bluuebunny/crossref_metadata_2025 huggingface dataset:
Hereditary Homozygous Heparin Cofactor II Deficiency and the Risk of Developing Venous Thrombosis
Authors: Villa Piedad , Vaya Amparo , España Francisco , Ferrando Fernando , Mira Yolanda , Estellés Amparo , Aznar Justo
Published: March 2018

Heparin cofactor II (HCII) is a specific inhibitor of thrombin in the presence of heparin or dermatan sulphate. Although there have been reports on families in which a heterozygous HCII deficiency is associated with thromboembolic events, several epidemiological studies revealed that heterozygous HCII deficiency is as prevalent among healthy subjects as it is among patients with deep venous thrombosis (DVT). It is therefore not yet clear whether HCII is or is not a thrombotic risk factor.

We analyze and describe in an extended family the biochemical and genetic thrombophilic risk factors and evaluate the potential thrombotic risk involved in homozygous and heterozygous HCII deficiency, either alone or associated with other thrombotic or circumstantial risk factors. The propositus has had three episodes of DVT and a pulmonary embolism. During the first episode of DVT the patient was diagnosed as having AT deficiency. Later, a functional and antigenic HCII deficiency, compatible with the homozygous form, was detected. The family study shows that both the propositus and her sister have homozygous HCII deficiency and that 12 of the 27 family members have heterozygous HCII deficiency.

This is possibly the first case report on a homozygous phenotype for the HCII deficiency with, in addition, partial AT deficiency. The propositus has suffered several thrombotic events, unlike the other 12 family members with heterozygous HCII deficiency and her sister, who is also homozygous for this disorder. We suggest that HCII deficiency may play a limited in vivo role as a thrombotic risk factor unless associated with AT deficiency or another congenital thrombotic risk factor.
Risk Factors Associated with Postpartum Ovarian Vein Thrombosis
Authors: Salomon Ophira , Apter Sara , Shaham Dorith , Hiller Nurith , Bar-Ziv Jacob , Itzchak Yacov , Gitel Sanford , Rosenberg Nurit , Strauss Simon , Kaufman Nathan , Seligsohn Uri
Published: March 2018

Thrombosis of the ovarian vein is a remarkable process occuring within a few days of labor in 1:500-1:2000 women. Its presentation is characterized by fever, abdominal pain and occasionally by a palpable abdominal mass that in earlier years sometimes lead to explorative laparotomy. With the advent of modern imaging techniques the diagnosis can be made relatively easily. The pathogenesis has been attributed to an infectious process expanding from the uterus to the right ovarian vein and stasis. A predisposition towards thrombosis has not been so far explored. In this study we retrospectively analysed the clinical features, diagnosis and treatment of 22 patients with objective documentation of post partum ovarian vein thrombosis (POVT) and assessed potential risk factors. In 11 of the 22 patients (50%) inherited prothrombotic risk factors were detected as follows: 4 were heterozygous for factor V G1691 A, 2 had protein S deficiency, one had protein S deficiency and was heterozygous for factor V G1691A, and 4 were homozygous for MTHFR C677T. Eight of the 11 patients who bore a prothrombotic predisposition underwent cesarean section. Taken together, the data suggest that POVT may result from the combined effect of an infection, cesarean section and a prothrombotic tendency.
Genetic Modulation of Plasma Protein S Levels by Two Frequent Dimorphisms in the PROS1 Gene
Authors: Duchemin J. , Levent M. , Gouault-Heilmann M. , Leroy-Matheron C.
Published: March 2018

We studied two polymorphisms located close to or within the 3’-untranslated (3’-UT) region of the PROS1 gene [an A to G transition at nt 2148 (Pro 626) and an A to C substitution at nt 2698] in 110 healthy volunteers. The allele frequency of the nt 2148 G variant was 35%, and that of the nt 2698 A variant was 27%. We found a relationship between the two dimorphisms (both separately and together) and the plasma total protein S antigen (tPS) level. The impact of the neutral Pro 626 dimorphism was more significant than that of nt 2698 C/A (p = 0.0003 and p = 0.013, respectively). The lowest tPS values were observed in subjects with the Pro 626;nt 2698 GG;CC genotype, and the highest values in those with the AA;AA genotype. Both polymorphisms acted independently of sex and age. The mechanisms by which the two polymorphisms regulate tPS synthesis were not revealed by the studies of platelet mRNA. This study provides the first evidence of a genetic modulation of tPS levels, which, in addition to age and sex, contributes to the wide normal range of tPS in plasma. Determination of these two polymorphisms could be a valuable additional tool for studying PS.
Familial Coagulation Factor V Deficiency Caused by a Novel 4 Base Pair Insertion in the Factor V Gene: Factor V Stanford
Authors: Hiraki D. D. , Jones C. D. , Gross N. , Grumet F. C. , Zehnder J. L.
Published: March 2018

An index patient with pseudohomozygosity for factor V Leiden was identified. Each of his two children inherited a different paternal factor V allele; a daughter was heterozygous for factor V Leiden, with 100% factor V activity, and a son was heterozygous for factor V deficiency, with 50% factor V activity. Genomic DNA was obtained from family members, and the 25 factor V exons and flanking intronic regions were sequenced in the proband and confirmed in the children. Within exon 13 of factor V, a 4 base insertion was found at NT 2856 in the proband and son, but not the daughter. This mutation, here designated factor V Stanford, results in a frameshift with loss of a thrombin activation site (R1545V) and premature termination of translation at amino acid 1560.
Adhesive Domains in the Collagen III Fragment α1(III)CB4 that Support α2β1- and von Willebrand Factor-mediated Platelet Adhesion under Flow Conditions
Authors: IJsseldijk Martin , Heijnen-Snyder Glenda , Huizinga Eric , Morton Laurence , Knight C. Graham , Sixma Jan , de Groot Philip , Barnes Michael , Verkleij Marilyn
Published: March 2018

