bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biochemical Characterization of PECAM-1 (CD31 Antigen) on Human Platelets
Authors: Metzelaar Marcel J , Korteweg Jeanne , Sixma Jan J , Nieuwenhuis H Karel 
Published: July 2018

SummaryThe platelet plasma membrane expresses several membrane glycoproteins with a high molecular weight. In this study we have investigated the properties of the CD31 antigen on platelets and endothelial cells using the monoclonal antibody (MoAb) RUU-PL 7E8. Comparative studies revealed that the CD31 antigen, PECAM-1 and endoCAM are the same protein. The CD31 antigen was immunoprecipitated with a molecular mass of 125 kDa nonreduced and 135 kDa reduced from Nonidet-P40 lysates of surface labeled human platelets. The relative position in two-dimensional nonreduced/reduced SDS-PAGE and IEF-PAGE, compared to other glycoproteins of similar molecular weight, was elucidated. The position of the CD31 antigen was clearly distinct from the position of the platelet membrane glycoproteins Ia, Ib, IIa, IIb, IIIa and the granule membrane protein GMP-140. Native resting platelets bound 7,760 ± 1,670 molecules/platelet, whereas thrombin-stimulated platelets bound 14,500 ± 3,790 molecules/platelet. Immunoelectron microscopy revealed the presence of the CD31 antigen on the membrane of both resting and thrombin-activated platelets. Immunofluorescence studies showed the presence of the CD31 antigen in the membrane of endothelial cells on sites of cell-cell contact, suggesting that the CD31 antigen might be involved in cell-cell interaction. In functional studies, MoAb RUU-PL 7E8 did not inhibit platelet aggregation, platelet adherence to the extracellular matrix of endothelial cells and purified collagen fibrils under flow conditions, nor was any influence found on endothelial cell detachment and growth.
Role of Internalization in Platelet Activation Induced by Collagen Fibers – Differential Effects of Aspirin, Cytochalasin D, and Prostaglandin E1
Authors: Ruf Andreas , Patscheke Heinrich , Morgenstern Eberhard 
Published: July 2018

SummaryWashed human platelets were stimulated with fibrillar collagen and platelet aggregation was prevented by non-stirring conditions. In these samples, electron microscopy revealed three fractions of platelets: 1) a majority without contacts to the collagen fibers, 2) with focal contacts to collagen, and 3) a small fraction of platelets with internalized collagen. All platelets had undergone shape change, and exhibited an internal contraction and granule release. However, only those with internalized collagen were completely degranulated. The internalized collagen was found to be in close contact to the contractile sphere in the platelet center, as it was demonstrable with computer assisted 3-D reconstruction from serial sections. Aspirin inhibited neither the adhesion to collagen nor its internalization by internal contraction. Also it did not impair the shape change and degranulation in the platelet fractions that internalized collagen. However, aspirin blocked the shape change and internal contraction of the other platelets and inhibited the [3H]serotonin release. Cytochalasin D 0.1 uM also suppressed the internalization of collagen, the shape change, the formation of a contractile gel, the degranulation, and the [3H]serotonin release in all platelets, whereas the number of platelets that adhered to collagen remained unchanged. The same effects were produced by prostaglandin E1. If the platelets were stimulated with the TXA2 mimetic, U46619, cytochalasin D at 0.1 εM had no effect; but at 20 εM it strongly enhanced the degranulation and the [3H]serotonin release, although the platelets remained discoid. It is concluded that collagen triggers a focal activation of an adherent platelet at the site of its initial contact to collagen. This subthreshold activation proceeds to degranulation and TXA2 formation via a feedback cascade which involves internal contraction, internalization of collagen and multiplication of the collagen membrane contacts.
In Vivo Recovery and Survival of Monoclonal-Antibody-Purified Factor VIII Concentrates
Authors: Kasper Carol K , Kim Hugh C , Gomperts Edward D , Smith Kenneth J , Salzman Phyllis M , Tipping Diane , Miller Robert , Montgomery Robert M 
Published: July 2018

