bluuebunny/crossref_metadata_2025_split huggingface dataset:
DDAVP Reduces Bleeding during Continued Hirudin Administration in the Rabbit
Authors: Bove Christina M , Casey Brenda , Marder Victor J 
Published: July 2018

SummaryHirudin is a potent thrombin inhibitor derived from the leech Hirudo medicinalis salivary gland which has considerable potential for therapeutic use in thrombotic disease. The major risk attendant its use is hemorrhage. This study investigates the hypothesis that the prohemostatic effects of DDAVP infusion can curtail the hemorrhagic effect induced by ongoing hirudin administration.In a randomized and blinded manner, rabbits were exposed to a 15-min intravenous infusion of DDAVP or saline midway through a continuous two-h intravenous infusion of hirudin. Bleeding time was monitored by full thickness ear punctures performed before, during and after hirudin exposure.Hirudin induced a significant hemorrhagic state, manifest as a 7-10-fold prolongation of the primary bleeding time. DDAVP reduced the mean duration of primary bleeding from 10.8 min to 5.9 min (p = 0.001) as well as the number of sites which bled for longer than 6 or 20 min (46% vs 27%, p = 0.002; and 18% vs 5%, p = 0.002, respectively). Although there was no difference in the incidence of spontaneous rebleeding from these sites (44 vs 36%, p = 0.21), rebleeding did not persist as long in animals that received DDAVP (8 vs 16 min, p = 0.005), and fewer sites rebled for longer than 20 min (8 vs 27%, p = 0.027). Results were essentially the same for two different commercial recombinant hirudin preparations.DDAVP appears to attenuate the bleeding caused by continuous hirudin infusion in rabbits and establishes a foundation for clinical assessment in patients.
The Relationship between Plasma Microparticles, Protein S and Anticardiolipin Antibodies in Patients with Human Immunodeficiency Virus Infection
Authors: Gris Jean-Christophe , Toulon Pierre , Brun Sophie , Maugard Claude , Sarlat Christian , Schved Jean-François , Berlan Jocques 
Published: July 2018

SummaryThe high prevalence of free protein S deficiency in human immunodeficiency virus (HlV)-infected patients is poorly understood. We studied 38 HIV seropositive patients. Free protein S antigen values assayed using the polyethylene-glycol precipitation technique (PEG-fS) were statistically lower in patients than in controls. These values using a specific monoclonal antibody-based ELISA (MoAb-fS) and the values of protein S activity (S-act) were not statistically different between patients and controls. C4b-binding protein values were not different from control values. In patients, PEG-fS values were lower than MoAb-fS values. Ten patients had a PEG-fS deficiency, 4 patients had a MoAb-fS deficiency and 8 had a S-act deficiency. Protein S activity and MoAb-fS were lower in clinical groups with poor prognosis and in patients with AIDS but PEG-fS was not. A trend for reduced S-act/MoAb-fS ratios was observed in patients. PEG-fS was negatively correlated with anticardiolipin antibody titers whereas MoAb-fS was not. The plasma of PEG-fS deficient HIV-patients contained high amounts of flow cytometry detectable microparticles which were depleted from plasma by PEG precipitation. The microparticles were partly CD42b and CD4 positive but CD8 negative. These microparticles were labelled by an anti free protein S monoclonal antibody. The observed differences between MoAb-fS and PEG-fS values were correlated with the amount of detectable plasma microparticles, just like the differences between MoAb-fS and S-act. Plasma microparticles correlated with anticardiolipin antibody titers.In summary, free protein S antigen in HIV infected patients is underestimated when the PEG precipitation technique is used due to the presence of elevated levels of microparticles that bind protein S. The activity of free protein S is also impaired by high levels of microparticles. The prevalence of free protein S deficiency in HIV positive patients is lower than previously published (4/38, -10%) and is correlated with poor prognosis. By implication, use of a PEG precipitation technique might give artefactually low free protein S antigen values in other patient groups if high numbers of microparticles are present. In HIV patients, high titers of anticardiolipin antibodies are associated with high concentrations of cell-derived plasma microparticles.
Differential Effects of Warfarin on the Intracellular Processing of Vitamin K-dependent Proteins
Authors: Wu Wei , Bancroft John D , Suttie J W 
Published: July 2018