Seven overlapping peptides derived from the bovine α1(III)CB4 fragment of collagen III support static platelet adhesion, and an integrin α2β1-recognition site has been assigned within this fragment to residues 522-528 of the collagen α1(III) chain; (25). In this study we found that two of the peptides, CB4(III)-6 and -7, were able to support platelet adhesion under flow conditions, whereas the other peptides showed either very little (CB4(III)-1 and -4) or no platelet adhesion at all (CB4(III)-2, -3 and -5). Using the recombinant leech anti-platelet protein (rLAPP), known to prevent both α2β1 integrin- and von Willebrand factor (vWF)-binding to collagen, we observed almost complete inhibition of platelet adhesion to peptides CB4(III)-6 and -7. In solidphase binding assays rLAPP bound to CB4(III)-6 and -7 and to CB4(III)-6/7, containing the peptide 6/7 overlap sequence, and not to any other peptide. Our results suggest that the overlap sequence GPP*-GPRGGAGPP*GPEGGK (single-letter amino acid code, P* = hydroxyproline), corresponding to residues 523-540 of the α1(III) collagen chain, contains a binding site for rLAPP. Monoclonal antibodies (MoAbs) directed against the α2 subunit of integrin α2β1 inhibited platelet adhesion to both CB4(III)-6 and -7 by about 50%, showing that the α2β1-recognition site in this locality in α1(III)CB4 detected under static conditions is of sufficient affinity to withstand shear forces. Solid-phase binding studies indicated that vWF binds to CB4(III)-7 and to a lesser extent to CB4(III)-4. Furthermore, rLAPP competed with vWF in binding to CB4(III)-7. Our results indicate that residues 541-558 of the α1(III)-chain may contain one of the critical vWF-binding sites involved in the initial phase of platelet adhesion to collagen III. MoAbs against vWF (A1 and A3 domain) and glycoprotein (GP)Ib confirmed that vWF is involved in adhesion to CB4(III)-7 and showed that vWF is also involved in adhesion to CB4(III)-6 despite the absence of direct binding of vWF to the peptide. The existence of α2β1-, vWF- and rLAPP-binding sites all in close proximity in α1(III)CB4 testifies to the importance of this locus in collagen III for its platelet reactivity.
Recombinant Factor VIIa Does not Induce Hypercoagulability In Vitro
Authors: Cvirn Gerhard , Muntean Wolfgang , Gallistl Siegfried
Published: March 2018

Recombinant factor VIIa (rVIIa) has been reported to be clinically effective and safe in haemophilic patients with inhibitor antibodies. Compared to activated prothrombin complex concentrates the risk of thrombotic complications seems to be very low after rVIIa administration. Determination of free thrombin generation has been shown to identify hypercoagulability. Therefore, free thrombin and prothrombinase activity (Xa generation) were assessed after extrinsic activation of rVIIa supplemented factor VIII and factor IX deficient plasma. Free thrombin generation was also determined after supplementation of (activated) prothrombin complex concentrates. Addition of 150 U rVIIa/ml shortened the clotting times markedly in control, factor VIII, and factor IX deficient plasma. In contrast, free thrombin and Xa generation were not different in the absence or presence of 150 U rVIIa/ml. Addition of (activated) prothrombin complex concentrates resulted in a marked increase of free thrombin generation in all investigated plasmas. Although in vitro studies cannot reflect specific clinical circumstances our results support the notion that rVIIa does not induce a hypercoagulable state as sporadically observed after administration of (activated) prothrombin complex concentrates.
Modulation of Platelet-neutrophil Interaction with Pharmacological Inhibition of Fibrinogen Binding to Platelet GPIIb/IIIa Receptor
Authors: Xiao Zihui , Frojmovic Mony , Théroux Pierre
Published: March 2018

The study investigated how drug inhibition of the GPIIb/IIIa receptor influences the interactions between platelets and leukocytes. These interactions are believed to play an important role in the etiology of the acute coronary syndromes. Thirty patients with unstable angina or non-Q-wave myocardial infarction were studied before the administration of tirofiban or placebo and after 4 h and 72 h. Platelet-leukocyte aggregates were characterized in whole blood using three-colour flow cytometry. The leukocyte population was isolated by a nucleic acid probe (LDS 751) and platelet-neutrophil coaggregates identified as particles binding both anti-CD42a-FITC and anti-CD45-PE. Tirofiban decreased by 25% the density of platelets in circulating platelet-neutrophil coaggregates (p <0.01), and prevented the increase induced by platelet agonist stimulation (p <0.0001). The reduction correlated with inhibition of fibrinogen binding to platelet (p <0.0001) and with inhibition of platelet aggregation (p <0.0001). The percentage of neutrophils with bound platelets following platelet agonist stimulation was, however, increased following GPIIb/IIIa inhibition. Thus, inhibition of GPIIb/IIIa receptor promotes platelet-neutrophil adhesion, but markedly reduces the binding density of platelets in the coaggregates.
Longitudinal Analysis of Factor VIII Inhibitors in a Previously Untreated Mild Haemophilia A Patient with an Arg593→Cys Substitution
Authors: Timmermans Simone , Turenhout Ellen , Bank Christine , Fijnvandraat Karin , Voorberg Jan , Peters Marjolein , van den Brink Edward
Published: March 2018

