bluuebunny/crossref_metadata_2025 huggingface dataset:
Tissue Factor as a Therapeutic Target
Authors: Bach Ronald , Key Nigel
Published: March 2018

Tissue factor (TF) is a member of the cytokine receptor superfamily that functions as the essential receptor and co-factor for factor VII/ VIIa. Assembly of the TF-VII(a) complex on cellular surfaces initiates blood coagulation by limited proteolysis of zymogen factors IX and X, ultimately leading to the generation of thrombin. The realization that the TF pathway is the primary (if not the sole) mechanism for activation of coagulation in vivo has sparked an explosion in research in the last decade that has documented the central role of TF in certain forms of pathological thrombosis. Although these are too numerous to list, several are especially noteworthy by virtue of strongly supportive data in animal models. These include disseminated intravascular coagulation (DIC) induced by sepsis, and arterial thrombosis overlying an atherosclerotic plaque - the usual final event in myocardial infarction and unstable angina. In the case of arterial injury, inhibition of TF in animal models has also suggested that this pathway is important in mediating intimal hyperplasia. Other recent seminal observations include the recognition of several possible roles for TF that may not depend upon activation of the coagulation mechanism. For example, TF expression by certain tumor cell lines may determine enhanced metastatic potential, and in some tumors TF may promote angiogenesis (1).
Crystal Structures of Fragments D and Double-D from Fibrinogen and Fibrin
Authors: Spraggon Glen , Everse Stephen , Doolittle Russell
Published: March 2018

Introduction

After a long period of anticipation,1 the last two years have witnessed the first high-resolution x-ray structures of fragments from fibrinogen and fibrin.2-7 The results confirmed many aspects of fibrinogen structure and function that had previously been inferred from electron microscopy and biochemistry and revealed some unexpected features. Several matters have remained stubbornly unsettled, however, and much more work remains to be done. Here, we review several of the most significant findings that have accompanied the new x-ray structures and discuss some of the problems of the fibrinogen-fibrin conversion that remain unresolved.

* Abbreviations: GPR—Gly-Pro-Arg-derivatives; GPRPam—Gly-Pro-Arg-Pro-amide; GHRPam—Gly-His-Arg-Pro-amide
Cyclic Nucleotide Phosphodiesterases (PDEs): Diverse Regulators of Cyclic Nucleotide Signals and Inviting Molecular Targets for Novel Therapeutic Agents
Authors: Degerman E. , Manganiello V. C.
Published: March 2018

Introduction

Cyclic adenosine 3’5’-monophosphate (cAMP) and cyclic guanosine 3’5’-monophoshpate (cGMP) are critical intracellular second-messengers involved in the transduction of a wide variety of extracellular stimuli, including peptide hormones, growth factors, cytokines, neurotransmitters and light. These messengers modulate many fundamental biological processes, including growth, differentiation, apoptosis, glycogenolysis, lipolysis, immune/inflammatory responses, etc.

By catalyzing hydrolysis of cAMP and cGMP, cyclic nucleotide phosphodiesterases (PDEs) are important determinants in regulating the intracellular concentrations and, consequently, the biological actions of these second-messengers (Fig. 1). The advent of molecular genetics has revealed the extraordinary complexity and diversity of the mammalian PDE superfamily, which contains at least 10 highly regulated and structurally-related gene families (PDEs 1-10).1-8 As depicted in Figure 1, some PDEs are highly specific for hydrolysis of cAMP (PDEs 4,7,8), some are cGMP-specific (PDEs 5,6,9), and some exhibit mixed specificity (PDEs 1,2,3,10). Most gene families are comprised of more than one isogene (indicated by A-D in Table 1). At least 19 genes encoding more than 30 isoforms have been identified. PDE families differ with respect to their primary structures, sensitivity to specific inhibitors, tissue distribution, subcellular localization, and mechanisms of regulation (Table 1).2-6 Within individual families, different mRNAs are generated from the same gene by use of different transcription initiation sites or by alternative mRNA splicing. These variant PDE isoforms are often tissue-specific and selectively expressed in various tissues and cell types.2-6 The importance of cyclic nucleotide signaling in cell regulation and the molecular diversity of PDEs has presented targets for selective interventions and development of family-specific PDE inhibitors as therapeutic agents. This brief review will discuss some general characteristics of PDEs and then focus on the cellular biology and diverse functions of different PDE isoforms and their potential as therapeutic targets.
Molecular Genetics of von Willebrand Disease
Authors: Ginsburg David
Published: March 2018

Introduction

Von Willebrand disease (vWD) is a common inherited bleeding disorder that is notable for a high degree of variability in clinical presentation and the considerable heterogeneity of its molecular basis. Confusion about the genetic origin of this disorder has existed since its original description by Eric von Willebrand in 1926.1 Dr. von Willebrand coined the term “pseudohemophilia” to describe the disease in the original pedigree. Though it resembled the bleeding diathesis of hemophilia, von Willebrand also noted findings suggesting an abnormality in platelet function. The severity of bleeding in this family varied widely from mild bleeding to severe hemorrhage, the latter resulting in the death of the proband at the time of her fourth menstrual period.

