Rotation thromboelastography for the detection and characterization of lipoteichoid acid-induced activation of haemostasis in an in vitro sepsis model.

OBJECTIVES: In gram-positive sepsis, lipoteichoic acid (LTA) can induce alterations of haemostasis, potentially leading to disseminated intravascular coagulation. PATIENTS AND METHODS: Here, we demonstrate the effects of LTA on haemostasis in an in vitro model of gram-positive sepsis based on rotation thromboelastrography (ROTEM). RESULTS: In this model, LTA leads to time- and dose-dependent shortening of the clotting time (CT), whereas other ROTEM parameters are unaffected. Following heat shock simulation, the LTA effect was blunted with equal CTs in the presence and in the absence of LTA. In addition, the shortening of CT by LTA was inhibited by addition of the protein synthesis inhibitor. CONCLUSION: Our work demonstrates that the ROTEM system is capable of detecting the LTA effect on haemostasis and provides a sensitive in vitro tool for research into the links between gram-positive sepsis and coagulation.

Rotation thromboelastography (ROTEM) parameters are influenced by age, gender, and oral contraception.

Rotation thromboelastography (ROTEM) is a screening method that allows the rapid detection of plasma- and platelet-related haemostatic abnormalities. To use this procedure more efficiently, reference values depending on gender, age, and oral contraception are required. In this study, five cohorts of healthy subjects were examined by ROTEM upon activation of the extrinsic or intrinsic pathway of coagulation, or recalcification alone. The cohorts comprised male subjects below (1) and above (2) 45 years of age, female subjects below 45 years of age with (3) or without (4) oral contraception, and female subjects above 45 years (5) without hormone replacement therapy. A significant influence of gender, age, and oral contraception on parameters determined by ROTEM was observed. Thus, adjustment for age, gender, and oral contraception is required when ROTEM is used to screen for distinct abnormalities of haemostasis.

The impact and management of acquired platelet dysfunction.

Platelet function can be abnormally increased, as in association with acute vascular events, or defective, as in a variety of clinical settings. Acquired platelet dysfunction may occur at any age and range in severity from mild to life-threatening haemorrhages. Diagnostic work-up of platelet disorders requires meticulous evaluation of medical history, specifically of any drugs interfering with platelet function, careful clinical examination and a staged laboratory protocol to assess the underlying platelet defect(s). To identify hyperactive platelets ex vivo, costly procedures may be required using flow cytometry and distict epitope-specific monoclonal antibodies. Currently, this approach can be recommended for research purposes only. Drugs represent the most common cause of platelet dysfunction in our overmedicated society. While aspirin, clopigogrel (more recently also prasugrel) and integrin αIIbß3 (GPIIb-IIIa) receptor antagonists (abciximab, eptifibatide and tirofiban) are well-known prototypes of antiplatelet drugs, other widely used agents (e.g. nonsteroidal anti-inflammatory drugs, antibiotics, serotonin reuptake inhibitors and volume expanders) can also impair platelet function and thus cause or aggravate hemorrhages. Identification of individual patients with pre-existing hemostatic defects remains crucial (i) to prevent bleeding complications, (ii) to manage symptoms adequately, (iii) to minimize the risk from invasive procedures, and (iv) to avoid unnecassary exposure to blood products. Screening for platelet dysfunction can be performed by point-of-care testing followed by platelet aggregometry in response to various agonists. While mild bleeding episodes due to antiplatelet therapy can be managed by withdrawal of the drug(s), severe hemorrhages may require immediate platelet transfusions. Apart from that, the prohemostatic armamentarium is limited to desmopressin, antifibrinolytic agents, and recombinant factor VIIa.

Monitoring of antiplatelet therapy. Current limitations, challenges, and perspectives.

