Patient blood management knowledge and practice among clinicians from seven European university hospitals: a multicentre survey.

BACKGROUND AND OBJECTIVES: The aim of this survey was to evaluate the knowledge about Patient Blood Management (PBM) principles and practices amongst clinicians working in seven European hospitals participating in a European Blood Alliance (EBA) project. MATERIALS AND METHODS: A web-based questionnaire was sent to 4952 clinicians working in medical, surgery and anaesthesiology disciplines. The responses were analysed, and the overall results as well as a comparison between hospitals are presented. RESULTS: A total of 788 responses (16%) were obtained. About 24% of respondents were not aware of a correlation between preoperative anaemia (POA) and perioperative morbidity and mortality. For 22%, treatment of POA was unlikely to favourably influence morbidity and mortality even before surgery with expected blood loss. More than half of clinicians did not routinely treat POA. 29%, when asked which is the best way to treat deficiency anaemia preoperatively, answered that they did not have sufficient knowledge and 5% chose to 'do nothing'. Amongst those who treated POA, 38% proposed red cell transfusion prior to surgery as treatment. Restrictive haemoglobin triggers for red blood cell transfusion, single unit policy and reduction of number and volumes of blood samples for diagnostic purposes were only marginally implemented. CONCLUSION: Overall, the responses indicated poor knowledge about PBM. Processes to diagnose and treat POA were not generally and homogeneously implemented. This survey should provide further impetus to implement programmes to improve knowledge and practice of PBM.

Peri-partum reference ranges for ROTEM(R) thromboelastometry.

BACKGROUND: Post-partum haemorrhage (PPH) causes rapidly developing deficiencies in clotting factors and contributes to substantial maternal morbidity and mortality. Rotational thromboelastometry (ROTEM(®)) is increasingly used as a point of care coagulation monitoring device in patients with massive haemorrhage; however, there are limited data on reference ranges in the peri-partum period. These are required due to the haemostatic changes in pregnancy. METHODS: In a Dutch multi-centre trial, 161 subjects were included; blood samples were obtained during labour (T1) and within 1 h of delivery (T2). Reference ranges of ROTEM(®) INTEM, EXTEM, FIBTEM, and APTEM were set and correlation with laboratory results was investigated using the guidelines of the International Federation of Clinical Chemistry. RESULTS: Reference ranges were obtained for clotting time (CT), clot formation time (CFT), α-angle, clot firmness at 10 and 20 min (A10, A20), maximum clot firmness (MCF), and maximum lysis (ML). These were comparable from centre to centre, and between T1 and T2. Reference ranges T1: EXTEM: CT 31-63 s, CFT 41-120 s, and MCF 42-78 mm. INTEM: CT 109-225 s, CFT 40-103, and MCF 63-78 mm. FIBTEM: CT 31-79 s and MCF 13-45 mm. APTEM: CT 33-62 s, CFT 42-118, and MCF 61-79 mm. CONCLUSIONS: Reference values for ROTEM(®) parameters are reported. The previously published correlation between FIBTEM parameters and plasma fibrinogen levels by the Clauss method is confirmed. Further research is needed to define threshold values for haemostatic therapy in the course of PPH. Clinical trial registration NTR 2515 (http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2515).

Perioperative dilutional coagulopathy treated with fresh frozen plasma and fibrinogen concentrate: a prospective randomized intervention trial.

BACKGROUND AND OBJECTIVES: Treatment of dilutional coagulopathy by transfusing fresh frozen plasma (FFP) remains sub-optimal. We hypothesized that partial replacement of transfused FFP by fibrinogen concentrate results in improved coagulant activity and haemostasis. This was tested in a controlled clinical intervention trial with patients experiencing massive bleeding during major surgery. METHODS: Patients undergoing major elective surgery were treated according to current protocols. When transfusion with FFP was required, patients were randomized as follows: group A received 4 units FFP and group B received 2 units FFP plus 2 g fibrinogen concentrate. Blood samples were taken before and after the intervention. Analysts were blinded to the treatment type. RESULTS: Group A (B) consisted of 21 (22) patients, in 16 (17) of whom bleeding stopped after intervention. Plasma fibrinogen increased significantly more in group B (0·57 g/l) than in group A (0·05 g/l). However, levels of prothrombin and factors VIII, IX and X increased more in group A than in group B. Rotational thromboelastometry (ROTEM) of whole blood and plasma revealed improved fibrin clot formation in group B but not in group A. Thrombin generation [calibrated automated thrombogram (CAT)] in plasma increased more in group A. Principal parameters determining whole-blood thromboelastometry were the fibrinogen level and platelet count. In vitro addition of fibrinogen and prothrombin complex concentrate to pre-intervention samples restored both ROTEM and CAT parameters. CONCLUSIONS: Partial replacement of transfused FFP by fibrinogen increases fibrin clot formation at the expense of less improved thrombin generation. Coagulation factors other than fibrinogen alone are required for full restoration of haemostasis.