SummaryThe vitamin K-dependent carboxylation of specific glutamyl residues to γ-carboxyglutamyl residues occurs during the endoplasmic reticulum processing of a limited number of proteins. The fate of the under-γ-carboxylated proteins during protein processing was studied. When human hepatoma (HepG2) cells were grown in the presence of warfarin, under-γ-carboxylated prothrombin was secreted into the medium. In contrast, prothrombin secretion from a rat hepatoma (H-35) cell line was blocked by warfarin, and intracellular forms which were retained were degraded. When rat prothrombin (rFII) was stably transfected into warfarin treated HepG2 cells, endogenous human prothrombin (hFII) was secreted in an under-γ-carboxylated form, while rFII accumulated intracellularly. These data indicate that retention and degradation of under-γ-carboxylated prothrombin by human hepato-cytes is related to a structural difference in rFII and hFII. When rFII and hFII were transfected into a warfarin treated transformed human embryonic kidney cell line (293), both proteins were secreted in an under-γ-carboxylated form and intracellular retention was not observed. However, the secretion of rFII was greatly diminished. Cellular retention of under-γ-carboxylated forms is therefore tissue specific, but degradation is not.
A Mutant (Arg327→His) GPIIb Associated to Thrombasthenia Exerts a Dominant Negative Effect in Stably Transfected CHO Cells
Authors: Ferrer Milagros , Fernandez-Pinel Marta , Gonzalez-Manchon Consuelo , Gonzalez Jose , Ayuso Matilde S , Parrilla Roberto 
Published: July 2018

SummaryThis work reports the structural and functional characterization of the platelet glycoprotein complex GPIIb-IIIa (integrin αIIbβ3) in a patient of type II Glanzmann thrombasthenia, bearing a homozygous G→A base transition at position 1074 of GPIIb that results in an Arg327→His substitution.CHO cells stably transfected with cDNA encoding His327GPIIb showed a drastic reduction in the surface expression of αIIbβ3 complex relative to control cells transfected with wild type GPIIb. Immunopre-cipitation analysis demonstrated that GPIIb synthesis, heterodimeriza-tion, and short term maturation were not impeded, suggesting that conformational changes dependent on Arg327 of GPIIb may play an essential role in either the rate of maturation and/or transport of heterodimers to the cell surface.Cotransfection of CHO cells with equimolar amounts of cDNAs encoding wild type and mutant His327-GPIIb led to a marked reduction in the surface expression of αIIbβ3. This novel observation of a dominant-negative effect of the mutant His327αIIb subunit provides a molecular basis for the reduced platelet αIIbβ3 content observed in the heterozygous offspring.
Results of a Screening for von Willebrand Disease Type 2N in Patients with Suspected Haemophilia A or von Willebrand Disease Type 1
Authors: Schneppenheim Reinhard , Budde Ulrich , Krey Sonja , Drewke Elke , Bergmann Frauke , Lechler Eberhard , Oldenburg Johannes , Schwaab Rainer 
Published: July 2018

SummaryA screening program for the detection of patients with von Willebrand disease type 2N (VWD 2N) was carried out in 177 unrelated patients previously diagnosed with haemophilia A and in 199 unrelated patients with VWD type 1 in comparison. By measuring the factor VIII (FVIII) binding capacity of von Willebrand factor (VWF), we detected 13 patients with VWD 2N within 8 unrelated families. The former diagnosis has been haemophilia A in 5 index patients, and VWD in the remaining 3. Included in this study were 14 patients with suspected haemophilia A, whose molecular analysis for mutations in the FVIII gene was unsuccessful. Five of them had VWD 2N. In all patients with the VWD 2N phenotype we were able to identify specific molecular defects in the corresponding DNA sequence of the FVIII binding domain of VWF. The most common defect was R91Q. Four patients from 4 families were homozygous for R91Q, six patients from 3 families were compound heterozygous for R91Q and a silent yet unidentified allele. The VWD 2N phenotype of father, daughter, and son in one family, was based on 2 different genotypes, compound heterozygosity for R91Q and VWD type 1 in the father and the daughter, and homozygosity for R91Q in the son. Two patients from one family were compound heterozygous for T28M and ΔC2680-2685 in exon 18, and one patient was compound heterozygous for a novel candidate missense mutation in exon 18 (E24K) and ΔC2680-2685 in exon 18 which is regarded the most common defect causing severe VWD type 3. FVIII:C values of 0.07 and 0.14 IU/ml were observed in patients with the genotype T28MIΔC2680-2685 whereas in patients being homozygous or compound heterozygous for R91Q, FVIII:C was 0.19 ° 0.071 IU/ml. In contrast to the other genotypes, E24KIΔC2680-2685 is correlated with a more severe haemophilic phenotype with a FVIII residual activity of only 0.01-0.02 IU/ml. This emphasizes the need for inclusion of the factor VIII binding assay in the diagnostic workup of suspected haemophilia A.
Familial And Constitutional Moderate Bleeding Disorder Associated With Defective Platelet Cyclo-Oxygenase
Authors: Lecrubier C , Fouque F , Chignard M , Horellou M H , Conard J , Vargaftig B B , Samama M 
Published: July 2018