Screening of platelet function can be performed by point-of-care testing followed by platelet aggregometry in response to agonists such as collagen, adenosine diphosphate, epinephrine, and arachidonic acid. Despite in use for decades, this technique is not well standardized. Monitoring of antiplatelet therapy is increasingly applied in patients at high risk for re-thrombosis or bleeding. To assess pharmacological inhibition of platelet function, agonist-induced platelet aggregation, thromboxane B2 (TxB2) and vasodilator-stimulated protein phosphorylation (VASP) are being measured. While serum TxB2 levels of < 2 ng/ml reflect aspirin-induced inhibition of cyclo-oxygenase-1 activity with high sensitivity, VASP exhibits a wide variability upon treatment with clopidogrel or prasugrel. Multiple studies reveal an association between high residual platelet reactivity and adverse cardiovascular events in patients on antiplatelet therapy. However, despite the plethora of platelet function assays currently under investigation, their use in daily practice cannot be recommended. This is due to several reasons: (i) there is no consensus on the method and a respective cut-off value associated with clinical adverse outcome, and (ii) data demonstrating any benefit of tailored antiplatelet therapy and its monitoring (based on assessment of platelet functions) are still limited. Thus, appropriate identification of 'resistant' or 'poor responders' to antiplatelet agents remains challenging in clinical practice.

Clinical features and outcome of acquired haemophilia A. Interim analysis of the Düsseldorf study.

UNLABELLED: We have performed a monocenter study on 29 consecutive patients with acquired haemophilia A who were referred for diagnosis and treatment to the Düsseldorf Haemophilia Comprehensive Care Center between March 2001 and February 2010. PATIENTS, METHODS: 18 men (age: 44-86 years) and 11 women (age: 20-83 years). For laboratory evaluation, a standardized staged protocol of aPTT, FVIII:C activity and concentration, mixing studies with patient and normal plasma, and quantification of inhibitor titers (Bethesda assay) was used. Diagnostic work-up included elaborate examinations for any underlying disease. RESULTS: In 18 (62%) of the 29 patients with acquired haemophilia A, an underlying disorder was identified, including 9 patients with respiratory diseases (31%), 7 patients with autoimmune disorders (24%), one with malignancy, and one with postpartum state, while in 11 patients (38%) acquired haemophilia A remained idiopathic. Haemotherapy of bleeding, suppression or elimination of the inhibitor, and induction of immunotolerance to endogenous FVIII:C were performed according to a treatment algorithm. Predefined clinical endpoints were control of bleeding, eradication of the inhibitor, complete or partial remission (CR, PR), relapse, or early death (< or =30 days). Of the 29 patients in total, 22 individuals achieved CR (76%), three had PR, one relapsed, and three died within 30 days (one of acute myocardial infarction while on antihaemorrhagic treatment, one of sepsis while on immunosuppression due to active acquired haemophilia A, one of lung bleeding in association with pre-existing pulmonary sarcoidosis). CONCLUSION: This monocenter study demonstrates that control of life-threatening bleeding, eradication of the inhibitor, and induction of tolerance to endogenous FVIII have significantly improved the clinical outcome of acquired haemophilia A. Our data also suggest a shift in underlying disorders associated with acquired haemophilia A, whereby, in comparison to published studies, a relative increase in the proportion of patients with respiratory diseases is present.

Is there an overlap between sudden neurosensorial hearing loss and cardiovascular risk factors?

INTRODUCTION: Sudden sensorineural hearing loss (SSHL) has been proposed as a symptom of underlying vascular problems. The purpose of this work is to evaluate the genetic and acquired risk factors. METHODS: Ninety-nine patients were tested for the presence of common polymorphisms related to thrombophilia (prothrombin and factor V Leiden) in order to assess genetic risk factors, and several parameters classically associated with vascular disorders (cardiovascular events, brain stroke and antiphospholipid syndrome) were evaluated. Additional assessments of personal and familial history risk factors for vascular disorders were performed in each patient. RESULTS: Thrombophilia studies did not demonstrate statistically relevant differences between the patients and control group. However, lipidemia profile and directed personal and familial histories showed positive trends for SSHL. CONCLUSION: The lack of clear relationships between SSHL and other vascular risk factors suggests multicausality as a predominant disease profile. Although preliminary results point at a vascular involvement in SSHL, a long-term prospective study is necessary to demonstrate that SSHL represents an early vascular symptom.

Management of bleeding in patients using antithrombotic agents: prediction, prevention, protection and problem-oriented intervention.

