Concentrated citrate locking in order to reduce the long-term complications of central venous catheters: a randomized controlled trial in patients with hematological malignancies.

PURPOSE AND METHODS: Central venous catheter (CVC)-related thrombosis and infections are frequently occurring complications in patients with hematological malignancies. At present, heparin is most often used as a locking solution. Trisodium citrate (TSC) had been shown to be a very effective antimicrobial catheter locking in hemodialysis patients. We performed a prospective randomized phase III multicenter trial to determine the efficacy of TSC as a locking solution compared to heparin in preventing CVC-related thrombosis and infections in patients with hematological malignancies. RESULTS: Thirty-four episodes of CVC-related bloodstream infections (CVC-BSI) occurred in the 108 patients who were randomized to locking with heparin compared with 35 episodes in the 99 patients who were randomized to locking with TSC (P = 0.654). We did find seven times more CVC-BSI with gram-negative rods in CVCs locked with heparin (P = 0.041). The cumulative incidence of symptomatic thrombosis was 10% in the heparin group and 5% in the TSC group (hazard ratio 0.525; 95% confidence interval 0.182-1.512). CONCLUSION: This study shows that locking with TSC in patients with hematological malignancies significantly reduced the incidence of CVC-BSI with gram-negative rods. However, the incidence of CVC-BSI with coagulase-negative staphylococcus or CVC-related thrombosis was not reduced by TSC locking.

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.

Differential protein expression in serum of abdominal aortic aneurysm patients - a proteomic approach.

OBJECTIVE: The aim of the study is to investigate the differential expression of proteins in serum of abdominal aortic aneurysm (AAA) patients in relation to aneurysm size (D(max)) and progression. METHODS: Two-dimensional differential in-gel electrophoresis (2D-DIGE) together with tandem mass spectrometry (MS/MS) was used to analyse the serum proteome from patients with small (D(max) 30-54 mm) AAA, either stable (increase D(max) <5 mm year⁻¹; n = 8) or progressive (increase D(max) ≥5 mm year⁻¹; n = 8), and large (D(max) ≥ 55 mm; n = 8) AAA. The identified proteins were quantitatively validated in a larger population (n = 80). RESULTS: Several proteins were differentially expressed in serum of small stable, small progressive and large AAA. Three validated proteins (immunoglobulin G (IgG), α1-antitrypsin (α1-AT) and Factor XII activity) showed strong correlation with D(max). Size combined with either Factor XII activity or α1-antitrypsin had minimal effect on the prognostic value in predicting aneurysm progression compared with size alone (area under the curve (AUC), 0.85; 95% confidence interval (CI), 0.73-0.97; p < 0.001 and AUC, 0.85; 95% CI, 0.72-0.98; p < 0.001 vs. AUC, 0.83; 95% CI, 0.71-0.96; p < 0.001, respectively). CONCLUSION: The present study indicates that both Factor XII and α1-antitrypsin are found in increased amounts in the serum of patients with expanding AAA. However, combination of either Factor XII or α1-antitrypsin with aneurysm diameter had little effect on prediction of aneurysm progression versus diameter alone.

[Old and new anticoagulants. Antidotes and measures for acute hemorrhaging and urgent interventions]. / Alte und neue Gerinnungshemmer. Antidota und Massnahmen bei akuter Blutung sowie dringenden Eingriffen.

Anticoagulation medications are frequently used for primary and secondary treatment of several thrombo-embolic disorders. An important side effect of all anticoagulants is hemorrhagic diathesis which necessitates acute treatment, ideally using medicinal therapy with an antidote. Much experience has been gained in treating bleeding while on traditional anticoagulants, such as heparins and vitamin K antagonists by the use of antagonists. A multitude of factor-specific anticoagulants have recently been introduced or will soon receive approval. With this new generation of anticoagulants no valid laboratory parameters or effective antagonists are presently available. Due to a lack of adequate studies regarding acute treatment this can at present only be carried out on a symptomatic basis.

