bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deglycosylation Increases the Fibrinolytic Activity of a Deletion Mutant of Tissue-Type Plasminogen Activator
Authors: Wilhelm James , Kalyan Narender K , Lee Shaw Guang , Hum Wah-Tung , Rappaport Ruth , Hung Paul P 
Published: June 2018

SummaryΔ2−89 t-PA is a deletion mutant lacking the finger (F) and epidermal growth factor (EGF) domains; thus, the fibrin interaction of this molecule must be mediated solely by the kringle region. In the present study, the influence of the oligosaccharide side-chains on the activity of Δ2−89 t-PA has been investigated. Δ2−89 t-PA was secreted in two forms, designated I and II, which presumably differ by the lack of one asparagine-linked oligosaccharide in the kiiugle 2 domain of form TT, Forms I and II of Δ2−89 t-PA weie puiified; form II displayed higher fibrinolytic activity than form I. When foini I was partially deglycosylated or treated to remove sialic acid, fibrinolytic activity was increased. Production of Δ2−89 in the presence of timicamycin led to secielion of a glyean-free activator with higher activity. These findings suggest that certain oligusacchaiide side chains, particularly (hose containing sialic acid, can interfere with the interaction between the kringle region of t-PA and fibrin.
Influence of Metoprolol Treatment on Sympatho-Adrenal Activation of Fibrinolysis
Authors: Larsson P T , Wiman B , Olsson G , Angelin B , Hjemdahl P 
Published: June 2018

SummaryThe effects of mental stress (a colour word conflict test, CWT) and adrenaline infusions (0.1 and 0.4 nmol kg−1 min−1) on t-PA activity, t-PA antigen, PAI-1 activity and PAI-1 antigen were studied in 18 healthy male volunteers. Furthermore, the effects of metoprolol (200 mg/day during 1 week) or placebo (double-blind cross-over study) on fibrinolytic responses to sympatho-adrenal activation, and relationships between fibrinolysis and blood lipids were investigated.Low and high dose adrenaline infusions yielding plasma adrenaline levels of 0.9 ± 0.1 and 3.4 ± 0.4 nmol/1, respectively, dose-dependently increased t-PA levels with a concomitant decrease in PAI-1 levels. A similar, but weaker, fibrinolytic response seemed to occur during CWT when plasma adrenaline levels were only moderately increased (to 0.4 ± 0.1 nmol/1). Metoprolol treatment did not influence the resting levels of the fibrinolytic variables studied, but tended to enhance the t-PA response to CWT and further reduce PAI-1 during adrenaline infusion. Metoprolol treatment was not accompanied by any rise in PAI-1 levels despite drug induced elevations of triglyceride levels. Thus, the present study shows that sympatho-adrenal activation increases fibrinolytic activity in vivo and that meto prolol treatment may have a favourable influence on this activity.
Human Platelet Factor 4 and Its C-Terminal Peptides: Heparin Binding and Clearance from the Circulation
Authors: Rucinski Boguslaw , Niewiarowski Stefan , Strzyzewski Marian , Holt John C , Mayo Kevin H 
Published: June 2018

SummaryHuman platelet factor 4 (PF4), a high affinity heparin binding protein, is released from stimulated platelets and stored at vascular sites, predominantly in liver, from where it can be brought back into circulation by heparin. We attempted to define structural requirements for PF4 binding to heparin and for the pattern of its clearance from the circulation. Intact PF4 bound strongly to heparin agarose and was eluted at 1.4 M NaCl, while reduced PF4 and PF4 C-terminal peptides PF4 (47-70) and PF4 (58-70) bound weakly and were eluted at 0.2-0.5 M NaCl. 125I-radiolabeled intact PF4, reduced PF4 and C-terminal PF4 peptides injected into rabbits were cleared from the circulation in a biphasic pattern with components having half-life time of 1-2 min and 20-140 min. Heparin eliminated the fast component of PF4 clearance, but it did not affect clearance of reduced PF4 or C-terminal PF4 peptides. In contrast to reduced PF4 and PF4 (47-70), intact PF4 that accumulated in the liver and spleen, was displaced by heparin into circulating blood. In conclusion, specific binding sites and native conformation of the molecule are critical for high affinity PF4 binding to insolubilized heparin and for a pattern of PF4 clearance from the circulation in the presence of heparin.
Dilute aPTT Prolongation by Antiphospholipid Antibodies in Patients with Liver Cirrhosis
Authors: Violi Francesco , Ferro Domenico , Quintarelli Claudio , Alessandri Cesare , Saliola Mirella , Valesini Guido , Balsano Francesco 
Published: July 2018

