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The optimal duration of treatment with vitamin K antagonists (VKA) after venous thromboembolism (VTE) in patients with Philadelphia-negative myeloproliferative neoplasms (MPNs) is uncertain. To tackle this issue, we retrospectively studied 206 patients with MPN-related VTE (deep venous thrombosis of the legs and/or pulmonary embolism). After this index event, we recorded over 695 pt-years 45 recurrences, venous in 36 cases, with an incidence rate (IR) of 6.5 per 100 pt-years (95% confidence interval (CI): 4.9–8.6). One hundred fifty-five patients received VKA; the IR of recurrent thrombosis per 100 pt-years was 4.7 (95% CI: 2.8–7.3) on VKA and 8.9 (95% CI: 5.7–13.2) off VKA (P=0.03). In patients receiving VKA, the IR of recurrent thrombosis per 100 pt-years was 5.3 (95% CI: 3.2–8.4) among 108 patients on long-term VKA and 12.8 (95% CI: 7.3–20.7) after discontinuation among the 47 who ceased treatment (P=0.008), with a doubled risk of recurrence after stopping VKA (hazard ratio: 2.21, 95% CI: 1.19–5.30). The IR of major bleeding per 100 pt-years was 2.4 (95%: CI: 1.1–4.5) on VKA and 0.7 (95% CI: 0.08–2.5) off VKA (P=0.08). In conclusion, in MPN patients with VTE recurrent thrombosis is significantly reduced by VKA and caution should be adopted in discontinuation; however, the incidence of recurrence on treatment remains high, calling for clinical trials aimed to improve prophylaxis in this setting.

A quantitative risk assessment was developed to describe the risk of campylobacteriosis and hemolytic uremic syndrome (HUS) linked to consumption of raw milk sold in vending machines in Northern Italy. Exposure assessment considered the microbiological status of dairy farms, expected milk contamination, storage conditions from bulk tank to home storage, microbial growth during storage, destruction experiments, consumption frequency of raw milk, age of consumers, serving size, and consumption preference. The differential risk between milk handled under regulation conditions (4°C throughout all phases) and the worst field handling conditions was considered. The probability of Campylobacter jejuniinfection was modeled with a single-hit dose-response beta-Poisson model, whereas for HUS an exponential dose-response model was chosen and two probabilities were used to model the higher susceptibility of children younger than 5 years old. For every 10,000 to 20,000 consumers each year, the models predicted for the best and worst storage conditions, respectively, 2.12 and 1.14 campylobacteriosis cases and 0.02 and 0.09 HUS cases in the 0- to 5-year age group and 0.1 and 0.5 HUS cases in the >5-year age group. The expected pediatric HUS cases do not differ considerably from those reported in Italy by the Minister of Health. The model developed may be a useful tool for extending the assessment of the risk of campylobacteriosis and HUS due to raw milk consumption at the national level in Italy. Considering the epidemiological implications of this study, the risk of illness linked to raw milk consumption should not be ignored and could be reduced by the use of simple measures. Boiling milk before consumption and strict control of temperatures by farmers during raw milk distribution have significant effects on campylobacteriosis and HUS and are essential measures for risk management.

In this overview we address the three phase III studies that compared new oral anticoagulants (dabigatran, rivaroxaban and apixaban) with warfarin in the setting of stroke prevention in atrial fibrillation. Strengths and weaknesses of the studies were examined in detail through indirect comparison. We analyze and comment the inclusion and exclusion criteria, the characteristics of randomized patients, the primary efficacy and safety end points and side effects. All new oral anticoagulants resulted in being non‐inferior to vitamin K antagonists in reducing stroke or systemic embolism in patients with atrial fibrillation. Dabigatran 150 mg and apixaban were superior to vitamin K antagonists. Importantly, new oral anticoagulants significantly reduced hemorrhagic stroke in all three studies. Major differences among new oral anticoagulants include the way they are eliminated and side effects. Both dabigatran and apixaban were tested in low‐ to moderate‐risk patients (mean CHADS2 [Congestive heart failure, Hypertension, Age, Diabetes, Stroke] score = 2.1–2.2) whereas rivaroxaban was tested in high‐risk patients (mean CHADS2 score = 3.48) and at variance with dabigatran and apixaban was administered once daily. Apixaban significantly reduced mortality from any cause. The choice of a new oral anticoagulant should take into account these and other differences between the new drugs.

Background: The optimal intensity of oral anticoagulation for the prevention of recurrent thrombosis in patients with antiphospholipid antibody syndrome is uncertain. Retrospective studies show that only high‐intensity oral anticoagulation [target international normalized ratio (INR) >3.0] is effective but a recent randomized clinical trial comparing high (INR range 3.0–4.0) vs. moderate (INR 2.0–3.0) intensities of anticoagulation failed to confirm this assumption. Methods: We conducted a randomized trial in which 109 patients with antiphospholipid syndrome (APS) and previous thrombosis were given either high‐intensity warfarin (INR range 3.0–4.5, 54 patients) or standard antithrombotic therapy (warfarin, INR range 2.0–3.0 in 52 patients or aspirin alone, 100 mg day−1in three patients) to determine whether intensive anticoagulation is superior to standard treatment in preventing symptomatic thromboembolism without increasing the bleeding risk. Results: The 109 patients enrolled in the trial were followed up for a median time of 3.6 years. Mean INR during follow‐up was 3.2 (SD 0.6) in the high‐intensity warfarin group and 2.5 (SD 0.3) (P < 0.0001) in the conventional treatment patients given warfarin. Recurrent thrombosis was observed in six of 54 patients (11.1%) assigned to receive high‐intensity warfarin and in three of 55 patients (5.5%) assigned to receive conventional treatment [hazard ratio for the high intensity group, 1.97; 95% confidence interval (CI) 0.49–7.89]. Major and minor bleeding occurred in 15 patients (two major) (27.8%) assigned to receive high‐intensity warfarin and eight (three major) (14.6%) assigned to receive conventional treatment (hazard ratio 2.18; 95% CI 0.92–5.15). Conclusions: High‐intensity warfarin was not superior to standard treatment in preventing recurrent thrombosis in patients with APS and was associated with an increased rate of minor hemorrhagic complications.