Coagulation factors and the protein C system as determinants of thrombin generation in a normal population.

BACKGROUND: Thrombin generation is a powerful tool to probe overall plasma coagulability. OBJECTIVE: To determine which plasma factors influence the various parameters of the thrombin generation curve, for example lag time, peak height and endogenous thrombin potential (ETP), under different experimental conditions. PATIENTS AND METHODS: Plasma levels of coagulation factors and inhibitors, as well as thrombin generation at 1 pm tissue factor (TF) +/- thrombomodulin (TM) and at 13.6 pm TF +/- activated protein C (APC), were determined in plasma from 140 healthy individuals. Data were analysed by multiple regression models. RESULTS: Thrombin generation increased with age and was higher in females than in males. Under all conditions, the lag time was mainly dependent on the levels of free tissue factor pathway inhibitor (TFPI), free protein S (PS), factor VII (FVII), FIX and fibrinogen. The major determinants of thrombin generation (ETP and peak height) at 1 pm TF were fibrinogen, FXII (despite inhibition of contact activation), free TFPI and antithrombin (AT), both in the absence and in the presence of TM. Thrombin generation in the presence of TM was also dependent on protein C levels. At 13.6 pm TF, thrombin generation was determined by prothrombin, AT, fibrinogen, free TFPI and FV levels in the absence of APC, and by free TFPI, free PS and FX levels in the presence of APC. CONCLUSIONS: The lag time, ETP and peak height of thrombin generation depend on the levels of multiple coagulation factors and inhibitors. The specific assay determinants vary with the experimental conditions.

Outcome of the subsequent pregnancy after a first loss in women with the factor V Leiden or prothrombin 20210A mutations.

BACKGROUND: The factor V Leiden (FVL) and prothrombin 20210A (PTm) mutations are associated with single late pregnancy loss and recurrent early pregnancy loss. The prognosis after an initial loss in women with thrombophilia is uncertain. OBJECTIVE: To assess the pregnancy outcome of the second pregnancy after a first loss in women with and without either FVL or PTm mutations. METHODS: We selected women with a first pregnancy loss out of two family cohorts of first degree relatives of probands with FVL or PTm mutations and a history of documented venous thromboembolism or premature atherosclerosis. RESULTS: Ninety-three women had had a first pregnancy loss and became pregnant a second time. Their risk of loss of the subsequent pregnancy was higher than in 825 women with a successful first pregnancy [25 vs. 12%, relative risk (RR) 2.0, 95% CI 1.4-3.0]. The live birth rate of the second pregnancy after an early first loss ( 12 weeks), the live birth rates were 68% (95% CI 46-85) and 80% (95% CI 49-94) for carriers and non-carriers, respectively (RR 0.9, 95% CI 0.5-1.3). CONCLUSIONS: Women with a first pregnancy loss have a 2-fold increased risk of loss of the subsequent pregnancy, regardless of their carrier status. More importantly, the outcome of the second pregnancy is rather favorable in absolute terms, even for those with thrombophilia and a late loss, which raises concern regarding the risks and presumed benefits of anticoagulant therapy in these women.

Changes in fibrinolytic activity after angiotensin II receptor blockade in therapy-resistant hypertensive patients.