SummaryThe behaviour of aPTT, as assessed by standard or diluted phospholipid mixture, was investigated in 20 patients suffering from liver cirrhosis. Standard aPTT was prolonged in 13 but it was corrected by 1:1 mixture with normal plasma. Dilute aPTT performed in samples mixed 1:1 with normal plasma and calculated by the difference in time between 1:80 and 1:5 phospholipid mixture was prolonged in 9 patients, who had also significantly higher titre of anticardiolipin antibodies (p <0.005). Unlike patients’ plasma with normal dilute aPTT, the addition of 0.05 M PC/PS liposomes to patient’s plasma with prolonged dilute aPTT significantly shortened dilute aPTT (p <0.001).This study shows the presence of antiphospholipid antibodies in some patients with liver cirrhosis; this seems to be responsible for the prolongation of dilute aPTT.
The Comparative Effects of Recombinant Hirudin (CGP 39393) and Standard Heparin on Thrombus Growth in Rabbits
Authors: Agnelli Giancarlo , Pascucci Claudia , Cosmi Benilde , Nenci Giuseppe G 
Published: July 2018

SummaryThe aim of this study was to compare the ability of standard heparin and recombinant (r-)hirudin, a specific inhibitor of thrombin, to inhibit thrombus growth in a rabbit jugular vein model. Doses of standard heparin and r-hirudin equivalent in prolonging the aPTT were first identified. The ability of these doses to inhibit 125I-fibrin accretion onto preexisting thrombi was then evaluated. 0.5 and 0.75 mg/kg of standard heparin and 0.8 and 1.25 mg/kg of r-hirudin infused over 3 h produced a mean prolongation of the aPTT of 1.5 and 2 times, respectively. In saline treated rabbits 62 ± 7 μg of 125I-fibrin were accreted on the pre-formed thrombi. The lower doses of standard heparin and r-hirudin produced a 125I-fibrin accretion of 44 ± 5 and 25 ± 4 μg, respectively (p <0.01). The two higher doses of standard heparin and r-hirudin produced a 125I-fibrin accretion of 34 ± 4 and 17 ± 3 μg, respectively (p <0.01). The increase in the dose of standard heparin up to 2.5 mg/kg produced a 125I-fibrin accretion of 26 ± 3 μg, a 58% reduction when compared with saline. The increase in the dose of r-hirudin up to 5 mg/kg produced a 125I-fibrin accretion of 12 ± 2 μg, an 81% reduction when compared with saline. No further inhibition was observed when the doses of both agents were further increased. We conclude that doses of standard heparin and r-hirudin equivalent in prolonging the aPTT have a different effect on thrombus growth inhibition, r-hirudin being twice as effective as standard heparin. Exclusive inhibition of thrombin without any other inhibiting effect on blood coagulation appears to be sufficient to inhibit thrombus growth. Our results seem to be promising in view of a clinical evaluation of r-hirudin
Sample Size in the Planning and Interpretation of Clinical Trials
Authors: levine Mark N , Hirsh Jack 
Published: June 2018