Three family members from two successive generations showed a moderate bleeding disorder. The bleeding times (Duke and Ivy-Borchgrevink) were both constantly prolonged. Platelet aggregation induced by ADP and adrenaline showed no second wave; collagen at low to moderate concentrations failed to aggregate and release ATP whereas higher amounts aggregated and released. Aggregation and release due to thrombin, ristocetin and synthetic epoxy derivatives (U 44069 and U 46619) were normal. Arachidonate (A.A.) was inactive and was not converted into thromboxane (TX) A2 activity evaluated on the rabbit aorta strip. The patient’s platelets did not respond to A.A. when PRP from an aspirin treated control was added. Platelet phospholipids (PL) were labelled by 14C - A.A. before stimulation by thrombin (T). Radioactivity of the PL of the propositus' platelets was affected with T to a similar extent as 5 laboratory controls, indicating that the phospholipase activity was not impaired. In contrast, no TXB2 was found: 0.9 p. cent as compared to 6 p. cent of total radioactivity in controls.Our data suggest a deficit in cyclo-oxygenase particularly since the levels of PGE2, PGF2a and PGD2 were within the limits of detection. These results seem to rule out the possibility of a TX-synthetase deficiency with excessive production of anti-aggregating PGs. This study suggests that transmission is autosomal dominant and confirms that cyclo-oxygenase is not needed for aggregation and ATP-release by high amounts of collagen.
Anti-Xa Potentiating Effect Of Low Molecular Weight Heparin
Authors: Junker W , Harenberg J , Fussi F , Mattes K , Zimmermann R , Weber E 
Published: July 2018

Recently special attention has been drawn to bleeding complications of commercial heparins in patients with increased risk for haemorrhages. Alternative heparin preparations with high antithrombotic and low haemostaseological properties have been developed. We now report on a new low molecular weight (LMW) heaprin (mean MW 5000, 85 USP/mg), which has been obtained by depolymerisation of a heparin from pig intestinal mucosa (mean MW 15000, 154 USP/mg).In vitro the anti-Xa-activity (chromogenic substrate S2222) was 15% higher for the LMW heparin in a range of 0.01-2.0 USP/ml plasma. No difference was seen on the anti-IIa-activity (thrombin clotting time)and the aPTT for both heparins in the same range. Both Heparins were injected s.c. in a dose of 100, 50 and 25 USP/kg bodyweight into each of six volunteers randomly at weekly intervalIs. The pharmacodynamic effects were controlled for 6-10 hrs by 8-12 blood samples in relation to the dose applied. Increasing dosis the effects of each heparin increased in all test systems. The anti- Xa-activity of LMW heparin was somewhat higher at 100 and 25 USP/kg. At 50 USP/kg the effect of LMW heaprin was in the same range as 100 USP/kg of the original preparation (MW 15000). The factor Ila activity and aPTT were not influenced differently by the two heparins at each dose.The data indicate, that the LMW heparin presented here may have a more pronounced antithrombotic property by a specific anti-Xa-activity than the compaired commercial heparin. This effect is most pronounced at doses, which have only small haemostaseological effects.
Influence Of Blood Flow On Platelet Interaction With The Vessel Wall And Thrombosis
Authors: Goldsmith H L , Karino T 
Published: July 2018

