bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation of Plasma Procarboxypeptidase U in Different Mammalian Species Points to a Conserved Pathway of Inhibition of Fibrinolysis
Authors: Schatteman Katinka , Goossens Filip , Scharpé Simon , Hendriks Dirk 
Published: March 2018

SummaryCarboxypeptidase U (CPU, EC 3.4.17.20) is a recently described basic carboxypeptidase which circulates in plasma as the zymogen procarboxypeptidase U (proCPU). In the current study, we report on the presence of the proCPU/CPU system in different mammalian species – pig, guinea pig, dog, mouse, rabbit, rat and human. The proCPU concentration, determined as carboxypeptidase activity following thrombin-thrombomodulin activation, ranged from 255 U/l (mouse) to 5051 U/l (pig). When the CPU activity is generated during controlled in vitro coagulation by recalcifying citrated plasma, consistently lower activities were found compared to thrombin-thrombomodulin activation. These data indicate that in all species studied the mechanism for activation of proCPU is present. We demonstrate that in all species studied the addition of PTCI – a CPU inhibitor – results in a marked reduction of the lysis time. Albeit the presence of proCPU, the mechanism of activation during coagulation and the substantial reduction of the clot lysis time in the presence of PTCI point to a conserved inhibitory pathway of fibrinolysis.
SM-20302, a Nonpeptide GPIIb/IIIa Receptor Antagonist, Exhibits a Wide Therapeutic Window in a Newly Developed Hemorrhage Model in Mice*
Authors: Kaneko Munekiyo , Sakurama Teruo , Horisawa Seiya 
Published: March 2018

SummaryWe have developed a gastrointestinal hemorrhage model in mice and thereby assessed the potential risk of bleeding following administration of SM-20302, a nonpeptide GPIIb/IIIa receptor antagonist. First, SM-20302 selectively inhibited the interaction between human platelets and fibrinogen in vitro. Second, SM-20302 dose-dependently inhibited ADP-induced ex vivo platelet aggregation in mice and produced an ED50 value of 0.02 mg/kg. ED50 values of cyclo(RGDT)2, aspirin and ticlopidine were 0.48, 0.74 and 13.3 mg/kg, respectively. Finally, the bleeding risk of SM-20302 was examined in our newly developed hemorrhage model. Gastrointestinal hemorrhage was assessed 24 h later when the antiplatelet agents tested were administered to mice prior to the oral dosing of 0.1 N hydrochloric acid in 90% ethanol. The resulting hemorrhage was classified into three grades, major, minor or no bleeding, primarily based on the criteria used in the TIMI trial. All compounds tested induced gastrointestinal hemorrhage in a dose-dependent manner. Minimum hemorrhagic doses, MHDs, of SM-20302, cyclo (RGDT)2, aspirin and ticlopidine were 3, 3, 1 and 100 mg/kg, respectively. The potential risk of bleeding was assessed by the ratio of MHD to ED50 value. MHD/ED50 values of SM-20302, cyclo(RGDT)2, aspirin and ticlopidine were calculated to be 150, 6.3, 1.4 and 7.5, respectively. These results suggest that this experimental hemorrhage model may be useful for the evaluation of the bleeding complications of antiplatelet agents and that SM-20302 may have a wider therapeutic window than nonspecific integrin inhibitor and conventional antiplatelet agents.
Low-molecular Weight Heparin Reduces the Generation and Activity of Thrombin in Unstable Coronary Artery Disease
Authors: Ernofsson Mats , Strekerud Finn , Toss Henrik , Abildgaard Ulrich , Wallentin Lars , Siegbahn Agneta 
Published: March 2018

SummaryUnstable coronary artery disease (UCAD) is associated with an increased risk of further coronary events. In the FRISC study, the risk was decreased during treatment with a high, twice-daily, dose of dalteparin, a low-molecular-weight heparin. However, lowering the dose resulted in raised risk of recurrences. To investigate the underlying pathophysiology, the thrombin generation and activity in patients with UCAD randomized to a 6-week placebo-controlled treatment with dalteparin were evaluated.Plasma prothrombin fragment 1+2 (F1+2) (n = 342), thrombin-antithrombin complex (TAT) (n = 186) and soluble fibrin (SF) (n = 298) were analyzed before and during treatment with dalteparin/placebo administered subcutaneously, 120 IU/kg bw twice daily for 5-8 days and 7,500 IU once daily the following 35-40 days. High-dose treatment with dalteparin resulted in significantly reduced levels of all coagulation markers, demonstrating diminished thrombin generation and activity. When reducing the dalteparin dose, plasma TAT and SF remained low, indicating minimal fibrin formation. However, F1+2 increased during this period, though the level at day 45 was still lower than in the placebo group. In the placebo group elevated thrombin generation and activity persisted during the entire period.In conclusion, high-dose treatment with dalteparin twice daily resulted in significantly reduced thrombin generation and activity. However, after changing to a lower, once-daily dose, the treatment was not sufficient in preventing a return to a procoagulable state. These changes of the coagulation activity might explain the changes in event rate observed during dalteparin treatment.
Importance of the FcγRIIa-Arg/His-131 Polymorphism in Heparin-induced Thrombocytopenia Diagnosis
Authors: Saffroy Raphaël , Lasne Dominique , Chatellier Gilles , Aiach Martine , Rendu Francine , Bachelot-Loza Christilla 
Published: March 2018