AbstractAn understanding of sample size determination is important in both planning and interpreting the results of clinical trials. A Type II error occurs when it is concluded that there is no difference between treatment groups, when in truth there is a difference. Such a false negative conclusion results from too few patients in a trial. In this review the principles of estimating sample size before a trial is commenced and evaluating the results of a negative completed trial are reviewed. Clinically relevant examples are used to illustrate these concepts.
Characterization of Na+/H+ Exchange in Platelets
Authors: Livne Avinoam , Grinstein Sergio , Rothstein Aser 
Published: June 2018

SummaryAcidification of the cytoplasm of human blood platelets leads to activation of Na+/H+ exchange. As a result, alkalinization occurs that is detectable by an intracellular fluorescent pH indicator. The activity of the exchanger can also be measured by the swelling of platelets suspended in Na-propionate medium using a Coulter Counter: the rapid entry of propionic acid leads to acidification and activation of Na+/H+ exchange with the parallel entry of Na+ and propionic acid leading to osmotic swelling. The Na+/H+ exchanger is sensitive to amiloride and to derivatives that are reported to be more specific inhibitors; it is specific for Na+ and Li+ with no measurable transfer of K+, Rb+ or Cs+; its Km for Na+ is 75 to 90 mM; it displays competitive behavior between Na+ and amiloride; its activity is decreased in cells loaded with Na+ by prolonged ouabain treatment; and it has a high temperature coefficient. These properties are in general similar to those of the exchanger in other cells. It is suggested that the Na+/H+ exchanger plays a role in platelet pH regulation.
Immunoradiometric Assay for the Calcium-Stabilized Conformation of Human Protein S
Authors: Poort S R , Deutz-Terlouw P P , van Wijngaarden A , Bertina R M 
Published: June 2018

SummaryRabbit polyclonal anti-protein S serum was fractionated with immobilized human protein S to establish solid-phase immunoradiometric assays recognizing Ca(II)-dependent and NonCa(II)-dependent epitopes of human protein S. The two assays were specific for PS:Ca(II)Ag and PS:NonCa(II)Ag and highly sensitive with a lower limit of detection of about 2.5 ng/ml.PS:Ca(II)Ag and PS:NonCa(II)Ag levels were measured in immunopurified protein S, thrombin-modified protein S and chy-motrypsin-cleaved protein S. Only in chymotrypsin-cleaved protein S an important discrepancy between the two antigen levels was observed.Ranges for the concentration of PS:Ca(II)Ag and PS:NonCa(II)Ag and their ratio were established in plasma of healthy individuals (0.92 ± 0.13 U/ml, 0.98 ± 0.21 U/ml, 0.96 ± 0.17, respectively). In a group of patients using oral anticoagulant therapy the ratio PS:Ca(II) Ag/PS : NonCa(II)Ag decreased at increasing intensity of anticoagulation suggesting the presence of sub- and noncarboxylated protein S molecules.In plasma of patients with a hereditary type I protein S deficiency PS:Ca(II)Ag and PS:NonCa(II) Ag were reduced to the same extent: mean ratio 1.02 ± 0.12 in the group not on oral anticoagulant treatment and 0.94 ± 0.10 in the group on oral anticoagulant therapy. Analysis of patients with a history of unexplained thrombo-embolic disease did not reveal individual patients with a PS:Ca(II)Ag/PS:NonCa(II)Ag ratio below the lower limit of the normal range (mean ratio 1.05 ± 0.17), suggesting that the frequency of genetic protein S variants with defects in the Ca(II)-stabilized conformation is very low.
Antithrombin III: Biodistribution in Healthy Volunteers
Authors: Knot E A R , Jong E de , Cate J W ten , Gie Liem Kian , van Royen E A 
Published: June 2018