Impaired thrombin generation and fibrin clot formation in patients with dilutional coagulopathy during major surgery.

Patients subjected to haemodilution during surgery are at increased risk of bleeding. We hypothesised that, in the acquired dilutional coagulopathy, insufficient haemostasis is due to either insufficient thrombin generation or insufficient fibrin clot formation. In tissue factor-activated plasmas from patients with coagulation deficiency, we measured time curves of thrombin generation and fibrin clot formation (thromboelastography). Investigated were in study A: 10 patients treated with vitamin K antagonist and five healthy subjects; in study B: 30 patients undergoing cardiopulmonary bypass (CPB) surgery and infused with on average 2,000 ml crystalloids and colloids (no major bleeding); in study C: 58 patients undergoing major general surgery, and transfused with >5,000 ml crystalloids, colloids and red cell concentrates, who experienced major bleeding and were post-transfused with fresh frozen plasma. The treatment with vitamin K antagonist led to a progressive reduction in thrombin generation but not fibrin clot formation. In CPB patients, plasma factor levels post-surgery were 53-60% of normal. This was accompanied by moderate reduction in both haemostatic processes. In plasmas from patients undergoing major surgery, factor levels were 38-41% of normal, and these levels increased after plasma transfusion. Taking preset thresholds for normal thrombin generation and fibrin clot formation, at least one of these processes was low in 88-93% of the patients with (persistent) bleeding, but only in 40-53% of the patients without bleeding. In conclusion, the ability of thrombin generation and fibrin clot formation is independently reduced in acquired dilutional coagulopathy, while minimal levels of both are required for adequate haemostasis.

Thrombotic and infectious complications of central venous catheters in patients with hematological malignancies.

Central venous catheters (CVCs) have considerably improved the management of patients with hematological malignancies, by facilitating chemotherapy, supportive therapy and blood sampling. Complications of insertion of CVCs include mechanical (arterial puncture, pneumothorax), thrombotic and infectious complications. CVC-related thrombosis and infections are frequently occurring complications and may cause significant morbidity in patients with hematological malignancies. CVC-related thrombosis and infections are related and can therefore not be seen as separate entities. The incidence of symptomatic CVC-related thrombosis had been reported to vary between 1.2 and 13.0% of patients with hematological malignancy. The incidence of CVC-related bloodstream infections varies between 0.0 and 20.8%. There is need for a specific approach regarding diagnosis and treatment of CVC-related thrombosis and infection with specific attention to the preservation of the catheter. Since data on CVC-related infections and thrombosis in hematological patients have been obtained mainly from retrospective studies of small sample size, prospective, randomized studies of prophylactic measures concerning CVC-related thrombosis and infection are warranted.

[Coagulation disorders in patients with trauma to the skull and brain: a frequent and potentially fatal combination]. / Stollingsstoornissen bij patiënten met schedel-hersentrauma: een frequente en potentieel fatale combinatie.

Abnormalities in blood coagulation are relatively common after traumatic brain injury (TBI) and play an important role in the morbidity and mortality after head injuries. Exposure oftissue factor, which is abundantly present in brain tissue, is the initiator of the coagulation cascade and plays an important role in the pathogenesis of coagulopathy after TBI. Coagulopathy after TBI is actually a manifestation of the disseminated intravascular coagulation (DIC) syndrome. The interplay between hypothermia, acidosis and progressive coagulopathy, referred to as the 'lethal triad', results in high mortality. This necessitates damage control in the treatment of such TBI patients. Repeated laboratory evaluation of the coagulation parameters in TBI patients is indicated, even if the initial values are normal. The DIC score, a combination of frequently used coagulation parameters, is not only a measure of the coagulopathy but can also predict the outcome and prognosis following TBI. Primary and secondary prevention of coagulopathy together with timely and effective intervention are the most important elements in the treatment of coagulation disorders. Nevertheless, the risk of death remains high.