BACKGROUND: In hypertensive patients, the activated renin-angiotensin system induces a prothrombotic state resulting from imbalance between coagulation and fibrinolysis. Although blood pressure cannot be regulated in therapy-resistant hypertensive patients, they may still be responsive to medication that attenuates the renin-angiotensin system. OBJECTIVE: our objective was to study possible attenuating properties of angiotensin II type 1 receptor blockers (AT1RBs) on the prothrombotic state in therapy-resistant hypertensive patients, focusing on parameters of fibrinolysis and coagulation. METHODS: Fourteen therapy-resistant hypertensive patients received AT1RB eprosartan infusion (45 and 150 microg kg(-1)) (study group), and 33 therapy-resistant hypertensive patients received saline (0.9%) infusion (control group) prior to renal angiography. Baseline values of parameters of coagulation and fibrinolysis were set at 1.00, and relative changes were calculated. RESULTS: Plasminogen activator inhibitor type 1 (PAI-1) antigen showed non-significant decreases in both the study group (arterial 1.00-0.45, venous 1.00-0.42) and control group (arterial 1.00-0.84, venous 1.00-0.88). PAI-1 activity significantly decreased in the study group (arterial 1.00-0.72, venous 1.00-0.71) and control group (arterial 1.00-0.83, venous 1.00-0.94). In the study group, tissue-type plasminogen activator (t-PA) antigen decreased significantly (arterial 1.00-0.62, venous 1.00-0.67), whereas t-PA activity significantly increased (arterial 1.00-6.15, venous 1.00-2.66). In the control group, t-PA antigen remained unchanged. No changes were observed in blood pressure during and after infusion of eprosartan. CONCLUSION: Therapy-resistant hypertensive patients show beneficial changes in fibrinolytic activity after infusion of a non-pressor dose of AT1RB.

The plasma kallikrein-kinin system and risk of cardiovascular disease in men.

BACKGROUND: The plasma kallikrein-kinin system (PKKS) has been implicated in cardiovascular disease, but activation of the PKKS has not been directly probed in individuals at risk of coronary heart disease (CHD) or stroke. OBJECTIVE: To determine the involvement of the PKKS, including factor XI, in cardiovascular disease occurring in a nested case-control study from the Second Northwick Park Heart Study (NPHS-II). METHODS AND RESULTS: After a median follow-up of 10.7 years, 287 cases of CHD and stroke had been recorded and 542 age-matched controls were selected. When FXIIa-C1 esterase inhibitor (C1-inhibitor) concentrations were divided into tertiles (lowest tertile as reference), the odds ratios (ORs) at 95% CIs for CHD were 0.52 (0.34-0.80) in the middle tertile and 0.73 (0.49-1.09) in the highest tertile (P = 0.01 for the overall difference; P = 0.01 for CHD and stroke combined). For kallikrein-C1-inhibitor complexes, the ORs for stroke were 0.29 (0.12-0.72) and 0.67 (0.30-1.52) in the middle and high tertiles, respectively (P = 0.02). FXIIa-C1-inhibitor and kallikrein-C1-inhibitor complexes were negatively related to smoking and fibrinogen (P < 0.005). FXIa-inhibitor complexes correlated strongly with FXIIa-inhibitor complexes. CONCLUSIONS: Lower levels of inhibitory complexes of the PKKS enzymes and particularly of FXIIa contribute to the risk of CHD and stroke in middle-aged men. This observation supports the involvement of the PKKS in atherothrombosis.

Soluble tissue factor is a candidate marker for progression of microvascular disease in patients with Type 2 diabetes.

OBJECTIVE: To determine the relationship between abnormalities in blood coagulation and prevalent or incident cardiovascular complications in Type 2 diabetes. DESIGN AND METHODS: Prospective cohort study of 128 patients with Type 2 diabetes in whom blood samples were collected at baseline and after 1 year of follow-up. All cardiovascular complications at baseline and follow-up were recorded. Forty-three healthy, age-matched subjects served as a control group. RESULTS: Logistic analysis revealed an independent relationship between soluble tissue factor (TF) and microvascular disease [per pg mL(-1) TF: Exp(B) = 1.008; CI(95%)1.002-1.014], or neurogenic disease [Exp(B) = 1.006; CI(95%)1.001-1.011]. The highest levels of soluble TF were observed in patients with microvascular and neurogenic disease (P < 0.001). Patients with Type 2 diabetes having a soluble TF concentration >300 pg mL(-1) are at a 15-fold higher risk for the presence of microvascular disease and at a 10-fold higher risk for the presence of neurogenic disease compared with the patients with concentrations below 100 pg mL(-1). Soluble TF was correlated with tissue type plasminogen activator, von Willebrand factor antigen, systolic blood pressure and age. Levels of F1' + 2, D-dimer, FVIII activity, t-PA and vWFag were not different among patients with micro-, macro- or neurogenic complications compared with patients without those complications. Forty-eight new micro-, macro- and/or neurogenic complications were diagnosed after 1 year follow-up. With the exception of higher F1 + 2 levels after 1 year all other markers remained unchanged. A trend toward higher soluble TF levels was observed in patients with new microvascular events (P = 0.056). CONCLUSIONS: Soluble TF is associated with existing microvascular and neurogenic complications in patients with Type 2 diabetes and is a candidate marker for progression of microvascular disease.

