Ursula Harbrecht

Polymorphisms in glutathione S-transferase omega-1 and AD, vascular dementia, and stroke.

Background: Glutathione S-transferase omega-1 (GSTO1) protects from oxidative stress, a risk factor for Alzheimer disease (AD), vascular dementia (VaD), and stroke. Polymorphisms in GSTO1 might influence the function of the protein and thus the risk of AD, VaD, and stroke. Methods: The GSTO1 gene was screened for variations. The effect of the detected polymorphisms on the risk of AD, VaD, and stroke was evaluated. CSF levels of cholesterol and plasma homocysteine levels were compared according to the GSTO1 genotype. Results: Two missense polymorphisms in exon 4 of GSTO1 (Ala140Asp and Glu155ΔGlu) were detected and tested for their association with AD, VaD, and stroke. The Asp/Asp and Ala/Asp genotypes increased the risk of stroke (p = 0.003, OR = 2.1), and the Asp/Asp genotype increased the risk of VaD (p = 0.02, OR = 2.2). GSTO1 polymorphisms did not influence the risk of AD, but the Asp allele influenced the age at onset (p = 0.05). In nondemented probands CSF levels of cholesterol were increased in carriers of the Asp/Asp genotype (p = 0.004); however, in patients with manifest dementia the authors found decreased CSF levels of cholesterol in carriers of the Asp/Asp genotype (p = 0.028). Serum homocysteine levels in stroke patients were higher in carriers of at least one Asp allele (p = 0.011). Conclusion: The GSTO1 Asp allele may be a genetic risk factor for cerebrovascular diseases, and might influence the course of Alzheimer disease, even though effects vary in different studies.

Deficiencies of antithrombin, protein C and protein S – Practical experience in genetic analysis of a large patient cohort

Deficiencies of natural anticoagulant proteins including antithrombin (AT), protein C (PC) and protein S (PS) are important causes of inherited thrombophilia. This study aimed to report on the practical experience gained in performing genetic analyses of a large cohort of patients with AT, PC and PS deficiencies and to relate this knowledge to clinical application. We genotyped a large cohort of 709 unrelated patients with AT (231), PC (234) and PS (244) deficiencies referred to us by physicians throughout Germany. Mutations were detected by direct sequencing and multiplex ligation-dependent probe amplification (MLPA). The highest mutation detection rate (MDR) was found for the SERPINC1 gene (83.5%), followed by the PROC (69%) and PROS1 (43%) genes. Even at AT activities close to the normal range (75%), the MDR was 70%. Contrastingly, for PC and PS deficiencies, the MDR dropped significantly and mildly lowered to subnormal values. At PS activities >55% for PS no mutations were detected. Mutation profiles of all three genes were similar with the highest prevalence for missense mutations (63-78%), followed by nonsense (7-11%), splice-site mutations (7-13%), small deletions (1-8%), small insertions/duplications (1-4%) and large deletions (3-6%). In conclusion, genetic testing is a useful diagnostic tool for diagnosing thrombophilia. Based on our data, genetic analysis for patients with AT deficiency is indicated for all subnormal activities. In contrast, genotyping is not advisable for PC activities >70% and for PS activities >55%.

Association between Anxiety and Factors of Coagulation and Fibrinolysis

Background: Psychological stress and anxiety have been shown to produce an activation of coagulation and fibrinolysis. Resulting hypercoagulability is a risk factor for cardiovascular diseases, and could therefore contribute to an increased prevalence of coronary artery disease in anxiety patients. However, hemostasis function has not yet been studied in patients with clinically relevant anxiety disorders. Methods: A group of anxiety patients (panic disorder with agoraphobia or social phobia) and a healthy control group (each n = 29) completed some questionnaires [SCL-K9 (a short form of the SCL-90-R), State Trait Anxiety Inventory, ADS (general depression scale)], and had blood drawn after a 15-min rest period. To assess the reaction of the hemostatic system by global entities, sum scores were computed from parameters of coagulation and fibrinolysis (fibrinogen, FVII, FVIII, vWF, F1 + 2, TAT, D-dimer, α2-AP, PAP, tPA, PAI-1). Interfering variables, such as age, gender, alcohol consumption and smoking status, were controlled. Results: Anxiety patients scored higher in a composite hemostatic score and a sum score of fibrinolysis in comparison to the control group, with a predominant activation of inhibitors in fibrinolysis. However, the psychological variable with the closest association to hemostasis was not trait anxiety, but self-perceived worry about blood drawing before blood sampling was performed. Conclusions: The coagulation and fibrinolysis system is activated in the direction of a hypercoagulable state in patients with severe phobic anxiety, triggered by fear of blood drawing. This could be one mediating factor for the increased risk of cardiovascular diseases in this population. Acute situational phobic anxiety should be monitored closely when studying the association between anxiety and hemostasis.

Heparin-induced thrombocytopenia in neurologic disease treated with unfractionated heparin

The risk for immune-mediated heparin-induced thrombocytopenia (HIT) in neurologic patients receiving unfractionated heparin (UFH) is not known. In a prospective study of 200 patients, the authors found a 2.5% rate of HIT and a 2% rate of HIT-associated thromboses, suggesting that neurologic patients treated with UFH are at considerable risk for development of HIT and its complications. Prevalence of heparin-induced antibodies was 20.5% and was dependent on heparin dose. It was higher in cerebrovascular than in noncerebrovascular (29.4% versus 11.2%, p < 0.01) patients.