Recombinant factor VIIa enhances platelet adhesion and activation under flow conditions at normal and reduced platelet count.

BACKGROUND: Recombinant factor VIIa (rFVIIa), which was developed for treatment of inhibitor-complicated hemophilia, appears suitable as prohemostatic agent in other clinical disorders including patients with thrombocytopenia. It is generally accepted that rFVIIa functions by enhancement of thrombin generation at the site of injury. It is, however, unknown if and how this affects platelet adhesion and aggregation. OBJECTIVES: To determine the effect of rFVIIa-mediated thrombin generation on platelet adhesion and aggregation under flow conditions at normal and reduced platelet counts. METHODS: Washed platelets and red cells were combined to obtain plasma-free blood with different platelet counts. The reconstituted blood was perfused over a collagen- or fibrinogen-coated surface in the absence or presence of a thrombin generating system consisting of purified coagulation factors rFVIIa, factor (F)X and prothrombin. RESULTS: Addition of coagulation factors rFVIIa, FX and prothrombin to washed platelets and red cells enhanced platelet adhesion and aggregation to collagen and adhesion and spreading to fibrinogen at normal platelet count and at platelet numbers as low as 10 000 microL(-1). rFVIIa-mediated thrombin generation enhanced the activation state of platelets as measured by intracellular calcium fluxes, and enhanced the exposure of procoagulant phospholipids as measured by annexin A5 binding. CONCLUSIONS: Taken together, increased platelet adhesion and aggregation by rFVIIa-mediated thrombin formation may explain the therapeutic effects of rFVIIa in thrombocytopenic conditions and in patients with a normal platelet count by (i) enhancement of primary hemostasis and (ii) enhancement of procoagulant surface leading to elevated fibrin formation.

Elevated levels of FVIII:C within families are associated with an increased risk for venous and arterial thrombosis.

Elevated levels of coagulation factor VIII:C (FVIII:C) are associated with an increased risk for venous and arterial thromboembolism. Whether relatives of patients with elevated levels of FVIII:C are also at increased risk for thrombotic disease is unknown. The objective was to determine the annual incidences of both venous and arterial thrombotic events in first-degree relatives of patients with elevated levels of FVIII:C and venous thromboembolism (VTE) or premature atherosclerosis. A retrospective study with 584 first-degree relatives of 177 patients with elevated levels of FVIII:C was performed. The level of FVIII:C was determined and relatives with elevated and normal levels of FVIII:C were compared. Of the participants, 40% had elevated levels of FVIII:C. The annual incidence of a first episode of VTE was 0.34% and 0.13% in relatives with elevated levels of FVIII:C and those with normal levels, respectively [OR 3.7 (95% CI 1.9-7.5)]. The absolute annual incidence in the youngest age group with elevated levels of FVIII:C was 0.16% (0.05-0.37) and gradually increased to 0.99% (0.40-2.04) in those older than 60 years of age, although the odds ratios were not statistically significant. The annual incidences of a first arterial thrombotic event were 0.29% and 0.14% in relatives with and without elevated levels of FVIII:C, respectively [OR 3.1 (1.4-6.6)]. In particular the risks for a first myocardial infarction [OR 4.3 (1.0-18.1); P =0.046] and a first peripheral arterial thrombosis [OR 8.6 (1.6-47.6)] were increased. Within families of patients with elevated levels of FVIII:C and VTE or premature atherosclerosis, 40% of their first-degree relatives has elevated levels of FVIII:C as well, and they are at increased risk for both VTE and arterial thrombosis as compared with their relatives with normal levels.

The prognostic value of the soluble urokinase-type plasminogen activator receptor (s-uPAR) in plasma of breast cancer patients with and without metastatic disease.