Biomarkers for Prediction of Central Venous Catheter Related-Thrombosis in Patients With Hematological Malignancies.

OBJECTIVE: In a prospective setting, we aimed to find associations between biomarkers of the hemostatic system and the occurrence of central venous catheter (CVC)-related thrombosis in patients with hematological malignancies undergoing intensive chemotherapy. METHODS: The study was conducted between July 2006 and August 2010 at the University Hospital Maastricht, the Netherlands. Consecutive adult patients with hematological malignancies who were going to receive a CVC for intensive chemotherapy were included. The primary end points were (a) symptomatic CVC-related thrombosis and (b) CVC-related infections. Blood samples were taken directly after catheterization, and easy to determine biomarkers (platelet count, leukocyte count, and hemoglobin level) in combination with blood group, factor VIII (FVIII), plasminogen activator inhibitor 1 (PAI-1), activated protein C (APC) resistance, and free protein S antigen were determined. RESULTS: Blood was collected and analyzed from 168 patients. The incidence of symptomatic CVC-related thrombosis was 9%. In univariate analysis, white blood cell count >10.6 × 109/L, mean FVIII activity, and PAI-1 >12.2 IU/mL were found to be associated with the development of symptomatic CVC-related thrombosis. CONCLUSION: Elevated leukocyte count, high PAI-1, and high FVIII were associated with an increased incidence of symptomatic CVC-related thrombosis. We hope in future that simple, easy to determine laboratory tests that reflect the hemostatic and fibrinolytic activity in combination with clinical parameters may help to identify hematological patients at highest risk of CVC-related thrombosis and help to tailor the management of thromboprophylaxis in hematological patients undergoing CVC placement.

The impact of a male or female thrombotic family history on contraceptive counseling: a cohort study.

UNLABELLED: Essentials It is unknown if a male or female thrombotic family history influences risk in female relatives. We assessed thrombotic risk in female relatives of male and female patients with thrombosis. A hormonally related female thrombotic family history further increases risk in female relatives. This information could be important in counseling women on contraceptive options. Click to hear Prof. Rosendaal's perspective on venous thrombosis: etiology, pathogenesis, and prognosis SUMMARY: Background Women from thrombophilic families have increased risk of venous thromboembolism (VTE), which increases further during oral contraceptive (COC) use and pregnancy-postpartum. Whether this additional risk differs between relatives of male and female patients, or is different when that female patient had a hormonally related VTE (during COC use/pregnancy), is unknown. Methods One thousand five female relatives of consecutive patients with VTE from a family-based cohort were retrospectively followed for incident VTE from ages 15 to 50, first VTE, or study inclusion. Absolute and relative VTE risks adjusted for factors of patients (sex, age) and relatives (thrombophilia, COC use, pregnancy) were estimated in relatives of female and male patients and in relatives of female patients with and without hormonally related VTE. Results Absolute risk in relatives of female (0.32 [95% confidence interval [CI] 0.23-0.43]) vs. male patients (0.39 [95% CI 0.28-0.53]) was comparable. However, the heterogeneity analysis of risk estimates suggested that in relatives of female vs. male patients, the contribution of pregnancy-postpartum (hazard ratio [HR] 11.6 [95% CI 6.3-21.3] vs. HR6.6 [95% CI 2.8-15.2]) and, to a lesser extent, COC use (HR3.6 [95% CI 1.8-7.1] vs. HR2.7 [95% CI 1.5-5.0]) to the VTE risk differs. Absolute risk was significantly higher in relatives of female patients with hormonally related VTE (0.43 [95% CI 0.3-0.6]) vs. relatives of female patients without hormonally related VTE (0.13 [95% CI 0.05-0.27]), HR3.28 [95% CI 1.5-7.9]). The higher contribution of pregnancy-postpartum and COC use to the VTE risk was mainly observed in relatives of patients with hormonally related VTE. Conclusions These findings suggest that a family history from a female patient, especially when VTE was hormonally related, may further increase VTE risk in her female relatives. This information could be important in counseling women on contraceptive options.

