bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effects of Quality and Timing of Venepuncture on Markers of Blood Coagulation in Healthy Middle-aged Men
Authors: Miller G J , Bauer K A , Barzegar S , Foley A J , Mitchell J P , Cooper J A , Rosenberg R D 
Published: July 2018

SummaryEffects of the quality and the time of venepuncture on factor VII coagulant activity (VIIC) and the concentrations of fibrinogen, prothrombin fragment 1 + 2 (F1 + 2) and fibrinopeptide A (FPA) were sought in 2665 men, of whom 2334 were re-examined after about one year. Venepunctures were categorised as satisfactory, not fully satisfactory or unsatisfactory according to pre-defined criteria. Neither the quality nor timing of the venepuncture influenced VIICor fibrinogen concentration. However, at baseline and re-examination F1 + 2and FPA were increased on average by about 9% and 45% respectively when venepunctures were not fully satisfactory, and by about 11% and 100% when unsatisfactory. Plasma collected after 1500 h had slightly but significantly lower levels of F1 + 2and FPA than samples taken earlier, possibly due to circadian rhythm. The results emphasise the need for careful surveillance of the venepuncture procedure and the value of FPA when using F1+ 2as a marker of risk of thrombosis.
Contrasting Effects of Thrombin and the Thrombin Receptor Peptide, SFLLRN, on Aggregation and Release of 14C-Serotonin by Human Platelets Pretreated with Chymotrypsin or Serratia marcescens Protease
Authors: Kinlough-Rathbone Raelene L , Perry Dennis W , Packham Marian A 
Published: July 2018

SummaryChymotrypsin cleaves glycoprotein Ib (GPIb) on platelets and reduces their responsiveness to thrombin; platelets from patients with the Bernard-Soulier syndrome, which lack GPIb, are also less responsive to thrombin than platelets from normal donors. However, Bernard-Soulier platelets respond normally to the thrombin receptor peptide SFLLRN (13). We compared responses of14C-serotonin-labeled, chymotrypsin-treated platelets (and control platelets) to thrombin (0.25-2 U/ml) and SFLLRN (5–40 μM). Chymotrypsin treatment strongly inhibited thrombin-induced aggregation and release of14C-serotonin when concentrations of thrombin of 0.5 U/ml or lower were used, even though these responses of control platelets remained near the maximum. In contrast, there was little difference between the responses of control and chymotrypsin-treated platelets to SFLLRN, even when the responses of control platelets were less than maximal. Thus, chymotrypsin treatment greatly inhibits the response to thrombin of the seven transmembrane domain thrombin receptor cloned by Coughlin’s group (1, 2). Since Serratia marcescens protease also hydrolyses GPIb, but has less effect than chymotrypsin on other glycoproteins, we pretreated platelets with several concentrations of S. marcescens protease. Concentrations that abolished aggregation and release of14C-serotonin in response to thrombin had little effect on these responses to SFLLRN. One interpretation of these findings would be that by cleaving GPIb, both proteases are affecting an interaction that may be important for activation of the cloned receptor by thrombin, but irrelevant to activation of this receptor by SFLLRN. Alternatively, it may be that in addition to cleaving GPIb, both chymotrypsin and S. marcescens protease also cleave the cloned receptor at a site that results in the loss of SFLLRN, but do not affect the site on this receptor with which SFLLRN interacts.
Axial Dependence of Collagen–Induced Thrombus Formation in Flowing Non-Anticoagulated Human Blood
Authors: Roald Helge E , Sakariassen Kjell S 
Published: July 2018

