bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anti-β2-glycoprotein I Antibody-mediated Inhibition of Activated Protein C Requires Binding of β2-glycoprotein I to Phospholipids
Authors: Izumi Tomonori , Pound Mary , Su Zuowei , Iverson G. , Ortel Thomas 
Published: March 2018

SummaryTo clarify the role(s) of anti-β2GPI antibodies on thrombosis in antiphospholipid antibody syndromes (APS), the effect of IgG from three patients on activated protein C (APC) was investigated using phospholipid vesicles and purified proteins. Two of the total IgG inhibited APC activity in the presence of β2GPI, whereas the third IgG did not. In addition, one IgG inhibited APC activity without β2GPI. Anti-β2GPI IgG from the two inhibitory IgG preparations inhibited APC activity only in the presence of β2GPI. Inhibition was suppressed partially by excess APC and almost completely by excess phospholipid vesicles. Cleaved β2GPI, a non-phospholipid-binding form, did not support inhibitory activity, even though the anti-β2GPI IgG bound to the cleaved molecule. This study confirms that anti-β2GPI antibodies from APS patients inhibit APC activity, and demonstrates the requirement of phospholipid binding of β2GPI for expression of the inhibitory activity of these antibodies.
Does Thrombin Activatable Fibrinolysis Inhibitor (TAFI) Contribute to Impairment of Fibrinolysis in Patients with Preeclampsia and/or Intrauterine Fetal Growth Retardation?
Authors: Hamad R. , Antovic A. , Blombäck M. , Bremme K. , Antovic J.P. 
Published: March 2018

SummaryThrombin Activatable Fibrinolysis Inhibitor (TAFI) is a relatively recently described glycoprotein (MM 55 KDa) that can be converted into its active form by the thrombin/thrombomodulin complex and potentially inhibits fibrinolysis. Since it represents a link between coagulation and fibrinolysis, TAFI can be expected to play a part in various clinical conditions associated with a thrombotic tendency. Preeclampsia (PE) and intrauterine fetal growth retardation (IUFGR) are fairly common complications of pregnancy that are characterized by hemostatic abnormalities. TAFI antigen and its influence on hemostasis was investigated in 46 women with PE and/or IUFGR and in 16 normal pregnancies. We found a significant decrease of TAFI antigen in the patient group. Using the recently described method Overall Hemostatic Potential (OHP) in plasma, we measured clot lysis time (CLT) and overall fibrinolytic potential (OFP). We found that CLT is prolonged and OFP decreased in patients with PE and/or IUFGR. Since OFP did not increase after addition of the specific inhibitor of TAFI (potato tuber carboxypeptidase inhibitor), it seems that TAFI does not contribute to the impairment of fibrinolysis in these patients. Since serum albumin was decreased together with presence of proteinuria and aminotransferases were increased in the patients, it seems that one explanation for the decrease in TAFI could be reduced hepatic synthesis and an increased loss in urine. It can be speculated that this mechanism can prevent more serious thrombotic complications in patients with PE and/or IUFGR.
Patients with Coronary Artery Disease who Present with Chest Pain Have Significantly Elevated Platelet Contractile Force and Clot Elastic Modulus
Authors: Krishnaswami Ashok , Jesse Robert L. , Kontos Michael C. , Minisi Anthony J. , Ornato Joseph P. , Vetrovec George W. , Martin Erika J. , Carr Marcus E. 
Published: March 2018

SummaryRapid laboratory markers that correlate with patient risk would facilitate the decision making regarding admission of patients with chest pain (CP). Platelet contractile force (PCF) and clot elastic modulus (CEM) are elevated in patients undergoing coronary bypass grafting. This study assessed PCF, CEM, and platelet aggregation in patients presenting to the emergency department with chest pain (CP). Results were compared with fifty normal controls. Both the total group of CP patients (n = 100) and the subset of patients (n = 36) with documented coronary arterys disease (CAD) had significantly elevated PCF and CEM, and significantly decreased platelet aggregation relative to normal (p <0.001 for the total group, p <0.008 for patients with CAD). Patients with electrocardiographic evidence of ischemia had the highest PCF and CEM values of any patient group. Increased PCF and CEM were not due to higher platelet counts, and PCF did not differ by race.
Hemophilia A Mutations within the Factor VIII A2-A3 Subunit Interface Destabilize Factor VIIIa and Cause One-stage/ Two-stage Activity Discrepancy
Authors: Hakeos William , Miao Hongzhi , Sirachainan Nongnuch , Kemball-Cook Geoffrey , Saenko Evgueni , Kaufman Randal , Pipe Steven 
Published: March 2018