SummaryHeparin-induced thrombocytopenia (HIT) involves heparin-dependent antibodies which induce platelet activation. In the present study, we searched for a relationship between the polymorphism of the Fc receptor (FcγRIIa) and the development of HIT. In this purpose, all the donors were genotyped for their FcγRIIA and HIT patients were selected on the basis of at least one positive answer by 14C-serotonin release assay (SRA). The frequency distribution of the FcγRIIa polymorphism in the HIT patient group was similar to that observed in the healthy control group. Moreover, a statistical analysis taking into account our results and those of 3 previously published studies, suggested at most only a weak association between HIT and the FcγRIIa-131 polymorphism.Laboratory tests used to diagnose HIT rely on the activation of normal donor platelets but fail to detect every HIT positive patient. We determined the role of FcγRIIa-131 polymorphism on the reactivity of control platelets to HIT plasmas. When control platelet FcγRIIa-131 was of Arg/Arg form, only 47% of the HIT plasmas were positive by SRA, compared to 81% and 74% for His/His or His/Arg forms, respectively. We also compared the level of anti PF4/heparin antibodies in the HIT plasmas with the response obtained by SRA. The mean anti PF4/heparin antibodies level in HIT plasma was significantly lower in negative SRA than in positive tests when using control platelets from FcγRIIa-Arg/Arg131 and heterozygous donors. Thus, the variability of control platelets to respond to HIT plasmas in the SRA test is related to both the FcγRIIa-131 polymorphism, and to the amount of anti PF4/heparin antibodies.
Transcriptional Regulation of Urokinase-type Plasminogen Activator Receptor by Cyclic AMP in PL-21 Human Myeloid Leukemia Cells: Comparison with the Regulation by Phorbol Myristate Acetate
Authors: Ozawa Tetsuo , Tsuzawa Toyokazu , Ueshima Shigeru , Matsuo Osamu , Sakuragawa Nobuo , Niiya Kenji 
Published: March 2018

SummaryWe investigated the effect of dibutyryl cyclic AMP (Bt2-cAMP) on urokinase-type plasminogen activator receptor (uPAR) expression in human PL-21 myeloid leukemia cells and compared it with the effect of phorbol myristate acetate (PMA). Flow cytometric analysis clearly demonstrated that Bt2-cAMP and PMA both induced the cell surface expression of uPAR. Northern analysis and nuclear run-on assay revealed that cAMP and PMA activated the uPAR gene transcription and both additively increased the uPAR mRNA level. However, actinomycin-D decay experiment showed that PMA, but not cAMP, prolonged the uPAR mRNA half-life. Furthermore, inhibition of the ongoing protein synthesis with cycloheximide abrogated completely the PMA-induced uPAR mRNA accumulation but only partially the induction by PMA plus cAMP, whereas the induction by cAMP alone was rather amplified, indicating that the de novo protein synthesis is necessary in the induction by PMA but not in the induction by cAMP and that the cAMP pathway may be dominant in uPAR gene expression in the PL-21 cells as compared to the PMA pathway. These results suggest that cAMP induces the uPAR expression exclusively through activating the gene transcription in which a preexisting transcriptional factor may be involved, whereas PMA transcriptionally and post-transcriptionally regulates the uPAR gene expression.
The Role of the Tissue Factor Pathway in the Hypercoagulable State in Patients with the Antiphospholipid Syndrome
Authors: Amengual Olga , Atsumi Tatsuya , Hughes Graham , Khamashta Munther 
Published: March 2018