Elevated levels of soluble uPAR (s-uPAR) and other fibrinolytic parameters functionally related to the urokinase-type plasminogen activator system might indicate the presence of cancer cells. In 25 breast cancer patients with metastases s-uPAR was significantly increased compared with 25 patients without metastases and with 25 healthy controls: 420 pg mL-1 vs. 145 pg mL-1 (P = 0.005) and 190 pg mL-1 (P = 0.003). Plasmin-alpha2-antiplasmin (PAP) complexes and d-dimers were significantly increased in breast cancer patients with metastases compared with patients without metastases and with healthy controls. The levels of plasminogen activator inhibitor (PAI)-1 activity, uPA antigen and factor (F)XIIa did not significantly differ between the patient groups and healthy controls. PAP complexes (529 microg L-1 vs. 420 microg L-1; P = 0.03), d-dimers (278.5 ng mL-1 vs. 79.0 ng mL-1; P = 0.005) and FXIIa (1.64 ng mL-1 vs. 1.19 ng mL-1; P = 0.01) were significantly higher in patients with metastases not surviving compared with patients with metastases surviving the 3-year follow-up period. Plasma s-uPAR levels in the patients with metastases did not discriminate between patients surviving and patients not surviving after 3-year follow-up. No significant differences in s-uPAR or any of the other parameters were found in the five patients developing metastases during follow-up. A single value of s-uPAR is of limited value in the follow-up of breast cancer patients with and without metastatic disease and does not predict survival or future metastases.

Prestorage leucocyte reduction of red cell components prevents release of bactericidal permeability increasing protein and defensins.

BACKGROUND AND OBJECTIVES: In this study we examined whether prestorage leucocyte reduction prevents the accumulation of bioreactive substances in red cell units. MATERIALS AND METHODS: Measurements were performed in the supernatants of buffy-coat-depleted (standard red cells) and leucocyte-reduced (filtered red cells) red cell units. The effect of storage was evaluated by taking repetitive samples up to 35 days after donation. We determined the concentrations of polymorphonuclear neutrophil (PMN)-derived bactericidal permeability increasing protein (BPI), defensins and annexin A5. In addition, leucocyte counts (using nageotte chamber) were performed on days 0 and 35. RESULTS: During storage, the concentrations of BPI, defensins and annexin A5 in standard red cells gradually increased. However, in the filtered red cells BPI and defensins were found in only a few samples, whereas the annexin A5 concentration in these units did not change during storage. Haemolysis data in both types of red cell components were similar at all time-points, except prestorage. Significant correlations were found between the release of BPI, defensins and annexin A5 into red cell units and the loss of leucocytes during storage. CONCLUSIONS: PMNs lose their membrane integrity during cold storage and release their contents into red cell components. Prestorage leucocyte reduction of red cell components prevents the accumulation of BPI, defensins and annexin A5.

Risk of venous thromboembolism in carriers of factor V Leiden with a concomitant inherited thrombophilic defect: a retrospective analysis.

Factor V Leiden is the most common genetic defect associated with venous thromboembolism. Its clinical expression is limited and shows a wide intrafamilial and interfamilial variation, which might be explained by the influence of other genetic risk factors. We retrospectively studied 226 patients with factor V Leiden and documented venous thromboembolism (probands) and 400 first-degree carrier relatives to assess the contribution of concomitant genetic risk factors to the occurrence of venous thromboembolism. The prothrombin G20210A mutation was found in 8.3%, homozygosity of factor V Leiden in 7.2%, and inherited deficiencies of antithrombin, protein C or protein S in 4.7% of symptomatic carriers (probands and relatives), as compared with 6.0, 3.4 and 0.9% of asymptomatic carriers, respectively. The total follow-up time in relatives was 11 049 years. Prevalences of venous thromboembolism were 10.8% in single heterozygous factor V Leiden carrier relatives, 16.0% in double-heterozygotes for factor V Leiden and the prothrombin mutation, 36.8% in homozygotes for factor V Leiden, and 40.0% in double-heterozygotes for factor V Leiden and an inherited deficiency of protein C or protein S. Annual incidences in these groups were 0.39, 0.57, 1.41, and 4.76%, respectively. Multivariate analysis showed a small, non-significant additional effect of the prothrombin mutation on the risk of venous thromboembolism in heterozygotes for factor V Leiden [adjusted hazard ratio, 1.3; 95% confidence interval (CI), 0.5-3.8]. This effect was more pronounced for homozygosity of factor V Leiden (adjusted hazard ratio, 3.9; 95% CI, 1.7-9.0) and inherited protein C or protein S deficiencies (adjusted hazard ratio, 17.5; 95% CI, 3.8-81.2). Our data provide evidence of clustering of the evaluated genetic thrombophilic defects in symptomatic factor V Leiden carriers and support the assumption that the clinical expression of factor V Leiden depends on clustering in a part of carriers.

