H. ten Cate

The 20210 G→ A mutation in the 3'-untranslated region of the prothrombin gene and the risk for arterial thrombotic disease

A sequence variation in the 3′‐untranslated region of the prothrombin (PT) gene (20210 G → A) was recently claimed to be associated with elevated plasma prothrombin levels and an increased risk for venous and arterial thrombosis. We examined the prevalence of the 20210 A allele in the prothrombin gene in 400 healthy controls and in 263 patients with proven premature atherosclerotic disease. In addition, we measured prothrombin, prothrombin fragment 1 + 2, thrombin–antithrombin (TAT) complex and D‐dimer levels in plasma from carrier and non‐carrier patients. The frequency of the variant allele was 1% in the control subjects and 2.7% in the patient group, yielding a relative risk (RR) for the 20210 A allele of 2.7 (95% CI 0.8–9.4). All heterozygotes in the patient group were found to have had a myocardial infarction (MI), yielding a RR for MI of 4.2 (95% CI 1.2–14.6). Plasma prothrombin levels in carriers (126 ± 10) were higher than in non‐carriers (103 ± 1, P = 0.02). The levels of TAT complexes (16 ± 9 v 6 ± 1 μg/ml, P = 0.02) as well as of prothrombin fragment 1 + 2 (1.5 ± 0.3 v 1.0 ± 0.1 nmol/l, P = 0.02) were also elevated in carriers of the mutation. Our findings suggest that the 20210 G → A mutation in the prothrombin gene is a genetic risk factor for MI. In addition, our data provide evidence for an association of the mutation with excessive thrombin generation, which may contribute to the understanding of its role in venous and arterial disease.

ADAMTS-13, von Willebrand factor and related parameters in severe sepsis and septic shock

Background: Insufficient control of von Willebrand factor (VWF) multimer size as a result of severely deficient ADAMTS‐13 activity results in thrombotic thrombocytopenic purpura associated with microvascluar thrombosis and platelet consumption, features not seldom seen in severe sepsis and septic shock. Methods: ADAMTS‐13 activity and VWF parameters of 40 patients with severe sepsis or septic shock were compared with those of 40 healthy controls of the same age and gender and correlated with clinical findings and sepsis outcome. Results: ADAMTS‐13 activity was significantly lower in patients than in healthy controls [median 60% (range 27–160%) vs. 110% (range 63–200%); P < 0.001]. VWF parameters behaved reciprocally and both VWF ristocetin cofactor activity (RCo) and VWF antigen (VWF:Ag) were significantly (P < 0.001) higher in patients compared with controls. Neither ADAMTS‐13 activity nor VWF parameters correlated with disease severity, organ dysfunction or outcome. However, a contribution of acute endothelial dysfunction to renal impairment in sepsis is suggested by the significantly higher VWF propeptide and soluble thrombomodulin levels in patients with increased creatinine values as well as by their strong positive correlations (creatinine and VWF propeptide rs = 0.484, P < 0.001; creatinine and soluble thrombomodulin rs = 0.596, P < 0.001). Conclusions: VWF parameters are reciprocally correlated with ADAMTS‐13 activity in severe sepsis and septic shock but have no prognostic value regarding outcome.

Is clinical outcome of dengue-virus infections influenced by coagulation and fibrinolysis? A critical review of the evidence.

Despite efforts to elucidate the pathogenesis of dengue fever, the progression into severe disease remains poorly understood. In-vitro findings suggest that coagulopathy and disturbances in fibrinolysis have a pivotal role in the pathophysiology. If disturbances in these processes are predictive of clinical outcome in this disease, there could be important consequences for both diagnosis and treatment. We have critically reviewed publications on this topic to assess whether there is an association between activation of coagulation and fibrinolysis and clinical outcome of dengue-virus infections. In general, the selected studies showed activation of both the coagulation and fibrinolytic systems in this infection. The activation was more pronounced in severe infections and in cases with a poor clinical outcome. However, the findings were not consistent, and owing to a lack of detailed information on characteristics of patients, disease, and study design, we could not ascertain whether inconsistencies were caused by differences in these characteristics, selection bias, or confounding factors. We conclude that an association between activation of coagulation and fibrinolysis and clinical outcome of dengue-virus infections is conceivable but has been inadequately assessed and that methodologically sound studies, complemented with complete and reliable reporting, are needed to show whether there is a true association.

