bluuebunny/crossref_metadata_2025_split huggingface dataset:
Platelet Aggregation Induced by Plasma from Type IIB von Willebrand’s Disease Patients Is Associated with an Increase in Cytosolic Ca2+ Concentration
Authors: Francesconi Maria Angela , Deana Renzo , Girolami Antonio , Pontara Elena , Casonato Alessandra 
Published: July 2018

SummaryThe effect of type IIB von Willebrand’s factor (vWF) on platelet cytosolic Ca2+ ion concentration, measured by means of the probe fura 2, was investigated. Seven patients with type IIB von Willebrand disease (vWD) were studied. Addition of type IIB vWD plasma to platelet suspensions induced a cytosolic calcium increase accompanied by platelet aggregation. Both processes were completely abolished by addition of the calciumchelating agent EGTA, indomethacin, peptide RGDS, and monoclonal antibodies blocking the vWF binding site on GPIb-IX (LJIB1) or the cytoadhesive receptor on GPIIb-IIIa (LJCP8). The ADP-scavenger apyrase and the protein kinase C-inhibitor staurosporine partially inhibited the rate of the cytosolic calcium increase. No direct correlation between the extent of Ca2+ rise and the phenotypic expression of IIB vWD, such as the degree of spontaneous platelet aggregation or thrombocytopenia was apparent. It is suggested that aggregation and cytosolic Ca2+ increase in platelets exposed to plasma from type IIB vWD patients is mediated by a self-potentiating mechanism involving both GPIb and GPIIb-IIIa receptors as well as the thromboxane biosynthetic pathway.
Induction of Endothelial Tissue Factor by Endotoxin and Its Precursors
Authors: Moldow Charles F , Bach Ronald R , Staskus Katherine , Rick Paul D 
Published: July 2018

SummaryThe structural determinants of lipopolysaccharide required for the induction of tissue factor in human umbilical vein endothelial cells were studied. Intact lipid A was essential for the induction of tissue factor whereas the incomplete lipid A precursors lipid IVA and lipid X, as well as monophosphoryl lipid A and acyloxyacyl hydrolase-treated lipopolysaccharide, were unable to induce tissue factor and tissue factor specific mRNA. However, the lipid A precursor, lipid IVA, was able to inhibit LPS-mediated induction of tissue factor; structural determinants distal to lipid A were found to be required for maximal induction of tissue factor activity and tissue factor mRNA. The presence of serum in the assay was found to amplify but was not obligate for tissue factor induction by LPS.
Adverse Influence of Cigarette Smoking on the Endothelium
Authors: Blann Andrew D , McCollum Charles N 
Published: July 2018

SummaryThe effect of smoking on the blood vessel intima was examined by comparing indices of endothelial activity in serum from smokers with that from non-smokers. Serum from smokers contained higher levels of von Willebrand factor (p <0.01), the smoking markers cotinine (p <0.02) and thiocyanate (p <0.01), and was more cytotoxic to endothelial cells in vitro (p <0.02) than serum from non-smokers. The acute effects of smoking two unfiltered medium tar cigarettes was to briefly increase von Willebrand factor (p <0.001) and cytotoxicity of serum to endothelial cells in vitro (p <0.005), but lipid peroxides or thiocyanate were not increased by this short exposure to tobacco smoke. Although there were correlations between von Willebrand factor and smokers consumption of cigarettes (r = 0.28, p <0.02), number of years smoking (r = 0.41, p <0.001) and cotinine (r = 0.45, p <0.01), the tissue culture of endothelial cells with physiological levels of thiocyanate or nicotine suggested that these two smoking markers were not cytotoxic. They are therefore unlikely to be directly responsible for increased von Willebrand factor in the serum of smokers. We suggest that smoking exerts a deleterious influence on the endothelium and that the mechanism is complex.
A Prospective, Randomized Trial of Prednisone and Cyclophosphamide in the Treatment of Patients with Factor VIII Autoantibodies
Authors: Green David , Rademaker Alfred W , Briët Ernest 
Published: July 2018