A prospective study of asymptomatic carriers of the factor V Leiden mutation to determine the incidence of venous thromboembolism.

BACKGROUND: The factor V Leiden mutation is a common genetic defect associated with an increased risk for venous thromboembolism. The clinical implications for asymptomatic carriers of this mutation and, consequently, the usefulness of screening families in which a proband has both the mutation and venous thromboembolism are unclear. OBJECTIVE: To determine the incidence of venous thromboembolism in asymptomatic carriers of the factor V Leiden mutation. DESIGN: Prospective cohort study. SETTING: University hospitals in the Netherlands. PARTICIPANTS: 470 asymptomatic carriers of the factor V Leiden mutation (234 men, 236 women; mean age, 43 years [range, 15 to 88 years]), 12 of whom were homozygous. Carriers were identified by screening the first-degree relatives (>15 years of age) of 247 symptomatic probands. MEASUREMENTS: Objectively diagnosed episodes of venous thromboembolism and the relationship between incidence and exposure to high-risk situations. RESULTS: Nine venous thromboembolic events were observed in 1564 observation-years, resulting in an annual incidence of 0.58% (95% CI, 0.26% to 1.10%). The incidence of spontaneous venous thromboembolism was 0.26% (CI, 0.07% to 0.65%) per year; 3.5% (CI, 0.1% to 17.8%) per episode of surgery, trauma, or immobilization; 0.0% (CI, 0.0% to 19.5%) per pregnancy; 1.8% (CI, 0.4% to 5.2%) per year of oral contraceptive use; and 2.9% (CI, 0.8% to 15.3%) per year of use of hormone replacement therapy. CONCLUSIONS: The absolute annual incidence of spontaneous venous thromboembolism in asymptomatic carriers of the factor V Leiden mutation is low and does not justify routine screening of the families of symptomatic patients.

Factor XIII Val34Leu and the risk of venous thromboembolism in factor V Leiden carriers.

A mutation in factor XIII (Val34Leu) was reported to protect against venous thromboembolism. We evaluated the effect of Val34Leu on thrombotic risk in 352 factor V Leiden carriers who were first-degree relatives of 132 thrombotic propositi carrying factor V Leiden. The total observation period was 2,594 years in 92 Val34Leu carriers and 7,444 years in 260 non-carriers. The annual incidence of a first episode of venous thromboembolism was 0.31% in Val34Leu carriers and 0.44% in non-carriers [relative risk (RR) for venous thromboembolism: 0.7, 95% CI 0.3-1.5]. Age-specific RR for venous thromboembolism were (for Val34Leu carriers and non-carriers respectively): 1.0 (95% CI 0.3-3.2) in the age group of 15-30 years, 0.4 (95%, CI 0.05-3.0) in the age group of 30-45 years, 0.6 (95% CI 0.1-2.9) in the group aged 45-60 years and 0.5 (95% CI 0.06-4.5) in relatives older than 60 years. In conclusion, the impact of FXIII Val34Leu on the venous thromboembolic risk is modest, suggesting that screening for this mutation in factor V Leiden carriers is not justified.

Increased D-dimer levels correlate with binding of activated protein C, but not tissue factor expression, on peripheral blood monocytes in cancer patients.

Monocyte tissue factor expression is supposed to play an important role in the hypercoagulability of blood in cancer patients. The relation between coagulation parameters and the expression of monocyte membrane proteins involved in hemostasis or monocyte activation was studied in 21 patients with a disseminated malignancy and 21 age- and sex-matched healthy controls. In the cancer patient group no increase of monocyte tissue factor expression was found (8. 4% vs. 7.8%; P = 0.83), but a significant increase of monocyte-bound activated protein C (APC) (28.8% vs. 13.4%; P = 0.009) and monocyte CD16 expression (34.5% vs. 27.0%; P = 0.007) was observed. There was also a significant increase of D-dimers (2.0 vs. 0.2 microg/ml; P = 0.001), a decrease of antithrombin (83.5% vs. 102.0%; P = 0.004), but no increase of TAT complexes (1.7 vs. 1.5 microg/l; P = 0.38) or factor VII(a) (68.5% vs. 75.0%; P = 0.52). The increase of D-dimers was significantly correlated with the monocyte APC (R = 0.60; P = 0. 005), but not with monocyte tissue factor levels (R = -0.22; P = 0. 35) or TAT complexes (R = 0.12; P = 0.60). These results reflect a local rather than systemic thrombin and fibrin formation. It is suggested that the APC formed locally enters the circulation and binds to peripheral blood monocytes. APC bound on monocytes is known to inhibit monocyte cytokine production and might therefore be involved in regulatory responses of monocytes in cancer patients.