SummaryPlatelet thrombus formation on collagen fibrils is most pronounced at the upstream end of the surface, and it gradually decreases along the axis in parallel with the direction of the blood flow. This phenomenon, known as axial dependent platelet thrombus formation, is explained by the balance of the platelet supply to the surface and the consumption of platelets by growing thrombi.In the present study we have affected this balance by (A) inhibiting the growth of platelet thrombi by aspirin (ASA) or clopidogrel, and thus increasing the platelet concentration at the surface, and by (B) utilising blood from cigarette smokers, who have enhanced thrombus formation immediately after smoking, and thus decreasing the platelet concentration at the surface. Thrombus formation in non-anticoagulated blood was triggered by collagen fibrils positioned in a parallel-plate perfusion chamber at a wall shear rate of 2600 s_1which is characteristic for moderately stenosed arteries. Morphometrical assessment of thrombus formation was performed at axial positions of 1 and 13 mm downstream to the blood flow inlet at the collagen surface.Platelet-collagen adhesion and thrombus volume in blood from nonsmokers were decreased at the downstream location by 39% (p ≤0.0001) and by 60% (p ≤0.0001), respectively. However, increasing the platelet concentration at the surface by partially inhibiting the thrombus growth by ASA or clopidogrel, reduced substantially the axial decrease in platelet adhesion and thrombus volume. The largest reduction was observed with clopidogrel which was also the strongest inhibitor of the thrombus growth at both axial positions investigated. The corresponding figures in blood from smokers with enhanced thrombus formation were 38% (p ≤0.0001) and 72% (p ≤0.001). Thus, enhanced upstream platelet consumption increased the axial reduction in thrombus volume, but not in platelet adhesion.These data substantiate the view that the “axial dependence phenomenon” may be explained by the balance between the platelet supply to the surface and the consumption of platelets by growing thrombi. It is also apparent that clopidogrel is a more potent inhibitor of platelet thrombus formation than ASA.
Effect of Plasma from Patients with Primary Antiphospholipid Syndrome on Platelet Function in a Collagen Rich Perfusion System
Authors: Reverter Joan-Carles , Tàssies Dolors , Escolar Ginés , Font Josep , Soto Alfonso López , Ingelmo Miguel , Ordinas Antoni 
Published: July 2018

SummaryThe effect on platelet function of plasma from 9 patients with primary antiphospholipid syndrome (PAS) with previous thrombotic episodes was investigated under flow conditions. Five asymptomatic individuals with antiphospholipid antibodies (aPL) (A-aPL) and 14 normal controls were also studied. Patients and controls plasmas were added (1:20 v/v) to anticoagulated blood and perfused through annular chambers containing collagen rich vessel segments. The interaction of platelets with vessel subendothelium was morphometrically evaluated in thin sections. An increase in both covered surface and thrombi formation was observed in perfusions in the presence of PAS-plasma (mean ± SD: 34.2% ± 9.6% and 23.2% ± 10.0% respectively) compared with control plasmas (21.4% ± 7.3% and 10.1% ± 7.7%, p<0.01). Affinity purified anticardiolipin antibodies from one PAS patient showed a similar effect when added to normal blood. In contrast, A-aPL plasma had no effect on platelet-subendothelium interaction. In parallel studies, the same plasmas were incubated with isolated normal platelets before and after activation with ADP or collagen and the binding of immunoglobulins (Ig) was determined by flow cytometry. A significantly increased binding of Ig was observed in 8 out of 9 plasmas from PAS patients when platelets had been activated with collagen but not when resting or ADP activated platelets were used. No increased Ig binding to platelets was seen using A-aPL individuals plasma. These observations might help to explain the pathophysiology of the thrombotic events occurring in patients with PAS.
Systematic Underestimation of Treatment Effects as a Result of Diagnostic Test Inaccuracy: Implications for the Interpretation and Design of Thromboprophylaxis Trials
Authors: Rodgers Anthony , MacMahon Stephen 
Published: July 2018

SummaryMany clinical trials that have assessed strategies for the prevention of deep vein thrombosis have employed diagnostic tests that are less accurate than venography. The correct interpretation of these trials has been the subject of considerable debate. This paper attempts to quantify the likely effects of the use of inaccurate diagnostic tests (in particular fibrinogen scanning) on the validity and precision of estimates of treatment effects. It is shown that, if there is no difference in the rate of misclassification of deep vein thrombosis between study and control groups, then treatment effects will tend to be systematically underestimated in trials that only use inaccurate diagnostic tests. However, for trials in which there are no false positive diagnoses, such as those employing venography, the estimate of relative treatment effects will be unbiased. This phenomenon is demonstrated empirically by data from randomised trials of antiplatelet therapy. The implications of these findings are two-fold. First, so long as the accuracy of the test is the same in study and control groups, positive trial results cannot be ascribed to diagnostic test inaccuracy. Second, unbiased estimates of relative treatment effects can be obtained by using cheap, practicable and non-invasive screening tests that are supplemented by venographic assessment of positive test results. This would facilitate the conduct of much larger randomised trials than has generally been possible when mandatory venography was used; if future trials randomised some thousands of patients and employed confirmatory venography then they would provide both unbiased and precise estimates of relative treatment effects.
Six Different Point Mutations in Seven Danish Families with Symptomatic Protein C Deficiency
Authors: Lind Bent , Schwartz Marianne , Thorsen Sixtus 
Published: July 2018