Recent studies suggest that certain missense mutations associated with mild to moderate haemophilia A predispose to inhibitor development. In this study, we present a longitudinal analysis of the epitope specificity of an inhibitor that developed in a mild haemophiliac with an Arg593→Cys mutation. Immunoprecipitation studies revealed the presence of antibodies directed towards the light chain and A2 domain of factor VIII. Limited reactivity was observed with metabolically labelled C2 domain. Almost complete inhibitor neutralization was achieved upon addition of A2 domain. Binding of the inhibitor was not affected by the presence of the Arg593→Cys substitution in the recombinant A2 fragment. Evaluation of the epitope specificity of anti-factor VIII antibodies in plasma samples obtained at different time-points of inhibitor development revealed initial development of a low titre inhibitor directed towards the A2 domain and factor VIII light chain. A second period of factor VIII replacement therapy resulted in a dramatic rise in factor VIII inhibitor titre, which maintained their original epitope specificity. Based on the results of this and previous studies (Fijnvandraat et al., 1997; Thompson et al., 1997) it is argued that inhibitor development in patients with the Arg593→Cys mutation may proceed via a similar mechanism.
Identification of the Binding Site for an Alloantibody to von Willebrand Factor which Inhibits Binding to Glycoprotein Ib within the Amino-terminal Region Flanking the A1 Domain
Authors: Shibata Masaru , Fujimura Yoshihiro , Takahashi Yukihiro , Nakai Hiroaki , Sakurai Yoshihiko , Asatani Masayo , Nomura Akihiko , Take Hiromichi , Giddings John , Yoshioka Akira , Shima Midori
Published: March 2018

An alloantibody to von Willebrand factor (vWF) which developed in a Japanese boy with type 3 von Willebrand disease has been characterized. The antibody was non-precipitating IgG and the main subclasses were IgG2 and IgG4. The antibody inhibited completely ristocetin-induced platelet aggregation (RIPA) and high shear stress-induced platelet aggregation (SIPA). Its predominant inhibitory role was focused, therefore, on the interaction between vWF and platelet gycoprotein Ib. The antibody reacted with a 52/48 kDa tryptic fragment of vWF (residues 449-728). No reaction was seen, however, with either a 39/34 kDa dispase fragment (480-718) or a recombinant vWF fragment (residues 465-728). These findings suggested that the essential epitope resided in the amino-terminal flanking region of the A1 domain. We synthesized overlapping peptides corresponding to the region containing D3/A1 boundary. A peptide, residues 458-472, bound to the antibody and dose-dependently blocked the antibody binding to the 52/48 kDa fragment. The same peptide neutralized the inhibitory effect of the alloanti-body on SIPA. The data are consistent with the presence of an epitope within residues 458-472 which reacted with the 52/48 kDa fragment.

Furthermore, the specific component of the antibody, directed against residues 458-472, blocked vWF binding to GPIb in absence of exogenous agonist. Our results suggest that the region flanking the A1 domain plays an important role in regulating vWF binding to GPIb.
A Synergistic Effect of Serotonin Transporter Gene Polymorphism and Smoking in Association with CHD
Authors: Ohtsuki Tsuyuka , Yamakawa-Kobayashi Kimiko , Amemiya Hiroshi , Fujiwara Hideomi , Kawata Ken-ichi , Ishiguro Hiroki , Hamaguchi Hideo , Arinami Tadao
Published: March 2018

Serotonin induces vasoconstriction in the presence of atherosclerotic lesions. Platelets acquire serotonin from the extracellular space by serotonin transporter and release it following aggregation. There is a functional polymorphism in the serotonin transporter (5-HTT) gene promoter associated with transcriptional efficacy and plasma serotonin levels. To examine whether the polymorphism is associated with coronary heart disease (CHD) in the Japanese, we analyzed 144 male CHD patients with an onset age before 65 and 222 apparently healthy men. The L allele was observed significantly more frequently in the CHD patients (26%) than in the control subjects (19%); the odds ratio was 1.48 (p <0.03). A significant interaction between the polymorphism and smoking was observed for CHD (p = 0.03), suggesting that the two have a synergistic effect on CHD. Odds ratio of the combination of the L allele and smoking was 1.95 (p <0.003). The 5-HTT gene promoter polymorphism may play a role in susceptibility to CHD, particularly when it is combined with smoking.
Vegetarians and Cardiovascular Risk Factors: Hemostasis, Inflammatory Markers and Plasma Homocysteine
Authors: Muñoz Ximena , Martínez Carlos , Cuevas Ada , Panes Olga , Aranda Eduardo , Guasch Viviana , Strobel Pablo , Muñoz Blanca , Rodríguez Soledad , Pereira Jaime , Leighton Federico , Mezzano Diego
Published: March 2018

We studied hemostatic and inflammatory cardiovascular risk factors (CVRF), and total plasma homocysteine (tHcy) in 26 vegetarians (23 lacto- or ovolactovegetarians and 3 vegans), matched by age, sex and socioeconomic status with omnivorous controls. Vegetarians had significantly lower proportion of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids in plasma lipids, significantly shortened bleeding time, and increased blood platelet count and in vitro platelet function (aggregation and secretion). Plasma levels of all coagulation or fibrinolytic factors and natural inhibitors synthesized in the liver were lower in vegetarians than in controls. Whereas for some factors this decrease was statistically significant (fibrinogen, factor VIIc, anti-thrombin III, protein S, plasminogen) for the remaining (factors VIIIc, Vc, prothrombin, protein C) a trend in the same direction was found. For hemostatic proteins of predominantly extrahepatic origin (von Willebrand factor, tPA, PAI-1) this tendency was not present. No significant differences in inflammatory proteins (C-reactive protein and α1-protease inhibitor) were detected in both groups. tHcy was significantly increased in vegetarians, and correlated only with cobalamin levels. The increased platelet function and tHcy found in vegetarians may counteract the known cardiovascular health benefits of vegetarian diet (VD).
Increased Thromboxane Metabolites Excretion in Liver Cirrhosis
Authors: Ferro Domenico , Basili Stefania , Iuliano Luigi , Camastra Caterina , Giammarresi Carlo , Santarone Stella , Rocca Bianca , Landolfi Raffaele , Ciabattoni Giovanni , Cordova Corrado , Violi Francesco , Davì Giovanni
Published: March 2018