Tissue factor pathway inhibitor activity in patients with IDDM.

Until now, several endothelium-dependent hemostatic parameters have been proposed as markers of vascular endothelial dysfunction in diabetes. We studied tissue factor pathway inhibitor (TFPI) activity in insulin-dependent diabetes mellitus (IDDM) patients without macro-or microvascular complications, before and after intravenous administration of heparin, in comparison with age-matched control subjects. We also examined the effect of acute hyperglycemia on TFPI activity in healthy men. A clotting and a chromogenic assay were used for determining TFPI activity. In the clotting assay, the COOH-terminus of TFPI is essential, but in the chromogenic assay, it is of minor importance. When the chromogenic assay was used, TFPI activity before heparin injection was significantly higher in the IDDM patients (92 +/- 24 vs. 112 +/- 23%, P < 0.01). The postheparin increase in TFPI activity, measured with both assays, was significantly higher in the diabetic subjects (area under the curve: clotting assay 64 +/- 14 vs. 81 +/- 24, P < 0.05; chromogenic assay 82 +/- 26 vs. 121 +/- 35, P < 0.0001). A positive correlation between TFPI activity and glycated hemoglobin was demonstrated. Acute hyperglycemia did not alter TFPI activity. It can be concluded that TFPI activity, especially after stimulation with heparin, is affected by chronic hyperglycemia in diabetic subjects without vascular complications. Alterations in TFPI activity may therefore reflect early endothelial dysfunction.

Endothelium-dependent vasodilatation, plasma markers of endothelial function, and adrenergic vasoconstrictor responses in type 1 diabetes under near-normoglycemic conditions.

It is unknown whether and to what extent changes in various endothelial functions and adrenergic responsiveness are related to the development of microvascular complications in type 1 diabetes. Therefore, endothelium-dependent and endothelium-independent vasodilatation, endothelium-dependent hemostatic factors, and one and two adrenergic vasoconstrictor responses were determined in type 1 patients with and without microvascular complications. A total of 34 patients with type 1 diabetes were studied under euglycemic conditions on two occasions (11 without microangiopathy, 10 with proliferative and preproliferative retinopathy previously treated by laser coagulation, 13 with microalbuminuria, and 12 healthy volunteers also were studied). Forearm vascular responses to brachial artery infusions of N(G)-monomethyl-L-arginine (L-NMMA), sodium nitroprusside, acetylcholine (ACh), clonidine, and phenylephrine were determined. The ACh infusions were repeated during coinfusion of L-arginine. Furthermore, plasminogen activator inhibitor type 1 (PAI-1) activity, tissue plasminogen activator antigen levels, von Willebrand factor antigen levels, tissue factor pathway inhibitor (TFPI) activity, and endothelin-1 levels were measured. No differences in endothelium-dependent or endothelium-independent vasodilatation or adrenergic constriction were observed between the diabetic patients and the healthy volunteers. In comparison to the first ACh infusion, the maximal response to repeated ACh during L-arginine administration was reduced in the diabetic patients, except in the patients with proliferative and preproliferative retinopathy previously treated by laser coagulation. In these patients, the combined infusion of L-arginine and ACh resulted in an enhanced response. TFPI activity was elevated, and PAI-1 activity was reduced in the type 1 diabetic patients. Furthermore, PAI-1 activity was positively correlated with urinary albumin excretion (r = 0.48, P < 0.01) and inversely correlated with the vasodilatory response to the highest ACh dose (r = -0.37, P < 0.05). The response to the highest ACh and L-NMMA dose were positively correlated with mean arterial blood pressure (r = 0.32, P < 0.01; r = 0.41, P < 0.01, respectively). Forearm endothelium-dependent and endothelium-independent vasodilatation and adrenergic responsiveness were unaltered in type 1 diabetic patients with and without microvascular complications. Relative to healthy control subjects, endothelium-dependent vasodilatation was depressed during a repeated ACh challenge (with L-arginine coinfusion) in the diabetic patients without complications or with microalbuminuria. In contrast, this vasodilatation was enhanced in the patients with retinopathy. Elevation of TFPI was the most consistent marker of endothelial damage of all the endothelial markers measured.