Steady-state sVCAM-1 serum levels in adults with sickle cell disease

Cytokines and adhesion molecules play an important role in the pathophysiology of vaso-occlusion in sickle cell disease (SCD), and their in vivo profiles are potential tools for assessing SCD severity. We compared steady-state soluble vascular cell adhesion molecule-1 (sVCAM-1) serum levels to clinical (painful crisis frequency, occurrence of acute chest syndrome, leg ulcers, and cerebrovascular disease) and related hematological parameters of SCD severity (such as HbF%, hemoglobin levels, and leukocyte counts) in 29 HbSS adults. Serum sVCAM-1 levels were not related to clinical severity, but an inverse correlation was demonstrated between sVCAM-1 and hemoglobin levels (r=−0.71, p<0.001) with a positive correlation to serum lactate dehydrogenase levels (r=0.59, p=0.008). Based upon these results, steady-state serum sVCAM-1 levels do not seem to reflect clinical disease severity. However, as VCAM-1 is involved in hematopoiesis, sVCAM-1 levels might reflect bone marrow activity in SCD. This underlies the pleiotropic nature of adhesion molecules in vivo and the need for further research in this area, especially since therapies targeting (cellular) adhesive interactions involving the endothelium are emerging for SCD.

Erythropoiesis and serum sVCAM-1 levels in adults with sickle cell disease.

Sickle cell patients are characterized by stress erythropoiesis involving cytokines, growth factors, and adhesion molecules. We set out to determine whether serum soluble vascular cell adhesion molecule-1 (sVCAM-1) levels, which are inversely related to red blood cell counts in sickle cell disease (SCD), reflect erythropoietic activity in adult HbSS patients. Serum levels of sVCAM-1 were compared to erythropoietin (EPO), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and soluble transferrin receptor (sTfR) levels in 29 adults with HbSS, and their respective levels were also compared to 29 race- and age-matched HbAA controls. EPO and sTfR levels were increased as compared to healthy controls, whereas IL-3 and GM-CSF were not. No significant correlation of sVCAM-1 levels could be detected with any of the measured erythropoietic markers. Patients, but not controls, with detectable IL-3 levels had lower sTfR and GM-CSF levels as compared to patients with undetectable IL-3 levels. Even though a link of sVCAM-1 to erythropoiesis could not be established, it cannot be ruled out that sVCAM-1 levels reflect the release of young red blood cells into the circulation. IL-3 and GM-CSF levels suggest that different rates of erythropoiesis may be characterized by specific cytokine profiles in SCD. Further research should focus on the potential cytokines and adhesion molecules involved in sickle cell erythropoiesis, as this may increase our understanding of sickle cell complications and may provide us with potential markers for risk assessment in sickle cell disease as well.

Differences between LaB6 and CeB6 by means of spectroscopic ellipsometry

The optical properties of LaB6 and CeB6 have been investigated using spectroscopic ellipsometry. The results were compared with band-structure calculations. The main features of the spectra of both materials originate from optical transitions starting at boron-derived levels of similar character. A sharp peak in the joint density of states for CeB6 around 0.5 eV is observed.

de Haas-van Alphen frequencies and upper critical field anisotropy in Nb3Sn

de Haas-van Alphen frequencies in the (100) and (110) planes of Nb3Sn have been measured with a typical accuracy of 1%. Several frequency branches have been found between 100 and 1000 T. Effective masses corresponding to some of the orbits at symmetry directions have been estimated from the experiments. A pronounced anisotropy ( approximately 10%) in the upper critical field was observed. The magnitude of the critical field was found to be sample dependent. The DHVA data are interpreted using self-consistent new ASW band-structure calculations which include tetragonal distortion of the unit cell.

Conservative surgical management of urological complications after cadaveric renal transplantation.

Review of a consecutive series of 85 cadaveric renal transplants revealed urinary fistulas in 7 cases. Bladder fistulas originated from the anterior cystostomy suture line in 3 patients and required secondary closure in every case. Ureteral fistulas from the donor ureter often required a multistaged operation. In every case the end result has been satisfactory, with closure of the fistula and preservation of renal function.