An augmented systemic production of thromboxane (TX) A2, as assessed by urinary excretion of the thromboxane metabolites, has been described in severe liver cirrhosis. However, the significance of this finding remains unclear since in liver cirrhosis a number of phenomena i.e. altered hepatic TXA2 metabolism, increased intrasplenic platelet destruction, may affect TXA2 entry into systemic circulation as well as its metabolism. In order to further clarify this, we measured both major enzymatic metabolites of TXB2 in the urine of 44 patients affected by liver cirrhosis, subdivided in three classes on the basis of Child-Pugh criteria. Urinary 11-dehydro-TXB2 and 2,3-dinor-TXB2 were assayed with previously validated RIA techniques.

The urinary excretion rate of 11-dehydro-TXB2 was significantly (p = 0.0001) increased in the cirrhotic patients (673.5 pg/mg cr, median) in comparison with the controls (275 pg/mg cr, median) but no significant difference could be demonstrated among the excretion rates of the three patient subgroups. The excretion rate of 2,3 dinor-TXB2 was also significantly (p = 0.0001) increased in the patients (824 pg/mg cr, median) in comparison with controls (175 pg/mg cr, median), with a significant (p <0.05) increase from class A (381 pg/mg cr) to class C (1337 pg/mg cr). The sum of the two enzymatic metabolites was significantly (p = 0.0001) increased in the cirrhotic patients in comparison to controls, with a progressive increase from class A (1003 pg/mg cr, median) to class C (2240 pg/mg cr, median). The urinary excretion of 2,3 dinor-TXB2 was significantly (p = 0.008) related to plasma prothrombin fragment 1+2 (F1+2).

This study provides further evidence of increased thromboxane biosynthesis in liver cirrhosis. Moreover, we demonstrate intraliver shift of thromboxane metabolic disposition, due to progressive liver decompensation, because only the fraction undergoing β-oxidation to 2,3-dinor-TXB2 was progressively increased with the degree of liver failure. We, also, find a significant correlation between urinary excretion of 2,3-dinor-TXB2 and plasma F1+2, suggesting that clotting activation could partly account for in vivo platelet activation.
Evaluation of the Factors Contributing to Fibrin–dependent Plasminogen Activation
Authors: Siebenlist Kevin , Voskuilen Marijke , Nieuwenhuizen Willem , Mosesson Michael
Published: March 2018

Polymerized fibrin strongly enhances tissue plasminogen activator (tPA)-mediated plasminogen activation, concomitant with exposure of ‘fibrin-specific’ epitopes at ‘Aα148-160’ and ‘γ312-324’. To investigate which aspects of polymerization are involved in these activities, we explored the fibrin polymerization process by evaluating the ability of factor XIIIa-crosslinked fibrinogen polymers to expose ‘fibrin-specific’ epitopes and enhance plasminogen activation. Crosslinked normal fibrinogen, fibrinogen with deficient [des Bβ1-42] or defective [Birmingham (AαR16H)] fibrin ‘D:E’ assembly sites (‘EA’), or with defective end-to-end self-association sites (‘D:D’) [Cedar Rapids (γR275C)], exposed both ‘fibrin-specific’ epitopes and enhanced tPA-dependent plasminogen activation, whereas non-crosslinked fibrinogens showed minimal or no such activities. Epitope expression in cross-linked fibrinogen was retained in the presence of the fibrin EA site peptide homolog, gly-pro-arg-pro (GPRP), which inhibits fibrin D:E association, except for the Aα148-160 epitope in des Bβ1-42 fibrinogen, which was not expressed. Fibrin prepared from crosslinked normal or abnormal fibrinogen, except for the des Bβ1-42 fibrin epitopes, which were reduced or absent, expressed ‘fibrin-specific’ epitopes even in the presence of GPRP, which otherwise impairs such expression in noncrosslinked fibrin. Epitope exposure in fibrin prepared from non-cross-linked fibrinogen was nearly normal in Cedar Rapids fibrin (heterozygous D:D defect), but reduced in Birmingham fibrin (heterozygous EA defect), nil in des Bβ1-42 fibrin (EA deficient), and absent in all cases in the presence of GPRP. In contrast, plasminogen activation stimula-tory activity that had been exposed in crosslinked normal fibrinogen or in crosslinked des Bβ1-42 or Cedar Rapids fibrin, was preserved to a large extent in the presence of GPRP, suggesting that once enhanced stimulatory activity and epitopes are exposed, they are not completely reversible. The findings indicate that end-to-end intermolecular associations (D:D) are not critical for ‘fibrin-specific’ epitope exposure, but that polymerization brought about in fibrinogen through factor XIIIa crosslinking, or in fibrin through ‘D:E’ interactions, is necessary for ‘fibrin-specific’ (more correctly, ‘polymerization-specific’) epitope exposure and enhancement of plasminogen activation.
The Distribution of the Secreted and Intracellular Forms of Plasminogen Activator Inhibitor 2 (PAI-2) in Human Peripheral Blood Monocytes Is Modulated by Serum
Authors: Ritchie Helen , Booth Nuala
Published: March 2018