Von Willebrand incorrectly characterized the inheritance pattern in the original Åland Island pedigree as X-linked dominant, because of the apparent greater frequency of the disease in female patients. Now, it is recognized that the greater frequency was largely by chance and due to increased penetrance related to the hemostatic stresses of menstruation and pregnancy. Nonetheless, von Willebrand clearly distinguished the inheritance pattern of vWD from that of classic hemophilia. It is now known that vWD is due to either quantitative or qualitative defects in von Willebrand factor (vWF), encoded by a gene on chromosome 12, whereas hemophilia is due to mutations in the factor VIII gene on the X chromosome.2
Regulation of Leukocyte-Endothelium Interaction by Fibrinogen
Authors: Altieri Dario
Published: March 2018

Introduction

The binding of neutrophils and mononuclear cells to vascular endothelium is an essential prerequisite in maintaining effective immune-inflammatory responses. This process has been unraveled as a regulated “adhesion cascade” that involves the expression of multiple adhesion receptors of the integrin, selectin, and immunoglobulin gene superfamilies on both cell types. These adhesive interactions are modulated by disparate environmental signals, ranging from inflammatory and chemotactic cytokines to changes in shear force at the vessel wall. Although of paramount importance in the preservation of immune-inflammatory surveillance, dysregulation of leukocyte-endothelium interaction also constitutes one of the earliest molecular events in the pathogenesis of such vascular diseases as atherosclerosis. This dysregulation leads to the aberrant accumulation of mononuclear cells in the damaged intima.

Recently, the interaction of fibrinogen with vascular cells has emerged as an alternate mechanism for recruiting leukocytes at the site of vascular injury. Although the role of fibrinogen as a risk factor for atherosclerosis has long been recognized, this pathway has been associated with complex mechanisms of intercellular adhesion, signal transduction, second-messenger generation, and modulation of gene expression in vascular cells. These studies have revealed a multifaceted and far-reaching molecular link between inflammation and hemostasis–a link that is of potential therapeutic relevance for the pathogenesis of vascular diseases.
Catheter-Directed Thrombolysis of Peripheral Arterial Occlusions and Deep Vein Thrombosis
Authors: Kandarpa Krishna
Published: March 2018

Introduction

This chapter describes the current status of catheter-directed lytic therapy for occlusive thrombi of arteries and veins. A recent international consensus document, concerning the use of lytic therapy for symptomatic lower extremity arterial thrombi, has been endorsed by several international societies.1 A review of this document will serve to summarize current opinion on this topic. The present chapter addresses issues such as patient selection, techniques, and therapeutic efficacy. The techniques of arterial thrombolysis are being adapted to treat venous thrombi. Early results in the venous system are encouraging, but the long-term efficacy is yet to be established.
Fine Mapping of Inhibitory Anti-factor V Antibodies Using Factor V C2 Domain Mutants
Authors: Izumi Tomonori , Greist Anne , Macedo-Ribeiro Sandra , Fuentes-Prior Pablo , Bode Wolfram , Kane William , Kim Suhng Wook , Ortel Thomas
Published: March 2018

Hemorrhagic factor V inhibitors frequently bind to the second C-type (C2) domain of factor V and interfere with phospholipid binding. To define specific residues recognized by inhibitors from four patients (one bovine thrombin-induced and three spontaneous antibodies), epitope mapping was performed using recombinant human factor V lacking most of the B-type domain (FV des B) and alanine-substituted mutants within the C2 domain (FV des B C2 mutants). FV des B C2 mutants located in the region between Lys2060 and Glu2069 were resistant to inhibition by three IgG preparations including the bovine thrombin-induced antibody in both prothrombinase and phospholipid-binding assays. In contrast, mutations at Lys2087 and Lys2092/ Glu2096 were significantly resistant to inhibition by the fourth IgG preparation in both prothrombinase and phospholipid-binding assays. These results confirm interference of phospholipid binding by hemorrhagic factor V inhibitors and support the role(s) of these residues in phospholipid binding.

Presented in part at the 41st Annual Meeting of the American Society of Hematology, New Orleans, Louisiana, December 3–7, 1999
Myocardial Troponin T Release Is Associated with Enhanced Fibrinolysis in Patients with Acute Coronary Syndromes
Authors: Büttcher Eva , Kazmaier Silke , Beyer Martin , Helber Uwe , Szabo Sebastian , Wendel Hans Peter , Hoffmeister Hans Martin , Ehlers Raila
Published: March 2018

Patients with acute coronary syndromes (ACS) frequently present with signs of disturbed fibrinolysis. The present study investigates the correlation of alterations in the fibrinolytic system and the amount of myocardial damage characterized by troponin release.

In 85 patients with ACS markers of plasmin activation, plasminogen activator system and troponin T (TnT) were measured initially and after 48 h. Patients with TnT release (≥ 0.01 g/l) at admission had higher TPA levels than those without release (10.2 ± 0.7 ng/ml vs. 7.6 ± 0.5 ng/ml; p <0.01). Additionally, patients with positive TnT had higher D-dimer levels initially (457 ± 39 ng/ml vs. 316 ± 22 ng/ml; p < 0.01) and 48 h later (451 ± 42 ng/ml vs. 275 ± 37 ng/ml; p < 0.01). The association of myocardial damage with a prothrombotic state and an enhanced fibrinolysis may explain the high prognostic value of troponin measurements in respect to future coronary events.
Imbalance of Plasminogen Activator Inhibitor-I/ Tissue Plasminogen Activator and Tissue Factor/Tissue Factor Pathway Inhibitor in Young Japanese Men with Myocardial Infarction
Authors: Saigo Masahiko , Ogawa Masakazu , Yamashita Tsuminori , Biro Sadatoshi , Minagoe Shinichi , Maruyama Ikuro , Tei Chuwa , Abe Satoshi
Published: March 2018