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.

Timing of initial administration of low-molecular-weight heparin prophylaxis against deep vein thrombosis in patients following elective hip arthroplasty: a systematic review.

BACKGROUND: Perioperative and postoperative venous thrombosis are common in patients undergoing elective hip surgery. Prophylactic regimens include subcutaneous low-molecular-weight heparin 12 hours or more before or after surgery and oral anticoagulants. Recent clinical trials suggest that low-molecular-weight heparin initiated in closer proximity to surgery is more effective than the present clinical practice. We performed a systematic review of the literature to assess the efficacy and safety of low-molecular-weight heparin administered at different times in relation to surgery vs oral anticoagulant prophylaxis. METHODS: Reviewers (A.F.M. and S.M.M.) identified studies by searching MEDLINE, reviewing references from retrieved articles, scanning abstracts from conference proceedings, and contacting investigators and pharmaceutical companies. Randomized trials comparing low-molecular-weight heparin administered at different times relative to surgery with oral anticoagulants in patients undergoing elective hip arthroplasty, evaluated using contrast phlebography, were selected. Two reviewers (A.F.M. and S.M.M.) extracted data independently. RESULTS: The literature review identified 4 randomized trials meeting predefined inclusion criteria. The results indicate that low-molecular-weight heparin initiated in close proximity to surgery resulted in absolute risk reductions of 11% to 13% for deep vein thrombosis, corresponding to relative risk reductions of 43% to 55% compared with oral anticoagulants. Low-molecular-weight heparin initiated 12 hours before surgery or 12 to 24 hours postoperatively was not more effective than oral anticoagulants. Low-molecular-weight heparin initiated postoperatively in close proximity to surgery at half the usual dose was not associated with a clinically or statistically significant increase in major bleeding rates (P =.16). CONCLUSIONS: The timing of initiating low-molecular-weight heparin significantly influences antithrombotic effectiveness. The practice of delayed initiation of low-molecular-weight heparin prophylaxis results in suboptimal antithrombotic effectiveness without a substantive safety advantage.

The interaction of the prostaglandin E derivative rioprostil with oral anticoagulant agents.

The prostaglandin E1 analogue rioprostil was tested for potential interaction with oral anticoagulant therapy in healthy male volunteers. The effect of rioprostil (0.3 mg, twice a day) was investigated on acenocoumarol (10 mg per subject, n = 7) and phenoprocoumon (0.2 mg/kg, n = 6) single-dose pharmacokinetics and pharmacodynamics. Plasma levels of thrombotest, prothrombin (factor II), and factor VII activities were assayed. Rioprostil, 7 days pretreatment, did not affect control parameters of blood coagulation activity. During the rioprostil period the effect of phenprocoumon on thrombotest and factor VII activities was significantly weaker (p less than 0.02, ANOVA) compared with the control experiment. The effect of acenocoumarol on thrombotest activity was significantly weaker at 24 and 31 hours. None of the pharmacokinetic parameters tested were affected by rioprostil medication. The findings suggest that prostaglandins, at least those of the E series, attenuate the anticoagulant action of the oral anticoagulant agents by a mechanism not related to any pharmacokinetic interaction.