Increased risk for fetal loss in carriers of the factor V Leiden mutation.

BACKGROUND: An increased risk for fetal loss caused by placental thrombosis is probable in carriers of the factor V Leiden mutation but has not been demonstrated consistently in previous studies. OBJECTIVE: To determine the overall risk for fetal loss and the separate risks for miscarriage and stillbirth in carriers of the factor V Leiden mutation. DESIGN: Retrospective cohort study. SETTING: Three university hospitals. PARTICIPANTS: 228 carriers of the factor V Leiden mutation (77 propositi, 151 relatives) and 121 noncarrier relatives (controls). All participants had been pregnant at least once. MEASUREMENTS: Risks for fetal loss, miscarriage (defined as fetal loss within 20 weeks of gestation), and stillbirth (defined as fetal loss after >20 weeks of gestation) in women and in pregnancies were estimated and compared in carriers and noncarriers. Adjusted odds ratios were calculated by using multiple regression analysis. A random-effects model was used for comparisons of pregnancies. RESULTS: Fetal loss occurred in 31.6% of carriers and 22.3% of noncarriers, miscarriage occurred in 29.4% of carriers and 17.4% of noncarriers, and stillbirth occurred in 5.7% of carriers and 5.0% of noncarriers. Fetal loss recurred in 10.1% of carriers and 4.1% of noncarriers (odds ratio, 2.60 [95% CI, 0.96 to 7.03]). Adjusted odds ratios were 2.12 (CI, 1.35 to 3.33) for fetal loss, 2.08 (CI, 1.33 to 3.25) for miscarriage, and 1.60 (CI, 0.58 to 4.43) for still-birth when pregnancies in carriers and noncarriers were compared. Homozygous carriers had a greater risk for fetal loss (odds ratio, 2.01 [CI, 0.94 to 4.32]) and stillbirth (odds ratio, 4.85 [CI, 0.82 to 25.58]) than heterozygous carriers. CONCLUSIONS: Carriers of the factor V Leiden mutation have a greater risk for fetal loss (particularly miscarriage) than noncarriers. These data further suggest a greater risk for recurrence of fetal loss in carriers than in noncarriers and a greater risk for fetal loss and stillbirth in homozygous carriers than in heterozygous carriers.

Myelodysplasia presenting with pulmonary manifestations associated with neutrophilic dermatosis.

We present the case of a patient who suffered from severe pneumonia. Extensive diagnostic procedures revealed negative cultures and a severe neutrophilia in the bronchoalveolar lavage fluid suggestive of Sweet's syndrome. The persistent toxic leukocyte differentiation (not induced by infection) suggested an underlying hematologic disorder. One week later, she developed cutaneous lesions indicative of neutrophilic dermatosis. Bone marrow investigation showed refractory anemia with excess of blasts (RAEB). Both the pulmonary and cutaneous infiltrates improved after treatment with chemotherapy.

Inter-individual variability in Ca2+ signalling in platelets from healthy volunteers: effects of aspirin and relationship with expression of endomembrane Ca2+-ATPases.