Antiplatelet agents and anticoagulants are effective in the prevention and treatment of a variety of thrombotic disorders. Several clinical settings require more intense antithrombotic regimens. These can be provided by combining (i) two antiplatelet drugs, (ii) antiplatelet monotherapy with an anticoagulant, or (iii) anticoagulation with dual antiplatelet treatment (triple therapy). A major side effect of all antithrombotic regimens, however, is the induction of a bleeding diathesis. This is especially true in patients with preexisting haemostatic defects of any kind that may remain compensated, unless platelet function and/or coagulation are not inhibited pharmacologically. To address the dilemma of the "double-edged sword" between thrombosis and bleeding, several strategies are currently under study, including (i) identification of high-risk patients, (ii) stratification of patient subgroups, (iii) individualized decision making, and (iv) administration of "tailor-made" risk-adapted regimens. Nonetheless, prevention and protection from bleeding in patients using antithrombotic agents remain an enduring challenge. For high-risk patients on antiplatelet agents with urgent need of surgery, an algorithm is discussed that allows short-term interruption of oral antithrombotic therapy and i.v. administration of a GPIIb-IIIa receptor antagonist for bridging without increasing perioperative bleeding. When individual patients, using antiplatelet or anticoagulant agents, experience serious or even life-threatening haemorrhages, haemotherapy with platelet units or prothrombin complex concentrates remains an integral part of the clinical management.

[Acquired platelet function disorders: pathogenesis, classification, frequency, diagnosis, clinical management]. / Erworbene Plättchenfunktionsstörungen: Pathogenese, Klassifikation, Häufigkeit, Diagnostik und Behandlung.

Given the high consumption of pharmacological agents in western societies, it is not surprising at all that drugs represent the most common cause of acquired platelet dysfunction. While acetylsalicylic acid, clopigogrel and integrin alphaIIbbeta3 (GPIIb-IIIa) receptor antagonists are well-known as prototypes of antiplatelet drugs, other widely used agents including non-steroidal anti-inflammatory drugs, antibiotics, serotonin reuptake inhibitors, and volume expanders can also impair platelet function and cause or aggravate haemorrhages. Besides pharmacological agents, certain clinical conditions are often associated with qualitative platelet disorders and bleeding diathesis. Consequently, in contrast to inherited platelet disorders, acquired platelet function defects are much more frequent in clinical practice and deserve special attention. Their pathogenesis is widespread and heterogeneous with various, sometimes overlapping abnormalities. Moreover, acquired platelet dysfunctions can occur at any age and range in severity from mild to life-threatening haemorrhages. Due to their heterogeneity, acquired platelet function disorders will be classified and discussed according to the underlying clinical setting or disease.

[Recombinant factor VIIa in patients with platelet function disorders or thrombocytopenia]. / Rekombinanter Faktor VIIa bei Patienten mit Plättchenfunktionsstörungen oder Thrombozytopenien.

Apart from on-label indications, recombinant factor VIIa (rFVIIa) is increasingly administered for treatment of life threatening bleeding events when appropriate standard therapy fails. Case reports and short treatment series document the efficacy and safety of rFVIIa to achieve haemostasis in patients with platelet function disorders and thrombocytopenias of various origin. An established on-label indication for the use of rFVIIa is given in patients with Glanzmann thrombasthenia with refractoriness to transfusions of platelet concentrates. Bolus applications of rFVIIa at dosages between 80 and 120 microg/kg body weight every 1.5 to 3 h are also administered successfully in patients with Bernard-Soulier syndrome, platelet storage pool defects, and other acquired platelet function disorders. In patients with Glanzmann thrombasthenia, at least three bolus injections are required to achieve effective haemostasis. In approximately half of the patients with thrombocytopenias, a single bolus of rFVIIa has been shown to be sufficient in managing otherwise untreatable bleeding complications. In these patients, haemostasis was achieved even at platelet counts <20,000/microl, although the efficacy of rFVIIa increases at higher platelet concentrations.

[Pregnancy-associated venous thromboembolic disease: prediction, prevention, and therapy]. / Venöse Thrombose in der Schwangerschaft. Prädiktion, Prävention und Therapie.