SummaryThe antiphospholipid syndrome (APS) is characterised by both arterial and venous thrombosis, recurrent pregnancy loss and thrombocytopaenia in association with antiphospholipid antibodies (aPL). To explore further the pathogenesis of thrombosis in APS, we evaluated the behaviour of tissue factor (TF) pathway in patients with APS. Plasma antigen levels of soluble TF and tissue factor pathway inhibitor (TFPI), a physiological regulator of TF dependent coagulation activation, were measured in 57 APS patients (36 primary and 21 secondary to systemic lupus erythematosus). Significantly elevated levels of both TF and TFPI were found in APS patients compared with 25 healthy controls (279 ± 15 vs. 217 ± 17 pg/ml, p = 0.01; 56.24 ± 2.00 vs. 47.92 ± 2.22 ng/ml, p = 0.01, respectively), suggesting in vivo upregulation of TF pathway in patients with APS. By flow-cytometry, monocytes from a healthy donor displayed higher TF antigen expression when incubated in the presence of APS plasmas than in control plasmas (24.23 ± 3.11 vs. 12.78 ± 1.57%, p = 0.002). Peripheral blood mononuclear cells (PBMC) also expressed more procoagulant activity (PCA) when incubated in the presence of APS plasmas than in control plasmas (1.80 ± 0.12 vs. 1.35 ± 0.054, p = 0.001) implying that TF up-regulation in APS was reproducible in vitro. Human monoclonal anticardiolipin antibodies induced PCA on PBMC and also TF mRNA on both PBMC and human umbilical vein endothelial cells shown by reverse-transcription polymerase chain reaction. These data strongly suggest that the TF pathway is implicated in the pathogenesis of aPL related thrombosis.
Aging and Venous Thromboembolism Influence the Pharmacodynamics of the Anti-Factor Xa and Anti-thrombin Activities of a Low Molecular Weight Heparin (Nadroparin)
Authors: Mismetti P. , Laporte-Simitsidis S. , Navarro C. , Sié P. , d’Azemar P. , Necciari J. , Duret J. P. , Gaud C. , Decousus H. , Boneu B. 
Published: March 2018

SummaryVenous thromboembolism may be efficiently treated by one single daily administration of a high dose of low molecular weight heparin (LMWH). The present study investigates if the physiological deterioration of renal function associated with normal aging or the presence of an acute venous thromboembolism influences the pharmacodynamic pattern of the anti-factor Xa and anti-thrombin activities. Three groups of 12 subjects were investigated. The first 2 groups were composed of healthy volunteers differing by age (25 ± 4 and 65 ± 3 yrs) and creati-nine clearance (114 ± 15 and 62 ± 6 ml · min –1). The third group was composed of patients hospitalized for deep vein thrombosis, having a mean age of 65 ± 11 yrs and creatinine clearance of 76 ± 8 ml · min –1. Nadroparin was administered subcutaneously once daily at the dose of 180 anti-factor Xa IU.kg–1 for 6 to 10 days. Serial sampling on day 1 and on the last day of administration (day n) allowed the pharmacodynamic parameters of the anti-factor Xa and anti-thrombin activities to be compared at the begining and at the end of the treatment. The main findings were the following: (1) After repeated administration, a significant accumulation of the anti-factor Xa activity was observed in the healthy elderly and in the patients but not in the healthy young subjects (accumulation factor: 1.3). There was no evidence of accumulation of anti-thrombin activity; (2) There were significant correlations between the clearance of creatinine and the clearance of the anti-factor Xa activity but not with that of the anti-thrombin activity; (3) In the patients, the clearance of the anti-factor Xa and of the anti-thrombin activities were 1.4 and 2 times higher respectively than those calculated in the healthy elderly; (4) The mean ratio of the of anti-factor Xa and anti-thrombin clearances was close to 2 in the healthy subjects but equal to 5.4 in the patients. These results suggest that the mechanisms involved in the clearance of polysaccharide chains which support the anti-thrombin activity are different from those of the anti-factor Xa activity and that the enhanced binding properties of plasma proteins to unfractionated heparin reported in patients presenting an acute venous thromboembolism also exists for LMWH, predominantly for the anti-thrombin activity.
Distinct Associations of HbA1c and the Urinary Excretion of Pentosidine, an Advanced Glycosylation End-product, with Markers of Endothelial Function in Insulin-dependent Diabetes mellitus
Authors: Smulders Ronald , Schalkwijk Casper , Donker Ab , van Hinsbergh Victor , TeKoppele Johan , Stehouwer Coen 
Published: March 2018

