alone died. The changes in coagulation parameters from the baseline values, between the 8 control rabbits which survived and the 8 animals which were preinjected with AT III were compared. The concentration of the preinjected human AT III declined significantly faster (P: <0.01) than that of the native rabbit AT III. AT III prevented the decline of F.XII throughout the infusion of the endotoxin. However, the decline in F.V, fibrinogen, prothrombin and platelets was not affected (P: >0.5) by the injection of AT III.
A Comparative Randomized Trial of Low-Dose Versus High-Dose Streptokinase in Deep Vein Thrombosis of the Thigh
Authors: Schulman Sam , Lockner Dieter , Granqvist Staffan , Bratt Göran , Paul Christer , Nyman Dag 
Published: July 2018

SummaryFibrinolytic treatment of acute deep vein thrombosis (DVT) of the leg with high-dose streptokinase (SK) (100,000 U/h) in 39 cases, or low-dose SK (approx 10,000 U/h) in combination with low-dose heparin in 41 cases, was studied in a prospective randomized trial. The degree of thrombolysis was similar in both groups and did not correlate with age or size of the thrombus or with fibrinogen level. The degree of late recanalization was also similar in both groups. There were however significantly more patients with postthrombotic changes in the low-dose group than in the high-dose group after a mean follow-up time of 31 and 38 months respectively. In the low-dose group 2 intracranial hemorrhages occurred (one was fatal) and one patient died of pulmonary embolism, but there were significantly less allergic side effects to SK. There were no cases of such serious side effects in the highdose group. Although low-dose SK has equal thrombolytic effect it seems inferior to high-dose SK, since it probably causes more severe hemorrhagic side-effects.
The Establishment of a Standard for Plasminogen (Glu-Type)
Authors: Gaffney P J , Curtis A D 
Published: July 2018

SummaryFollowing an international collaborative study, a preparation of glutamic acid-(glu-)human plasminogen was established as a British Standard. This study compared the activity of the proposed standard following full activation to plasmin with the 2nd International Reference Preparation (IRP) for plasmin using both fibrinolytic and chromogenic assays. There was good agreement between the results of the two assay methods. The activity of the standard was 10 units per ampoule, these units being equivalent to those defined by the 2nd IRP for plasmin.
The Increased Sensitivity of Platelets to Prostacyclin in Marathon Runners
Authors: Dix Clive J , Hassall David G , Bruckdorfer K Richard 
Published: July 2018

SummaryPlatelet-rich plasma was obtained 24 hr after the race ended from athletes who ran in the London marathon. The platelets were only marginally less sensitive to adrenaline than were those of non-runners using conventional aggregation tests. However, the runners’ platelets were much more sensitive to inhibition by prostacyclin, a prostaglandin synthesized by endothelial cells. It appeared that this effect was due to a greater activity in the platelets of the membrane-bound adenylate cyclase enzyme which generates intracellular cyclic AMP. Cyclic AMP production is known to be stimulated by prostacyclin and to cause the inhibition of platelet aggregation. The results indicate another possible protective effect of exercise against cardiovascular disease which is independent of the known changes in lipoprotein concentrations previously observed in athletes.
Anticoagulant Properties of Purified X-Like Fragments of Human Fibrinogen Produced by Degradation with Leukocyte Elastase
Authors: Sterrenberg Lydi , van Liempt Gert Jan , Nieuwenhuizen Willem , Hermans Jo 
Published: July 2018

SummaryThe anticoagulant properties of fibrinogen digestion products change with stage of digestion. On digestion with leukocyte elastase, in the presence of calcium ions, the anticoagulant potency of fibrinogen digests first increases, then decreases sharply, and in late stages increases again. This is different from plasmin digestion where only an increase in anticoagulant activity is seen followed by a slow decrease.From SDS-gel electrophoresis it appears that both the early rise and the decrease in anticoagulant activity are associated with the stage of elastase-produced X-like fragments. This is confirmed with pure fragments: X-like fragments (purified from elastase digests of fibrinogen of different stages by ammonium sulphate precipitation and ion-exchange chromatography) give an increase and decrease in anticlotting activity which correlates very well with that of the potency of the digest from which they are purified. As expected, and in contrast with (late) plasmic X- fragments, late elastase X-like fragments have a low anticoagulant potency. The molecular basis for the gain and loss in anticoagulant activity going from early to late X-like fragments is obscure. Immunological tests, calcium-binding experiments and affinity chromatography on immobilized thrombin-activated NDSK suggest that the changes in anticoagulant activity are not due to a proteolytic change in the carboxyl-terminal part of the γ-chain in the D moiety of the molecule. Our data suggest a correlation with the stage of digestion of the Aa-chain in the X-like fragments.
Biological and Thrombolytic Properties of Proenzyme and Active Forms of Human Urokinase – III. Thrombolytic Properties of Natural and Recombinant Urokinase in Rabbits with Experimental Jugular Vein Thrombosis
Authors: Collen D , Stassen J M , Blaber M , Winkler M , Verstraete M 
Published: July 2018