SummaryThirty-one non-hemophilic patients with acquired antibodies to factor VIII were entered into a prospective, randomized, multi- institutional trial to determine the safety and efficacy of prednisone (P), cyclophosphamide ©, or the combination in the treatment of this disorder. Patients were eligible if they had antibody demonstrated by the Bethesda assay, had not received these agents previously, and gave informed consent. All patients were treated initially with P, 1 mg/kg, for 3 weeks. If the antibody persisted and there was no rise in factor VIII activity, patients were randomized to either continue P for an additional 6 weeks; taper P and begin C, 2 mg per kg; or continue P and add C. Antibody disappeared in 10 during the initial P therapy, and in three of four others randomized to continue on P; one patient was discontinued because of an herpetic infection. Antibody disappeared in three of six patients treated with C alone, and five of ten given C and P. The titer of antibody was significantly lower in responders than in non-responders (p = 0.003), but seven patients with titers of more than five Bethesda units had complete remissions. There was no difference in antibody titers between those responding to P and those responding to C. We conclude that all patients with acquired antibodies to factor VIII should receive initial management with P, and that C is effective as second-line therapy for many of those who are steroid-resistant.
Female Twins with Severe Christmas Disease (Hemophilia B)
Authors: Wollina Karin , Bowen D J , Syrbe G , Zintl F 
Published: July 2018

SummaryHemophilia B is an X-linked bleeding disorder. We report on female twins, who were conspicious in prolonged bleeding after venipuncture as well as hematomas after intramuscular injections even in the first months of their life. Their father suffering from a severe hemophilia B deceased in 1992. Their mother, half-brother and grandmother from their father’s side had no signs of bleeding disorders. Clotting analysis performed in both twins revealed a markedly prolonged partial thromboplastin time (>100 s). The factor IX levels were below 2%. In order to detect mutations, a general screen using the polymerase chain reaction (PCR) followed by single strand conformation polymorphism (SSCP) analysis of the PCR products have been performed. PCR products have been cut into smaller fragments using restriction endonucleases (RE) for an in-depth SSCP screen. A general screen for gross abnormalities in the factor IX gene including deletions, insertions and rearrangements was performed by Southern blot analysis of RE-digests of genomic DNA using the factor IX cDNA as a hybridization probe. Furthermore, we screened for mutations in the CG dinucleotides comprising part of RE-recognition sequences (exon 1, 2, 3, 4, 5, and 8). By all methods applied herein, no mutations have been detected in these twins. On the basis of our results the hemophilia B of these twins might be explained by extreme non-random lyonization.
Synergistic Antiplatelet Effect of Ridogrel, a Combined Thromboxane Receptor Antagonist and Thromboxane Synthase Inhibitor, and UDCG-212, a cAMP-Phosphodiesterase Inhibitor
Authors: Hoet B , Arnout J , Deckmyn H , Vermylen J 
Published: July 2018

SummaryRidogrel, a combined thromboxane receptor antagonist and thromboxane synthase inhibitor (1), inhibits platelet aggregation. Following stimulation with arachidonic acid, cAMP-levels are increased in human platelets preincubated with ridogrel, this is due to the known reorientation of the metabolism of the formed endoperoxides towards adenylate cyclase stimulating prostaglandins.Pretreatment of resting platelets with UDCG-212, a cAMP-phosphodiesterase inhibitor (2), also inhibits platelet aggregation induced by arachidonic acid, concomitant with an increase in cAMP levels, due to an inhibition of its breakdown. Under basal conditions, cAMP also is increased.By combining the two drugs, a more than additive action was observed on platelet aggregation and on both resting and stimulated platelet cAMP content. The appropriate combination may result in a more effective antiplatelet strategy.
Two Independent Binding Sites on Monolayers of Human Endothelial Cells Are Responsible for Interaction with Coagulation Factor VII and Factor VIIa
Authors: Reuning Ute , Preissner Klaus T , Müller-Berghaus Gert 
Published: July 2018

