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Introduction: Known genetic variants with reference to preeclampsia only explain a proportion of the heritable contribution to the development of this condition. The association between preeclampsia and the risk of cardiovascular disease later in life has encouraged the study of genetic variants important in thrombosis and vascular inflammation also in relation to preeclampsia. The von Willebrand factor-cleaving protease, ADAMTS13, plays an important role in micro vascular thrombosis, and partial deficiencies of this enzyme have been observed in association with cardiovascular disease and preeclampsia. However, it remains unknown whether decreased ADAMTS13 levels represent a cause or an effect of the event in placental and cardiovascular disease., Methods: We studied the distribution of three functional genetic variants of ADAMTS13, c.1852C>G (rs28647808), c.4143_4144dupA (rs387906343), and c.3178C>T (rs142572218) in women with preeclampsia and their controls in a nested case-control study from the second Nord-Trøndelag Health Study (HUNT2). We also studied the association between ADAMTS13 activity and preeclampsia, in serum samples procured unrelated in time of the preeclamptic pregnancy., Results: No differences were observed in genotype, allele or haplotype frequencies of the different ADAMTS13 variants when comparing cases and controls, and no association to preeclampsia was found with lower levels of ADAMTS13 activity., Conclusion: Our findings indicate that ADAMTS13 variants and ADAMTS13 activity do not contribute to an increased risk of preeclampsia in the general population., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The complex relation between thrombotic thrombocytopenic purpura (TTP) and pregnancy is concisely reviewed. Pregnancy is a very strong trigger for acute disease manifestation in patients with hereditary TTP caused by double heterozygous or homozygous mutations of ADAMTS13 (ADisintegrin And Metalloprotease with ThromboSpondin type 1 domains, no. 13). In several affected women disease onset during their first pregnancy leads to the diagnosis of hereditary TTP. Without plasma treatment mother and especially fetus are at high risk of dying. The relapse risk during a next pregnancy is almost 100% but regular plasma transfusion starting in early pregnancy will prevent acute TTP flare-up and may result in successful pregnancy outcome. Pregnancy may also constitute a mild risk factor for the onset of acute acquired TTP caused by autoantibody-mediated severe ADAMTS13 deficiency. Women having survived acute acquired TTP may not be at very high risk of TTP relapse during an ensuing next pregnancy but seem to have an elevated risk of preeclampsia. Monitoring of ADAMTS13 activity and inhibitor titre during pregnancy may help to guide management and to avoid disease recurrence. Finally, TTP needs to be distinguished from the much more frequent hypertensive pregnancy complications, preeclampsia and especially HELLP (Hemolysis, Elevated Liver Enzymes, Low Platelet count) syndrome., (© 2015 Elsevier Ltd. All rights reserved.)

Objective: In sepsis, activation of coagulation and inhibition of fibrinolysis lead to microvascular thrombosis. Thus, clot stability might be a critical issue in the development of multiple organ dysfunction syndrome. Activated FXIII (FXIIIa) forms stable fibrin clots by covalently cross-linking fibrin monomers. Therefore, we investigated the impact of FXIII antigen and activity levels on disease severity and fatality in sepsis patients., Patients and Methods: FXIII subunit A (FXIIIA) and FXIII cross-linking activity (FXIIICA) were measured in 151 controls, in 32 patients with severe sepsis and 8 with septic shock. In addition, FXIII subunit B (FXIIIB) was measured in the sepsis patients. Moreover, clotting parameters were determined., Results: Patients suffering from sepsis (n=40) had significantly (p<0.005) lower FXIIIA levels (median [range]: 36.5% [8.8-127.4%]) and FXIIICA levels (76.5% [9.4-266%]) as compared to healthy controls (n=151, 119% [31.3-283.2] and 122.4% [40.6-485.3], respectively). No difference in FXIIIA, FXIIIB and FXIIICA levels between survivors and non-survivors, nor between patients with severe sepsis and septic shock was found. The specific activity of FXIII (FXIIICA/FXIIIA, SA(FXIII)) was significantly (p<0.001) higher in sepsis patients (2.0 [0.8-5.3]) as compared to healthy controls (1.0 [0.4-5.1]). SA(FXIII) significantly (p<0.05) increased with fatality (non-survivors [n=13] vs. survivors [n=27]: 3.3 [1.2-5.0] vs. 1.9 [0.8-5.3]) and disease severity (septic shock vs. severe sepsis: 3.4 [1.8-4.3] vs. 1.9 [0.8-5.3])., Conclusion: We show decreased FXIIICA and FXIIIA levels, but higher SA(FXIII) in sepsis as compared to controls. Increased SA(FXIII) correlates with disease severity and fatality in sepsis patients.