SummaryFive healthy volunteers were injected intravenously with 73-90 uCi purified human 131I-Antithrombin III (AT III), specific biological activity 5.6 U/mg. The tracer data were analysed using a three compartment model. The plasma radioactivity half life was 66.2 ± 1.2 (sem) h, the fractional catabolic rate constant of the plasma pool was 0.025 ± 0.002 (sem) h-1. These data were comparable with those described in the literature. Because of the difficulty in translating the mathematical analysis of various compartments into the biological model, biodistribiition was monitored by a gamma camera linked to a DEC PDF 11/34 computer system. Dynamic and static images were obtained at fixed time intervals following the injection of 131I-AT III.Whole body scanning at intervals between the time of injection (t=0)and t=24.5 h showed 131I-AT III distribution over the heart, lungs, liver, spleen and great vessels. Dynamic scanning was performed over the heart, spleen and liver. Overlayed frames in the first ten minutes after the 131I-AT III injection showed the following radioactivity expressed as percentage of the injected dose; 5.9% ± 0.3(sem) over the heart, 10.6% ± 0.9 (sem) over the liver and 1.1% ⊥ 0.1(sem) over the spleen.A slower decline of the radioactivity between t = 0 and t = 24 h; (19%) was measured over the liver compared with the radioactivity disappearance over the heart region. This shows, in combination with the fact that the radioactivity disappearance over the heart was identical with the radioactivity decline measured in the plasma samples that retention of 131I-AT III occurred in the liver. Heparin iv injected 6 h after the 131I-AT III injection in two volunteers induced a sharp increase of radioactivity over the liver region during the scanning demonstrating that heparin enhances the 131I-AT III uptake in the liver.
Intravenous and Subcutaneous Administration of Desmopresssin (DDAVP) to Hemophiliacs: Pharmacokinetics and Factor VIII Responses
Authors: Mannucci P M , Vicente V , Alberca I , Sacchi E , Longo G , Harris A S , Lindquist A 
Published: June 2018

SummaryWhen desmopressin (DDAVP) is given to mild and moderate hemophiliacs intravenously (i. v.) or subcutaneously (s.c.), there is a very large between-patient variability for peak levels of factor VIII coagulant activity (VIII :C). To evaluate whether or not between-patient variability is related to DDAVP levels achieved in plasma, we measured drug levels in 14 hemophilic volunteers (VIII: C 2 to 31 U/dL) who were randomly given 0.3 μg/Kg of i. v. or s. c. DDAVP and crossed-over to the other treatment after an interval of 15–30 days. Peak DDAVP levels (Cmax) were higher for i.v. DDAVP (p <0.02), times to peak levels (tmax) were shorter for i.v. DDAVP (p <0.001). There was no difference between the i.v. and s.c. routes for plasma DDAVP time curve (AUC) and half-life (ti/,), but there was much larger variability for pharmacokinetic parameters with i.v. than with s.c. DDAVP. Post-DDAVP VIII:C increased 3.4 ± 1.6 fold (i.v.) and 3.3 ±1.3 fold (s. c.) over baseline levels, with no significant correlation between peak VIII :C and DDAVP levels for either route of administration. These findings establish the s. c. route of DDAVP administration to be bioequivalent in effect to the i.v. route, albeit with less variability. At the DDAVP dosage used in this study and currently recommended for therapy, the VIII: C response is neither a function of the rate of absorption of the compound nor of the magnitude of its plasma concentration.
Circulating Activities During Constant Infusion of Heparin or a Low Molecular Weight Derivative (Enoxaparine): Failure to Demonstrate any Circadian Variations
Authors: Toulon P , Vitoux J F , Leroy C , Lecomte T , Roncato M , Motobashi Y , Aiach M , Fiessinger J N 
Published: June 2018

SummaryWe compared in six patients successively treated with an unfractionated heparin (UFH) and a low molecular weight heparin (LMWH) the variations in plasma anti-Xa activity, measured in a chromogenic assay, during a 36 h constant infusion. The values varied in a wider range during UHF infusion, but remained in the therapeutic range except once in one patient. No circadian rhythm could be demonstrated in our six patients. LMWH infusion yielded very constant anti-Xa circulating activities. In both cases, there were no significant modifications of three proteins with high heparin affinity (antithrombin III, heparin cofactor II, histidine-rich glycoprotein).Our results suggest that the circadian rhythm of the biological activities previously observed in patients treated with constant heparin infusion using clotting method is due to other factors than heparin itself.
Endothelial Cells and Normal Circulating Haemopoietic Cells Share a Number of Surface Antigens
Authors: Favaloro Emmanuel J , Moraitis Nick , Koutts Jerry , Exner Thomas , Bradstock Kenneth F 
Published: June 2018