SummaryThe interaction of radiolabeled factor VII (FVII) and factor VIIa (FVIIa) with endotoxin-stimulated endothelial cells (EC), known to express tissue factor (TF), and unstimulated EC was studied. FVII/FVIIa binding to EC-monolayers was saturable within 4.5-6 h, reversible, temperature and calcium dependent on both, endotoxin-stimulated and on unstimulated EC. Upon 2 h of incubation on EC, FVII was partially converted to FVIIa in the absence of protease inhibitors. The affinity of this binding was K
d = 45.4 ± 18.7 nM with a calculated number of binding sites B
max = 3.75 ± 0.31 × 106 molecules/cell. In addition to unlabeled FVII and FVIIa, other vitamin K-dependent proteins reduced binding of [125I]-FVII/FVIIa to about 60-70%, and this type of common binding site for vitamin K-dependent proteins revealed a K
d = 32.2 ± 5.6 nM and a B
max = 3.03 ± 0.14 × 106 molecules/cell. Moreover, in the presence of 1 μM prothrombin to suppress common binding sites, only on endotoxin-stimulated EC additional inhibition of FVII/FVIIa binding was achieved by anti-TF antibodies. The characteristics of the FVII/FVIIa-TF interaction with a K
d = 17.2 ± 5.2 nM and a B
max = 342,000 ± 1,100 binding sites/cell revealed a similar saturation kinetics in radioligand binding and in functional factor X activation within 90-120 min. These data indicate the presence of at least two independent binding sites for FVII/FVIIa on stimulated EC of which about 10% are TF specific. The existence of binding sites common for vitamin K-dependent proteins on both types of EC may improve the availability of FVII/FVIIa once EC become stimulated and express TF on their surface.
Influence of Long Term Oral Anticoagulants upon Prothrombin Fragment 1 + 2, Thrombin-Antithrombin III Complex and D-Dimer Levels in Patients Affected by Proximal Deep Vein Thrombosis
Authors: Elias A , Bonfils S , Daoud-Elias M , Gauthier B , Sié P , Boccalon H , Boneu B 
Published: July 2018

SummaryWe have investigated the influence of long term oral anticoagulants (OAC) upon the plasma levels of prothrombin fragment 1 + 2 (F1 + 2), of thrombin-antithrombin III complexes (TAT) and of D-Dimer in 20 patients affected by a proximal deep vein thrombosis (DVT) diagnosed by ultrasonic duplex scanning. Patients (63 ± 17 years, mean ± SD) were sampled at the beginning of the OAC treatment (day 1), which was started 1 to 6 days after diagnosis confirmation and full heparinization, and then 8, 35 and 92 days after. The results were compared to those obtained in a blood donor population (39 ± 10 years) and to an age-matched healthy population (63 ± 19 years). The mean INR determined on days 8, 35 and 92 were almost identical (2.8 ± 0.7, 2.9 ± 0.9 and 2.8 ± 0.6 respectively). In contrast, highly significant variations of the three markers were recorded during the observation period. Eight days after the beginning of OAC, increased levels of TAT complexes were associated with subnormal levels of F1 + 2 suggesting persistence of a hypercoagulable state. On the further sampling times, TAT complexes were in the normal range while F1 + 2 were far below the normal range. Between day 1 and day 92, the levels of D-Dimer continuously decreased reflecting a long-term fibrinolytic process.This study clearly indicates that high INR are not systematically associated with very low F1 + 2 levels, particularly in the acute phase of thrombosis. Whether or not it is possible to reduce the intensity of the anticoagulant treatment 1 month after its initiation on the basis of very low levels of F1 + 2 can only be determined by prospective clinical trials.
Thrombotic and Hemorrhagic Complications in Patients with Mechanical Heart Valve Prosthesis Attending an Anticoagulation Clinic
Authors: Cortelazzo S , Finazzi G , Viero P , Galli M , Remuzzi A , Parenzan L , Barbui T 
Published: July 2018

SummaryThis study evaluated the advantage of an anticoagulation clinic in terms of the improvement of the clinical quality of oral anticoagulation (i.e. prevention of thromboembolism and low rate of hemorrhagic complications). The incidence of thromboembolic events and major hemorrhagic complications was assessed in a series of 271 patients on oral anticoagulation for mechanical heart valve prosthesis before and after their enrollment in our anticoagulation clinic from January 1987 to December 1990. Risk factors for hemostatic events were also analyzed. The incidence of major hemostatic complications was significantly lower when patients attended the clinic: 1.0 vs 4.9%/pt-yr for hemorrhage and 0.6 vs 6.6%/pt-yr for thrombosis. This depended on three main factors: better dose regulation of warfarin, continuous patient education and early identification of clinical conditions potentially at risk for thrombosis and hemorrhage. Only previous hemorrhagic or thromboembolic events were recognized as major risk factors for hemostatic complications.In conclusion, our study shows that an anticoagulation clinic offers a real advantage to patients with mechanical heart valve prosthesis in terms of prevention of thromboembolic events and hemorrhagic complications.
Distribution of Tissue Factor Pathway Inhibitor in Normal and Malignant Human Tissues
Authors: Werling Robert W , Zacharski Leo R , Kisiel Walter , Bajaj S Paul , Memoli Vincent A , Rousseau Sandra M 
Published: July 2018

