André B. Mulder

Association of polymorphism in the cytochrome CYP2D6 and the efficacy and tolerability of simvastatin

Because clinical data about the therapeutic consequences of polymorphic oxidation of simvastatin by CYP2D6 have not been well reported, we sought to investigate the possible link between polymorphism of CYP2D6 and the efficacy and tolerability of simvastatin treatment in a group of 88 patients with hypercholesterolemia.

A prospective cohort study on the absolute risks of venous thromboembolism and predictive value of screening asymptomatic relatives of patients with hereditary deficiencies of protein S, protein C or antithrombin

See also Keeling D. Thrombophilia screening or screaming. This issue, pp 1191–2.

In Normal Controls, Both Age and Gender Affect Coagulability as Measured by Thrombelastography

BACKGROUND:Our objective was to analyze the effects of age, gender, and the use of oral contraceptives (OCs) on coagulation using thrombelastography (TEG®), a single test to analyze both plasma coagulation factors and cellular elements in whole blood. METHODS:TEG® variables were measured in native whole blood and in recalcified citrated blood from 120 healthy adults (60 men and 60 women) with various ages and in an additional 29 healthy women using OCs. RESULTS:We observed hypercoagulability in women compared with men and in women using OCs compared with age-matched nonusers. Moreover, we found hypercoagulability with aging. Using the method of Bland and Altman (Lancet 1986;1:307–10), we demonstrated no correlation between TEG® measurements in native and recalcified citrated blood. CONCLUSIONS:Aging, female gender, use of OCs, and low-normal hematocrit levels have significant procoagulant effects. TEG® measurements in native and recalcified citrated blood are not interchangeable, as indicated by differences between the 2 measurements ranging from 20%in maximal amplitude to 246% in clotting time. Furthermore, the limits of agreement strongly exceeded clinical acceptability to conclude interchangeability.

Clinical relevance of decreased free protein S levels: results from a retrospective family cohort study involving 1143 relatives

Conflicting data have been reported on the risk for venous thrombosis in subjects with low free protein S levels. We performed a post-hoc analysis in a single-center retrospective thrombophilic family cohort, to define the optimal free protein S level that can identify subjects at risk for venous thrombosis. Relatives (1143) were analyzed. Relatives with venous thrombosis (mean age 39 years) had lower free protein S levels than relatives without venous thrombosis (P < .001), which was most pronounced in the lowest quartile. Only relatives with free protein S levels less than the 5th percentile (< 41 IU/dL) or less than the 2.5th percentile (< 33 IU/dL) were at higher risk of first venous thrombosis compared with the upper quartile (> 91 IU/dL); annual incidence 1.20% (95% confidence interval [CI], 0.72-1.87) and 1.81% (95% CI, 1.01-2.99), respectively; adjusted hazard ratios 5.6, (95% CI, 2.7-11.5) and 11.3 (95% CI, 5.4-23.6). Recurrence rates were 12.12% (95 CI, 5.23-23.88) and 12.73% (95% CI, 5.12-26.22) per year; adjusted hazard ratios were 3.0 (95% CI, 1.03-8.5) and 3.4 (95% CI, 1.1-10.3). In conclusion, free protein S level can identify young subjects at risk for venous thrombosis in thrombophilic families, although the cutoff level lies far below the normal range in healthy volunteers.

Gene expression profiling in the leukemic stem cell-enriched CD34 + fraction identifies target genes that predict prognosis in normal karyotype AML

In order to identify acute myeloid leukemia (AML) CD34+-specific gene expression profiles, mononuclear cells from AML patients (n=46) were sorted into CD34+ and CD34− subfractions, and genome-wide expression analysis was performed using Illumina BeadChip Arrays. AML CD34+ and CD34− gene expression was compared with a large group of normal CD34+ bone marrow (BM) cells (n=31). Unsupervised hierarchical clustering analysis showed that CD34+ AML samples belonged to a distinct cluster compared with normal BM and that in 61% of the cases the AML CD34+ transcriptome did not cluster together with the paired CD34− transcriptome. The top 50 of AML CD34+-specific genes was selected by comparing the AML CD34+ transcriptome with the AML CD34− and CD34+ normal BM transcriptomes. Interestingly, for three of these genes, that is, ankyrin repeat domain 28 (ANKRD28), guanine nucleotide binding protein, alpha 15 (GNA15) and UDP-glucose pyrophosphorylase 2 (UGP2), a high transcript level was associated with a significant poorer overall survival (OS) in two independent cohorts (n=163 and n=218) of normal karyotype AML. Importantly, the prognostic value of the continuous transcript levels of ANKRD28 (OS hazard ratio (HR): 1.32, P=0.008), GNA15 (OS HR: 1.22, P=0.033) and UGP2 (OS HR: 1.86, P=0.009) was shown to be independent from the well-known risk factors FLT3-ITD, NPM1c+ and CEBPA mutation status.

