bluuebunny/crossref_metadata_2025_split huggingface dataset:
Animal Testing of Retroviral-Mediated Gene Therapy for Factor VIII Deficiency
Authors: Jolly Douglas , Greengard Judith 
Published: March 2018

IntroductionHemophilia A results from the plasma deficiency of factor VIII, a gene carried on the X chromosome. Bleeding results from a lack of coagulation factor VIII, a large and complex protein that circulates in complex with its carrier, von Willebrand factor (vWF).1 Severe hemophilia A (<1% of normal circulating levels) is associated with a high degree of mortality, due to spontaneous and trauma-induced, life-threatening and crippling bleeding episodes.2 Current treatment in the United States consists of infusion of plasma-derived or recombinant factor VIII in response to bleeding episodes.3 Such treatment fails to prevent cumulative joint damage, a major cause of hemophilia-associated morbidity.4 Availability of prophylactic treatment, which would reduce the number and severity of bleeding episodes and, consequently, would limit such joint damage, is limited by cost and the problems associated with repeated venous access. Other problems are associated with frequent replacement treatment, including the dangers of transmission of blood-borne infections derived from plasma used as a source of factor VIII or tissue culture or formulation components. These dangers are reduced, but not eliminated, by current manufacturing techniques. Furthermore, approximately 1 in 5 patients with severe hemophilia treated with recombinant or plasma-derived factor VIII develop inhibitory humoral immune responses. In some cases, new inhibitors have developed, apparently in response to unnatural modifications introduced during manufacture or purification.5
Gene therapy could circumvent most of these difficulties. In theory, a single injection of a vector encoding the factor VIII gene could provide constant plasma levels of factor in the long term. However, long-term expression after gene transfer of a systemically expressed protein in higher mammals has seldom been described. In some cases, a vector that appeared promising in a rodent model has not worked well in larger animals, for example, due to a massive immune response not seen in the rodent.6 An excellent review of early efforts at factor VIII gene therapy appeared in an earlier volume of this series.7 A summary of results from various in vivo experiments is shown in Table 1. This chapter will focus on results pertaining to studies using vectors based on murine retroviruses, including our own work.
Gene Therapy for Hemophilia A and B: Patient Selection and Follow-up, Requirements for a Cure
Authors: Lusher Jeanne 
Published: March 2018

IntroductionThe treatment of hemophilia A and B has improved considerably in recent years. The availability of hepatitis A and B vaccines, safer clotting factor concentrates (particularly recombinant factor VIII and recombinant factor IX concentrates), and synthetic agents, such as desmopressin,1 has resulted in earlier, more aggressive treatment and prophylactic regimens aimed at preventing chronic, debilitating joint disease.2-8There have been no new cases of human immunodeficiency virus (HIV) disease attributable to clotting factor in North America since 1987, and documented instances of hepatitis transmission by clotting factor concentrates have been rare in the 1990s. Concerns remain that certain nonenveloped viruses, such as human parvovirus B19 and hepatitis A virus, can still be transmitted by some plasma-derived clotting factor concentrates,9and questions linger as to whether the agents causing Creutzfeld-Jacob disease (CJD) and new variant CJD might also be transmitted. Overall, however, the products available to treat hemophilia today are safer than ever before.An increasing number of persons with hemophilia are receiving exclusively recombinant (r) products, and manufacturers are now producing new, second-generation r-factor VIII products that are stabilized with sugars, rather than albumin, or are smaller, truncated molecules.10 Scientists are now designing specific changes into the factor VIII genes in an attempt to derive unique and improved forms of r-factor VIII.11 The next logical areas of focus are to bring to fruition the promise of an “unlimited supply” of r-factor VIII and r-factor IX products, to meet the needs of persons with hemophilia, not only in developed countries, but throughout the world, and to be able to cure hemophilia through gene therapy.As gene therapy trials begin in humans with hemophilia, the scientists involved, the United States Food and Drug Administration (FDA), and perhaps most importantly, members of the hemophilia community must decide which categories of affected individuals should be entered in these trials, particularly the earliest, Phase I trials. Who is most likely to benefit if gene therapy proves to be both effective and safe? Who should be the first patients to be enrolled in each new trial? Who is at greatest risk if something unexpected happens? What would be considered a good outcome? Clearly, some of these questions are more difficult to answer than others.
Use Of Fibrinogen and Fibrin D-Dimer in Prediction of Arterial Thrombotic Events
Authors: Rumley Ann , Lowe Gordon D.O. 
Published: March 2018