SummarySpecific antibodies to tissue factor pathway inhibitor (TFPI) were used in immunohistochemical procedures to determine the distribution of TFPI in normal and neoplastic human tissues. TFPI was restricted to megakaryocytes and the endothelium of the microvasculature in normal and abnormal tissues, but was not found in the endothelium of larger vessels or in hepatocytes. TFPI was also detected in macrophages in the villi of term placenta. Tumor-associated macrophages in several types of malignancy that we have shown previously to express a complete tissue factor-initiated pathway of coagulation and thrombin generation also manifested TFPI. By contrast, malignant cells in small cell carcinoma of the lung, renal cell carcinoma, and malignant melanoma that we have shown previously to express coagulation factors together with tumor cell-associated fibrin formation failed to stain for TFPI. We postulate that TFPI may be lacking from the latter malignancies because of the absence of the appropriately configured tissue factor – factor VII a – factor Xa complex required for TFPI binding.
Role of Urokinase Type Plasminogen Activator (u-PA) in Corneal Epithelial Migration
Authors: Morimoto Keisuke , Mishima Hiroshi , Nishida Teruo , Otori Toshifumi 
Published: July 2018

SummaryThe role of plasminogen activator (PA) in the migration of comeal reepithelialization was studied. Rabbit corneal blocks were cultured, and both the extent of epithelial migration over the exposed corneal stroma and the activity of PA released into the culture media were measured. A significant, direct correlation between epithelial migration and PA activity in the medium was observed, even when the migration was stimulated by fibronectin or EGF, or was inhibited by cytochalasin B or cycloheximide. Zymography confirmed that the PA released into the culture medium was of the urokinase type (u-PA). Immunohistochemical studies showed that u-PA and plasmin(ogen) were present at the leading edge of the migrating epithelium. Studies of corneal cell cultures indicated that epithelial cells rather than endothelial cells or fibroblasts were the source of the u-PA. The addition of anti-human u-PA IgG or protease inhibitors retarded the migration of the comeal epithelium in a dose-dependent manner, indicating that u-PA activity is essential for the migration of the corneal epithelium. These findings suggest that the migration of corneal epithelial cells requires not only cell attachment to the extracellular matrix through the fibronectin but also degradation of the fibronectin by the release of cellular u-PA.
Characterization of a Form of Bovine Factor VIII Which Does Not Aggregate Human Platelets
Authors: Kirby Edward P 
Published: July 2018

SummaryFractionation of partially purified bovine factor VIII on tricalcium citrate columns produces a material which contains high levels of factor VIII procoagulant activity and factor VIII- related antigen, but does not aggregate human platelets. The procoagulant activity can be blocked by human inhibitors of factor VIII: C and by rabbit antibody to bovine factor VIII. Its activity can be increased by thrombin modification. The apparent molecular weight of this form of factor VIII is significantly lower than that of the forms of factor VIII which contain platelet aggregating activity, and it exhibits a higher mobility on agarose electrophoresis.
Quantitation of Human Platelet Transformation on Siliconized Glass: Comparison of “Normal” and “Abnormal” Platelets
Authors: Rosenstein R , Zacharski L R , Allen R D 
Published: July 2018

SummaryA series of typical morphological stages, representing progression of transformation, may be defined following adhesion of platelets to a siliconized glass surface. Platelets are visualized by new light microscopic techniques that allow quantitative categorization of transformation of large platelet populations by morphological stage, and thus the detection and elucidation of platelet defects which influence transformation. Living platelets from each of five subjects with bleeding disorders, due to platelet defects, exhibited a pattern of morphologic transformation which differed from normal. In addition, the pattern observed with the platelets from a subject with Glanzmann’s thrombasthenia was sufficiently different from that observed with the platelets from four subjects with thrombopathy, so as to point to a qualitative difference in the activity of the platelets in the two disorders. These findings indicate that the analysis of platelet transformation in vitro through the use of light microscopy may allow for detection and further classification of platelet abnormalities.
Testosterone Potentiation of Ionophore and ADP Induced Platelet Aggregation : Relationship to Arachidonic Acid Metabolism
Authors: Pilo R , Aharony D , Raz A 
Published: July 2018