Fluid mechanical factors play an important role in platelet aggregation in the circulation and platelet interaction with vessel walls. Theory and experiment show that, at the high rates of shear prevailing in flow near the vessel walls, inwardly directed forces cause single blood cells to migrate toward the axis. At normal hematocrits, however, migration is opposed by an outward dispersion due to the continual, shear-induced interactions between red cells. The latter also leads the less numerous platelets to move in directions normal to the flow and to collide with the wall at rates which increase with the hematocrit. Thus, there exists a mechanism providing for the presence of platelets close to the endothelium and enabling them to adhere to sites of vessel injury.More important with respect to thrombosis and wall adhesion are the flow patterns and fluid stresses existing at bifurcations, T-junctions, curved segments and stenoses in the arterial circulation, and at valves in the venous circulation. Here, flow is disturbed, the mainstream may separate from the vessel wall and a vortex forms in the region vacated by the flow. Using a glass model of a symmetrical stenosis, we have shown that in the absence of any aggregating agents, platelets circulating and colliding with each other in the orbits of the annular vortex distal to the stenosis form small aggregates which rapidly grow and are trapped in the vortex. Moreover, the adhesion of platelets to the collagen-coated wall exhibit a peak on either side of the reattachment point of the flow. This is explained by curvature of the streamlines carrying platelets to the wall. Detailed studies of vortices having similar flow patterns have been made at bifurcations and T-junctions in models as well as in cleared, fixed arteries, and in veins with bileaflet valves. The phenomena described will be illustrated with a 16 mm ciné film.Supported by MRC, Canada, and the Quebec Heart Foundation.
Blood Group (BG) Prevalence In End-Stage (ES) Renal Disease (RD): Relationship To Ristocetin Willebrand Factor (VIII: RWF) And Platelet Survival (PS)
Authors: Torres V , Fuster V , Moore B , Donadio J , Kazmier F , Bowie E 
Published: July 2018

BG 0 patients (pts) have lower risk for cardiovascular-thromboembolic disease than A-AB-B pts, particularly males. This might be related to blood hypocoagulability (lower Factor VIII). We report BG frequencies in our Caucasian renal transplant population divided in two groups, ES reflux nephropathy (RN) and ESRD of other etiologies excluding diabetes mellitus.BG 0 male pts are protected, especially for ESRN. To determine whether this sex dependency could be related to different VIII: RWF levels or PS, VIII:RWF levels (n=82) and 51Cr-labelled PS (n=74) were analyzed in controls according to sex and BG.VIII: RWF is sex independent and lower in BG 0. PS is BG independent and shortened in males. A hypercoagulable State reflected by high VIII: RWF and short PS might explain the increased risk of non-BG 0 males to develop ESRD. Non-BG 0 male pts with RN may be more susceptible to develop progressive RD.
The Use Of High Performance Liquid Chromatography In The Examination Of The Lipid Class Composition Of Thromboplastin Reference Preparations
Authors: Stevenson K J 
Published: July 2018

A pressure liquid chromatographic method has been developed for separation and quantitation of lipid classes of reference thromboplastins.The method employs a column of high capacity silica, eluted with a three-component gradient system. Detection is by a “moving-wire” flame ionization detector. Fractions of column effluent may be collected for further examination.Three reference thromboplastins of rabbit, bovine and human (British Comparative Thromboplastin) origin have recently been prepared for the European Economic Community. Markedly contrasting lipid class compositions of these preparations have been detected with this method. The human preparation contains more lipid (13 g/1) than the rabbit (7 g/1) and bovine (3 g/1) preparations and less negatively-charged phospholipid (7.5% compared with 11% and 18% respectively). The animal preparations contained plasmalogens not found in the human material. The significance of these differences in terms of the predicted stability of these reference reagents is considered.
A Novel Animal Model For Plasma Hypercoagulability
Authors: Harenberg J , Stehle G , Haas R , Zimmermann R 
Published: July 2018