Plasminogen activator inhibitor 2 (PAI-2) is produced by activated monocytes in two forms, intracellular and secreted. We have studied the distribution of these two forms in unstimulated human peripheral blood monocytes and after stimulation by thrombin. Fetal calf serum (FCS) in the culture medium was absolutely necessary for accumulation of intracellular PAI-2; but not for synthesis and secretion. Even at a concentration as low as 0.1%, FCS restored accumulation of intra-cellular PAI-2. Increasing concentrations of FCS resulted in an increase in the ratio of intracellular to secreted PAI-2. The factor that promoted accumulation of intracellular PAI-2 was not a platelet product. Failure of monocytes to accumulate PAI-2 did not reflect leakage due to cell death, as assessed by LDH in culture supernatants. We propose that accumulation of intracellular PAI-2 is not simply due to poor secretion, but is an active process that is modulated by factor(s) found in serum.
Rap1b Association with the Platelet Cytoskeleton Occurs in the Absence of Glycoproteins IIb/IIIa
Authors: Fischer Thomas , Duffy Christina , White Gilbert
Published: March 2018

Platelet membrane glycoproteins (GP) IIb/IIIa and rap1b, a 21 kDa GTP binding protein, associate with the triton-insoluble, activation-dependent platelet cytoskeleton with similar rates and divalent cation requirement. To examine the possibility that GPIIb/IIIa was required for rap1b association with the cytoskeleton, experiments were performed to determine if the two proteins were linked under various conditions. Chromatography of lysates from resting platelets on Sephacryl S-300 showed that GPIIb/IIIa and rap1b were well separated and distinct proteins. Immunoprecipitation of GPIIb/IIIa from lysates of resting platelets did not produce rap1b or other low molecular weight GTP binding proteins and immunoprecipitation of rap1b from lysates of resting platelets did not produce GPIIb/IIIa. Finally, rap1b was associated with the activation-dependent cytoskeleton of platelets from a patient with Glanzmann’s thrombasthenia who lacks surface expressed glycoproteins IIb and IIIa. Based on these findings, we conclude that no association between GPIIb/IIIa and rap1b is found in resting platelets and that rap1b association with the activation-dependent cytoskeleton is at least partly independent of GPIIb/IIIa.
Oligosaccharide Configuration of Fibrinogen Kaiserslautern: Electrospray Ionisation Analysis of Intact γ Chains
Authors: Loreth Ralph , George Peter , Brennan Stephen
Published: March 2018

Electrospray ionisation mass spectrometry was used to probe the structure of the new N-linked oligosaccharide in fibrinogen Kaiserslautern (γ 380 Lys→Asn). The mass increase of 2177 Da in the new γ chain indicated the attachment of a fully sialylated biantennary oligosaccharide on the new Asn residue; the expected increase for this change being 2192 Da. Some 95% of the new oligosaccharide was in the disialylated state while only 5% of the endogenous γ chain carbohydrate was disialylated in the control. Mass measurements of intact Kaiserslautern γ chains after neuraminidase treatment of the native fibrinogen confirmed a total of three residues of sialic acid in the dominant isoform. Incubation with endoglycosidase F showed that the new oligosaccharide was more resistant to hydrolysis than the endogenous one. Recent X-ray analyses of covalently linked D domains show that position γ 380 is distant from both the GPR binding pocket and the D-D interface. It appears that the polymerisation defect of this fibrinogen results from electrostatic repulsion between condensing protofibrils and that this is induced by the two new residues of sialic acid that are present on the new γ chain.
Differences in Platelet α-granule Release between Normals and Immune Thrombocytopenic Patients and between Young and Old Platelets
Authors: Tracey Jayne , Recht Michael , DeCastro Laura , Rinder Christine , McHugh Colleen , Smith Brian , Rinder Henry
Published: March 2018

The risk of serious bleeding in patients with immune thrombocytopenic purpura (ITP) appears to be less than in comparably thrombocytopenic patients with megakaryocytic hypoplasia. It has been proposed that this difference is due to enhanced hemostatic activity of young platelets, which are increased in the circulation during ITP. We examined α-granule release in reticulated platelets (RP), which are thought to be the youngest circulating platelets, and in older non-reticulated platelets (non-RP) in normal human controls and ITP patients. Normal controls had a mean RP of 7%, compared with 42% in ITP patients. The mean concentration of thrombin receptor agonist peptide (TRAP) causing 50% of control RP to express CD62P (EC50) was 0.82 ± 0.08 μM (SEM), significantly higher than the TRAP CD62P EC50 for RP in ITP, 0.57 ± 0.06 uM (p = 0.04). Similarly, the TRAP EC 50 for non-RP in controls, 0.84 ± 0.09 μM, was significantly higher than in ITP, 0.56 ± 0.07 μM (p = 0.03), suggesting that all platelets in ITP have an enhanced α-granule threshold response to TRAP compared with controls, while RP and older platelets within each patient group have similar threshold sensitivities to TRAP. By contrast, high-dose TRAP caused RP to express twice as much mean and total CD62P as non-RP in both ITP patients and controls (p <0.05 for both comparisons). We conclude that compared with controls, all platelets in ITP are primed to undergo α-granule release to TRAP, while in both ITP and controls, the newly circulating, reticulated platelets have the potential to contribute greater amounts of CD62P surface ligand compared with older platelets (non-RP) after stimulation. Both the increased RP% and enhanced platelet response to agonist in ITP may contribute to maintenance of hemostasis despite thrombocytopenia.
SR 121787, a New Orally Active Fibrinogen Receptor Antagonist
Authors: Savi Pierre , Badorc Alain , Lalé Alain , Bordes Marie-Françoise , Bornia Josette , Labouret Catherine , Bernat André , Cointet Paul de , Hoffmann Peter , Maffrand Jean-Pierre , Herbert Jean-Marc
Published: March 2018