SummarySix different point mutations of the protein C gene are described in seven Danish families with protein C deficiency associated with an increased risk of venous thromboembolism. All affected family members are heterozygotes for the mutated protein C genotype. One mutation is a G2992→A transition at position +5 in the 5’ splice site of intron D. The other five mutations affect the protein coding region. One is a Cl432→T transition in exon III converting the highly conserved Arg15 to Trp in the Gla-domain. Another mutation is a G3157→C transversion in exon V converting the non-conserved Gly72 to Arg in the epidermal growth factor domain. The remaining three mutations are located in non-conserved amino acid positions in exon IX and affect the serine proteinase domain. The first is a G8559→C transversion converting Gly282 to Arg. The second is a C8571→T transition (present in two families) converting Arg286 to Cys. The third is a C8695→T transition converting Pro327 to Leu. In each family the protein C deficiency cosegregates or probably cosegregates (one family, G8559→C) with the mutation. All affected family members exhibit a reduction of both the antigen and the functional plasma concentration of protein C to approximately 50% of normal indicating that the mutated protein C is not present (type 1 deficiency) or only present in low amounts in plasma. Agarose gel electrophoresis followed by Western blotting shows that the Arg15→Trp substitution is associated with a normal as well as an abnormal migrating plasma protein C band. This provides positive evidence for that both the normal and mutated alleles are expressed (type 2 deficiency). The five other mutations are associated with only one band with the mobility of normal protein C. In one family a novel G1390→A transition converting the normal Ala1 to Thr was demonstrated. This mutation is not linked to the patient specific G8559→C transversion. In conclusion one splice site mutation and five different missense mutations of the protein C gene are described.
Dietary Changes in Fasting Levels of Factor VII Coagulant Activity (FVII: C) Are Accompanied by Changes in Factor VII Protein and other Vitamin K-dependent Proteins
Authors: Bladbjerg E M , Tholstrup T , Marckmann P , Sandström B , Jespersen J 
Published: July 2018

SummaryThe mechanisms behind dietary effects on fasting coagulant activity of factor VII (FVII: C) are not clarified. In the present study of 15 young volunteers, two experimental diets differing in composition of saturated fatty acids (C18:0 [diet S] or C12:0 + C14:0 [diet ML]) were served for 3 weeks each. Fasting blood samples were collected before and after the dietary regimen and analysed for triglycerides, FVII:C, and protein concentrations of FVII, FII, FX, protein C, CRP, albumin, fibrinogen, and F1+2. FVII:C was significantly reduced on diet S compared with diet ML. This was accompanied by a decrease in FVII protein, F1+2 and the vitamin K-dependent proteins FII, FX, and protein C. In contrast, no changes were observed in triglycerides, FVII:C/FVII: Ag, albumin and CRP. Fibrinogen was increased on diet S compared with diet ML. Our findings suggest that the change in fasting FVII:C was part of a general change in concentrations of vitamin K-dependent proteins.
Internalization of an Anti-Glycoprotein IIb/IIIa Antibody by HEL Cells
Authors: Hamamoto Kenjiro , Nomura Shosaku , Suzuki Masahiko , Ohga Shigetoshi , Fukuhara Shirou 
Published: July 2018

SummaryPlatelets are known to internalize monoclonal antibodies directed against the glycoprotein (GP) IIb/IIIa complex. We investigated whether an antibody directed against this complex (NNKY 2-11) was transported from the surface membrane to the intracellular pool in HEL cells. Flow cytometry showed that the percent binding of NNKY 2-11 to the surface membrane of HEL cells was decreased after incubation for 24 h compared with 1 h, while the binding of an anti-GPIb antibody (NNKY 5-5) did not change. It did not seem likely that the GP Ilb/IIIa complex antibody was shed from the surface membrane of the HEL cells during incubation, because the medium conditioned by incubation with these cells for 24 h showed almost no binding to washed platelets. In addition, immunoelectron microscopy demonstrated that GP IIb/IIIa complex antibodies were incorporated into the intracellular pool of HEL cells and were associated with alpha granules. These findings indicated that an anti-GP IIb/IIIa antibody could be internalized by megakaryocytes, as has been previously shown with platelets, suggesting that megakaryocyte GP IIb/IIIa may act as a carrier for various adhesion proteins.
Antithrombin III Concentrates-Are they Clinically Useful?
Authors: Lechner K , Kyrle P A 
Published: July 2018