To evaluate the association between haemostatic parameters and increased risk of myocardial infarction (MI) at a young age, we measured fibrinogen, factor VII, antithrombin III, protein C, protein S, tissue factor (TF), free form tissue factor pathway inhibitor (TFPI), plasminogen, 2-antiplasmin, tissue plasminogen activator (tPA), plasminogen activator inhibitor-I (PAI-I), and lipoprotein (a) in 140 young men with MI before age 45 and 150 age-matched healthy men. TF, TF/TFPI ratio, PAI-I, PAI-I/tPA ratio, plasminogen, and lipoprotein (a) in young MI patients were all significantly higher than controls, while TFPI, antithrombin III, and tPA were significantly lower (P <0.001 of each). Significant determinants of MI risk were PAI-I/tPA ratio (R2 = 0.300, P <0.001), TF/TFPI ratio (R2 = 0.049, P <0.001), antithrombin III (R2 = 0.034, P <0.001), hyperlipidaemia (R2 = 0.019, P = 0.004), diabetes (R2 = 0.014, P = 0.015), lipoprotein (a) (R2 = 0.012, P = 0.023), 2-antiplasmin (R2 = 0.014, P = 0.012), and protein C (R2 = 0.012, P = 0.018). We conclude that the imbalances of PAI-I/tPA and TF/TFPI are significantly associated with MI at a young age, perhaps mediated via impaired fibrinolytic activity.
Role of Protease-activated Receptor 1 in Tumor Metastasis Promoted by Tissue Factor
Authors: Bailly Michelle , Konigsberg William , Bromberg Michael
Published: March 2018

Tissue factor (TF) is a transmembrane glycoprotein that complexes with factor VIIa to initiate blood coagulation. We previously reported that expression of high levels of TF in a human melanoma cell line promotes metastasis. Both the cytoplasmic domain of TF and its extracellular domain complexed with factor VIIa are required for the meta-static effect. To further explore the mechanism of TF-mediated metastasis, we investigated the possibility that a protease-activated receptor (PAR) might play a role. For this purpose, we first determined the expression levels of the known PARs (PAR1-4) in a human melanoma cell line, SIT1, that has low endogenous levels of TF and low meta-static potential. We found negligible levels of all of the known PARs and transfection of this cell line with human TF cDNA did not alter expression of the known PARs. To study the possible role of PAR1 in TF-mediated metastasis, we prepared a panel of transfected cell lines with varying levels of TF and PAR1. Our studies show that TF promotes metastasis by a pathway that does not involve high expression of known PARs by tumor cells. In addition, while overexpression of PAR1 is insufficient to induce metastasis in cells with low TF expression, it enhances the metastatic potential of cells with high TF expression, indicating a possible synergy between TF and PAR1 in promoting metastasis.
The Kringle V-Protease Domain Is a Fibrinogen Binding Region within Apo(a)
Authors: Xue Song , Madison Edwin , Miles Lindsey
Published: March 2018

Lp(a) binds directly to fibrin and competes for the interaction of plasminogen with this substrate. This competition may play a role in the proatherothrombogenic consequences of high Lp(a) levels. Previous studies by us and others showed that apo(a) Kringle IV-10 competes for the interaction of Lp(a) with plasmin-treated fibrinogen. However, kringle IV-10 cannot account for the entire high affinity interaction of Lp(a) with fibrinogen. Therefore, we tested the hypothesis that the apo(a) kringle V protease-like domain (KV-PD) could interact with plasmin-treated fibrinogen. We cloned the apo(a) KV-PD region from a human liver cDNA library. Fusion apo(a) KV-PD was expressed in COS 7 cells and purified from the conditioned media. Western blotting of the apo(a) KV-PD protein revealed two bands migrating with apparent molecular weights of 45K and 48K. When fusion apo(a) KV-PD was treated with O-glycosidase and neuraminidase, the higher molecular weight band disappeared suggesting that the apo(a) KV-PD was O-glycosylated. Apo(a) KV-PD bound to plasmin-treated fibrinogen in a dose-dependent fashion. An EC50 of 3.9 ± 0.2 μM was determined for this interaction. Treatment of the apo(a) KV-PD with O-glycosidase did not significantly affect its ability to bind to plasmin-treated fibrinogen. In addition, apo(a) KV-PD competed for the binding of 125I-Lp(a) to plasmin-treated fibrinogen. An IC50 of 7.90 ± 0.95 μM was obtained. Our data suggest that the KV-PD of apo(a) shares binding sites on plasmin-treated fibrinogen with Lp(a) and also may participate in the interaction of the Lp(a) particle with plasmin-treated fibrinogen.
A Missense Mutation (Tyr88 to Cys) in the Platelet Membrane Glycoprotein Ibβ Gene Affects GPIb/IX Complex Expression
Authors: Kurokawa Yumi , Kamijo Takehiko , Kunishima Shinji , Kenny Dermot , Kitano Kiyoshi , Koike Kenichi , Ishida Fumihiro
Published: March 2018

This study examined the molecular basis of a missense mutation of the platelet glycoprotein (GP) Ibβ gene in two families. In the propositus with a novel form of Bernard-Soulier syndrome (BSS) from Family I, only GPIbα was detectable in reduced amounts on platelet surfaces by flow cytometry. There were no GPIX or GPIbβ found by immunoblotting. DNA sequencing analysis showed a homozygous mutation in the GPIbβ gene which changed Tyr (TAC) to Cys (TGC) at residue 88. Her parents were heterozygous for Tyr88Cys in the GPIbβ gene. In transient transfection studies on 293T cells, both Tyr88Cys and Tyr88Ala mutations suppressed the expression of GPIb/IX complexes. In addition, Tyr88Cys GPIbβ mutation was found to exert a dominant negative effect on the GPIb expression.