The aim of this study was to describe the pharmacological properties of SR 121787, a new antiaggregating drug which is metabolized in vivo into SR 121566, a potent non-peptide antagonist of Gp IIb/IIIa. In vitro, SR 121566 antagonized the binding of [125I]-fibrinogen (IC50 = 19.8 ± 6.3 nM) and of [125I]-L-692,884, an RGD-containing peptide (IC50 = 291 ± 96 nM) to activated human platelets. SR 121566 inhibited the aggregation of human platelets induced by ADP, collagen, thrombin, arachidonic acid and PAF at concentrations lower than 0.1 μM. Adhesion of human platelets to adhesive proteins was inhibited by SR 121566 (IC50 = 40.3 ± 2.5 nM) only when Gp IIb/IIIa and fibrinogen were involved. No effect was found with regard to other adhesive proteins and/or other integrins. SR 121787 demonstrated a potent and sustained antiaggregating effect when administered intravenously to baboons at a dose 50 μg/kg, and eight hours after the administration of 100 μg/kg, ADP-induced aggregation was still strongly inhibited (more than 80%). A single oral administration of 2 mg/kg of SR 121787 produced a nearly complete inhibition of platelet aggregation for up to 8 h (ED50 at 8 h = 193 ± 20 μg/kg), a significant residual antiaggregating activity being still observed 24h after the administration. When administered orally to rabbits, SR 121787 exhibited a potent antiaggregating (ED50 = 2.3 ± 0.3 mg/kg) and antithrombotic activity in an arterio-venous shunt thrombosis model (ED50 = 10.4 ± 0.8 mg/kg). After oral and IV administration, SR 121787 was well tolerated suggesting that SR 121787, the most potent and long lasting orally active Gp IIb/IIIa antagonist described to date, is a promising antithrombotic compound.
Heparin Regulates ICAM-1 Expression in Human Endothelial Cells: An Example of Non-Cytokine-Mediated Endothelial Activation
Authors: Hoggatt A. M. , Faulk W. Page , Miller Steven
Published: March 2018

Activated endothelial cells up-regulate the expression of several molecules on their plasma membranes, including intercellular adhesion molecule-1 (ICAM-1). The role of heparin in regulating endothelial cell gene expression is unclear. We thus have investigated the ability of heparin to regulate ICAM-1 gene expression by using flow cytometry and the ribonuclease protection assay with human umbilical vein and aortic endothelial cells cultured in growth medium supplemented with 90 μg/ml heparin (heparin-sufficient, HS) or in growth medium without added heparin (heparin-deficient, HD). We found that HD medium increased plasma membrane protein and mRNA for ICAM-1 but not for HLA-DR, even though both ICAM-1 and HLA-DR protein and mRNA were inducible by gamma interferon (IFN-γ). In addition, phorbol ester and IFN-γ increased the expression of plasma membrane ICAM-1 or ICAM-1 and HLA-DR, respectively, more in HD medium than in HS medium. We found that the HD-mediated increase of ICAM-1 mRNA was reversible by the addition of heparin, and that the half-life of ICAM-1 mRNA was the same in both HS- and HD-treated cells. Also, heparin was found to suppress increases in ICAM-1 mRNA at a concentration as low as 5 μg/ml. These findings indicate that heparin deficiency induces endothelial activation characterized by increased ICAM-1, and that such induction is not dependent on cytokines or endotoxin. The modulation of ICAM-1 expression by heparin appears to occur at the transcriptional level. Thus, heparin may have a role in regulating endothelial function by affecting the expression of ICAM-1, thereby impacting upon the trans-endothelial trafficking of leukocytes.
Fibrin-Rich and Platelet-Rich Thrombus Formation on Neointima: Recombinant Tissue Factor Pathway Inhibitor Prevents Fibrin Formation and Neointimal Development following Repeated Balloon Injury of Rabbit Aorta
Authors: Asada Yujiro , Hara Seiichiro , Tsuneyoshi Atsushi , Hatakeyama Kinta , Kisanuki Atsushi , Marutsuka Kousuke , Sato Yuichiro , Kamikubo Yu-ichi , Sumiyoshi Akinobu
Published: March 2018

Thrombus formation and neointimal growth are the critical events in restenosis after balloon angioplasty. However, the responses of diseased vessels to injuries caused by balloon angioplasty have not been well examined. We investigated the thrombus formation and neointimal development following the balloon injury to the previously induced neointima in the rabbit aorta and the effects of recombinant tissue factor pathway inhibitor (rTFPI) on these responses. Rabbit thoracic aortas were subjected to injury with a Fogarty 4F balloon catheter at 1.75 atm (first injury), and 4 weeks later the same vessels were subjected to the second injury with a Swan-Ganz 5F balloon catheter at 1.4 atm (mild-injury group) or 1.8 atm (severe-injury group), and immediately after that a retrograde bolus injection of rTFPI (100 μg/kg body weight) or saline was performed into the injured segments via the central tube of the Swan-Ganz catheter. Twenty minutes after the second injury, the injured surfaces were covered with platelet-rich thrombi in the mild-injury group and with fibrin-rich thrombi in the severe-injury group. Damaged intimal smooth muscle cells, which were immunohistochemically positive for tissue factor (TF), were observed beneath the fibrin-rich thrombi. The neointima 4 weeks after the second injury was significantly thicker in the severe-injury group than in the mild-injury group. The bolus infusion of rTFPI markedly inhibited fibrin formation on the injured surfaces, and significantly reduced the neointimal development in the severe-injury group at 4 weeks after the second injury. These results indicate that TF-dependent coagulation pathway is primarily responsible for fibrin-rich thrombus formation and may play an important role in neointimal development following the balloon injury to the rabbit aortic neointima. Additionally the bolus administration of rTFPI to the injured vessels could prevent mural thrombus formation and neointimal growth after balloon angioplasty.
A Role of Plasminogen in Atherosclerosis and Restenosis Models in Mice
Authors: Ploplis Victoria A. , Busuttil Steven , Carmeliet Peter , Collen Desire , Plow Edward F.
Published: March 2018