SummaryThrombin-activated factor VIII (FVIIIa) is a heterotrimer with the A2 subunit in a weak ionic interaction with the A1 and A3-C1-C2 subunits. Dissociation of the A2 subunit correlates with inactivation of FVIIIa. A homology model (Blood 89:2413, 1997) of the triplicated A domains of factor VIII (FVIII) predicts a pseudo-threefold axis at the tightly packed hydrophobic core with several interdomain interactions. These lie at the interface of A1-A2, A2-A3 and A1-A3. We have previously demonstrated that hemophilia A mutations (R531H, A284E, S289L) within the predicted A1-A2 and A1-A3 interface disrupt potential intersubunit hydrogen bonds and have the molecular phenotype of increased rate of inactivation of FVIIIa due to increased rate of A2 subunit dissociation. Patients with these mutations exhibit a clinical phenotype where the FVIII activity by one-stage(1-st) assay is at least two-fold higher than by two-stage(2-st) assay. We have now also explored mutations within the predicted A2-A3 interface (N694I, R698W and R698L) that also have the phenotype of 1-st/2-st activity discrepancy. These mutations exhibit the same molecular mechanism of increased instability of FVIIIa as those mutations described along the A1-A2 and A1-A3 interfaces. This suggests that the entire tightly packed hydrophobic core within the predicted pseudo-threefold axis contributes to stabilization of FVIIIa.
Association Between Increased Homocysteine Levels and Impaired Fibrinolytic Potential: Potential Mechanism for Cardiovascular Risk
Authors: D’Agostino Ralph , Jacques Paul , Bostom Andrew , Wilson Peter , Lipinska Izabela , Mittleman Murray , Selhub Jacob , Tofler Geoffrey 
Published: March 2018

SummaryElevated homocysteine levels increase cardiovascular risk although the mechanism is not well understood. Since thrombosis plays an important role in plaque development and acute coronary syndromes, hyperhomocysteinemia may increase risk by increasing the thrombotic potential.Hemostatic risk factors were measured in 3216 individuals (1451 men and 1765 women) free of cardiovascular disease who participated in cycle 5 of the Framingham Offspring Study. An increase in homocysteine level was associated with a rise in plasminogen activator inhibitor (PAI-1), tissue plasminogen activator (TPA) antigen, von Willebrand factor and fibrinogen level. After regression analyses adjusting for covariates, there remained significant associations between homocysteine and PAI-1 and TPA antigen.Increasing homocysteine levels are associated with impaired fibrinolytic potential, as indicated by increased PAI-1 and TPA antigen levels. These data suggest that folic acid and other homocysteine lowering therapies may decrease cardiac events through a reduction in thrombotic tendency.
Should Patients with Deep Vein Thrombosis Alone be Treated as Those with Concomitant Asymptomatic Pulmonary Embolism? A Prospective Study
Authors: Büller Harry , Lensing Anthonie , Bonet Montserrat , Roncales Javier , Muchart Jordi , Fraile Manuel , Monreal Manuel 
Published: March 2018

SummaryThe established initial treatment of patients with deep vein thrombosis (DVT) or pulmonary embolism (PE) consists of the administration of subcutaneous, weight adjusted, low-molecular weight heparin (LMWH). However, the use of the same LMWH dosages for patients with either DVT or PE is not supported by data from comparative studies.1,000 consecutive patients with acute, proximal DVT were prospectively evaluated. All patients underwent a ventilation-perfusion lung scan on admission, and remained in hospital for at least 7 days. Patients with silent PE received once daily 10,000 to 15,000 IU subcutaneous LMWH dalteparin according to body weight for 7 days, and then vitamin K antagonists. Patients with DVT alone received LMWH in a fixed dose of 10,000 IU once daily for at least 5 days, and then vitamin K antagonists. The rate of both, major bleeding and symptomatic PE episodes during the 7-day study period was evaluated.Thirteen patients (1.3%) developed recurrent PE (1 died) and 16 patients (1.6%) had major bleeding (7 died). Recurrent PE was significantly more common in patients with silent PE (9 of 258 patients, 3.5%) than in those with DVT alone (4 of 742 patients, 0.5%. Odds ratio: 6.5; p <0.001). There were no significant differences in bleeding rate between patients with silent PE and those with DVT alone. However, the use of a fixed 10,000 IU dose in patients with DVT alone led to a significantly lower bleeding rate in patients weighing over 70 kg: 1 of 349 patients (0.3%) as compared to 9 of 393 patients (2.3%) in those weighing less than 70 kg (odds ratio: 0.12; p = 0.018).Fixed-dose 10,000 IU of LMWH dalteparin once daily proved to be both effective and safe in patients with DVT alone. The observed recurrence rate of 0.5% in these patients compares favourably with the 3.5% rate in patients with silent PE. Furthermore, this fixed-dosage was also safe. Patients weighing over 70 kg had a significant decrease in the rate of major bleeding, and no compensatory increase in the rate of recurrent PE.
Combined Activation of Coagulation and Inflammation has an Important Role in Multiple Organ Dysfunction and Poor Outcome after Severe Trauma
Authors: Kameue Takashi , Matsuda Naoyuki , Hayakawa Mineji , Ishitani Toshiteru , Morimoto Yuji , Kemmotsu Osamu , Gando Satoshi 
Published: March 2018