A sensitive and reproducable animal model for plasma hypercoagulability has not been described so far. We report now on the determination of fi- brinopeptide A immunoreactivity (FPAi) in rabbit blood. Human FPA antiserum of the rabbit was used. The radioimmunological method with a high affinity second antibody was described previously.The experiments were carried out in 90 rabbits, which were allocated randomly to one of the treatment groups. Normal FPAi in rabbits were 3-21 ng/ ml plasma (mean 12.5 ng/ml). In 12 rabbits only basline FPAi was determined. In 28 rabbits 6|ig, 3ug, 1.5μg sythetic FPA analog/kg bodyweight or saline were injected i.v. The elimination of FPA from blood followed a two phase kinetic without dose dependence. A t/2 of 20 sec was calculated for the a-phase and of 90 sec for the ß-phase. The in vivo recovery of FPA was more than 95%. After saline no changes of FPAi were measured. In 50 rabbits 10mg, 5mg, 2.5mg, 0.66mg phenprocoumon/kg bodyweight or saline were injected i.p. A standardized haematoma was obtained by puncture of the ear artery. After saline an increase of FPAi from 15.0 to 45.7 ng/ml was measured after three days. (p < 0.05). This increase could be inhibited by phenprocoumon in relation to the dose applied.The data indicate, that the animal model may be appropriate to induce plasma hypercoagulability and useful to investigate trigger mechanisms and the treatment of plasma hypercoagulability. Determination of FPAi in rabbits seem to be sensitive enough to study these problems as shown by the dose related decrease of FPAi under treatment with phenprocoumon after a standardized arterial lesion.
Prothrombin Frankfurt: A Dysfunctional Prothrombin Characterized by Substitution of Glu-466 by Ala
Authors: Friezner Degen Sandra J , McDowell Susan A , Sparks Leah M , Scharrer Inge 
Published: July 2018

SummaryWe have identified a patient with a dysfunctional prothrombin that we have designated Prothrombin Frankfurt. The proband was characterized by a prothrombin activity level of 13% and 20% compared to normal controls using two different assays with a normal prothrombin antigen level of 91% of normal controls. The genetic defect responsible for the abnormal prothrombin activity was determined by the polymerase chain reaction followed by single-strand conformation polymorphism (PCR-SSCP) analysis and by DNA sequence analysis of the human prothrombin gene. Substitution of a C for an A at nucleotide 10177 in the human prothrombin gene of the proband was identified, which results in the replacement of Glu-466 by Ala. The proband and one sister were homozygous for this mutation. Both parents, as well as one brother, were found to be heterozygous for this mutation. The same amino acid substitution was previously identified to be responsible for the dysfunctional protein Prothrombin Salakta and was hypothesized to result in altered substrate specificity. Four polymorphisms were also identified in the prothrombin gene from the proband when compared to the published sequence at nucleotides 554, 4048, 4272 and 10253.
Determinants of Plasminogen Activator Inhibitor-1 Activity in Survivors of Myocardial Infarction
Authors: Gray Rosaire P , Mohamed-Ali Vidya , Patterson David L H , Yudkin John S 
Published: July 2018

SummaryA significant relationship has been described between plasminogen activator inhibitor-1 (PAI-1) and plasma insulin concentrations. However, most radioimmunoassays (RIA) substantially overestimate plasma insulin concentrations because of cross reaction with proinsulin-like molecules and it has been proposed that proinsulin-like molecules may be important determinants of PAI-1 activity. We measured fasting plasma immunoreactive insulin by conventional RIA, fasting plasma insulin (EIMA) by specific two site immuno-enzymometric assay, and intact proinsulin and des-31,32-proinsulin by two site immunoradiometric assay (IRMA) in 74 (50 nondiabetic and 24 diabetic) subjects who had survived a myocardial infarction between 6 and 24 months previously. In univariate analysis, PAI-1 activity correlated with serum triglycerides (rs=0.43; p <0.0001), insulin sensitivity (rs = -0.30; p = 0.004), and immunoreactive insulin (rs = 0.45; p <0.0001). However, the relationship between PAI-1 activity and plasma specific insulin (IEMA) was weaker (rs = 0.24; p = 0.019) than those with intact proinsulin (rs = 0.53; p <0.0001) and des-31,32-proinsulin (rs = 0.54; p <0.0001) despite the low concentrations of these proinsulin-like molecules. In multiple regression analysis, only des-31,32-proinsulin (p = 0.001) and serum triglycerides (p = 0.013) were significant determinants of PAI-1 activity. In conclusion, these results suggest that proinsulin-like molecules and serum triglycerides are important determinants of PAI-1 activity in survivors of myocardial infarction.