SummaryTreatment with AT III concentrates is a good example for the discrepancy between the optimistic expectations based on theoretical considerations or animal experiments and the result of clinical studies. 15 years after the introduction into clinical practice, a benefit for patients treated with AT III concentrates has not been proven. In hereditary antithrombin III deficiency, randomized clinical trials are completely lacking and only few and small sized randomized studies were performed in patients with acquired AT III deficiency. In none of these trials, a significant clinical benefit with regard to reduction of morbidity or mortality was detectable. Based on the published data, one can state that AT III concentrates may be beneficial in some special clinical situations in patients with hereditary antithrombin III deficiency (such as delivery, acute serious thromboembolic complications and postoperative thromboprophylaxis). In acquired AT III deficiency, there is no proven indication for the use of AT III concentrates.
Accelerated Degradation Test of Lyophilized Recombinant Tissue Factor-Liposome Preparations
Authors: van den Besselaar A M H P , Witteveen E , Mansfeld Schaefer-van H , Meeuwisse-Braun J , Strebus A 
Published: July 2018

SummaryAccelerated degradation experiments were performed to assess the heat stability of lyophilized recombinant tissue factor-liposome preparations from two different manufacturers. When stored at 4° C, these preparations did not show a significant change of the prothrombin time (PT). Two preparations (coded rTF-2 and rTF-a) showed a progressive prolongation of the PT on storage at 30° C, 37° C, and 44° C. The third preparation showed an initial decrease of the PT at 37° C and 44° C followed by a progressive prolongation. Although none of the three preparations was absolutely stable at 30° C, 37° C and 44° C, rTF-2 had the advantage that its PT-ratio (and hence its International Sensitivity Index) did not change under the conditions used in this study. The PT-ratio with a reference material for rabbit brain tissue factor (CRM149S) stored under similar conditions, did not change either.
A Comparative Study of Three Low-molecular Weight Heparins (LMWH) and Unfractionated Heparin (UH) in Healthy Volunteers
Authors: Eriksson Bengt I , Söderberg Karin , Widlund Lars , Wandeli Baback , Tengborn Lilian , Risberg Bo 
Published: July 2018

SummaryThe levels of anti-IIa and anti-Xa activity, as reported in laboratory and clinical studies on low molecular weight heparin (LMWH) preparations, show a high degree of variability. This variation has been proposed as correlated to the variation in incidence of postoperative deep vein thrombosis (DVT) (8-30%) in different LMWH studies on comparable populations undergoing elective hip surgery. The aim of this study was to compare the ex vivo potency of Clexane® (enoxaparin), Fragmin® (dalteparin) and Logiparin® (tinzaparin), applying the concept of bioequivalence, although unknown which activity/activities are best correlated to efficacy. Unfractionated heparin (UH) was included in the study as a reference drug.The drugs were studied with a cross-over technique in 12 healthy subjects and given subcutaneously in the doses recommended for orthopedic surgery. Blood samples were drawn each hour up to 10 h and at 12 h after administration. Anti-Xa and anti-IIa activities were measured using chromogenic substrate methodsThe anti-Xa peak activity (Cmax) and the area under the curve (AUC) were highest for Clexane® and Fragmin® and lower for Logiparin® and UH. Clexane® and Fragmin® were considered bioequivalent in anti-Xa activity. Regarding anti-IIa activity, no bioequivalence was found between the products. Fragmin® was clearly different, with Cmax and AUC approximately twice as high as the other drugs. Whether the demonstrated differences in anti-Xa and anti-II activities are of any clinical significance remains unclear and can only be established by comparative clinical studies.
The Strong Positive Correlation between Factor VII Clotting Activity Using Bovine Thromboplastin and the Activated Factor VII Level
Authors: Kario Kazuomi , Matsuo Takefumi , Asada Reiko , Sakata Toshiyuki , Kato Hisao , Miyata Toshiyuk 
Published: July 2018