SummaryWe tested the hypothesis that activated neutrophil-endothelial cell interaction in DIC can cause endothelial injury contributing to multiple organ dysfunction syndrome (MODS) and a poor outcome after trauma. Fifty-eight severe trauma patients, 29 with DIC and 29 without DIC were studied. Serial levels of soluble L-, P-, and E-selectins, ICAM-1, VCAM-1, thrombomodulin, and neutrophil elastase were measured on days 0-4 after trauma. The numbers of systemic inflammatory response syndrome (SIRS) criteria that patients met were determined, simultaneously. In the DIC patients, higher DIC scores, lower platelet counts, and a longer duration of SIRS were found compared with the non-DIC patients. The incidence of ARDS and MODS were higher in patients with DIC than in those patients without DIC, and the DIC patients had poor outcome. Soluble L-selectin (sL-selectin) level on Day 1 in the DIC patients who died was markedly lower than those in the non-DIC patients. The levels of sPand sE-selectins, sICAM-1, and sVCAM-1 were more elevated in the patients with DIC than in those without DIC on days 2 to 4. Neutrophil elastase and sThrombomodulin levels in the DIC patients persistently increased during the study period compared to those in the non-DIC patients. Maximum DIC scores in the DIC group showed good correlations with peak levels of sICAM-1, sVCAM-1, neutrophil elastase, sThrombomodulin, and the number of dysfunctioning organs. Highly activated and sustained inflammation caused by neutrophil-endothelium interaction in DIC gives rise to MODS and poor outcome in patients with severe trauma. These results suggest a close relationship between inflammation and thrombosis in posttrauma DIC.
Arterial Intima-Media Thickness and its Relationship with Cardiovascular Disease and Atherosclerosis: A Possible Contribution of Medium-Sized Arteries
Authors: Šrámek A. , Reiber J. H. C. , Rosendaal F. R. , Bucciarelli P. 
Published: March 2018

SummaryThe intima-media thickness (IMT) of the arterial wall, measured by B-mode ultrasonography, has been related to cardiovascular disease and atherosclerosis in many studies, most of which have considered carotid and common femoral arteries. No study has related the IMT of medium-sized arteries (e.g. brachial) to the atherosclerotic process. The aim of this study was to evaluate whether more peripheral arteries (e.g. brachial, superficial femoral and popliteal) represent a good model in studies of arterial wall IMT, as well as carotid artery. Twenty-six male patients with demonstrated coronary artery disease (median age 63 yrs; range 41–70) and twenty-four male controls (median age 62 yrs; range 53–74) were studied. The far-wall IMT of the common carotid, brachial, superficial femoral and popliteal arteries was measured by high-resolution B-mode ultrasonography. Its relationship with ischemic cardiovascular disease and the presence of atherosclerotic plaques in all the arteries was also evaluated. Mean IMT values were higher in patients than controls, more so in superficial femoral artery (IMT difference 0.08 mm [95% confidence interval 0.02 – 0.14]) and popliteal artery (0.08 [0.01–0.15]) than in common carotid artery (0.02 [−0.070.11]) or brachial artery (0.01[−0.01–0.03]). The difference did not change after adjustment for age. The prevalence of plaques was consistently higher in patients than controls, except for brachial artery, in which no plaque was found either in patients and controls. In all the arteries except brachial we found an association between increase in IMT and number of plaques. Age was strongly related to the presence of plaques in the carotid artery, and less markedly in superficial femoral and popliteal arteries.The brachial artery does not seem a good model to study atherosclerosis by ultrasound measurements of arterial IMT, whereas superficial femoral and popliteal arteries might be chosen for these studies besides carotid artery.
Rescue of Prothrombin-deficiency by Transgene Expression in Mice
Authors: Sun William , Coleman Mallory , Witte David , Degen Sandra 
Published: March 2018