Five individuals from Family II, four of whom reported elsewhere as having giant platelet disorders with normal aggregation (BLOOD, 1997; 89: 2404) and one newly analyzed in this study, were heterozygous for Tyr88Cys in the GPIb gene. Microsatellite analysis of chromosome 22 showed a common haplotype in 8 of the individuals with Tyr88Cys mutations in Families I and II. Tyr88 in the GPIbβ gene plays a significant role in the GPIb/IX expression; the defect causes BSS in a homozygous form and possibly giant platelets in a heterozygous form.
The Value of Ultrasound Screening for Proximal Vein Thrombosis after Total Hip Arthroplasty
Authors: Verlato Fabio , Bruchi Olinto , Camporese Giuseppe , Maso Gianni , Busonera Flavio , Girolami Antonio , Andreozzi Giuseppe Maria , Prandoni Paolo ,   for the W. O. D. O. S. Investigators Group
Published: March 2018

The role of ultrasound screening for proximal deep-vein thrombosis (DVT) following major hip surgery is controversial. 202 consecutive patients, who had received warfarin prophylaxis after total hip arthroplasty underwent a bilateral ultrasound assessment of the proximal vein system (using the criterion of vein compressibility) before hospital discharge. In the 9 patients (4.5%; 95% CI, 2.1-8.3%) with positive test anticoagulant treatment was successfully continued for three months. In all the remaining 193 patients the warfarin treatment was withdrawn. A second ultrasound test was performed 15 days later, and showed a new (asymptomatic) abnormality compatible with proximal DVT in 2 patients (1.0%; 95% CI, 0.1-3.7%). All other 191 patients remained asymptomatic until the completion of a 3-month follow-up period (rate of symptomatic thromboembolism, 0/191, 0%; 95% CI, 0-1.9%).

Because of the relatively high incidence of proximal DVT in patients undergoing major orthopaedic surgery under warfarin prophylaxis, screening for proximal DVT at hospital discharge in these patients is indicated. The negativity of this test has the potential of safely preventing the extension of anticoagulation beyond hospital stay. A larger controlled study in which the value of this strategy is tested against the prolongation of oral anticoagulation in patients with a negative ultrasound screening at discharge is indicated.
Early Inhibition of Activated Fibrinolysis Predicts Microbial Infection, Shock and Mortality in Febrile Medical Patients
Authors: Raaphorst Joost , Bossink Ailko , Hack C. Erik , Groeneveld A. B. Johan
Published: March 2018

To evaluate the contribution of an imbalance between coagulation activation and fibinolysis activation and inhibition to morbidity and mortality in sepsis, we determined in medical hospitalized patients at inclusion (day 0) for fever (temperature above 38.0° C axillary or 38.3° C rectally), and daily thereafter for two days, circulating thrombin-antithrombin III (TAT) complexes, plasmin- 2-antiplasmin (PAP) complexes (day 0 only), tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1) and interleukin (IL)-6, the latter as a marker of the inflammatory host response. Study variables were 1) positive microbiological results for specimens from local sites associated with a clinical infection, positive blood cultures (including parasitemia) or both, within 7 days after inclusion, 2) development of shock, i.e. systolic blood pressure <90 mmHg or a reduction of 40 mmHg from baseline within 7 days after inclusion, and 3) death related to febrile illness within 28 days after inclusion. The peak plasma levels of TAT complexes were elevated in 44% and the PAP complexes in all patients. The t-PA and PAI-1 levels were elevated in 74 and 94% of patients, respectively. Values for TAT and PAP did not differ among subgroups, while peak t-PA and IL-6 levels were higher in patients with positive microbiological results, developing shock or ultimately dying than in those without the complications (p <0.005). Peak PAI-1 levels were elevated in patients developing shock and ultimate death versus those with an uncomplicated course (p <0.05). Peak IL-6 related to PAI-1 and t-PA levels, which interrelated. Patients with elevated TAT levels had increased plasma levels of IL-6, PAP, PAI-1 and t-PA versus those with normal TAT (p <0.05). Our data indicate that inhibition of activated fibrinolysis, which may partly depend on both cytokinemia and activation of coagulation, predicts microbial infection, septic shock and mortality of febrile medical patients. This suggests an early pathogenic role of inhibition of activated fibrinolysis in the downhill course of serious microbial infection.
Complementary Roles for Fibrin(ogen), Thrombospondin and vWF in Mediating Shear-dependent Aggregation of Platelets Stimulated at Threshold Thrombin Concentrations
Authors: Kasirer-Friede Ana , Legrand Chantal , Frojmovic Mony
Published: March 2018

We have evaluated the relative contribution of the adhesive ligands, von Willebrand factor (vWF), fibrinogen (Fg) and thrombospondin (TSP), all surface-expressed on washed platelets (WP) activated with a threshold thrombin concentration (~ 0.04 U/ml), to platelet micro-aggregation (PA) at shear rates (G) from 300-2000 s-1. In suspensions of thrombin-activated WP sheared immediately (τ0), all three ligands were required for optimal aggregation at all G, as shown by a 50-70% inhibition of capture efficiencies of PA (measured from initial rates of PA), by antibodies (Abs) directed against each protein. This aggregation involved both GPIb and GPIIbIIIa, as indicated by ~ 80% and 100% inhibition by Ab 6D1 and Ab 10E5, respectively. For WP preexposed to thrombin for 10 min to ensure maximal surface expression of secreted ligands and activated GPIIbIIIa (τ10), vWF was predominantly required at all G (63-75% inhibition by anti-vWF Ab), together with TSP (35-50% inhibition by anti-TSP Ab). Under these conditions, Fg was extensively converted to fibrin, so that fibrin, rather than Fg, could participate in microaggregation, with GPIb less required than GPIIbIIIa as indicated by a 30-60% inhibition by Ab 6D1 as compared to 100% inhibition by Ab 10E5. Our results show that interactions between multiple ligands and receptors favour microaggregation depending on shear and thrombin activation conditions.
The Conformational Basis of Thrombosis
Authors: Huntington James , Mushunje Alec , Zhou Aiwu , Robin Carrell
Published: March 2018