SummaryDysfunction of the vascular endothelium is considered an early step in the development of diabetic angiopathy. Hyperglycaemia results in endothelial dysfunction, both through direct effects of glucose and through formation of advanced glycosylation end-products (AGEs). We hypothesized that the effects of glucose and AGEs on endothelial function in insulin-dependent diabetes mellitus (IDDM) are distinct and are reflected by distinct plasma markers of endothelial function. We therefore measured plasma levels of von Willebrand factor (vWF), soluble (s) E-selectin and vascular cell adhesion molecule-1 (sVCAM-1), and evaluated the relationship with HbA1c and urinary excretion of pentosidine, an AGE product, in 56 patients with IDDM. Urinary pentosidine excretion was higher in the diabetic than in a control group (n = 60) of similar age (P <0.0001) and showed a steeper increase with age (P <0.02 vs controls). In the diabetic group, sE-selectin was correlated to HbA1c (r = 0.52, P <0.0001), whereas sVCAM-1 was not (r = 0.11, P = 0.47). In contrast, sVCAM-1 showed a trend towards a correlation with log (pentosidine excretion) (r = 0.27, P = 0.06), whereas sE-selectin did not (r = –0.16, P = 0.27). Log(vWF) was correlated to HbA1c (r = 0.50, P <0.0001) and tended to correlate with log (pentosidine excretion) (r = 0.25, P = 0.07). Multivariate analyses with both pentosidine and HbA1c as independent variables showed significant associations of sE-selectin with HbA1c, of sVCAM-1 with pentosidine, and of log(vWF) with both HbA1c and pentosidine (all P-values <0.02). Our results imply that the effects of glucose and AGEs on the endothelium can be reflected by distinct endothelial markers. Plasma sE-selectin may reflect short-term effects of glucose on the endothelium, sVCAM-1 the effects of AGEs, and vWF the combined effect of glucose and AGEs.
Binding of Human Single Chain Urokinase to Chinese Hamster Ovary Cells and Cloning of Hamster u-PAR
Authors: Fowler Bruce , Mackman Nigel , Parmer Robert , Miles Lindsey 
Published: March 2018

SummaryThe plasminogen activator, urokinase (u-PA), interacts with the u-PA receptor (u-PAR) which results in enhanced plasminogen activation on cell surfaces. The u-PAR is comprised of three homologous domains of ~90 amino acids, defined by the pattern of disulfide bonds. Domain 1 (amino acids 1-87) binds the ligand. Within this domain, Y57, and a site between residues 47 and 53, have been suggested as ligand contact points. Intradomain interactions also contribute to the interaction of u-PA and u-PAR.The interaction of u-PA with its receptor exhibits some species specifity. Previous studies have shown that human u-PA does not bind to the murine u-PAR and murine u-PA does not recognize human u-PAR. However, human u-PA does interact with bovine cells with high affinity. To further examine the interaction of the human ligand with the u-PAR of a different species, we characterized the binding of human 125I single chain u-PA (scu-PA) to hamster cells. Chinese Hamster Ovary (CHO) cells bound human scu-PA with high affinity and capacity (Kd = 1.13 ± 0.8 nM; B max = 5.45 ± 0.98 × 104 sites/cell). In ligand blotting with human 125I-scu-PA, major bands migrating with apparent Mr’s of 74, 49 and 38 kDa were observed. The cDNA of hamster u-PAR was cloned and a single 1.4 kb mRNA species identified in Northern blots of CHO cell RNA. For comparison, we also cloned u-PAR cDNA from human THP-1 cells. Our human sequence was identical to those published for U937 and endothelial cells. These sequences were aligned with the published sequences for the murine, bovine and rat u-PAR’s to obtain a consensus sequence for five species. The cysteine residues could be aligned for all species. Y57, which has been suggested as a ligand contact point was also conserved across species. In addition, 5 of the 7 amino acids between amino acids 47 and 53 were conserved in all species. Gly283, the most likely glycosylphosphatidyl inositol attachment site, was also conserved in all species. The conservation of these amino acid residues across all five species, attests to their importance in u-PAR function. In addition, the results of
Development and Practical Use of the New Quantitative Bleeding Time Test Apparatus
Authors: Takami Hideki , Nakahata Rieko , Nakui Yuka , Akagi Tomoaki , Munakata Akihiro , Tamai Yoshiko 
Published: March 2018

SummaryWe have developed a new computerized system for measurement of quantitative bleeding time (QBT) to detect subtle abnormalities of primary hemostasis that are difficult to detect with the standard bleeding time determination. This new apparatus can simultaneously measure the bleeding time (BT; sec), amount of total blood loss (Tv; μl), maximum bleeding rate (Rmax; μl/sec) and bleeding pattern from the bleeding time incision. We have also developed a new holder for the Simplate that enables more consistent incisions and thus improves the reproducibility of the BT test.In this study, the newly developed QBT test was performed in 137 normal healthy volunteers and 10 patients having defined abnormalities of either primary or secondary hemostasis. Comparisons of the standard BT test and our QBT were made in 5 normal subjects and 7 thrombocytopenic patients. Additionally, 6 normal subjects were examined with both tests before and after administration of aspirin. Those results show that our QBT appears to be a more sensitive indicator of primary hemostasis than the standard BT method.
The Prevalence of a Non-phospholipid-binding Form of β2-Glycoprotein I in Human Plasma
Authors: Oort Erica van , Tempelman Mariëlle , Derksen Ronald , de Groot Philip , Horbach Daniëlle 
Published: March 2018