SummaryProthrombin has diverse biological functions in addition to its well established role in blood coagulation. In order to study these functions in more detail mouse model systems are needed. Since deficiency of prothrombin in mice results in partial embryonic lethality and neonatal death, alternative approaches are required to study the biology of prothrombin in the adult mouse. The liver is the major site of synthesis of prothrombin and therefore liver-specific promoters were used to express prothrombin in transgenic mice. Mice generated from crosses with these transgenic mice and mice hemizygous for the knock-out allele were used to test whether liver-specific expression is sufficient to correct the phenotype of null mice and whether liver-specific expression is sufficient for the development and survival of mice to adulthood. The mouse albumin promoter/enhancer was used initially for transgene expression without success in obtaining transgene positive, endogenous prothrombin null mice. Two lines of transgene positive, endogenous prothrombin deficient mice were obtained using the mouse transthyretin (TTR) promoter/enhancer driving expression of a human prothrombin cDNA. One line was able to rescue both the embryonic and the neonatal lethality while the other line was only able to correct the embryonic lethality. Expression of prothrombin was restricted to the liver and stomach in one line and to the liver, pancreas, stomach and kidney in the other line of mice. Thrombin activity for one line was determined to be at 5-10% of wildtype levels. These mice developed normally and did not have spontaneous bleeding events unless traumatized. Therefore, transgenic expression of human prothrombin is sufficient for the rescue of the lethality found for prothrombin deficiency in mice.
A Fully Recombinant Partial Prothrombin Complex Effectively Bypasses fVIII
In Vitro
and
In Vivo
Authors: Himmelspach Michèle , Richter Günter , Muhr Evelyn , Varadi Katalin , Turecek Peter , Dorner Friedrich , Schlokat Uwe , Schwarz Hans 
Published: March 2018

SummaryThe development of inhibitory antibodies is a serious complication in hemophilic patients, severely compromising therapeutic success. Bleeding episodes in affected patients are controlled by treatment with a plasma-derived prothrombin complex concentrate (PCC), activated PCC (APCC) or recombinant activated factor VII. We hypothesized that a recombinant two-component agent consisting of recombinant prothrombin (rfII) and activated factor X (rfXa) would have substantial fVIII bypassing activity and could be a safe alternative therapeutic option. To test this hypothesis we assembled an agent in vitro solely consisting of rfII and rfXa at a molar ratio of 37,500:1. These factors are believed to be responsible for the activity of APCC preparations. Recombinant fX, used as the source for fXa generation, and rfII were purified from serum-free and protein-free conditioned media of stably transfected CHO and BHK tissue culture cells, respectively. Activation of rfX to rfXa was accomplished by the plant protease ficin, obviating the need for a protease derived from a human or animal source. We found that in vitro the complex reduced the abnormally prolonged activated partial thromboplastin time (APTT) of a high-titer fVIII inhibitor plasma similar to an APCC preparation. Furthermore, addition of increasing amounts of rfII/rfXa to inhibitor plasma resulted in a linear dose-dependent increase in the rate of thrombin generation. In a rabbit fVIII inhibitor model, treatment with rfII/rfXa statistically significantly reduced the intensity of the abnormal cuticle bleeding. In the Wessler test, rfII/rfXa showed no thrombogenicity. These data show that a well-defined, particularly safe and efficacious agent with fVIII bypassing activity can be generated from recombinant fII and fXa.
Combined Effects of Eptifibatide and Anticoagulants: Differences between LMWH and UH or rH in Thrombin Generation Inhibition but not in Platelet Aggregation Inhibition
Authors: Gallistl Siegfried , Cvirn Gerhard , Roschitz Birgit , Petritsch Martina , Leschnik Bettina , Muntean Wolfgang , Koestenberger Martin 
Published: March 2018