IntroductionThere is increasing clinical and laboratory interest in the measurement of both plasma fibrinogen and fibrin D-dimer to predict arterial thrombotic events, such as cardiovascular death, myocardial infarction (MI), stroke, leg ischemia, arterial surgery (e.g., angioplasty, bypass grafting), and postsurgical arterial occlusion. There are several possible reasons for such interest.First, there is substantial evidence from prospective studies that the plasma fibrinogen level is a strong, consistent predictor of such cardiovascular events in people with or without clinically detectable arterial disease. Furthermore, fibrinogen adds to the predictive valve of major conventional risk predictors (e.g., smoking, blood pressure, serum cholesterol) in healthy people (Fig.1).1-7
Second, we and others have shown, in several prospective studies, that plasma fibrin D-dimer (measured quantitatively by enzyme-linked immunosorbent assays [ELISAs]) is also a strong, consistent predictor of such cardiovascular events in people with or without clinically detectable arterial disease.8-14 Again, fibrin D-dimer may add to the predictive value of major conventional risk predictors (e.g., smoking, blood pressure, serum cholesterol, plasma fibrinogen) in healthy people (Fig. 2).Third, there are several interactive, plausible, potential biological mechanisms through which increasing plasma fibrinogen levels, which are due to multiple gene-environment interactions, may promote ischemic events. These include increased blood viscosity, atherogenesis, and platelet-fibrin thrombogenesis (Fig. 3). Increased plasma D-dimer levels are a marker of turnover of cross-linked fibrin, whether vascular or extravascular (Fig. 3).Fourth, not only is there more evidence for fibrinogen and D-dimer as predictors of arterial thrombotic events than for other hemostatic or thrombotic variables, but these two assays are more stable and more practical to measure in clinical and epidemiological studies. These tests are also already available in many district hospitals for the diagnosis of disseminated intravascular coagulation (DIC) and, in the case of D-dimer, venous thromboembolism.15,16 As with other major cardiovascular risk factors (e.g., smoking, blood pressure, serum cholesterol), there is a need for standardization of both fibrinogen assays17-23 and D-dimer assays.24
Finally, clinical interest in plasma assays of fibrinogen also may increase in the event that ongoing clinical trials of plasma fibrinogen reduction (e.g., with certain fibrates or ancrod) show that such treatments are beneficial.25 Likewise, clinical interest in plasma assays of D-dimer may also increase if future studies show that oral anticoagulant prophylaxis is the most costeffective and risk-effective in people with elevated plasma D-dimer levels, who are normalized by full-dose warfarin.15,19,26-28 This review discusses each of these aspects of fibrinogen and fibrin D-dimer.
Antithrombotic Treatments in Acute Ischemic Stroke
Authors: del Zoppo Gregory 
Published: March 2018

IntroductionStroke may be defined as a syndrome of thrombohemorrhagic disorders affecting the central nervous system. In this setting, considerable efforts have been directed to improve clinical outcome with antithrombotic agents, including platelet inhibitors, anticoagulants, and plasminogen activators. The search for a role for antithrombotic agents in ischemic stroke rests on the observation that, overall, 75% to 80% of strokes involve thrombotic events. Recent experience with plasminogen activators (PAs) in acute ischemic stroke indicates that, in select patients, clinical improvement is associated with shorter interval from symptom onset to treatment, while clinically significant hemorrhagic transformation increases with delays in treatment. The time-dependence and the subpopulation characteristics of outcomes following PA exposure is entirely compatible with an evolution of brain injury and varies individually, but where microvascular integrity in the ischemic bed decreases with time. These relationships have not been developed or explored with other antithrombotic agents, including antiplatelet agents or anticoagulants. Thus, among antithrombotic agents, only certain PAs have been used in a strictly “acute” setting, that is within 6 to 8 hours of symptom onset. This presentation summarizes current experience with antithrombotic interventions in focal cerebral ischemia in the acute and early (>8) hours following symptom onset.
Plasma Levels of Free and Total TFPI, Relationship with Cardiovascular Risk Factors and Endothelial Cell Markers
Authors: Morange P. E. , Renucci J. F. , Charles M. A. , Aillaud M. F. , Giraud F. , Grimaux M. , Juhan-Vague I. 
Published: March 2018