SummaryThe presence of antiphospholipid antibodies (aPL) is strongly correlated with venous and arterial thrombosis, fetal loss and thrombocytopenia. This relation is called the antiphospholipid syndrome (APS). It is well recognized that thrombosis related aPL are not directed against phospholipids alone, but to phospholipid bound plasma proteins like β2-glycoprotein I (β2GPI). aPL that need β2GPI for the binding to negatively charged phospholipids are called anti-β2GPI-antibodies. Recently, a mutation in the gene encoding β2GPI has been described, which results in an amino acid substitution Trp316 into Ser316. This Ser316-β2GPI did not bind to negatively charged phospholipids. Because only phospholipid bound β2GPI is recognized by human anti-β2GPI-antibodies, it might be argued that individuals carrying the Trp316Ser mutation are protected against the development of anti-β2GPI-antibodies.To investigate this hypothesis, the prevalence of the Trp316Ser mutation was measured in 170 systemic lupus erythematosus (SLE) patients and in 18 patients with the primary antiphospholipid syndrome (PAPS) and the mutation was correlated with the presence of anti-β2 GPI-antibodies. In the total patient group 1 homozygous patient and 21 heterozygous patients were found. The allele frequency of the mutation in SLE patients with anti-β2GPI-antibodies (0.063) was comparable to that found in SLE patients without anti-β2-GPI-antibodies (0.062). These results indicate that the heterozygous presence of Trp316Ser mutation does not prevent an individual from developing anti-β2GPI-antibodies. We showed that this can be explained by the concentration of Trp316-β2GPI in heterozygous patients, which is far above the minimal β2GPI level necessary for optimal phospholipid binding. In our single patient homozygous for the Trp316Ser mutation no binding of β2GPI to the phospholipid surface was detected and no anti-β2GPI-antibodies were present in the plasma of this patient.In conclusion, heterozygous Trp316Ser β2GPI persons are not protected against the development of anti-β2GPI-antibodies. To confirm that homozygotes do not develop anti-β2GPI-antibodies a very large population is needed, due to the relatively low prevalence of the mutation.
Secreted ADP Plays a Central Role in Thrombin-induced Phospholipase D Activation in Human Platelets
Authors: Marx-Grunwitz Alexandra , Presek Peter , Martinson Elizabeth , Scheible Stephan 
Published: March 2018

SummaryThrombin and other agonists that induce secretion and aggregation in human platelets also activate phospholipase D (PLD), but the signaling cascade leading to activation of PLD in human platelets is not yet clear. We have determined that apyrase, which scavenges ADP secreted during platelet activation, is able to block or reduce the PLD activation stimulated by low (0.1 U/ml or less) or high (0.3-1.0 U/ml) concentrations of thrombin, respectively. Neither ADP (up to 100 μM) nor its more potent analogue 2-methylthio-ADP (up to 100 μM), however, are able to stimulate PLD alone, and even the addition of fibrinogen, which results in platelet aggregation, is not sufficient for PLD activation. In contrast, ADP is able to stimulate PLD in the presence of low concentrations of thrombin that alone have little or no effect, suggesting ADP may play an amplifying role in platelet PLD activation. This hypothesis is supported by the finding that the purinergic receptor antagonist ARL 66096, an ATP analogue, reduces in a concentration-dependent fashion the PLD response to thrombin (IC50 = 28 nM with 0.1 U/ml thrombin). ARL 66096 also abolishes the PLD activation by ADP observed in the presence of low concentrations of thrombin, confirming that the antagonist inhibits an ADP-dependent component of the response. In addition, the thromboxane A2 receptor agonist U46619 activates PLD, and this response is markedly reduced by ARL 66096. Concomitantly, phosphorylation of the protein kinase C substrate pleckstrin in response to thrombin or U46619 is partially or totally inhibited by ARL 66096, respectively, consistent with ADP stimulation of protein kinase C being involved in the PLD response to these agonists. Based on these findings, we conclude that ADP secretion and activation of purinergic ADP receptors is an important amplification mechanism in the signal transduction pathways leading to PLD activation in human platelets.