Antithrombin readily undergoes a spontaneous transition from its active five-stranded form to a six-stranded inactive latent form. The recognition of this change in plasma has been obscured by the immediate linkage of newly formed latent antithrombin to a molecule of active antithrombin to give a dimer with an electrophoretic mobility readily confused with that of native active antithrombin. A new micromethod now allows unequivocal identification of latent antithrombin in whole plasma. This shows that at 37° C some 10% of plasma antithrombin is converted to the latent form in 24 h. The rate of conversion is greatly accelerated at increased temperatures, as occurs in the pasteurisation of plasma concentrates that should now be checked for efficacy. But increased transition also occurs in the plasma at the slightly increased temperatures that accompany incidental infections. This is of particular significance if there is a conformationally unstable variant of antithrombin; here fever can provoke a sudden transition with the onset of a characteristically severe episode of thromboembolism. Such variants are not rare and include those previously classified as pleiotropic. The precise structural pathway, now known with antithrombin, provides a model of the changes occurring in other conformational diseases, including Alzheimer’s and the prion dementias.
Tissue Factor: An Enzyme Cofactor and a True Receptor
Authors: Morrissey James
Published: March 2018

Tissue factor is considered to be the physiologic trigger of the blood clotting system in normal hemostasis and in many – perhaps most – thrombotic diseases. A wealth of new knowledge is available regarding the structure and assembly of the TF:VIIa complex and the role of factor VIIa and tissue factor in hypercoagulable states. The exciting recent finding that tissue factor can function as a signaling receptor, and suggestions that tissue factor may have important, non-hemostatic roles, will be the subject of much additional study in the near future.
Thrombophilia, Thrombosis and Pregnancy
Authors: Eldor Amiram
Published: March 2018

The risk of venous thromboembolism (VTE) in pregnancy is 0.05-1.8%, six times greater than in the non-pregnant state, and pulmonary embolism remains the most common cause of maternal death. Maternal age, previous history of VTE, Caesarean section and the presence of thrombophilia, significantly increase the risk of VTE. Acquired or hereditary thrombophilia occur in almost two-thirds of women presenting with recurrent miscarriages, pre-eclampsia, intrauterine growth restriction, abruptio placentae, or stillbirth, which are associated with microvascular thrombosis in placental blood vessels. Women with VTE during pregnancy and especially those with thrombophilia require individualized management, based on the type of defect, the family history and the presence of additional risk factors. These factors are important in determining the dose and duration of antithrombotic therapy during pregnancy and the puerperium, and the thromboprophylactic strategy for future pregnancies. Oral anticoagulants are now seldom used during pregnancy because of their significant side effects. Low-molecular-weight heparins (LMWHs) are increasingly replacing unfractionated heparin in the prevention and treatment of VTE during pregnancy. LMWHs have also been shown to be effective in improving the outcome of pregnancy in women with previous obstetric complications.
Integrin Activation
Authors: Woodside D. G. , Liu S. , Ginsberg M. H.
Published: March 2018

Integrins are cell surface adhesion receptors that participate in a variety of important processes throughout the vasculature. Here we summarize some recent findings on the regulation of integrin mediated cellular adhesion. Particular emphasis is placed on the regulation of integrin affinity for ligand (activation), although this is just one mechanism by which regulation of integrin-dependent cell adhesion can occur. Also discussed are recent observations on the structural basis of integrin activation, the role of the cytoplasmic domain in integrin affinity regulation, and potential mechanisms by which activation signals are propagated from integrin cytoplasmic domains to the extracellular ligand binding domain.
Thrombolysis in Deep Vein Thrombosis: Is there still an Indication?
Authors: Forster Alan , Wells Philip
Published: March 2018

The most accepted therapy for DVT consists of anticoagulation with unfractionated heparin or low molecular weight heparin, followed by variable duration oral anticoagulation but thrombolytic therapy has been proposed in addition to standard anticoagulation. This paper reviews the literature on post thrombotic syndrome, the natural history of vein patency after therapy, and we perform a systematic review, using accepted standards for meta-analysis, to determine the outcomes when thrombolytic therapy is used to treat DVT. We demonstrate that thrombolytic therapy for DVT results in a significant increase in the risk of major hemorrhage and a significant increase in the rate of vein patency. However, although thrombolytic therapy is advantageous over anticoagulation as measured by early vein patency, a benefit in terms of a reduction in PTS risk, is unproven. Our review also shows that there is no evidence that there is a difference in efficacy between thrombolytic agents or that local therapy differs from systemic therapy. Finally, the potential role of catheter directed therapy is unknown since appropriate trials have not been performed but it is reasonable to use catheter directed therapy in patients with phlegmasia cerulea dolens. We conclude that more work is needed to define the role of thrombolytic therapy but it is too early to abandon this therapeutic modality.
Nichtalkoholische Fettleber bei Kindern und Jugendlichen
Authors: Zöhrer E. , Baumann U. , Jahnel J.
Published: March 2018

Die nichtalkoholische Fettleber ist die häufigste chronische Lebererkrankung im Kindes- und Jugendalter und ist oft mit Adipositas und Diabetes mellitus Typ 2 assoziiert. Der Begriff „Nichtalkoholische Fettleber-Erkrankung“, kurz NAFLD („nonalcoholic fatty liver disease“), beinhaltet ein Erkrankungsspektrum reichend von Fettleber mit fehlender Progression bis hin zur nichtalkoholischen Steatohepatitis (NASH). Bildgebende Verfahren und laborchemische Parameter helfen bei der primären Beurteilung und zur Verlaufsbegutachtung – für die Prognose ausschlagegebend ist die Histologie der Leberbiopsie. Die Therapie von NAFLD beschränkt sich primär auf Änderungen des Lebensstils und der Ernährung, die bariatrische Therapie wird zunehmend angewendet.
Update Epilepsie
Authors: Steinhoff B. J.
Published: March 2018