In addition to its preeminent role in fibrinolysis, the plasminogen system is believed to play a key role in mediating cell migration. Leukocyte migration into the vessel wall is a key and early event in the development of the lesions of atherosclerosis and restenosis, pathologies which may be viewed as specific examples of vascular inflammatory responses. The development of mice in which the plasminogen gene has been inactivated affords an opportunity to test the contribution of plasminogen in leukocyte migration during in vivo. This article summarizes recent studies conducted in murine models of the inflammatory repsonse, restenosis and atherosclerosis in which leukocyte migration, and in particular monocyte/macrophage migration, has been evaluated in plasminogen-deficient mice. Recruitment of these cells through the vessel wall in inflammatory response models and into the vessel wall in restenosis and transplant atherosclerosis models is substantially blunted. These data implicate plasminogen in the migration of leukocytes in these murine models. With the numerous correlations between components and/or activation of the plasminogen system in restenosis and atherosclerosis, these results also support a role of plasminogen in the corresponding human pathologies.
Plasminogen Activator Inhibitor Type-1 (PAI-1) and its Role in Cardiovascular Disease
Authors: Peter Karlheinz , Ruef Johannes , Kübler Wolfgang , Bode Christoph , Nordt Thomas K.
Published: March 2018

Cardiovascular disease is responsible for approximately 50% of total mortality in Europe, the USA and Japan (1). Established risk factors including smoking, hypercholesterolemia, and hypertension explain about half of the incidence of cardiovascular disease only (2). Reduced endogenous fibrinolytic activity secondary to increased plasma activity of plasminogen activator inhibitor type-1 (PAI-1) is now considered as a new cardiovascular risk factor. In this review, evidence is gathered for the notion that PAI-1 constitutes a predictor of cardiovascular disease and also contributes to the development of cardiovascular disease as a pathogenetic factor. The review will focus on experimental studies modulating PAI-1 activity and clinical studies addressing coronary heart disease, myocardial infarction, restenosis after coronary angioplasty, and graft occlusion after coronary artery bypass grafting.
Structure and Function of the Urokinase Receptor
Authors: Resnati Massimo , Mondino Anna , Blasi Francesco
Published: March 2018

The binding of the urokinase plasminogen activator (uPA) to its receptor (uPAR) regulates cell adhesion, surface proteolysis, chemotaxis and cell extravasation in a number of experimental systems. Recent evidences have suggested that uPAR can by itself mediate chemotaxis of human monocytes and cause profound changes in cytoskeletal organization indicating that this receptor has the properties of a cell-surface regulated chemokine. Indeed, it is likely that upon binding to uPA, uPAR undergoes a conformational change that uncovers a new epitope located in the linker region between domain 1 and 2 of the receptor and is endowed with a potent chemotactic activity. This conformational change can be mimicked in vitro by enzymatic processing of a recombinant receptor. We have shown that chymotrypsin cleaves uPAR between domain 1 and 2 in an area that can be also cleaved by uPA at high efficiency and generate a receptor that can mediate monocytes migration independently of uPA binding. This mechanism is pertussis-toxin sensitive and involves activation of tyrosine kinases and cytoskeletal reorganization events in vitro. These studies indicate that in addition to its receptor function, upon binding to uPA, uPAR becomes a pleiotropic ligand for other still to be identified surface molecules.
Treatment of Ischaemic Stroke
Authors: Einhäupl K. , Masuhr F.
Published: March 2018

Stroke is a neurological emergency that requires rapid diagnostic workup and immediate treatment. Basic medical management such as maintenance of a high level of systemic blood pressure, provision of an optimal supply of oxygen, and correction of hyperthermia, hyperglycaemia and hypovolemia can contribute to a more favourable clinical outcome of stroke patients. Neuroprotective drugs have shown to be effective in reducing cerebral infarct size in several animal species but their clinical benefit in stroke patients remains to be proven. Neither heparin nor aspirin can improve neurological outcome or significantly reduce death or dependency several months after the ischaemic event, but aspirin is clearly effective in reducing early death or stroke recurrence within the first few weeks. Early anticoagulation should be used for patients at high risk for recurrent cardioembolic stroke and with carotid or vertebral artery dissection, although this recommendation is not based on the results of randomised controlled trials.
Pharmacokinetics and Pharmacodynamics of Lanoteplase (n-PA)
Authors: Moser Martin , Kohler Benedikt , Kübler Wolfgang , Bode Christoph , Nordt Thomas K.
Published: March 2018

In acute myocardial infarction rapid, complete, and sustained reperfusion of the infarct-related coronary artery is the most important therapeutic principle. Lanoteplase or n-PA, a third-generation plasminogen activator consisting of a deletion and point mutant of tissue-type plasminogen activator (t-PA), is a promising agent to appraoch this therapeutic goal. The molecule exhibits an increased plasma half-life allowing single-bolus administration. In this article, after characterizing the n-PA molecule, the currently available pharmacokinetic and pharmacodynamic data including the results of the InTIME study are reviewed.
Anticoagulation after Artificial Valve Replacement with or without Atrial Fibrillation: How Much Is Really Needed?
Authors: Verheugt Freek W. A.
Published: March 2018

Insertion of a mechanical artificial heart valve is an absolute indication for the use of lifelong oral anticoagulation, irrespective the presence or absence of atrial fibrillation. Depending on the type and position of the artificial valve the optimal International Normalized Ratio (INR) for these patients is between 2.5 and 4.5, although more prospective studies on the optimal range of oral anticoagulation are necessary. Addition of low dose antiplatelet therapy may further decrease the rate of thromboembolism, but also here more studies are needed. Patients with a bioprosthesis need only oral anticoagulation for the first three months following surgery in the absence of an indication for anticoagulation for other conditions.