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.

4-Hydroxycoumarin oral anticoagulants: pharmacokinetics-response relationship.

The blood coagulating factors II and VII and prothrombin times (Thrombotest) were followed during a dosage interval (= 24 h) in patients on acenocoumarol (n = 6) and on phenprocoumon (n = 6) therapy. The patients were on stable anticoagulation (%TT: 7-13%) for at least 6 months. The study was performed to investigate the concentration-response relationship of the 4-hydroxycoumarin-type oral anticoagulants. The three parameters were stable during the 24-h interval for patients on phenprocoumon therapy. Patients on acenoumarol showed fluctuations in their factor VII levels; peak activities were observed at about 2 h, trough activities at about 16 h after acenocoumarol intake. Factor II and Thrombotest activities were stable. Plasma levels of phenprocoumon were stable during daytime whereas acenocoumarol levels declined exponentially (t1/2 about 12 h). The results indicate the oral anticoagulants to exhibit a concentration-response relationship common to drug-receptor interactions. The results also suggest that for stable and long-lasting anticoagulant therapy oral anticoagulants with half-lives beyond the dosage interval (t1/2 greater than 24 h) should be preferred.

Circulating osteocalcin during oral anticoagulant therapy.

In this paper we present the following observations: 1) In sheep vitamin K-antagonists like phenprocoumon induce a decrease of the serum levels of osteocalcin (bone Gla-protein) and of the affinity of the circulating osteocalcin for hydroxyapatite. 2) In sheep vitamin K counteracts the effect of phenprocoumon on the blood coagulation system, but not that on the osteocalcin production. 3) In human subjects vitamin K-antagonists also lead to decreased levels of serum osteocalcin and a low affinity of the protein for hydroxyapatite. 4) These two variables reached steady-state levels within 24 h after the start of oral anticoagulant treatment and--at continuation of the therapy--they remained low for at least several years.

The effect of DDAVP infusion on thrombin generation in platelet-rich plasma of von Willebrand type 1 and in mild haemophilia A patients.

In von Willebrand disease (vWD) type 1 and mild haemophilia A patients we studied the effect of an infusion of DDAVP (0.3 microg/kg body weight) on thrombin generation in platelet-rich plasma (PRP) and platelet-poor plasma (PPP). Baseline thrombin generation in PRP was diminished both in the haemophilia A and vWD patients. It was normal in vWD plasma when sufficient procoagulant phospholipids were present, either via adding phospholipid vesicles to PPP or via scrambling of the platelet membrane with ionomycin in PRP. In haemophilia A plasma, thrombin generation did not normalize by providing procoagulant phospholipids. Treatment with DDAVP temporarily restored thrombin generation in PRP to normal in both diseases. To investigate the individual roles of von Willebrand factor (vWF) and factor VIII, we also studied the effect of factor VIII infusion on thrombin generation in a severe haemophilia patient. It appears that at a fixed normal vWF concentration, <25% factor VIII is sufficient for normal thrombin generation in PRP. At a sufficient factor VIII concentration, however, thrombin generation is still lower than normal in vWD patients; approximately 40% of vWF is required for half-normal thrombin generation in PRP. It thus appears that vWF is also a clotting factor, in the sense that it is required for normal thrombin generation. This underlines the importance of the interaction between coagulation and the platelets in normal haemostasis. Thrombin generation in PRP appears to be a suitable test to reflect the combined function.