SummaryFree-TFPI (f-TFPI) presents high anticoagulant activity and its plasma level correlates with unfavorable outcomes in unstable angina. Total TFPI (t-TFPI) represents mainly the lipid-bound form which seems to have a poor anticoagulant activity. Until now, it is not known whether the variations of f-TFPI plasma levels are determined by environmental factors. The aim of our study was to evaluate the influence of cardiovascular risk factors on plasma levels of f-TFPI and relations with other endothelial derived molecules in a population of 626 patients (277 men and 349 women) attending a metabolic ward for primary prevention of coronary disease.Free and total TFPI plasma levels were poorly correlated. f-TFPI levels increased with age in both sexes, t-TFPI in women only. Ageadjusted correlations of TFPI levels with conventional cardiovascular risk factors and endothelial cell markers showed different patterns for f-TFPI and t-TFPI. f-TFPI correlated with parameters associated with insulin resistance, particularly in females. f-TFPI was also positively associated in both genders with fibrinogen and endothelial cell markers: t-PA, thrombomodulin (TM) and von Willebrand factor (vWF). t-TFPI correlated strongly with LDL-C in both sexes. It also correlated negatively with parameters of the insulin resistance syndrome. t-TFPI also correlated with TM but not with other endothelial cell markers. The results of the multivariate step by step analysis showed that cardiovascular risk factors poorly explained the f-TFPI variability (7% and 4% in men and women, respectively), whereas they explained 16 and 20% of t-TFPI variability in men and women respectively (mostly related to LDL-C).In conclusion, this study showed that free- and total-TFPI are regulated differently. f-TFPI strongly correlates with endothelial cell markers and t-TFPI is more related to conventional cardiovascular risk factors. The strong gender effect on f-TFPI levels remains to be explained.
Polymorphisms in the Prothrombin Gene and their Association with Plasma Prothrombin Levels
Authors: Bertina R. M. , van Hylckama Vlieg A. , Rosendaal F. R. , Vos H. L. , Ceelie H. 
Published: March 2018

SummaryTo find genetic causes of high plasma prothrombin levels, an established prothrombotic risk factor, we searched for sequence variations in the prothrombin gene. We selected subjects with the 20210-GG genotype (since the 20210-A allele is already known to be associated with high levels) and elevated prothrombin levels (≥ 130 U/dl) from the Leiden Thrombophilia Study (LETS). No mutations were found in the 1 kb promoter region of the prothrombin gene in seven individuals with an isolated high prothrombin level. Comparison of the allelic frequencies of four different polymorphisms in the prothrombin gene in healthy volunteers and in the control subjects among the selected LETS individuals indicated a higher frequency of the 19911-G allele in the latter group (allele frequency 52 vs. 78%, respectively). Homozygous carriers of the 19911-G allele had 8 U/dl higher plasma prothrombin levels than 19911-AA carriers. This difference in prothrombin levels did not affect the thrombotic risk in 20210-GG carriers. In heterozygous 20210-A carriers the odds ratio increased from 1.6 (95% CI: 0.6-4.3) in subjects with 19911-A to 4.7 (1.6-14.0) in subjects with 19911-G on the other prothrombin allele.
Analytical Considerations for Free Protein S Assays in Protein S Deficiency
Authors: Hillarp Andreas , Dahlbäck Björn , Persson Kristina 
Published: March 2018

SummaryProtein S is an anticoagulant protein that circulates in plasma in complex with C4b-binding protein (C4BP) or in free form. Deficiency of protein S increases the risk of venous thrombosis. Measurement of free protein S, as compared to total levels, has been shown to be superior for prediction of protein S deficiency. We studied the effects of different handling protocols for an immuno- and a ligand (C4BP)-based assay for free protein S. When the assay was performed at 37° C, the levels of free protein S in plasma from protein S deficient patients were approximately twice those obtained at room temperature. The reason for this phenomenon was that plasmas from protein S deficient patients exhibited a time-, temperature-, and dilution-dependent increase in free protein S, which was more pronounced than corresponding dilution of the normal plasma that was used to create the standard curve. These findings demonstrate the importance of assay procedure and sample handling in assays for free protein S.
Prediction of Pulmonary Embolism Extent by Clinical Findings, D-dimer Level and Deep Vein Thrombosis Shown by Ultrasound
Authors: Galle Cécile , Papazyan Jean-Pierre , Miron Marie-José , Slosman Daniel , Bounameaux Henri , Perrier Arnaud 
Published: March 2018