SummaryHuman endothelial cells, cultured from umbilical cord veins, have been evaluated for expression of a large number of cell surface antigens with known haemopoietic, particularly myeloid, cell distribution. This was achieved by evaluating endothelial reactivity (using non-fixed cells) with groups of monoclonal antibodies (MAB) belonging to distinct Clusters of Differentiation (CD), as defined by the Third International Workshop on Leukocyte Differentiation Antigens (ILWS). Results indicate that many antigens known to be present on haemopoietic cells, including those on platelets, are co-expressed on endothelial cells. The most intense degree of reactivity was seen using MAB to CD-9 and CD-13, although significant reactivity was also observed using MAB to CD-31 and CD-32. Data also suggests weak binding to endothelial cells of MAB belonging to CD-14, CD-15 and CD-16. A number of unclustered MAB reactive with haemopoietic antigens can also be shown to bind to endothelial cells.
In Vitro Effects of Ethanol on Rabbit Platelet Aggregation, Secretion of Granule Contents, and Cyclic AMP Levels in the Presence of Prostacyclin
Authors: Rand Margaret L , Gross Peter L , Jakowec Donna M , Packham Marian A , Mustard J Fraser 
Published: June 2018

SummaryEthanol, at physiologically tolerable concentrations, inhibits platelet responses to low concentrations of collagen or thrombin, but does not inhibit responses of washed rabbit platelets stimulated with high concentrations of ADP, collagen, or thrombin. However, when platelet responses to high concentrations of collagen or thrombin had been partially inhibited by prostacyclin (PGI2), ethanol had additional inhibitory effects on aggregation and secretion. These effects were also observed with aspirin- treated platelets stimulated with thrombin. Ethanol had no further inhibitory effect on aggregation of platelets stimulated with ADP, or the combination of ADP and epinephrine. Thus, the inhibitory effects of ethanol on platelet responses in the presence of PGI2 were very similar to its inhibitory effects in the absence of PGI2, when platelets were stimulated with lower concentrations of collagen or thrombin. Ethanol did not appear to exert its inhibitory effects by increasing cyclic AMP above basal levels and the additional inhibitory effects of ethanol in the presence of PGI2 did not appear to be brought about by further increases in platelet cyclic AMP levels.
Prostacyclin and Thromboxane Production by Autogenous Femoral Veins Grafted into the Arterial Circulation of the Dog
Authors: de Castellarnau C , Cullare C , Lopez S , Bonnin O , Montesinos A , Guix M , Rutllant M LL 
Published: June 2018

SummaryVascular prostacyclin (PGI2) production is different in the arteries and veins of the dog. Experiments were performed to determine whether chronic grafting of the femoral vein into the arterial circulation would alter the normal PGI2 and thromboxane (TxA2) synthesis of the “arterialized” veins. Spontaneous and arachidonic acid (AA) stimulated PGI2 and TxA2 production (measured by radioimmunoassay of 6-keto PGF1α and TxB2 respectively) were analysed in full thickness punch biopsies of the middle part of the grafts after 3 and 16 months and compared with unoperated veins and arteries. PGI2 production was significantly higher in arteries than in veins but no significant difference in TxB2 production was found. Middle “arterialized” venous graft produced significantly lower amounts of PGI2 and higher amounts of TxB2 than unoperated vessels. PGI2 production was more reduced in the distal than in the middle or the proximal parts of the venous grafts especially when stimulated with AA. These findings do not support the concept that the venous graft was biochemically adapted or “arterialized” in terms of PGI2 production when implanted for 3 months or longer. Rather the markedly decreased PGI2/TxB2 ratio in the middle of the graft may be a contributory cause of thrombogenicity and may be implicated in the pathogenesis of neointimal hyperplasia.
Heparin Inhibition of Endotoxin-Dependent Limulus Amebocyte Lysate Coagulation
Authors: Marcum James A , Levin Jack 
Published: June 2018