SummaryIn response to reports of discrepant in vitro assays of high-purity concentrates, a double-blind crossover study of in vivo recovery and half-life of two brands of monoclonal-antibody-purified factor VIII concentrates (Monoclate and Hemofil-M) was performed in 23 patients with hemophilia A. In vivo recoveries were close to values predicted from the labelled unitage when plasma samples were assayed by a one-stage method. When a two-stage assay was used, lower recoveries were calculated and the recovery with Hemofil-M was slightly but significantly lower than that with Monoclate. The concentrates were re-assayed in vitro by the two-stage method. Monoclate (which is assayed by the manufacturer using a two-stage method) contained 97% of the labelled potency and Hemofil-M (which is assayed by the manufacturer using a one-stage method) contained 81% of the labelled potency. Differences in in vitro and in vivo assay methods contribute to disparities between expected and observed factor VIII recovery. Clearance of Hemofil-M was significantly faster than that of Monoclate, but volume of distribution at the steady state, mean residence time, and plasma half-disappearance times of the two concentrates were not significantly different.
A Rapid and Sensitive Test for Diagnosing Heparin-Associated Thrombocytopenia
Authors: Greinacher A , Michels I , Kiefel V , Mueller-Eckhardt C 
Published: July 2018

SummaryHeparin-associated thrombocytopenia (HAT) is a severe complication of heparin therapy. Its diagnosis is difficult. Conventional assays employ platelet aggregometry (PAA) and/or 14C-serotonin release (SRA) which are either insensitive (PAA) or require radioactive tracers (SRA). We here describe a newly developed sensitive and rapid assay based on visual evaluation of heparin-induced platelet activation (HIPA) in microtiter wells. Using sera of 34 patients with clinically suspected HAT we found the HIPA assay to be as sensitive as the SRA and superior to PAA. The HIPA assay allows investigation of crossreactivity with different types of heparins, low molecular weight (LMW) heparins and heparinoids. Three patients who required further parenteral anticoagulation and in whom the HIPA assay was negative before treatment with the LMW heparinoid Org 10172, were treated with this new heparinoid without adverse reactions. We conclude that the HIPA assay may be a useful tool for differential diagnosis and therapy in patients with HAT.
Heparin Neutralizing Activity in Patients with Renal Disease on Maintenance Haemodialysis
Authors: Aronstam A , Dennis B , Friesen M J , Clark W F , Linton A L , Lindsay R M 
Published: July 2018

SummaryHeparin neutralizing activity (HNA) was increased in plasma of patients with end-stage renal disease treated by maintenance haemodialysis. It was not raised in non-dialyzed patients with chronic renal failure, nor in patients with normal renal function who had been exposed to the extracorporeal circulation of the heart-lung bypass 48–72 hr before testing. It is postulated that the trauma of extracorporeal circulation causes platelets to release HNA which is not cleared by the dialysis membranes of the artificial kidney but is by the human kidney. This may have therapeutic implications for heparin dosage schedules during haemodialysis.
Plasmin Digestion of factor VIII: Characterization of the Breakdown Products with Respect to Antigenicity and von Willebrand Activity
Authors: Guisasola J A , Cockburn C G , Hardisty R M 
Published: July 2018

SummaryHighly purified factor VIII was incubated for up to 24 hours in the presence of plasmin, and the biological activities and peptide structure of the digestion products determined at intervals. Procoagulant activity (VIIIC) was rapidly lost, but 17-32% of the initial ristocetin cofactor (VIIIR: WF) activity remained after 24 hours. Immunoelectrophoresis showed a progressive increase in rocket height and a concomitant increase in electrophoretic mobility of the factor-VIII-related antigen (VIIIR: AG). Crossed immunoelectrophoresis of the 24- hour digest showed three distinct precipitin arcs, of which the major one, with intermediate anodal mobility, gave reactions of non-identity with the other two. On sepharose gel chromatography the 24-hour digest gave three peaks: peak II contained about 80% of the residual VIIIR: WF and resolved on SDS-polyacrylamide gels into a series of peptides with apparent molecular weights between 125,000 and 185,000; these were reduced by mercaptoethanol to fragments of 15,000-80,000 daltons, a 65,000 dalton fragment being particularly strongly PAS positive. We conclude that large molecular size is not a prerequisite for VIIIR :WF activity, and that the presence of factor-VIII breakdown products may be a cause of misleading results in the determination of VIIIR:AG by immunoelectrophoresis.
Calcium-Dependent Activation of Protein C by Thrombin/Thrombomudulin: Role of Negatively Charged Amino Acids within the Activation Peptide of Protein C
Authors: Friedrich Ute , Pötzsch Bernd , Preissner Klaus T , Müller-Berghaus Gert , Ehrlich Hartmut 
Published: July 2018