SummaryPulmonary embolism (PE) may encompass a wide spectrum of severity. To determine whether clinical findings, D-dimer (DD) concentration, and deep vein thrombosis (DVT) shown by lower-limb venous compression ultrasonography (US) might predict the scintigraphic extent of PE, we studied 104 hemodynamically stable consecutive outpatients with acute PE diagnosed by a high-probability ventilation-perfusion lung scan. Scintigraphic extent of PE was classified into three categories: perfusion defects corresponding to <30%, 30–50%, or >50% of the total lung area. Median respiratory and heart rates were found to be significantly related to the extent of PE. Higher median alveolar-arterial oxygen difference values were observed as the proportion of lung perfusion defects increased (>50% vs. <30%, 6.3 vs. 3.6 kPa, P <.0001). Median plasma DD concentration was 7950 g/L in patients with >50% perfusion defects compared to 2731 g/L in those with <30% defects (P = .0001). DD levels above 4000 g/L were associated to more extensive perfusion defects (>50% vs. <30% defects, OR 30; 95% CI 5.8–155). Finally, a proximal DVT was more likely among patients with larger perfusion defects (>50% vs. <30% defects, OR 4.5; 95% CI 1.5–13.6). In conclusion, clinical signs such as tachypnea and tachycardia, alveolar-arterial oxygen difference, plasma DD concentration, and presence of DVT on US are predictors of a larger PE, as assessed by the extent of perfusion defects on high probability lung scans.
Anti-β2 Glycoprotein I Antibodies Cause Inflammation and Recruit Dendritic Cells in Platelet Clearance
Authors: Bondanza Attilio , Manfredi Angelo , Zimmermann Valérie , Iannacone Matteo , Tincani Angela , Balestrieri Genesio , Sabbadini Maria Grazia , Querini Patrizia Rovere 
Published: March 2018

SummaryScavenger phagocytes are mostly responsible for the in vivo clearance of activated or senescent platelets. In contrast to other particulate substrates, the phagocytosis of platelets does not incite pro-inflammatory responses in vivo. This study assessed the contribution of macrophages and dendritic cells (DCs) to the clearance of activated platelets. Furthermore, we verified whether antibodies against the β2 Glycoprotein I (β2GPI), which bind to activated platelets, influence the phenomenon. DCs did not per se internalise activated platelets. In contrast, macrophages efficiently phagocytosed platelets. In agreement with the uneventful nature of the clearance of platelets in vivo, phagocytosing macrophages did not release IL-1β, TNF-α or IL-10. β2GPI bound to activated platelets and was required for their recognition by anti-ββ2GPI antibodies. DCs internalised platelets opsonised by anti-ββ2GPI antibodies. The phagocytosis of opsonised platelets determined the release of TNF-α and IL-1β by DCs and macrophages. Phagocytosing macrophages, but not DCs, secreted the antiinflammatory cytokine IL-1β0. We conclude that anti-ββ2GPI antibodies cause inflammation during platelet clearance and shuttle platelet antigens to antigen presenting DCs.
Magnesium Inhibits Arterial Thrombi after Vascular Injury in Rat: In Vivo Impairment of Coagulation
Authors: Sironi Luigi , Tedeschi Luca , Calvio Anna Maria , Colli Susanna , Tremoli Elena , Mussoni Luciana 
Published: March 2018

SummaryMagnesium deficiency is associated with a high frequency of cardiac arrhythmia, hypertension and sudden ischemic death. We investigated the in vivo effects of intravenous magnesium administration in a rat model of chemically induced (FeCl3) carotid thrombosis. The infusion of magnesium sulfate (MgSO4) before the topical application of FeCl3 prevented thrombus formation at concentrations of 0.3 M and 0.6 M, and delayed it even at 0.15 M. Similar results were obtained with MgCl2. The infusion of MgSO4 0.6 M seven minutes after FeCl3 application delayed but did not prevent thrombus formation. MgSO4 slightly reduced platelet aggregation ex vivo without affecting plasma clotting tests, but in vivo blood clotting time was markedly prolonged (tail transection method), thus indicating profoundly impaired coagulation. These data provide a rationale for the use of magnesium as an anti-thrombotic agent, but its pharmacological effect critically depends on the timing of administration.
Different Effects of Oral and Transdermal Hormone Replacement Therapies on Factor IX, APC Resistance, t-PA, PAI and C-reactive Protein
Authors: Upton Mark , Rumley Ann , McConnachie Alex , O’Reilly Denis , Watt Graham , Lowe Gordon 
Published: March 2018