Increased Ca2+ signal generation may lead to hyperactivity of platelets and contribute to thrombotic complications. Using fura-2-loaded platelets from 51 healthy volunteers, high variability was detected in the Ca2+ responses evoked by the receptor agonists, thrombin and collagen, and the inhibitor of sarco/endoplasmic reticulum Ca2+-ATPases (SERCA), thapsigargin (Tg). Oral intake of 500mg aspirin reduced the magnitude of the Ca2+ responses, and lowered the intra-individual coefficients of variance of the responses by 50%. However, the corresponding inter-individual variance coefficients were only a little influenced by aspirin intake, pointing to subject-dependent factors in Ca2+ handling that are unrelated to thromboxane formation. With each agonist, 6-9% of the subjects had platelets with relatively high Ca2+ responses (> mean + SD) both before and after aspirin intake. In 90% (9/10) of these cases the high responsiveness was confirmed in platelets obtained 6-12 months later. The Tg- but not thrombin-induced Ca2+ responses correlated inversely with the expression levels of SERCA PL/IM 430 (SERCA-3b) in platelets. After aspirin intake, the Ca2+ responses with collagen but not thrombin correlated inversely with SERCA-2b expression. These results suggest that, in the absence of potentiating effects of thromboxane, (i) the amount of PL/IM 430-recognizable SERCA may control the Ca2+ signal when SERCA-2b is specifically inhibited (with Tg), and (ii) the expression of SERCA-2b determine the collagen- but not the thrombin-evoked Ca2+ signal. Accordingly, limited Ca2+-pumping activity by low expression of one of the SERCA isoforms is likely to be one of the factors resulting in increased platelet activity towards collagen or thapsigargin but not thrombin.

The incidence of venous thromboembolism in family members of patients with factor V Leiden mutation and venous thrombosis.

BACKGROUND: The factor V Leiden mutation is a genetic defect associated with an increased incidence of venous thromboembolism. When the incidence of venous thromboembolism in relatives of patients known to have the mutation outweighs the disadvantages of prophylactic strategies, family screening may be necessary. OBJECTIVE: To determine the incidence of venous thromboembolism in first-degree relatives of symptomatic carriers of the factor V Leiden mutation. DESIGN: Retrospective blinded study. SETTING: University hospitals. PARTICIPANTS: 437 first-degree relatives of 112 heterozygous propositi and 30 relatives of 6 homozygous propositi. MEASUREMENTS: Before DNA testing, information on previous venous thromboembolism and concomitant risk factors was obtained. Relatives with and without the FV: Q506 mutation were compared. RESULTS: The annual incidence of thromboembolism in relatives of heterozygous propositi was 0.45% (95% CI, 0.28% to 0.61%) in those with the mutation and 0.10% (CI, 0.02% to 0.19%) in those without the mutation (relative risk, 4.2 [CI, 1.8 to 9.9]). Among carriers, the incidence increased from 0.25% (CI, 0.12% to 0.49%) in the 15- to 30-year-old age group to 1.1% (CI, 0.24% to 3.33%) in persons older than 60 years of age. Half of the episodes of venous thromboembolism occurred spontaneously, 20% were related to surgery, and 30% were associated with pregnancy or use of oral contraceptives. CONCLUSIONS: The observed low annual risk for venous thromboembolism in persons carrying the factor V Leiden mutation does not seem to outweigh the risks for bleeding associated with coumarin prophylaxis or justify discouragement of the use of oral contraceptives. A general policy of screening the families of all patients with the factor V Leiden mutation does not seem to be indicated. The observations in this moderate-size, retrospective study need to be confirmed by prospective follow-up studies.

Contribution of thromboxane and endomembrane Ca2+-ATPases to variability in Ca2+ signalling of platelets from healthy volunteers.

Inter-individual variability in Ca2+ signal generation was studied in platelets from 15 healthy volunteers. The possible involvement of variation in thromboxane A production and variation in sarco/endoplasmic reticulum Ca2+-ATPases (SERCAs) was investigated by using platelets isolated before and after intake of 500 mg aspirin, and by measuring the expression levels of two main SERCA isoforms (SERCA-2b and PL/IM 430-recognizable SERCA). Considerable difference in Ca2+ responses were detected after platelet stimulation with thrombin, collagen or the SERCA-2b inhibitor, thapsigargin (TG), with inter-individual coefficients of variance of 22-43% in the absence and 15-41% in the presence of aspirin. Differences in thromboxane A2 generation and SERCA expression contributed to this variability in various ways. In the absence of aspirin, the amount of formed thromboxane A2 partially explains the level of the Ca2+ response induced by TG. On the other hand, in the absence of thromboxane-dependent effects, the expression levels of SERCA-2b and SERCA PL/IM 430 were inversely related to the responses evoked by collagen and TG, respectively. None of these factors were related to the level of the thrombin-evoked Ca2+ signal.