Haemostatic variables during normal menstrual cycle A systematic review

For a number of haemostatic factors menstrual cycle variation has been studied. Such variation could have clinical implications for the timing of haemostatic testing in women. It was our objective to systematically review the literature about evidence for timing of haemostatic testing during menstrual cycle.We searched MEDLINE, EMBASE and the Cochrane library to identify studies that measured haemostatic variables [platelet function, von Willebrand factor (VWF), factor VIII (FVIII), factor IX (FIX), factor XI (FXI), factor XIII (FXIII), D-dimer, plasminogen activator inhibitor-I (PAI-I), tissue plasminogen activator (tPA), urokinase-type plasminogen activator (uPA), α2-antiplasmin and fibrinogen] during normal menstrual cycle without hormonal contraceptives. Two investigators independently selected studies, and abstracted data in duplicate. We identified 1,046 studies of which we included 30 studies (25 longitudinal and 5 cross-sectional studies). All studies reported on haemostatic variables during menstrual cycle. Overall, most of the studies found no cyclic variation in VWF, FVIII, FXI, FXIII, fibrinolytic factors (PAI, t-PA, uPA, D-dimer and α2-antiplasmin) and fibrinogen. However, in studies where these variables showed any variation, they reached the lowest levels during menstrual and early follicular phase, especially for VWF, FVIII and platelet function tests. In conclusion, the optimal timing for haemostatic testing during menstrual cycle seems to be menstrual and early follicular phase.

Tryptase and histamine metabolites as diagnostic indicators of indolent systemic mastocytosis without skin lesions.

Risk indicators of indolent systemic mastocytosis (ISM) in adults with clinical suspicion of ISM without accompanying skin lesions [urticaria pigmentosa (UP)] are lacking. This study aimed at creating a decision tree using clinical characteristics, serum tryptase, and the urinary histamine metabolites methylimidazole acetic acid (MIMA) and methylhistamine (MH) to select patients for bone marrow investigations to diagnose ISM.

The acute phase reaction explains only a part of initially elevated factor VIII:C levels: A prospective cohort study in patients with venous thrombosis

We determined in a prospective cohort of patients treated with vitamin K antagonists for venous thrombosis, the course of factor VIII (FVIII:C), C-reactive protein (CRP) and fibrinogen levels, to assess the influence of the acute phase reaction on FVIII:C levels. Second, we hypothesized that patients with preceding infectious symptoms might have higher levels of FVIII:C at baseline than patients without those. We included 75 patients. Blood was sampled at baseline, once during treatment (t=1) and at the end of treatment (t=2). Mean levels of FVIII:C were 207, 186 and 175IU/dL (p for trend 0.003) at baseline, t=1 and t=2 respectively. Eight-eight percent of patients had an elevated FVIII:C at baseline, 75% at t=1 and 72% at t=2 (p for trend 0.045). Mean levels of FVIII:C were not different in patients with or without preceding infectious symptoms (206 versus 205IU/dL respectively). A baseline CRP level below 62mg/L could best distinguish between patients who will keep an elevated FVIII:C and those who will drop below 150IU/dL. We conclude that FVIII:C levels are partially influenced by the acute phase reaction, especially in patients who keep a persistent elevated FVIII:C during treatment. Preceding infectious symptoms did not influence baseline FVIII:C levels.

Thrombocytopenia affects plasmatic coagulation as measured by thrombelastography

Thrombelastography (TEG) is used as a point-of-care test of hemostasis. Different components of the test tracing are considered to reflect various parts of the hemostatic system and to distinguish low platelet count, platelet dysfunction or both from lack of plasmatic coagulation factors. To analyze the influence of one single element of the coagulation system, namely the platelet count, we used TEG serially in patients with well documented transient thrombocytopenia. A total of 189 TEG analyses were performed from 16 patients with a hematological malignancy in remission, receiving consolidation courses of chemotherapy. TEG outcomes using unmanipulated and citrated blood samples at a median of 11 times (range 1–17) in the same patients during the decrease of platelet count in response to chemotherapy were compared with outcomes in 120 healthy adults from various age categories. We found a correlation (r = 0.7, P < 0.001) between TEG clot strength (maximum amplitude) and platelet count. Moreover, platelet count was correlated respectively with the initial rate of clot formation (reaction time and clotting time), the rate of clot growth (alpha angle), and also with maximum thrombus generation, time to maximum thrombus generation and total thrombus generation. We conclude that platelet count not only affects the strength of clot formation, as was expected, but also all other phases of plasmatic coagulation. Citration of the blood sample, aiming at easy storage of the material, masked some of the important biological parameters of coagulation.

Implementation of flow cytometry in the diagnostic work-up of myelodysplastic syndromes in a multicenter approach: report from the Dutch Working Party on Flow Cytometry in MDS

Flow cytometry (FC) is recognized as an important tool in the diagnosis of myelodysplastic syndromes (MDS) especially when standard criteria fail. A working group within the Dutch Society of Cytometry aimed to implement FC in the diagnostic work-up of MDS. Hereto, guidelines for data acquisition, analysis and interpretation were formulated. Based on discussions on analyses of list mode data files and fresh MDS bone marrow samples and recent literature, the guidelines were modified. Over the years (2005-2011), the concordance between the participating centers increased indicating that the proposed guidelines contributed to a more objective, standardized FC analysis, thereby ratifying the implementation of FC in MDS.