Hereditary plasma prekallikrein (PK) deficiency was diagnosed in a 71-year-old man with an 8-year history of osteomyelofibrosis. PK deficiency was suspected in view of a severely prolonged activated partial thromboplastin time (aPTT) that nearly normalized following prolonged preincubation (10 min) of patient plasma with kaolin-inosithin reagent. Hereditary PK deficiency was demonstrated by very low PK values in the propositus (PK clotting activity 5%, PK amidolytic activity 5%, PK antigen 2% of normal plasma, respectively) and half normal PK values in his children. Normalization of a severely increased aPTT (>120 s) after prolonged preincubation with aPTT reagent occurred in plasma deficient in PK but not in plasma deficient in factor XII (FXII), high-molecular-weight kininogen (HK), factor XI (FXI), factor IX, factor VIII, Passovoy trait plasma or plasma containing lupus anticoagulant. Autoactivation of FXII in PK-deficient plasma in the presence of kaolin paralleled the normalization of aPTT. Addition of OT-2, a monoclonal antibody inhibiting activated FXII, prevented the normalization of aPTT. We conclude that the normalization of a severely prolonged aPTT upon increased preincubation time (PIT), characteristic of PK deficiency, is due to FXII autoactivation.

Low-molecular weight dextran sulfate (DXS 5000, M(r) 5 kDa) was found to control selectively complement activation without affecting contact activation. However, DXS 5000 being a glycosaminoglycan (GAG) may inhibit coagulation, which might bear the risk of bleeding complications and limit its clinical use. We investigated the influence of DXS 5000 on the prothrombin time (PT), the activated partial thromboplastin time (aPTT), the thrombin time (TT), the inhibitory capacity of human plasma against activated factor X (FXa), and on platelet function as assessed by the platelet function analyzer (PFA-100) and by platelet aggregation studies. The PT steadily increased with increasing DXS 5000 concentration, whereas the aPTT was already prolonged (>300 s) at low DXS 5000 concentrations (100 microg/ml). The TT was >120 s at DXS 5000 concentrations of 1000 microg/ml. The inhibitory capacity of human plasma against FXa was dose-dependently increased by DXS 5000. With increasing DXS 5000 concentrations, a prolonged PFA-100 closure time (CT) was observed. Detailed aggregation studies revealed a dose-dependent inhibition of platelet aggregation with ristocetin by DXS 5000, whereas aggregation with ADP, collagen, and arachidonate was unaffected. DXS 5000 induces a disturbance of primary and secondary hemostasis.

The first measurable event upon interaction of artificial surfaces with blood is adsorption of proteins within seconds or minutes. At a later stage, blood cells interact with the surfaces through the initially deposited protein layer. The chemical composition of the surface is only one criterion for differential deposition of various plasma proteins, with molecular motion (polymer chain ends, loops and their flexibility), and topography (roughness, porosity) of the surface decisively influencing the interactions as well. Initially incompatible surfaces, which may be dangerous to the patient, may be rendered compatible by physicochemical surface modifications. Modern methods to estimate biocompatibility have become so sensitive that they may detect biological modifications of the blood after contact with a surface, which has no consequence for the patient. In these cases it is often difficult to decide whether a material should be classified as biocompatible or non-biocompatible. This paper discusses some methods that we have used for the study of biocompatibility of extracorporeal circuitry. It seems to us that minute signs of laboratory evidence for bioincompatibility should not preclude usage of the material in a clinical setting.