Thromboembolic disease remains a leading cause of maternal mortality during pregnancy and the puerperium. Rational and risk-adapted administration of heparin prophylaxis depends on 1. the identification of those women who have an increased risk of thrombosis and 2. the accurate quantification of this risk. In women without prior thrombosis, the presence of a heterozygous factor V Leiden or heterozygous G20210A mutation in the prothrombin gene is associated with a pregnancy-associated thrombotic risk of approximately 1 in 400. Thus, in pregnant carriers of either one of these mutations the risk of venous thromboembolism is low. Therefore, no heparin prophylaxis is recommended. A combination of the two genetic risk factors can increase the risk to a modest level of 1 in 25. In women with a single episode of prior thrombosis associated with a transient risk factor, e.g. surgery or trauma, and no additional genetic risk factor, the probability of a pregnancy-associated thrombosis appears also to be low. However, data are sparse and conflicting. In contrast, in women with a prior idiopathic venous thrombosis who carry an additional hereditary risk factor or who have a positive family history of thrombosis, a high risk (>10%) can be expected supporting the indication for active antepartum and postpartum heparin prophylaxis. Despite the remarkable progress in risk stratification, the absolute magnitude of risk and the optimal management in many cases is an issue of ongoing debate.

Associations between thrombophilic risk factors and determinants of atherosclerosis and inflammation in patients with non-arteritic anterior ischaemic optic neuropathy.

UNLABELLED: Non-arteritic anterior ischaemic optic neuropathy (NAION) is caused by ischaemia of the optic nerve head. The pathophysiology of NAION is unclear, and no proven effective treatment exists. PATIENTS, METHODS: We analyzed thrombophilic risk factors and determinants of atherosclerosis and inflammation in 109 consecutive patients and 109 age- and sex-matched volunteers using a case-control design. RESULTS: High levels of fibrinogen (>384 mg/dl; OR 3.2, p = 0.003), factors VIII:C (>183%; OR 2.6, p = 0.02), IX (>153%; OR 2.6, p = 0.026), XI (>142%; OR 3.4, p = 0.006), von Willebrand factor (activity >205%; OR 3.1, p = 0.005; antigen >194%; OR 3.5, p = 0.002), and triglycerides (>228 mg/dl; OR 2.8, p = 0.026), higher platelet counts (>294,000/µl; OR 2.5, p = 0.04), low levels of HDL cholesterol (<40 mg/dl; OR 2.7, p = 0.032), and an accelerated erythrocyte sedimentation rate (>20 mm/h; OR 4.4, p = 0.003) were associated with NAION. CONCLUSION: Our findings support the contention of a complex pathogenesis of NAION resulting from the coincidence of proatherogenic, prothrombotic and proinflammatory processes. The alterations described could be causative, side effects, or just coincidental findings.

Mg- and Ca-actin filaments appear virtually identical in steady-state as determined by dynamic light scattering.

Dynamic light scattering measurements show that although Mg-actin polymerizes more rapidly than Ca-actin (actin at 0.04-0.4 mg/ml polymerized with 0.1 M KCl +/- 2 mM MgCl2 or CaCl2, at room temperature or at 10 degrees C), steady-state filaments exhibit nearly identical intensity autocorrelation functions and similar mean scattered intensities. The dynamic data are used to measure the persistence length of the filaments which is found to be 4.2 microns independent of the bound cation and of the actin concentration.

Association of polymorphisms of platelet membrane integrins alpha IIb(beta)3 (HPA-1b/Pl) and alpha2(beta)1 (alpha807TT) with premature myocardial infarction.

Conflicting results of an association of the human platelet antigen 1b (HPA-1b/PlA2), localized on the beta-subunit of the integrin alpha(IIb)beta3, and the alpha(2)807TT genotype of the integrin alpha2beta1 with coronary atherosclerosis and myocardial infarction have been reported. Both platelet receptor polymorphisms were genotyped in 3261 patients who had undergone coronary angiography, including 1175 survivors of a myocardial infarction, 1211 individuals with coronary artery disease but no history of myocardial infarction, and 571 control patients without angiographic coronary artery disease, and in 793 blood donors. In a case-control design, the prevalence of HPA-1b and alpha(2)807TT genotypes did not differ significantly between the patient groups with coronary artery disease or myocardial infarction and patient controls or blood donors. By contrast, using a multivariate case-only design, it was found that the median age of onset of myocardial infarction was 5.2 years earlier (P = 0.006) in carriers of the HPA-1b allele and 6.3 years earlier (P = 0.006) in carriers of the alpha(2)807TT genotype in the 264 survivors of myocardial infarction of recent onset with one- or two-vessel coronary artery disease. A significant interaction with the conventional risk factors hypercholesterolemia, smoking, diabetes, hypertension, and hyperfibrinogenemia was excluded. Human platelet antigen 1b and alpha(2)807TT are associated with premature myocardial infarction but not with coronary artery disease, suggesting a role of distinct integrin genotypes for increased platelet thrombogenicity. This association requires confirmation in follow-up studies.