SummaryIn the absence of its cofactor thrombomodulin (TM) thrombin is only a poor activator of the anticoagulant serine protease protein C (PC). The TM-dependence of PC-activation has been restricted to a series of molecular structures of the PC molecule including high-affinity calcium binding sites and single amino acid residues. However, thrombin induced activation of a PC derivative altered in all these critical positions is markedly enhanced by TM indicating that additional structures of the PC molecule are involved in determining the TM specificity. Based on the hypothesis that such an additional regulatory element should be located near the thrombin cleavage site and should include negatively charged amino acids to ascertain calcium binding, we studied whether Glu and Asp in positions P7 and P6 relative to the thrombin cleavage site together with Asp in P3 are involved in formation of such a regulatory element. Three PC derivatives containing the neutral counterpart of the negatively charged amino acids in positions P3; P3 and P6; and P3, P6, and P7, respectively, were generated using site-directed mutagenesis. Compared to rPC-wt the initial rates of PC activation of all three mutants were increased 4.0-fold for thrombin/TM and 4.0-, 5.3-fold for activation by thrombin alone. However, compared to the PC derivative neutralized exclusively in P3, additional changes in P6 and P7 showed no increase in the thrombin activation kinetics and calcium binding properties were identical in all of the three mutants. We conclude that .1) among the three negatively charged amino acids at the COOH-terminal end of the activation peptide of PC, only Asp in P3 is involved in calcium-dependent inhibition of PC activation by thrombin; 2) the residues in P7 and P6 do not contribute to the calcium binding properties of PC; 3) P7 and P6 sites are not required for calcium-dependent activation of PC by the thrombin/TM complex.
A New Hypothesis: Possible Mechanisms in the Involvement of the Increased Plasminogen Activator Activity in Branching Regions of the Aorta in the Initiation of Atherosclerosis
Authors: Smokovitis A 
Published: July 2018

SummaryBranching regions of the aorta are predilection regions for atherosclerosis. The intima in the branching regions of the normal aorta shows a constantly increased plasminogen activator activity from early life. At these areas, the endothelium is also damaged, it shows increased permeability, etc. The constantly increased plasminogen activator activity (local plasmin production) might play a protective role or on the contrary might participate in the initiation of atherosclerosis at the branching regions through a number of proved or suggested mechanisms.No matter what the actual role of the locally increased plasminogen activator activity in the initiation of atherosclerosis is, the role of the fibrinolytic system in the progression of the atherosclerotic lesion seems to be clear. There is an accumulation of evidence that the impaired fibrinolytic activity in atherosclerotics participates in the progression and the complications of the disease.
Acquired von Willebrand’s Syndrome in the Course of Waldenström’s Disease
Authors: Mazurier Claudine , Parquet-Gernez Armelle , Descamps Jacques , Bauters Francis , Goudemand Maurice 
Published: July 2018

SummaryAcquired von Willebrand's syndrome with a regressive evolution is described in a 66 year old man with Waldenström's disease. An inhibitor electively directed against Ristocetin cofactor activity has been demonstrated, active in vitro after incubation at 37° C. Serum fractionation showed that the inhibitor was independant of the monoclonal IgM and subsequent purification that it was IgG in nature. The results permit its classification as an auto-antibody.
Upper Extremity Deep Venous Thrombosis in Cancer Patients with Venous Access Devices - Prophylaxis with a Low Molecular Weight Heparin (Fragmin)
Authors: Monreal Manuel , Alastrue Antoni , Rull Miquel , Mira Xavier , Muxart Jordi , Rosell Rafael , Abad Albert 
Published: July 2018