SummaryWe compared factor VII clotting activity (FVIIc) assays using different thromboplastins to determine which is the most sensitive for activated FVII (FVIIa) or for FVII antigen (FVIIag). FVIIc levels were measured using thromboplastins derived from bovine brain (FVIIc Bov), human placenta (FVIIc Hum), and rabbit brain (FVIIc Rab). FVIIa levels were measured by fluorogenic assays using human soluble tissue factor (rsTF) or bovine rsTF. We also measured FVII activity by an amidolytic assay (FVIIc:am Hum) using human thromboplastin and a chromogenic substrate for thrombin. FVIIag levels were determined by ELISA. In the FVIIa assay, the reaction time obtained from using bovine rsTF was shorter than that with human rsTF, suggesting that the interaction of plasma FVIIa with bovine rsTF was stronger than with human rsTF. The plasma FVIIa levels measured using human rsTF and bovine rsTF were almost the same (r=0.947, p<0.0001). Among the three FVIIc assays, FVIIc Bov had the strongest positive correlation with the plasma FVIIa level (r=0.886, p<0.000l), but had no correlation with FVIIag. An increase of 1 ng/ml in the plasma FVIIa level yielded a 27.9% increase of FVIIc Bov. Plasma FVIIc Hum and FVIIc:am Hum showed moderate correlations with both FVIIa (r=0.520, p<0.02 and r=0.569, p<0.01, respectively) and FVIIag (r=0.438, p<0.05 and r=0.468, p<0.05, respectively). FVIIc Rab had the lowest correlation with FVIIa (r=0.367, p<0.1), but had a moderate correlation with FVIIag (r=0.436, p<0.05). After in vitro cold activation, FVIIc Bov levels increased the most and FVIIc:am levels showed the least change. These findings indicate that consideration of the thromboplastin used for assay is necessary when assessing the clinical significance of FVII activity as a cardiovascular risk factor.
Multicenter Evaluation of Nine Commercial Kits for the Quantitation of Anticardiolipin Antibodies
Authors: Reber G , Arvieux J , Comby E , Degenne D , de Moerloose P , Sanmarco M , Potron G ,   On behalf of the working group on Methodologies in Haemostasis from the GEHT (Groupe d’Etudes sur I’Hémostase et la Thrombose), France
Published: July 2018

SummaryThe performances of nine commercial kits and an in-house method (HM) for the quantitation of anticardiolipin antibodies (ACA) have been evaluated in a multicenter study. Ninety control and patient samples and six standards from Louisville University were run with kits and with the HM. Marked differences in positivity rate between kits were observed, ranging from 31 to 60% for IgG and 6 to 50% for IgM. Concordance between kits occurred in 59 and 51% of samples for IgG and IgM respectively. Concordance coefficients (kappa) ranged from 0.13 to 0.92. Slopes of regression lines between the declared units of Louisville standards and the units measured from the calibrators of the kits showed great diversity and ranged from 0.159 to 0.931 for IgG and from 0.236 to 0.836 for IgM. The β2-glycoprotein I (β2-GPI) content of the dilution buffers and the wells supplied with the kits revealed noticeable differences. However samples containing anti-(β2-GPI antibodies were classified similarly by all but one kit. In contrast the ability to measure samples devoid of anti-β2-GPI antibodies differed markedly between the kits.This study shows that differences in positivity rates between the commercial kits may contribute to the differences in ACA prevalence rate found in the literature. The choice of cut-off levels may partly explain the moderate concordance between the kits. In addition some samples behave very differently depending on the kits. In spite of the expression of results in PL units, standardization of ACA assays has not been achieved.
Ultrasound Increases Flow through Fibrin Gels
Authors: Siddiqi Farhan , Blinc Ales , Braaten Julie , Francis Charles W 
Published: July 2018

SummaryUltrasound accelerates fibrinolysis in vitro and in animal models of thrombosis. Since transport of fibrinolytic enzymes into clots by permeation may be an important determinant of the rate of fibrinolysis, we examined the effect of ultrasound on permeation through fibrin gels in vitro. Gels of purified fibrin were prepared in plastic tubes, and the rate of pressure-mediated fluid permeation was measured. Exposure to 1 MHz ultrasound at 2 W/cm2 and a duty cycle of 5 msec on, 5 msec off resulted in a significant (p = .005) increase in flow through the gel of 29.0 ± 4.2% (SEM). The ultrasound-induced flow increase was intensity-dependent, increasing from 17.0 ± 1.2% at 1 W/cm2 to 30.1 ± 1.9% at 2.3 W/cm2. Increased flow was not due to heating, detachment of fibrin from the tube wall or fragmentation of the gel resulting in channeling. However, degassing the fluid by autoclaving significantly reduced the ultrasound-induced increase in flow. We conclude that exposure of fibrin gels to ultrasound increases pressure-mediated permeation. This effect may be related to cavitation-induced changes in fibrin gel structure, and could contribute to the accelerated fibrinolysis observed in an ultrasound field.