The G20210A prothrombin-gene mutation and the plasminogen activator inhibitor (PAI-1) 5G/5G genotype are associated with early onset of severe preeclampsia.

Hereditary risk determinants of venous thrombosis have been reported to be associated with severe preeclampsia. So far there are no data to support whether these risk determinants are related to the time of onset of severe preeclampsia. We used a case-control design, studying 97 women with severe preeclampsia in previous pregnancies and 277 normal women, to assess hereditary risk factors of venous thrombosis as risk determinants for severe preeclampsia. A case-only design comprising solely the 97 women with a history of preeclampsia was used to evaluate these risk factors as risk determinants for early onset of severe preeclampsia. Using the case-control design, there was no significant risk association of the hereditary risk factors with severe preeclampsia [factor V Leiden, odds ratio (OR) 0.9, 95% confidence interval (CI) 0.4, 2.2; prothrombin mutation, OR 1.9, 95% CI 0.5, 7.0; methylentetrahydrofolate reductase 677TT genotype, OR 0.8, 95% CI 0.4, 1.8; plasminogen activator inhibitor (PAI-1) 4G/4G genotype, OR 1.2, 95% CI 0.7, 2.1; PAI-1 5G/5G genotype, OR 1.0, 95% CI 0.5, 1.8]. However, the onset of severe preeclampsia was significantly earlier in women with the G20210A prothrombin gene mutation (24.5 weeks vs. 30.1 weeks, P = 0.046) and in women with the PAI-1 5G/5G genotype (25.7 weeks vs. 30.8 weeks, P = 0.024). Hereditary risk factors for venous thrombosis do not predispose for severe preeclampsia. However, women who are carriers of the G20210A prothrombin gene mutation and the PAI-1 5G/5G genotype are at risk for early onset of severe preeclampsia. It appears that these risk factors do not induce the pathomechanism but accelerate the course of preeclampsia.

[The ambivalence of progress - do we need a less-is-more strategy?**. **Extract from the programmtic opening speech delivered at the 59th Annual GTH Congress 2015]. / Die Ambivalenz des Fortschritts - ist weniger mehr?*. *Auszug aus der programmatischen Eröffnungsansprache zum 59. Jahreskongress der GTH 2015.

Economizing health care systems has led to industrialized hospitals. The consequences and side effects are substantial and rather promote costs explosion due to the dictated increase in cases and efficiency. Hence, position sensing and change in direction are required. Effective ways to find out of the current crisis are discussed.

Management of acquired haemophilia A.

Acquired haemophilia A (AHA) is caused by autoantibody inhibitors of coagulation factor VIII (FVIII : C). Recent onset of bleeds and isolated prolongation of the activated partial thromboplastin time (aPTT) are characteristic features of the disorder. Reduced FVIII : C activity and a detectable FVIII : C inhibitor in the Bethesda assay confirm the diagnosis. Patients should be referred to expert centres, whenever possible, and invasive procedures with a high risk of bleeding must be avoided, until haemostasis has been secured by adequate therapy. Bypassing agents capable of inducing sufficient thrombin formation in the presence of FVIII : C inhibitors are treatment of choice, including currently available recombinant factor VIIa (NovoSevenTM) and activated prothrombin complex concentrate (FEIBATM). These agents represent first line therapy to control acute or severe bleeds. To eradicate inhibitors, immunosuppressive treatment (IST) is indicated in patients with AHA. Glucocorticoids, cytotoxic agents and rituximab are most widely used. However, an ideal IST regimen has not been established so far. Adverse events of IST, including infections as the foremost cause death, are frequent complications in AHA.

In vitro thromboxane synthesis of depleted blood platelets following renal transplantation.