Atrial fibrillation is often seen in patients with artificial heart valves. Stroke prevention can be instituted by the mandatory oral anticoagulant therapy. The presence of atrial fibrillation and the use of oral anticoagulation prior to heart valve surgery support the indication for the insertion of a mechanical artificial heart valve. However, relative contraindications to oral anticoagulation and the presence of sinus rhythm may favor the use of a bioprosthesis.
Platelet Glycoprotein IIb/IIIa Receptor Blockade: Lessening the Risk of Coronary Interventions
Authors: Pitts William R. , Lange Richard A.
Published: March 2018

For the patient undergoing percutaneous coronary intervention, the administration of a platelet glycoprotein IIb/IIIa receptor blocker reduces the incidence of a periprocedural nonfatal myocardial infarction and the need for unplanned emergency stenting. In the diabetic patient undergoing intracoronary stenting, the use of a platelet glycoprotein IIb/IIIa receptor blocker appears to decrease the need for subsequent target vessel revascularization. There is considerable evidence in support of the use of glycoprotein IIb/IIIa receptor inhibitors in all categories of patients – “high-risk” patients, “low-risk” patients, and those undergoing primary angioplasty for acute myocardial infarction – and for the full armamentarium of percutaneous procedures (angioplasty, directional atherectomy, rotational atherectomy, and intracoronary stenting).
Low-molecular Weight Heparins in Venous and Arterial Thrombotic Disease
Authors: Hettiarachchi Rohan , Peters Ron , Prins Martin H. , Levi Marcel , Büller Harry R. , Bijsterveld Nick R.
Published: March 2018

Introduction: Since the introduction of low-molecular-weight heparins (LMWHs) in the early 1980's, the use of these compounds has been extensively investigated as a substitute for unfractionated heparin (UFH) in patients with venous and arterial thrombotic diseases. LMWHs have several advantages as compared to UFH, such as the subcutaneous route of administration, the predictable anticoagulant response and the lack of the need for laboratory monitoring. The present systematic review evaluates randomised clinical trials which investigated the efficacy and safety of LMWH in the acute treatment of venous thromboembolims, myocardial infarction, unstable coronary syndromes and ischemic stroke.

Methods: A computerised and manual search was performed to identify all relevant clinical trials. All randomised studies, with an a priori defined study population, clinical outcome measurement and adequate follow-up, were reviewed by two independent assessors. Whenever possible a common effect estimate of the included studies was calculated.

Results: Thirteen studies in approximately 4000 patients with acute venous thromboembolism revealed an odds ratio for the 3-month recurrent thromboembolism rate and major bleeding complications during exposure of 0.77 (C.I. 0.57-1.04) and 0.61 (C.I. 0.39-0.95), respectively, in favour of LMWH as compared to UFH. In patients with acute myocardial infarction, one study suggested a reduction in the incidence of reinfarction and cardiac death in LMWH recipients compared to UFH, while a placebo-controlled study revealed no beneficial effect of LMWH on these outcomes. In six studies including over 7000 patients with acute unstable coronary syndromes, there was an odds ratio for recurrent angina, myocardial infarction, urgent revascularisation and major bleedings of 0.88 (C.I. 0.76-1.01), 0.84 (C.I. 0.69-1.01), 0.83 (C.I. 0.70-0.99), 1.09 (C.I. 0.70-1.70), respectively, in favour of LMWH compared to UFH. The three studies comparing LMWH treatment with placebo in approximately 1000 patients with acute ischemic stroke revealed an odds ratio for the 10-day recurrent stroke, death or disability after 3 months and major bleeding complications of 0.68 (C.I. 0.41-1.13), 0.94 (C.I. 0.78-1.15), 2.92 (C.I. 1.88-4.55), respectively.

Conclusion: Fixed-dose subcutaneous LMWH appears to be a safe and effective alternative for dose-adjusted intravenous heparin in the treatment of patients with acute venous thrombotic disease as well as in patients with acute unstable coronary syndromes. The effectiveness of LMWH in patients with acute myocardial infarction remains unclear. There seems to be no beneficial effect of LMWH treatment as compared to placebo in patients with acute ischemic stroke, while the risk of major bleeding was clearly increased.
Prevention of Restenosis after Percutaneous Coronary Interventions: The Medical Approach
Authors: Tocchi Monica , Patterson Cam , Rosanio Salvatore , Runge Marschall S.
Published: March 2018

Restenosis following successful percutaneous coronary revascularization continues to represent a major problem limiting the clinical efficacy of this procedure. The underlying mechanisms of restenosis are comprised of a combination of effects from vessel recoil, negative vascular remodeling, thrombus formation and neointimal hyperplasia. Indeed, there are important interactions among all of these mechanisms. For example, neointimal hyperplasia is stimulated by growth factors, which are released by local thrombi and the injured arterial segment itself, and act to enhance the expression of other growth-regulating proteins, in particular “second messengers“, proto-oncogenes and other cell cycle controlling proteins. This results in an inflammatory and myofibroproliferative response, which may worsen vessel narrowing caused by recoil and result in the formation of a clinically significant restenotic lesion.

A multitude of pharmacologic trials have been conducted in an attempt to prevent restenosis, but most have demonstrated little benefit. Studies in smaller numbers of patients have suggested a potential benefit for several classes of agents, including: 1) the antiproliferatives, angiopeptin, trapidil and tranilast; 2) selective elimination or alteration of proliferating cells; 3) enhancement of natural growth inhibitors; and 4) signal transduction blockade or inhibition of the gene expression for various growth-stimulating proteins. Finally, there have been advances in related areas, including development of antithrombotic catheters, novel polymers, and more efficient methods for transferring genes into the vessel wall. All of these offer the possibility of delivering agents (drugs, genes, or antisense oligonucleotides) locally at the site of intervention in a way that may optimize antiproliferative effects while minimizing systemic effects – ultimately leading to a more specific inhibition of the restenosis process.