SummaryCentral venous access devices are often essential for the administration of chemotherapy to patients with malignancy, but its use has been associated with a number of complications, mainly thrombosis. The true incidence of upper extremity deep vein thrombosis (DVT) in this setting is difficult to estimate since there are very few studies in which DVT diagnosis was based on objective tests, but its sequelae include septic thrombophlebitis, loss of central venous access and pulmonary embolism.We performed an open, prospective study in which all cancer patients who underwent placement of a long-term Port-a-Cath (Pharmacia Deltec Inc) subclavian venous catheter were randomized to receive or not 2500 IU sc of Fragmin once daily for 90 days. Venography was routinely performed 90 days after catheter insertion, or sooner if DVT symptoms had appeared. Our aims were: 1) to investigate the effectiveness of low doses of Fragmin in preventing catheter-related DVT; and 2) to try to confirm if patients with high platelet counts are at a higher risk to develop subclavian DVT, as previously suggested.On the recommendation of the Ethics Committee, patient recruitment was terminated earlier than planned: DVT developed in 1/16 patients (6%) taking Fragmin and 8/13 patients (62%) without prophylaxis (Relative Risk 6.75; 95% Cl: 1.05-43.58; p = 0.002, Fisher exact test). No bleeding complications had developed. As for prediction of DVT, there was a tendency towards a higher platelet count in those patients who subsequently developed DVT, but differences failed to reach any statistical significance (286 ±145 vs 207 ±81 X 109/1; p = 0.067). According to our experience, Fragmin at the dosage used proved to be both effective and safe in these patients.
The Effects of Long-term Heparin Therapy During Pregnancy on Bone Density
Authors: Douketis James D , Ginsberg Jeffrey S , Burrows Robert F , Duku Eric K , Webber Colin E , Brill-Edwards Patrick 
Published: July 2018

SummaryWe performed a prospective matched cohort study to investigate the effects of long-term (>1 month) heparin therapy on lumbar spine bone density. Twenty-five women who received heparin during pregnancy, and 25 matched controls underwent dual photon absorptiometry of the lumbar spine in the post-partum period. Zero of 25 heparin-treated patients developed fractures. Heparin-treated patients had a 0.082 g/cm2 lower bone density compared to untreated controls, which is clinically and statistically significant (p = 0.0077). There were 6 matched pairs in which only the heparin-treated patient had a bone density below 1.0 g/ cm2, compared to only one pair in which only the control patient had a bone density below this level (p = 0.089). The correlation coefficients of the difference .in bone density in each matched pair, and the duration of heparin therapy, the mean daily dose, and the total dose of heparin were 0.042, -0.015, and 0.021, respectively; none of these values is statistically significant. We conclude: 1) long-term heparin therapy was associated with a significant reduction in bone density, although fractures are uncommon, 2) there was no significant correlation between lumbar bone density and the dose or duration of heparin.
Elevated Levels of Prothrombin Activation Fragment 1+2 in Plasma from Patients with Heterozygous Arg506 to Gin Mutation in the Factor V Gene (APC-Resistance) and/or Inherited Protein S Deficiency
Authors: Zöller Benget , Holm Johan , Svensson Peter , Dahlbäck Björn 
Published: July 2018

SummaryInherited resistance to activated protein C (APC-resistance), caused by a point mutation in the factor V gene leading to replacement of Arg(R)506 with a Gin (Q), and inherited protein S deficiency are associated with functional impairment of the protein C anticoagulant system, yielding lifelong hypercoagulability and increased risk of thrombosis. APC-resistance is often an additional genetic risk factor in thrombosis-prone protein S deficient families. The plasma concentration of prothrombin fragment 1+2 (F1+2), which is a marker of hyper-coagulable states, was measured in 205 members of 34 thrombosis-prone families harbouring the Arg506 to Gin mutation (APC-resistance) and/or inherited protein S deficiency. The plasma concentration of F1+2 was significantly higher both in 38 individuals carrying the FV:Q506 mutation in heterozygous state (1.7 ± 0.7 nM; mean ± SD) and in 48 protein S deficient cases (1.9 ± 0.9 nM), than in 100 unaffected relatives (1.3 ±0.5 nM). Warfarin therapy decreased the F1+2 levels, even in those four patients who had combined defects (0.5 ± 0.3 nM). Our results agree with the hypothesis that individuals with APC-resistance or protein S deficiency have an imbalance between pro- and anti-coagulant forces leading to increased thrombin generation and a hypercoagulable state.
Plasma Ascorbate Protects Coagulation Factors against Photooxidation
Authors: Parkkinen Jaakko , Vääränen Outi , Vahtera Elina 
Published: July 2018