In der Epileptologie hat sich eine intensive Diskussion zur Klassifikation epileptischer Anfälle und Syndrome entwickelt, die noch nicht abgeschlossen ist. Sie reflektiert die erheblichen Fortschritte, die im Verständnis der Ätiologie und Pathophysiologie gewonnen wurden, aber auch den lange noch nicht abgeschlossenen Erkenntniszugewinn. Weitere Modifikationen sind daher zwingend zu erwarten. Die diagnostischen Möglichkeiten haben sich weiter verbessert. Hauptproblem ist, dass sie nicht angemessen angewendet werden. Die Grundsätze der Epilepsietherapie haben sich in letzter Zeit nicht verändert. Es hat sich gezeigt, dass Lamotrigin und Levetiracetam zu den Standardantikonvulsiva werden. Neueste Antikonvulsiva haben zum Teil überzeugt. Leider wird ihre nachhaltige Anwendung in Deutschland im Gegensatz zum Rest der Welt durch die Auswirkungen des Arzneimittelmarktneuordnungsgesetzes praktisch verhindert. Neurostimulationsverfahren bieten interessante Perspektiven, aber nicht mehr.
Tissue-Faktor im akuten Koronarsyndrom
Authors: Steppich B. A. , Ott I.
Published: March 2018

Die Ruptur einer arteriosklerotischen Plaque mit nachfolgender Thrombusbildung und Gewebsischämie stellt das führende pathophysiologische Korrelat des akuten Koronarsyndroms dar. Gewebsthromboplastin oder Tissue-Faktor (TF) als wichtigster physiologischer Initiator der extrinsischen Gerinnungskaskade nimmt eine zentrale Rolle in der Pathogenese des akuten Koronarsyndroms ein. Das Ausmaß des thrombotischen Prozesses wird zum einen durch den Gehalt an lokalem, vaskulären TF des rupturierten Plaques zum anderen durch zirkulierenden TF moduliert. Neben seiner gut charakterisierten Bedeutung bei der Atherothrombose ist TF darüber hinaus über eine Aktivierung von Signaltransduktionskaskaden an entzündlichen Prozessen sowie am vaskulären Remodeling beteiligt. Der vorliegende Artikel zeigt die gegenwärtige Vorstellung über die Beteiligung von TF beim akuten Koronarsyndrom auf und diskutiert mögliche Konsequenzen und therapeutische Ansatzpunkte.
New locations of intravascular tissue factor
Authors: Reinhardt C.
Published: March 2018

Tissue factor (TF) is the major initiator of blood coagulation, and a mediator of inflammation, angiogenesis, and carcinogenesis. According to recent evidence, preformed TF and inducible expression of the protein is observed in several blood components. TF is apparently constitutively expressed on circulating microparticles, and can be exposed within minutes on the cell membrane of activated eosinophils and platelets, and, potentially, on neutrophils. Expression in monocytes and neutrophils largely requires transcriptional activation of the TF gene. Eosinophils appear to harbour the highest concentration of preformed TF among all blood components under resting conditions. TF expression in eosinophil progenitor cells is substantially higher than in precursors of other granulocyte fractions. Eosinophil TF promotes transendothelial migration, which documents that presynthesized TF in blood supports functions apart from coagulation. It is still an open question how the intravascular TF is activated to trigger initiation of coagulation. TF activation in different blood components is likely to be differentially regulated according to the (patho)physiologic context.
Blood coagulation dynamics in haemostasis
Authors: Orfeo T. , Butenas S. , Undas A. , Brummel-Ziedins K. , Mann K. G.
Published: March 2018

Our studies involve computational simulations, a reconstructed plasma/platelet proteome, whole blood in vitro and blood exuding from microvascular wounds. All studies indicate that in normal haemostasis, the binding of tissue factor (TF) with plasma factor (F) VIIa (extrinsic FXase complex) results in the initiation phase of the procoagulant response. This phase is negatively regulated by tissue factor pathway inhibitor (TFPI) in combination with antithrombin (AT) and the protein C (PC) pathway. The synergy between these inhibitors provides a threshold-limited reaction in which a stimulus of sufficient magnitude must be provided for continuation of the reaction. With sufficient stimulus, the FXa produced activates some prothrombin. This initial thrombin activates the procofactors and platelets required for presentation of the intrinsic FXase (FVIIIa- FIXa) and prothrombinase (FVa-FXa) complexes which drive the subsequent propagation phase; continuous downregulation of which is provided by AT and the thrombinthrombomodulin- PC complex. FXa generation during the propagation phase is largely (>90%) provided by the intrinsic FXase complex. TF is required for the initiation phase of the reaction but becomes non-essential once the propagation phase has been achieved. The propagation phase catalysts (FVIIIa-FIXa and FVa-FXa) continue to drive the reaction as blood is resupplied to the wound site by flow. Ultimately, the control of the reaction is governed by the pro- and anticoagulant dynamics and the supply of blood reactants to the site of a perforating injury. Our systems have been utilized to examine the qualities of hypothetical and novel antihaemorrhagic and anticoagulation agents and in epidemiologic studies of venous and arterial thrombosis and haemorrhagic pathology.
Key transcriptional regulators of the vasoprotective effects of shear stress
Authors: Boon R. A. , Horrevoets A. J. G.
Published: March 2018