SummaryAddition of commercial heparin to preparations of the coagulation system obtained by hypotonic lysis of Limulus amebocytes, prior to the addition of endotoxin from gram-negative bacteria, inhibited gelation. Activation of the cell-lysate proclotting enzyme, utilizing a diluted lysate preparation and synthetic substrates, was inhibited to a comparable extent with either anticoagulantly active or inactive heparin. Other glycosaminoglycans, including heparan sulfate, dermatan sulfate, chondroitin 4-sulfate, and chondroitin 6-sulfate, did not inhibit the generation of clotting enzyme activity. Experiments conducted with preparations of proactivator(s) and proclotting enzyme, obtained by fractionation of lysate with heparin-Sepharose, revealed that inhibition of endotoxin-dependent activation of amebocyte lysate by heparin is mediated by precipitation of the proactivator(s) and can be prevented by increasing the salt concentration.
Effect of the Lupus Anticoagulant on Endothelial Fibrinolytic Activity In Vitro
Authors: Francis Robert B , Neely Sara 
Published: June 2018

SummaryWe investigated the effect of plasma and serum from 10 subjects with the lupus anticoaguiant and thrombosis and 9 normal subjects on the secretion of tissue-type plasminogen activator (t-PA) and its rapid inhibitor (type 1 plasminogen activator inhibitor, or PAI-1) by cultured human endothelial cells. Confluent monolayers of human umbilical vein endothelial cells were incubated for 48 hours with plasma or serum diluted ten-fold in serum-free endothelial cell growth medium, and the secretion of t-PA and PAI-1 measured by enzyme-linked immunosorbent assay. No consistent differences in mean t-PA and PAI-1 release were found between cells exposed to normal plasma or serum and plasma or serum from subjects with the lupus anticoagulant and thrombosis. No plasma or serum sample produced consistent inhibition of t-PA release or stimulation of PAI-1 release (defined as t-PA levels less than the mean minus two standard deviations for normal subjects, and PAI-I- levels greater than the mean plus two standard deviations for normal subjects, respectively). These findings do not support a role for altered endothelial fibrinolytic activity in the pathogenesis of thrombosis in subjects with the lupus anticoagulant, and are consistent with previous observations that these subjects have normal fibrinolytic activity in vivo.
High Levels of Plasma FVIII and vWF in the Toxic Epidemic Syndrome Patients
Authors: López-Fernández M F , López-Berges C , Fermoso J , Martín-Pascual A , Sánchez-Hernández J J , López-Borrasca A , Batlle J 
Published: June 2018

SummaryFactor VIII and von Willebrand factor proteins were evaluated in 115 patients having the chronic phase of the Toxic Epidemic Syndrome (TES), a new multisystemic disease probably caused by the ingestion of denatured rapeseed oil, and in 50 control volunteers. Higher circulating levels of factor VIII procoagulant activity (VIII :C) (158 ± 58.4 U/dl), von Willebrand factor antigen (vWF: Ag) (166.1 ± 55.5 U/dl) and von Willebrand factor ristocetin cofactor activity (vWF:RCo) (178.7 ± 55.2 U/dl) were seen in TES patients (p < 0.001, TES patients versus control subjects, for each parameter). The increased levels of vWF:Ag and vWF:RCo observed in TES patients correlated with the scleroderma like lesion of the skin, with the sicca syndrome and with Raynaud's phenomenon (p < 0.01), but not with other clinical manifestations. The multimeric analysis of vWF in 92% of the TES patients was similar to that found in normal plasma, but in the remaining 8% a very slight increase of larger vWF multimers in plasma were observed. The raised levels of vWF found in TES patients in the chronic phase may reflect an “in vivo” vascular injury.