SummaryThe effects of hormone replacement therapy (HRT) on thrombosis risk, thrombotic variables, and the inflammatory marker C-reactive protein (CRP) may vary by route of administration (oral versus transdermal). We studied the relationships of 14 thrombotic variables (previously related to cardiovascular risk) and CRP to menopausal status and to use of HRT subtypes in a cross-sectional study of 975 women aged 40-59 years. Our study confirmed previously-reported associations between thrombotic variables and menopausal status. Oral HRT use was associated with increased plasma levels of Factor IX, activated protein C (APC) resistance, and CRP; and with decreased levels of tissue plasminogen activator (t-PA) antigen and plasminogen activator inhibitor (PAI) activity. Factor VII levels were higher in women taking unopposed oral oestrogen HRT. The foregoing associations were not observed in users of transdermal HRT; hence they may be consequences of the “first-pass” effect of oral oestrogens on hepatic protein synthesis. We conclude that different effects of oral and transdermal HRT on thrombotic and inflammatory variables may be relevant to their relative thrombotic risk; and suggest that this hypothesis should be tested in prospective, randomised studies.
Impairment of the Plasmin Activation System in Primary Pulmonary Hypertension: Evidence for Gender Differences
Authors: Graf Senta , Huber-Beckmann Renate , Zorn Gerlinde , Lang Irene , Kneussl Meinhard , Binder Bernd , Huber Kurt , Christ Günter 
Published: March 2018

SummaryPrimary pulmonary hypertension (PPH) is a rare disorder, with marked in-situ thrombosis of small pulmonary vessels occurring primarily in adult women. We investigated whether differences in the plasmin- and thrombin activation system are associated with the predominate affection of females. Plasma levels of plasminogen activator inhibitor type 1 (PAI-1), tissue-type plasminogen activator (t-PA), fibrinogen, thrombin-antithrombin (TAT) complexes, and prothrombin fragments (F1.2) were measured at baseline and after standardized venous occlusion (VO) in patients with PPH (24 female, 9 male). At baseline, females showed significant higher TAT levels (p = 0.05), higher t-PA antigen levels (p = 0.01) and higher fibrinogen levels (p = 0.03) with positive correlation to mean pulmonary artery pressure (mPAP), as well as nonsignificant lower t-PA activity, higher PAI-1 antigen and activity and F1.2 levels. After VO, females showed a significantly blunted increase in t-PA antigen (p = 0.01) and t-PA activity (p = 0.001), correlating with mPAP, as well as increased PAI-1 activity (p = 0.05). We hypothesize, that the observed presence of gender differences in the plasmin- and thrombin activation system in PPH leading to an antifibrinolytic/prothrombotic state might, in part, explain the female predominant incidence of this disease.
Quantification of Lupus Anticoagulants in Clinical Samples Using Anti- β2GP1 and Anti-Prothrombin Monoclonal Antibodies
Authors: Querrec A. Le , Arnout J. , Arnoux D. , Borg J. Y. , Caron C. , Darnige L. , Delahousse B. , Reber G. , Sié P. 
Published: March 2018

SummaryQuantification of lupus anticoagulant (LA) in clinical samples is hampered by the lack of a suitable standard of activity. We evaluated the use of mAbs displaying LA activity for this purpose. As most patient samples contain both β2Glycoprotein I (β2GP1) and prothrombin dependent LA, a combination of two mAbs, one of each specificity, was added to normal plasma in a concentration from 0 to 60 g/ml. Eight assay systems using different reagents and instruments were used. The calibration curves were linear for all but one, with marked differences between the responsiveness to each mAb. A panel of plasmas from 69 patients with persistent LA diagnosed using the SSCISTH criteria was tested. An antiphospholipid syndrome (APS) was present in 40, whereas 29 were asymptomatic. LA activities of individual plasmas varied between assays (p <10–4), but homogeneous subgroups were identified. In a majority of samples, LA activity displayed a prothrombin-dependent profile, with a variable contribution of β2GP1-dependent activity. The latter was associated to β2GP1 antibodies detected by solid-phase immunoassay. By using 3 dilute Russell viper venom time assays, higher LA titers were found in APS, compared to asymptomatic patients (p <0.05).