Atherosclerotic plaque rupture and subsequent thrombosis is the main cause of sudden coronary death. Remarkably, atherosclerosis only develops in certain predisposed areas of the vasculature. Endothelial cells in these predisposed areas experience low or oscillatory shear stress, which activates the proinflammatory and procoagulant transcription factors activator protein 1 (AP-1) and nuclear factor B (NFB), thus inducing a proinflammatory, procoagulant surface. In contrast, healthy endothelial cells that are exposed to prolonged high laminar shear stress, express antiinflammatory and anticoagulant genes. The key shear stress-induced transcription factors that govern the expression of these genes are Krüppel-like factor 2 (KLF2) and nuclear factor erythroid 2-like 2 (Nrf2). Together KLF2 and Nrf2 govern ~70% of the shear stress-elicited gene sets. Nrf2 potently induces anti-inflammatory/antioxidant enzymes, while KLF2 induces anti-inflammatory and anticoagulant proteins, most specifically endothelial Nitric oxide synthase (eNOS) and thrombomodulin (TM). KLF2 also inhibits proinflammatory and antifibrinolytic genes through inhibition of the proinflammatory transcription factors AP-1 and NFB. The widespread beneficial effects of the key transcription factors KLF2 and Nrf2 on endothelial phenotype, holds the promise that their targeted modulation might lead to a new class of cardiovascular drugs.
Mikropartikel in der Frauenheilkunde
Authors: Toth B.
Published: March 2018

Mikropartikel (MP) werden bei Aktivierung oder Apoptose von zirkulierenden Blut- bzw. Endothelzellen sowie unter der Wirkung von Scherkräften freigesetzt. Sie nehmen u.a. Einfluss auf Gerinnung, Entzündungsprozesse und dienen als Transportmedium. Bislang gibt es wenige Untersuchungen zu zirkulierenden MP bei Patientinnen der Gynäkologie und Geburtshilfe. Erste Daten legen nahe, dass es zyklusabhängig Unterschiede in der Freisetzung von MP bei Frauen gibt und dass junge Frauen signifikant mehr Plättchen-MP und endotheliale MP aufweisen als altersentsprechende Männer. Pathologische Schwangerschaftsverläufe wie Abort und Präeklampsie gehen mit erhöhten MP-Konzentrationen einher. Inwieweit MP in die Pathophysiologie des Abortgeschehens bzw. der Präeklampsie eingreifen, ist Gegenstand weiterführender Untersuchungen. Studien an Mammakarzinom-Patientinnen legen nahe, dass die Konzentration zirkulierender MP mit dem Tumorstadium korreliert und MP ein ähnliches Sensitivitäts/Spezifitäts-Profil aufweisen wie etablierte Tumormarker.
Pathophysiologic significance of procoagulant microvesicles in cancer disease and progression
Authors: Castellana D. , Kunzelmann C. , Freyssinet J.-M.
Published: March 2018

Microvesicles (MV) are submicrometric membrane fragments (0.1 to 1 μm), released from the plasma membrane of activated or apoptotic cells. They are characterized by most of the antigenic profile of the cells they originate from, and by the presence of procoagulant phospholipids at their surface. MV are detectable in the peripheral blood of mammals and considered as efficient effectors in the haemostatic or thrombotic responses, able to remotely initiate or amplify beneficial or deleterious processes, depending on the circumstances. Variations in their level and pheno-type make them relevant pathogenic markers of thrombotic disorders and vascular damage. To date, MV are recognized as mediators of communication allowing cells to influence a target present in the local microenvironment as well as to at distant sites. The mechanisms by which MV interact with target cells are still unclear, but a number of studies suggest involvement of MV-cell fusion or ligand-receptor interactions. More importantly, MV have been shown implicated in horizontal transfer of genetic material. This review focuses on the role of MV in the context of cancer, and their possible part in cancer associated thrombosis.
Acute immune thrombocytopenic purpura
Authors: Bolton-Maggs P.
Published: March 2018

Immune thrombocytopenia in children is usually a self-limiting illness, but in adults the disease is likely to be chronic, and may be associated with other pathology which predisposes to bleeding. Despite very low platelet counts serious bleeding is rare in both adults and children. More than 80% of children have mild clinical manifestations. Intracranial haemorrhage is rare at all ages, is unpredictable and can occur at any time when the count is very low. Currently recommended therapies for both adults and children are associated with significant side effects and occasional deaths. Treatment may interfere with quality of life more than the illness itself. Drugs can be withheld in the majority of children with appropriate advice to child and family. Treatment can be individualised, taking into account the person’s needs and lifestyle as well as bleeding. In chronic ITP many need no active therapy. The situation with adults is more complex but those with a platelet count above 30 x 109/l usually need no treatment as bleeding is rare, and those adults with refractory ITP unresponsive to treatment live with very low counts for years without significant bleeding suggesting the need to re-evaluate the balance of risks of treatment versus bleeding. It is notable that adults with ITP may die from infection, probably related to therapy.
Chronic immune thrombocytopenic purpura
Authors: Ruggeri M. , Rodeghiero F.
Published: March 2018

First generation thrombopoietic growth factors (rhTPO and PEG-rHuMGDF), investigated in the early 2000s, proved effective in increasing platelet count in normal volunteers, in thrombocytopenia due to chemotherapy and also in a few cases of immune thrombocytopenic purpura (ITP). These agents did not complete their clinical development since one of them induced antibodies in the recipients that cross reacted with endogenous thrombopoietin (TPO), thus causing thrombocytopenia. This promoted the ingenious design of a new generation of thrombopoietic growth factors having no sequence homology with natural TPO. The two main agents are romiplostim, a peptibody already approved for clinical use in USA and eltrombopag, a non-peptide, orally active small molecule. In open label and placebo-controlled trials both agents proved to predictably increase platelet count in normal volunteers and in patients with ITP. With appropriate dosages (1–10 µg/kg weekly sub cutaneously for romiplostim; 50–75 mg/die per os for eltrombopag ) a platelet increase becomes significant after 7–10 days and peaks between 10–14 days. By dis -continuing treatment, platelet count returns to baseline level in 10–15 days. The response rate with both agents is above 70–80%, also in patients that had undergone several lines of treatment, or that have failed splenectomy. The response is maintained during the treatment, but is almost invariably lost even after several months of successful administration. Due to the lack of a curative potential and to the incomplete knowledge of long-term side effects, the place of these new drugs in the management of ITP is still unsettled and their use is best restricted to refractory patients or in preparation of splenectomy. It seems however that a new paradigm in the treatment of ITP has been established where the focus is not on reducing platelet consumption but on increasing platelet production.
The importance of quality assurance in molecular genetic laboratories
Authors: Mannhalter C.
Published: March 2018