We investigated whether the measurement of N-ethylmaleimide stimulated malondialdehyde (MDA) formation by blood platelets from normal subjects is equally sensitive to acetylsalicylic acid intake as are platelet aggregation studies. MDA production and platelet aggregation by collagen and arachidonate were assayed in ten healthy volunteers before and up to ten days after a single oral dose of 500 mg aspirin. Discordant results of the two tests were seen in several subjects 4 to 6 days after aspirin intake. In three cases with still suppressed MDA values on day 4, collagen or arachidonate induced aggregation was normalized. However, on day 6, when MDA was normalized in all subjects, the aggregation response to arachidonate was still pathologic in 5 of the ten volunteers. In case of a patient with abnormal aggregation response to arachidonate and/or collagen, therefore, a normal MDA value does not permit to exclude aspirin as the cause of the platelet dysfunction.

Anti-plasma protein C monoclonal antibodies were prepared and characterized, and quantitative immunoblotting techniques were developed to determine the molecular forms of protein C in whole plasma. Two antibodies reacted with the heavy chain of protein C, four reacted with the light chain, and two reacted only with nonreduced protein C. A doublet of protein C (MW = 63-66K) was seen on nonreduced immunoblots of normal plasma and 30 heterozygous protein C deficient plasmas (2-77% protein C antigen). In reduced plasma, approximately 75% of protein C presented as doublet heavy chains (MW = 39-42K) and doublet light chains (MW = 22-25K), and approximately 25% was single chain (MW = 64K). The immunoblotting technique was quantitative, specific, sensitive, and correlated with electroimmunoassay results. It also provided visual qualitative information not obtainable with other methods of quantitation.

The administration of the anabolic steroid stanozolol during 7, 8 days as pretreatment before thrombolytic therapy of acute or subacute arterial occlusions enhances the fibrinolytic potential significantly. On average the plasminogen increased from 101% to 133%, the euglobulin lysis time after venous stasis was shortened and the alpha 2-antiplasmin remained constant. This effect could be favourable to prepare patients undergoing thrombolytic treatment.

The immunoblotting technique was applied to the study of Factor XII (F.XII) in plasma. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of whole plasma followed by electroblotting of the electropherograms to nitrocellulose (NC) membranes and immunologic detection by a double antibody technique was used. 125I-F.XII was transferred to the NC membrane in amounts proportional to the amount applied to the gel provided that a constant amount of carrier protein was present. Based on this, a quantitative assay was developed using either normal plasma or F.XII dilutions in F.XII-deficient plasma as standards. The measurement of F.XII antigen by immunoblotting was reproducible and gave values similar to those obtained by radial immunodiffusion. Two normal plasma pools contained 26 and 29 micrograms/ml of F.XII according to the immunoblotting assay. Compared to other immunoassays, immunoblotting has the advantage of directly estimating the apparent molecular weight (MW) of the protein of interest. Thus, we could confirm the normal apparent MW (80,000) of a F.XII-like molecule previously isolated from a cross reacting material (CRM)-positive F.XII-deficient plasma. None of eight CRM-negative F.XII-deficient plasmas showed an 80,000 MW immunoreactive molecule. However, five of these eight plasmas had a faint autoradiographic band at 115,000 MW that was similarly seen in only three out of 43 individual normal plasmas. The nature of this 115,000 MW band remains to be defined.

A number of tests are available to measure plasma fibrinogen. Of these, the determination of the thrombin induced rate of plasma clotting is the most widely used in a clinical laboratory. Quantitative fibrinogen assays are calibrated with commercially available standards. There exists no internationally recognized standard against which the manufacturers could calibrate their fibrinogen preparations and lyophilized normal plasmas. In the present study, the amount of clottable material was determined in ten commercially available fibrinogen standards. Following clotting with thrombin, the fibrin clots were extensively washed with citrated saline and subjected to nitrogen analysis. The proportions of intact and partially degraded fibrinogens in each standard were determined by SDS-polyacrylamide gel electrophoresis of the washed clots. Knowing the amino acid composition and the relative proportions of these fractions, the nitrogen contents of the clots were converted to fibrinogen. More than 30% deviation from the declared values was observed in three standards, in one of them even 80%. Our results indicate that fibrinogen standards of markedly differing quality are commercially available and that an accurate, international standard for fibrinogen assay should be established.