Heparin-induced thrombocytopenia in neurologic patients treated with low-molecular-weight heparin

The authors prospectively studied the risk for immune-mediated heparin-induced thrombocytopenia (HIT) in neurologic patients during administration of low-molecular-weight heparin (LMWH) vs unfractionated heparin (UFH). None of 111 neurologic patients receiving LMWH developed HIT, whereas HIT occurred in 2.5% of 200 patients treated with UFH (p = 0.17). The rate of heparin-induced antibodies in patients treated with LMWH was lower than in patients treated with UFH (1.8 vs 20.5%; p < 0.001).

Molecular analysis of thrombophilic risk factors in patients with dural arteriovenous fistulas

Abstract. Dural arteriovenous fistulas (DAVFs) are direct artery-to-cerebral venous sinus shunts. Our recent finding of a significantly increased prevalence of factor V (FV) Leiden in patients with DAVFs prompted us to evaluate prothrombinG20210A, MTHFRC677T, β-fibrinogenG455A, PAI-14G/5G and FXIIIVal34Leu as additional risk factors for thrombophilia in 26 patients with DAVFs and a group of age- and gender-matched controls. There was no significantly increased prevalence of these risk factors in DAVF patients. We conclude that FV Leiden is of pathogenetic significance in the aetiology of a subgroup of DAVFs whereas the other thrombophilic risk factors are not likely to be involved.

Coagulation activation and fibrinolysis impairment are reduced in patients with anxiety and depression when medicated with serotonergic antidepressants.

Aims:  Anxiety disorders have been shown to be correlated with an activation of coagulation and impairment of fibrinolysis. The aim of the study was to assess whether medication with a serotonergic antidepressant, which has been associated with abnormal bleeding, may modify this effect.

Thrombin inhibition profiles in healthy individuals and thrombophilic patients

Inhibition of thrombin by endogenous inhibitors plays a central role in the spatiotemporal control of clot formation. A failure to adequately inactivate thrombin such as in antithrombin deficiency generates a strong prothrombotic phenotype. To study if and to what extent delayed thrombin inactivation rates beyond antithrombin deficiency contribute to the prothrombotic phenotype we measured thrombin inhibition profiles in plasma samples obtained from 16 healthy individuals and 39 thrombophilic patients, including 17 patients diagnosed positive for anti-prothrombin/phospholipid antibodies. To test thrombin inhibition, thrombin was added to plasma, and endogenous thrombin inhibition stopped by addition of the reversible thrombin inhibitor argatroban. Subsequently, the amount of argatroban-complexed thrombin was measured using an oligonucleotide-based enzyme capture assay. In normal human plasma thrombin at concentrations up to 4 ng/ml (109 pM) became inactivated with an average half-life time of 56.4 ± 4.7 seconds (s). In antithrombin-deficient plasma the thrombin half-life was prolonged to 168.2 ± 14.9 s. Among the thrombophilic patients, only one with mild antithrombin deficiency showed impaired thrombin inactivation rates, whereas all other patients including the antiphospholipid positive patients showed thrombin inhibiting capacities within the normal range. We conclude that thrombin added to normal human plasma at subthreshold levels of ~100 pM or below becomes inactivated with a half-life time below 1 minute. Antiphospholipid antibodies do not prolong thrombin half-life times, making it unlikely that delayed thrombin inactivation contributes to the thrombotic phenotype of the antiphospholipid syndrome. In contrast, plasma levels of antithrombin falling below 80% of normal markedly prolong the thrombin half-life.

Circulating Adhesion Molecules in Patients with Internal Carotid Artery Stenosis

To study the association of plasma concentrations of soluble adhesion molecules (sICAM-1, sVCAM-1 and sE-selectin) with atheroslerotic lesions at the origin of the internal carotid artery (ICA). 179 subjects were investigated by color Doppler ultrasound of whom 133 had and 46 had no plaques at the ICA origin. Stepwise logistic regression analysis revealed that hypertension (p < 0.001), sICAM-1 concentrations (p < 0.01) and smoking (p < 0.05) were independently associated with the presence of ICA plaques. Multivariate regression analysis revealed that sICAM-1 concentrations in subjects with plaque were negatively associated with the degree of ICA stenosis (p < 0.01) and positively associated with previous cerebral ischemia (p < 0.01), coronary heart disease (p < 0.05) and peripheral artery disease (p < 0.05). In conclusion, elevated sICAM-1 concentrations are independently associated with atherosclerosis of the ICA origin and are predominantly increased in patients with low-grade lesions and with clinical manifestations of vascular disorders.

Common genetic coagulation variants are not associated with ischemic stroke in a case-control study

Abstract Objective: Abnormalities in the coagulation pathway are often included in the diagnostic work-up of stroke patients, especially in young adults with cryptogenic stroke. Methods: Three common genetic variants within the coagulation cascade were investigated in 500 control subjects and in 167 patients with ischemic stroke defined by TOAST subclassification. Analysed variants were factor V Leiden, prothrombin 20210G→A and factor XIII Val34Leu. Results: The factor V Leiden mutation was over-represented in patients with cardioembolic stroke for trend, whereas the prothrombin 20210G→A variant and the factor XIII polymorphism Val34Leu were not associated with stroke of any subtype. The three polymorphisms showed no association with stroke in subgroups of patients defined by age (<40, 40–49, 50–59, ≥60 years). Discussion: This study suggests that the analysis of prothrombin 20210G→A and factor XIII Val34Leu is not a useful diagnostic procedure in the work-up of ischemic stroke.