SummaryThe role of arachidonic acid oxygenated products in human platelet aggregation induced by the ionophore A23187 was investigated. The ionophore produced an increased release of both saturated and unsaturated fatty acids and a concomitant increased formation of TxA2 and other arachidonate products. TxA2 (and possibly other cyclo oxygenase products) appears to have a significant role in ionophore-induced aggregation only when low concentrations (<1 μM) of the ionophore are employed.Testosterone added to rat or human platelet-rich plasma (PRP) was shown previously to potentiate platelet aggregation induced by ADP, adrenaline, collagen and arachidonic acid (1, 2). We show that testosterone also potentiates ionophore induced aggregation in washed platelets and in PRP. This potentiation was dose and time dependent and resulted from increased lipolysis and concomitant generation of TxA2 and other prostaglandin products. The testosterone potentiating effect was abolished by preincubation of the platelets with indomethacin.
The In Vitro Inhibitory Effect on Thrombin by 2,3-Diphosphoglycerate
Authors: Principe D Del , Strappini P M , Vecchio S Del , Menichelli A , Biancini G , Cosmi E V , Bastianon V , D’Arcangelo C 
Published: July 2018

SummaryThrombin, incubated with 2,3-diphosphoglycerate (150 nmol 2,3-DPG/1 NIH thrombin unit) lost up to 70% of its clotting activity, whereas the esterase activity remained unchanged. No fibrinopeptide release by thrombin was observed in the presence of 2,3-DPG. The fibrin polymerization was normal. By chromatography on Amberlite IRC-50, α-thrombin was eluted at pH 8.0. In presence of 2,3-DPG, α-thrombin was not eluted. Likely, 2,3-DPG can interfere with thrombin.
Thermography in the Diagnosis of DVT
Authors: Lockner Dieter , Paul Christer , Hedlund Birger , Schulman Sam , Nyman Dag 
Published: July 2018

Summary161 consecutively admitted medical patients with the clinical suspicion of acute deep venous thrombosis (DVT) were thermographed and phlebographed in order to study the congruence of these methods. The sensitivity of thermography in the detection of DVT was found to be 99%, whereas the specificity was only 49%.The low specificity is explained by the fact that all thermographs suggestive of DVT were classified as pathologic to keep the sensitivity of the method as high as possible. Patients with dilated veins which may closely resemble DVT on thermography may in these cases give false positive results.Of 76 patients with phlebographically verified DVT, 22% became thermographically normal within 22 days, whereas 78% did not normalize within the mean observation time of 31 days.In another part of the study all medical patients (101) who were residing in our wards during a period of a week were screened by means of thermography. From this unselected group 17 patients were found to have thermographs suggestive of DVT. In 5 of these patients no reason for pathological thermography could be found.Thermography is a cheap and highly sensitive screening method for DVT, but findings of false positives caused by older thromboses and dilated veins are not unusual. The frequency of such false positives may be minimized by performing thermography after exercise.
Autopsy Findings in an Elderly Man Suffering from Severe von Willebrand’s Disease
Authors: Kernoff Leslie M , Rose Alan G , Hughes Jane , Jacobs Peter 
Published: July 2018

SummaryA platelet derived growth factor released following platelet adhesion to the subendothelium of damaged arteries may promote the development of atherosclerotic lesions. Consequently patients with von Willebrand’s disease in whom platelet adhesion is abnormal may be protected from atherosclerosis. This possibility was investigated by performing an autopsy study on an elderly patient who had suffered from severe von Willebrand’s disease. Extensive atherosclerotic lesions were found at post mortem suggesting that platelets may not play a clinically significant role in the causation of atherosclerosis
The Lupus Inhibitor: A Study of Its Heterogeneity
Authors: Coots M C , Miller M A , Glueck H I 
Published: July 2018

SummaryThe plasmas of six patients with prolonged activated partial thromboplastin times were studied in detail. In five of the six, the Russell’s viper venom and prothrombin times were likewise prolonged. Five of the patients had documented systemic lupus erythematosus; one lacked the necessary criteria for this diagnosis. On quantitation, factor XI was decreased in all six; factors X and XII were diminished in five of the six. When tested for inhibitory activity, plasma from each of the patients prolonged the celite eluate inhibition test for factor XII and/or XI inhibition. In the formation of the Xa-V-phospholipid-Ca2+ complex (prothrombinase), factors X and Xa were inhibited to a greater degree than factor V or the phospholipid. Finally, each plasma was isofocused, the inhibitory fractions were identified and the clotting factor specificity of each inhibitory peak was determined.Fractions inhibitory against factors XI and XII isofocused with the IgG in each patient’s plasma. Based on the data presented from these six patients, the “lupus inhibitor” is in fact a heterogeneous collection of inhibitors directed against factors XII, XI and X rather than a homogeneous entity.