Several challenges arise from the wide application of molecular genetic analyses, among them the need to introduce rules to evaluate molecular genetic test systems as well as test laboratories. This article specifically addresses laboratories performing molecular genetic tests for diagnosis, prevention and therapy of various diseases. The topics that will be discussed will support these laboratories to achieve and sustain a high quality and avoid mistakes and errors. The article covers important preanalytic, analytic and postanalytic aspects in regard to molecular genetic testing as well as quality management issues. In addition laboratory responsibilities, training of personnel, data protection issues, as well as informed consent aspects will be discussed. Beyond that, some molecular genetic methods will be dealt with in regard to potential quality criteria.
Innendurchmesser der Vena femoralis communis als diagnostischer und prognostischer Parameter für die CVI
Authors: Marshall M. , Lewandowski Z. , Dyszynski T. J.
Published: March 2018

Ziel: Überprüfung der Hypothese über den Zusammenhang zwischen dem Innendurchmesser der V. femoralis communis (VFC) sowie der Magna-Krosse (M-K) und der Anwesenheit und Ausprägung der chronischen Veneninsuffizienz (CVI). Methode: erstmalige phlebologische Untersuchung von 199 ambulanten Patientinnen im Alter von 20-75 Jahren mit Berücksichtigung der Duplex-sonographischen Diametervermessung der proximalen Beinvenen bei Valsalva-Preß-versuch. Ergebnis: Im Material von insgesamt 181 rechten Beinen erschienen 54 Extremitäten klinisch unauffällig (CVI 0), 93 mit CVI 1., 34 mit CVI 2. oder 3. Grades. Die statistische Analyse bestätigte, daß größere Durchmesser der VFC signifikant öfter mit einer klinisch manifesten CVI einhergehen. Dagegen wurde die Hypothese über einen Zusammenhang zwischen diesem Parameter und der CVI-Progression nicht bestätigt. In der logistischen Multivarianz-Regressions-analyse, unter Berücksichtigung des Alters, Gewichts, der Körperlänge, der Varikosis, der Wiederauffüllzeit und mehrerer Refluxe, wurde die Bedeutung des Diameters der VFC für die CVI-Manifestation bestätigt, nicht aber die vom M-KDurchmesser (grenzwertige Signifikanz). Das Risiko einer klinisch manifesten CVI bei Frauen ohne ausgedehnte Stamm-Astvarikosis mit einem Durchmesser der VFC >14,0 mm wurde 15fach höher eingeschätzt (95% CI 3,5-65,2) als bei Frauen mit einem Durchmesser ≤14,0 mm. Schlußfolgerung: Der sonographische Innendurchmesser der VFC erscheint als ein wichtiger, von anderen Faktoren unabhängiger Prädiktor der CVI.
Safety of plasma-derived factor concentrates
Authors: Joch Ch. , Heindl B. , Spannagl M.
Published: March 2018

Elaborate measures for donor selection and the production of clotting factor concentrates have led to a high safety standard of these products. A multimodal approach to eliminate unwanted contents has been established by strict screening of possible donors and various inactivation procedures within the production process. The systematic registration of adverse events shows very few allergic and nonallergic reactions to plasma derived clotting factor concentrates. In none of the registered cases transmission of infections could be verified. The worldwide registration of such adverse events is not yet sufficiently established, since adequate structures are lacking in some countries. According to estimates, far less than half of occurring adverse events are registered in Germany. A European solution in the form of an official register is about to be introduced.
Rekombinanter Faktor VIIa bei Patienten mit Plättchenfunktionsstörungen oder Thrombozytopenien
Authors: Scharf R. E. , Zotz R. B.
Published: March 2018

Rekombinanter Faktor VIIa (rFVIIa) wird über die zugelassenen Indikationen hinaus zunehmend zur Behandlung lebensbedrohlicher Blutungsereignissen bei Versagen der jeweiligen Standardtherapien eingesetzt. Kasuistiken und Fallserien dokumentieren die Wirksamkeit und Sicherheit von rFVIIa zur Blutstillung bei Patienten mit Thrombozytopathien und Thrombozytopenien verschiedener Ursache. Eine Zulassung zur Anwendung von rFVIIa liegt bei Patienten mit Thrombasthenie Glanzmann im Falle eines Refraktärzustandes auf die Transfusion von Thrombozytenkonzentraten vor. rFVIIa-Bolusapplikationen mit Dosierungen zwischen 80 und 120 μg/kg Körpergewicht alle 1,5 bis 3 Stunden werden auch bei Bernard-Soulier-Syndrom, Plättchen- Storage-Pool-Defekten und verschiedenen erworbenen Thrombozytopathien erfolgreich eingesetzt. Bei Thrombasthenie Glanzmann sind zur Gewährleistung einer effektiven Hämostase mindestens drei Bolusgaben notwendig. Bei Thrombozytopenie hat sich bei annähernd der Hälfte der Patienten ein einzelner rFVIIa-Bolus zur Beherrschung sonst unstillbarer Blutungen als ausreichend erwiesen. Dabei kann eine Blutstillung unter rFVIIa auch bei Thrombozytenwerten unter 20 000/μl erreicht werden, wenngleich bei höheren Thrombozytenkonzentrationen eine bessere Wirksamkeit erzielbar ist.