SummaryIt has been suggested that proteins, unlike lipids, are not protected against oxidative damage by antioxidants in plasma. We have studied the effect of photodynamic virus inactivation treatment of fresh human plasma on coagulation factor activities. Photodynamic treatment generates singlet oxygen which causes inactivation of fibrinogen and factor VIII. Other coagulation factors or anticoagulant proteins are clearly less affected. We found that there is an inverse correlation between the extent of coagulation factor inactivation during the treatment and the plasma ascorbate concentration. The inactivation of coagulation factors was prevented in a dose-dependent manner by adding ascorbate to the plasma before the treatment. Ascorbate was consumed during the treatment at an apparently linear rate. Oxidation of urate and coagulation factors was enhanced when ascorbate had disappeared from plasma. These results indicate that ascorbate is a primary antioxidant against photooxidation in plasma and that it effectively prevents oxidative damage to coagulation factors and other proteins.
Markers of Hemostatic System Activation during Thromboprophylaxis with Recombinant Hirudin in Total Hip Replacement
Authors: Cofrancesco E , Cortellaro M , Leonardi P , Corradi A , Ravasi F , Bertocchi F 
Published: July 2018

SummaryCoagulation activation markers were studied in 148 patients undergoing total hip replacement under recombinant-hirudin (Desirudin, TMRevasc) prophylaxis with the aim of investigating the efficacy and safety of this anticoagulant compared with heparin in terms of biological effects on coagulation variables and bleeding. Hirudin (10, 15 or 20 mg s.c. b.i.d.) or unfractionated heparin (5000IU s.c. t.i.d.) was administered immediately before surgery and continued for 8-12 days. Activated partial thromboplastin time (aPTT), prothrombin activation fragment F1+2 (F1+2), thrombin-antithrombin III complexes (TAT) and D-dimer were measured at baseline and on postoperative days 1,3 and 6, immediately before the morning injection.In comparison with baseline values, heparin had little effect on aPTT whereas the three hirudin doses prolonged aPTT significantly with no differences among the three doses. Moreover, there were no group differences in perioperative or cumulative blood loss or transfusion requirements. F1+2 fragment, TAT and D-dimer plasma levels were higher than at baseline during the entire postoperative period, with different trends (F1+2 increasing, TAT decreasing, D-dimer increasing, decreasing and then increasing again), but without significant differences among the four treatment groups. Our findings suggest that specific inhibition of thrombin seems a safe and efficacious mode of blocking thrombin activity after hip surgery although it does not prevent thrombin generation.
Evaluation of a New Rapid Quantitative D-dimer Assay in Patients with Clinically Suspected Deep Vein Thrombosis
Authors: D’Angelo Armando , D’Alessandro Gabriella , Tomassini Loredana , Pittet Jean Louis , Dupuy G , Crippa Luciano 
Published: July 2018

SummaryThe sensitivity and specificity for deep vein thrombosis (DVT) of a new rapid, quantitative and precise (total imprecision < 10%) D-dimer assay suitable for individual measurements (VIDAS D-DIMER, bio-Merieux, France) were evaluated in a consecutive series of 103 in- and out-patients submitted to serial compression ultrasonography (C-US) for the clinical suspicion of DVT (n = 66) or of DVT recurrence (n = 37) and symptoms lasting from 1 to 15 days. DVT was found in 22 patients at baseline testing and no patient with an initially negative C-US developed vein incompressibility at follow up. The time elapsed from the onset of symptoms was negatively associated with D-dimer levels both in patients with and in those without DVT. In the entire series of patients, the sensitivity of a positive D-dimer test (≥1.0 Μg/ml) for the presence of DVT was 96% (21/22 patients, 95% confidence interval 75-100%) with a specificity of 75% (64-84%), a negative predictive value of 98% (90-100%), a positive predictive value of 51% (35-67%), and an overall accuracy of 80% (70-87%). A normal D-dimer value (0.22 Μg/ml) was observed in one patient with DVT and symptoms lasting from 15 days. The approach of withholding C-US testing in patients with symptoms lasting from less than 11 days and D-dimer levels below the cut-off value was compared to serial C-US testing alone in a cost-effectiveness analysis subdividing the 66 patients with a first episode according to their clinical pretest probability of DVT. Thrombosis was detected in 6.7% of the patients in the low probability group (n = 15), 16.7% of the patients in the moderate probability group (n = 24), 51.9% of the patients in the high probability group (n = 27) and 8.1% of patients with suspected DVT recurrence. Calculated cost-savings for each DVT diagnosed ranged from 5% in the high pretest probability group to 55% in the low pretest probability group and to 77% in patients with suspected DVT recurrence.The safety of avoiding C-US testing in symptomatic patients with a negative D-dimer test should be evaluated in clinical management studies.