Renal transplant rejection is associated with platelet activation in vivo which may lead to partially alpha- and delta-granule-depleted platelets that continue to circulate. These "exhausted" platelets are hemostatically defective. To quantitate the extent of platelet granule depletion following kidney transplantation, we determined intraplatelet levels of beta-thromboglobulin (beta TG), platelet factor 4 (PF4), and serotonin (5-hydroxytryptamine, 5-HT) ex vivo in Triton X-100-treated platelet lysates. To explore biochemical alterations of partially depleted platelets, we studied platelet thromboxane A2 (TXA2) synthesis in citrated platelet-rich plasma (PRP) upon stimulation with thrombin or collagen in 45 recipients of renal allografts and 10 healthy volunteers. The patients were divided into subjects with acute and chronic allograft rejection (N = 15), those with compensated renal failure after kidney transplantation but without evidence of allograft rejection (N = 15), and those with functioning renal transplant (N = 15). The mean intraplatelet content of beta TG (38.6 +/- 4.2 micrograms/10(9) platelets), PF4 (11.8 +/- 1.8 micrograms/10(9) platelets), and 5-HT (274 +/- 31 ng/10(9) platelets) in patients with acute or chronic renal allograft rejection was significantly lower than in other recipients of kidney transplants or healthy volunteers (beta TG: 59.9 +/- 4.7 micrograms/10(9) platelets; PF4: 20.4 +/- 2.3 micrograms/10(9) platelets; 5-HT: 461 +/- 48 ng/10(9) platelets; p less than 0.005 in all cases).(ABSTRACT TRUNCATED AT 250 WORDS)

Failure of preactivated human blood platelets to restore defective thromboxane synthesis despite prolonged incubation in plasma.

Acquired platelet storage pool disease has been shown to be associated with reduced platelet thromboxane synthesis. However, the mechanisms for this dysfunction are incompletely understood. The present experiments were designed to evaluate some of the possible defects which may account for impaired thromboxane formation in human platelets previously exposed to thrombin in vitro. Washed platelets pretreated with 0.5 U/ml thrombin for 20 sec and subsequently recovered as single degranulated platelets were incapable of forming normal amounts of thromboxane upon a second stimulation with thrombin (as compared to Tyrode-pretreated control platelets). In contrast, thrombin-degranulated platelets released additional amounts of thromboxane in response to arachidonate, or collagen, indicating that short-time exposure to thrombin does not irreversibly inactivate platelet cyclooxygenase or thromboxane synthetase. Upon incubation of the thrombin-pretreated platelets in autologous plasma in the presence of 14C-arachidonate, the label became associated with the platelets to the same extent as with control platelets. However, the platelets did not recover their ability to synthesize normal amounts of thromboxane upon restimulation with thrombin, and only about half of the label was lost from the thrombin-pretreated platelets as compared to control platelets in response to thrombin. The ability of collagen to cause loss of 14C-arachidonate and formation of thromboxane was the same regardless of whether or not the platelets had been pretreated with thrombin. Incubation of platelets in plasma in the presence of added arachidonate for 90 min resulted in complete refractoriness to a second stimulation with thrombin but not with collagen.(ABSTRACT TRUNCATED AT 250 WORDS)

Mutation in the gene coding for coagulation factor V and resistance to activated protein C: detection of the genetic mutation by oligonucleotide ligation assay using a semi-automated system.

Resistance of coagulation factor Va to inactivation by activated protein C (APCR) is associated with a point mutation in which adenine is substituted for guanine at nucleotide 1691 in the gene coding for factor V (FV Leiden). To date, this mutation of factor V is the most frequent genetic risk factor for venous thrombophilia. In this report, we describe the adaptation of an automatable oligonucleotide ligation assay (OLA) to detect the mutation in polymerase chain reaction-amplified DNA samples from 40 normal, 20 affected heterozygous, and 3 affected homozygous individuals. The genotypes determined by conventional allele-specific restriction enzyme site analysis were in complete concordance with the results obtained by ELISA-based oligonucleotide-ligation assay. The automated oligonucleotide ligation assay provides a rapid, reliable, nonisotopic method to detect the mutation responsible for APCR that can rapidly be applied to large population screening.