SummaryThe thrombolytic properties of recombinant pro-urokinase (Rec-pro-UK), recombinant active urokinase (Rec-UK) and natural urinary urokinase (Nat-UK) were compared with those of tissue-type plasminogen activator (t-PA) in rabbits with a radiolabeled thrombus in the jugular vein. The thrombolytic agents were infused intravenously over a time period of 4 hr and the extent of thrombolysis measured two hours later.In control animals the extent of thrombolysis was 11 ± 2% (n=8) after 6 hr. Nat-UK and Rec-UK had very similar thrombolytic properties. Significant thrombolysis was only obtained with infusion of 240,000 IU per kg (41 ± 2%, n=4 for Nat-UK and 37 ± 4%, n=4 for Rec-UK) and this was associated with a marked systemic activation of the fibrinolytic system, as evidenced by consumption of plasminogen and α2-antiplasmin and fibrinogen breakdown.Infusion of Rec-pro-UK induced thrombolysis at a dose of 60,000 IU per kg (44 ± 8%, n=3) but without associated systemic activation of the fibrinolytic system. In this respect the properties of Rec-pro-UK were similar to those of t-PA, which, however, had a 2- to 4-fold higher specific thrombolytic activity (30,000 IU/ kg yielding 48 ± 1% lysis, n=4).It is concluded that Rec-UK has very similar thrombolytic properties as Nat-UK and that Rec-pro-UK has a beter thrombus- selectivity and less systemic side effects than the active enzymes.
Evaluation of Dose and Route Effects of Platelet Activating Factor-Induced Extravasation in the Guinea Pig
Authors: Handley Dean A , Van Valen Ronald G , Melden Mary Kay , Saunders Robert N 
Published: July 2018

SummaryPlatelet-activating factor (PAF) is a naturally occurring lipid that is reported to induce vessel hyperpermeability leading to loss of protein-rich plasma (extravasation). We have quantitated the systemic extravasation effects of synthetic PAF in the guinea pig by monitoring increases in hematocrit. When given intravenously (10-170 ng/kg), PAF produced dose-dependent increases in hematocrit, with maximal hemoconcentration developing in 5-7 min. In leukopenic animals the expected hematocrit increase was reduced by 57%. PAF given intra-arterially produced the dose-dependent changes in hematocrit similar to the intravenous effects of PAF. However, PAF given intraperitoneally (10-2500 μg/kg) was 800-1100-fold less effective than the other routes and hemoconcentration continued for 30-45 min until a maximal hematocrit was observed. These results show that PAF may markedly influence extravasation of plasma in a dose and route-dependent manner.
Platelet Accumulation on Collagen: Drugs Which Inhibit Arachidonic Acid Metabolism and Affect Intracellular Cyclic AMP Levels
Authors: Adams G A , Feuerstein I A 
Published: July 2018

SummaryWe have studied the accumulation of washed platelets on collagen-coated glass from flowing platelet-red blood cell suspensions in the presence and absence of drugs. Glass tubes were 10 cm long and the flow rate was 1 ml/min, 80 s-1. For all experiments, platelet accumulation was greatest near the tube’s inlet with a continuous decrease to the exit. A common feature, of those drug treatments which lead to reduced accumulation at the inlet, was an increase in outlet accumulation when compared with outlet control values. Platelet-collagen adhesion resulted in maximal release of 3H-serotonin in the presence of agents that prevent platelet aggregation on collagen. Only drug treatment known to raise cAMP levels (PGE1 and dipyridamole) or prevent the formation of prostaglandins and thromboxanes (sulfinpyrazone, indomethacin and ASA) were found to inhibit aggregate growth. Platelet aggregation on collagen in the absence of thrombin likely proceeds through the liberation of prostaglandins and thromboxanes from surface-bound platelets into the flow where they may stimulate flow-bom cells. An alternate hypothesis is that such treatments affect the release of a-granule components necessary for aggregation.
Elimination of Intravenously Administered Radiolabelled Antithrombin III and Heparin in Humans
Authors: de Swart Cees A M , Nijmeyer Bertha , Andersson Lars-Olov , Holmer Erik , Sixma Jan J , Bouma Bonno N 
Published: July 2018

SummaryAntithrombin III was purified from normal plasma by DEAE- Sephadex chromatography and heparin affinity chromatography; the protein was subsequently radiolabelled with 125I. 125I-anti- thrombin III alone and 125I-antithrombin III in the presence of high affinity 35S-heparin fractions were injected into normal humans. 125I-radiolabel and protein bound 35S-radioactivity were followed separately. In semilogarithmic plots 125I-antithrombin III disappeared according to a double exponential curve with a half-life in the second phase of 56.8 hr in the absence of heparin and of 33.7 hr in the presence of heparin. Protein bound 35S- radioactivity disappeared much faster than the 125I-radiolabel. These data support the concept that heparin disappears as free heparin from the equilibrium heparin – antithrombin III ⇄ heparin + antithrombin III. Immuno-reactive antithrombin III decreased from 100% to 85-90% immediately after injection of 125I-antithrombin III in the presence of heparin and returned to normal values within 30 min. This suggests that antithrombin III is transiently sequestered, possibly in trimolecular complexes consisting of antithrombin III, heparin and either lipases or other vascular bound proteins.
The Mesothelial Cell as a Non-Thrombogenic Surface
Authors: Nicholson L J , Clarke J M F , Pittilo R M , Machin S J , Woolf N 
Published: July 2018

SummaryA technique for harvesting mesothelial cells is described. This entails collagenase digestion of omentum after which the cells can be cultured. The technique has been developed using the rat, but has also been successfully applied to human tissue. Cultured rat mesothelial cells obtained in this way have been examined by scanning electron microscopy. Rat mesothelial cells grown on plastic film have been exposed to blood in an in vitro system using a Baumgartner chamber and have been demonstrated to support blood flow. No adhering platelets were observed on the mesothelial cell surface. Fibroblasts similarily exposed to blood as a control were washed off the plastic.