SummaryAim of our study was to investigate effects of eptifibatide and anticoagulants on platelet aggregation and thrombin generation under low and high coagulant challenge in tissue factor-activated platelet rich plasma using a model allowing simultaneous determination of the time course of platelet aggregation and thrombin generation. Eptifibatide exerted a dose-dependent anti-aggregating effect under both high and significantly stronger under low coagulant challenge. Combination of eptifibatide and anticoagulants resulted in significant additive prolongation of the lag phase until the onset of platelet aggregation, more pronounced under low coagulant challenge. Under high, but not under low coagulant challenge combination of eptifibatide and anticoagulants had a significant synergistic inhibitory effect on platelet aggregation. Under low coagulant challenge combination of eptifibatide with LMWH, but not with UH, or rH, resulted in significantly reduced thrombin potential, F 1+2 generation, and FXa formation compared to measurements in the absence of eptifibatide.We demonstrate a synergistic effect of eptifibatide and anticoagulants on platelet aggregation inhibition and an additional inhibitory effect of LMWH and eptifibatide on thrombin generation. Our results support the notion that combination of eptifibatide and anticoagulants might be beneficial in atherosclerotic disease to palliate the thrombogenic potency of ruptured atherosclerotic plaques.
Molecular mechanisms of leukocyte recruitment: organ-specific mechanisms of action
Authors: Kubes Paul , Liu Lixin 
Published: March 2018

SummaryLeukocyte recruitment in the microcirculation is a critical process underlying inflammatory responses in tissues. The mechanism of recruitment is summarized by the generally accepted paradigm: selectin-mediated leukocyte rolling, subsequent integrin activation, followed by integrin-mediated firm adhesion. This simple paradigm may not be able to explain the leukocyte recruitment mechanisms in some organs including the liver and brain. Recent studies suggested that these organs have their own leukocyte recruitment paradigms in acute and even chronic inflammation. The combination of unique hemo-dynamic patterns and specific structural and functional features of the vessels and endothelium in liver may dictate and select the specific patterns of leukocyte recruitment in this organ. In the brain microvasculature, where shears are high and adhesion molecule expression low, platelets may play an important role as a bridge between the leukocytes and endothelium.
A randomized trial of initial warfarin dosing based on simple clinical criteria
Authors: Patel Jeetendra , Kumar Juhi , Malik Aamir , Jaeger Joseph , Maida Mahamadu , Ord Linda , Burrows Grover , Shine Daniel 
Published: March 2018

SummaryWarfarin induction is accomplished by titrating dosage to coagulation test results. Algorithms can guide this process but not identify the starting dose. We hypothesized that an initial warfarin dose approximating the maintenance value would safely enhance rapidity of induction. In a randomized trial we compared a fixed-dose to a maintenance-dose strategy for beginning warfarin therapy. To predict the maintenance dose among patients with differing warfarin requirements we performed regression analysis on clinical factors derived from chart review. Four community hospitals supplied records for retrospective analysis. The prospective trial was conducted in one, a 350-bed teaching institution. A sample of inpatients anti-coagulated during 1998 formed the development set for retrospective study; a 1999 sample formed the validation set. A one-year trial recruited consecutive eligible inpatients initiated on warfarin. We randomly assigned patients to a first warfarin dose calculated using our regression formula or fixed at 5 mg. All patients’ subsequent doses were determined (as a percentage of initial) from coagulation testing. We compared days to anticoagulation, hospitalized hours, complications, and activity of factor II and protein C in a patient sample at intervals after induction. Weight, age, serum albumin, and presence of malignancy explained 25-30% of variance in maintenance dose. Ninety patients (44 calculated-dose and 46 standard-dose) evaluated in the clinical trial. Mean time to anticoagulation (among patients achieving anticoagulation) was 4.2 and 5.0 days, respectively (p = 0.007). We observed no significant differences in other endpoints. Individualized initial dosing may safely hasten war-farin induction.
Effect of clotting factors concentrates on lymphocyte and neutrophil function in vitro
Authors: Ghio Massimo , Contini Paola , Ottonello Luciano , Arduino Nicoletta , Gringeri Alessandro , Indiveri Francesco , Dallegri Franco , Puppo Francesco 
Published: March 2018

SummaryImmunological abnormalities have been reported in haemophiliacs. Although infections with HIV, hepatitis and other viruses may contribute to these abnormalities, immune defects are detectable also in HIV seronegative haemophiliacs. It is likely that chronic exposure to extraneous proteins in clotting factor concentrates (CFCs) may play a role in immunomodulation, but the underlying mechanisms remain unclear. The results of the present paper show that: a) soluble HLA class I (sHLA-I), soluble Fas-ligand (sFas-L) and transforming growth factor beta 1 (TGF-β1) are detectable in plasma derived but not in recombinant CFCs; b) the level of sHLA-I and sFas-L is proportional to the grade of CFCs purity whereas TGF-β1 showed very variable levels; c) soluble molecules detected in CFCs exert immunomodulatory effects in vitro like apoptosis induction in Jurkat cells and inhibition of mixed lymphocyte reaction response, antigen-specific lymphocyte cytotoxic activity and neutrophil chemotaxis.