We have investigated the effects of the light-induced thylakoid transmembrane potential on the turnover of the b(6)f complex in cells of the unicellular green alga Chlamydomonas reinhardtii. The reduction of the potential by either decreasing the light intensity or by adding increasing concentrations of the ionophore carbonylcyanide p-(trifluoromethoxy)phenylhydrazone (FCCP) revealed a marked inhibition of the cytochrome b(6) oxidation rate (10-fold) without substantial modifications of cytochrome f oxidation kinetics. Partial recovery of this inhibition could be obtained in the presence of ionophores provided that the membrane potential was re-established by illumination with a train of actinic flashes fired at a frequency higher than its decay. Measurements of isotopic effects on the kinetics of cytochrome b(6) oxidation revealed a synergy between the effects of ionophores and the H(2)O-D(2)O exchange. We propose therefore, that protonation events influence the kinetics of cytochrome b(6) oxidation at the Qi site and that these reactions are strongly influenced by the light-dependent generation of a transmembrane potential.

With the aim of establishing whether the HR2 haplotype in factor V affects the risk of venous thromboembolism, a retrospective multicenter cohort study was performed in 810 family members identified through 174 probands who suffered from at least 1 episode of deep vein thrombosis and/or pulmonary embolism and had an inherited defect associated with thrombophilia (antithrombin, protein C, or protein S deficiency; factor V R506Q or prothrombin G20210A). Fifty-eight percent (468/810) of the family members had an inherited defect and 10% (47/468) were symptomatic. The HR2 haplotype was found in association with factor V R506Q more frequently in family members with venous thromboembolism (18%) than in those without (8%). Double heterozygosity for factor V R506Q and HR2 conferred a 3- to 4-fold increase in the relative risk of venous thromboembolism compared with factor V R506Q alone. The median age at first event was lower when the 2 defects were associated (46v 52 years). No increase in risk of venous thromboembolism could be demonstrated when the HR2 haplotype was associated with inherited thrombophilic defects other than factor V R506Q. Because both factor V R506Q and the HR2 haplotype are very frequent, the effect of their coinheritance on the risk of venous thromboembolism might represent a clinically relevant issue, and screening for HR2 in carriers of factor V R506Q should be considered.

Abstract:  Acute leukemia and myelodysplastic syndromes are rare, but almost invariably fatal, evolutions of essential thrombocythemia (ET). Three major factors are associated with blastic transformation: cytogenetic abnormalities, myelofibrotic features, and the use of cytotoxic agents. Hematological malignancies have been reported in ET patients after treatment with alkylating agents, such as busulphan, as well as other cytoreductive drugs, such as hydroxyurea. Concerns about leukemogenicity have led some to suggest limiting the indications of these drugs to patients at higher risk of bleeding and thrombosis. Major risk factors for thrombosis are age above 60 years and a previous thrombotic event, whereas an increased bleeding tendency has been reported with platelet counts in excess of 1000–1500×109/l. No myelosuppressive therapy is recommended for younger patients if they are asymptomatic or their platelet counts are below 1500×109/l. The threshold of 1500×109/l is controversial, however, and cytoreduction can be considered when platelets are above 1000×109/l or in the presence of risk factors for cardiovascular disease. In the presence of thrombotic events or extreme thrombocytosis, young ET patients can be managed with cytoreductive agents theoretically devoid of leukemogenic risk, such as a-interferon or anagrelide. Nevertheless, the mutagenic risk of anagrelide has not been investigated in long-term follow-up studies, and the ultimate place of these 'new' drugs in the management of ET patients remains to be established in prospective and controlled clinical trials.

With the aim of establishing whether the HR2 haplotype in factor V affects the risk of venous thromboembolism, a retrospective multicenter cohort study was performed in 810 family members identified through 174 probands who suffered from at least 1 episode of deep vein thrombosis and/or pulmonary embolism and had an inherited defect associated with thrombophilia (antithrombin, protein C, or protein S deficiency; factor V R506Q or prothrombin G20210A). Fifty-eight percent (468/810) of the family members had an inherited defect and 10% (47/468) were symptomatic. The HR2 haplotype was found in association with factor V R506Q more frequently in family members with venous thromboembolism (18%) than in those without (8%). Double heterozygosity for factor V R506Q and HR2 conferred a 3- to 4-fold increase in the relative risk of venous thromboembolism compared with factor V R506Q alone. The median age at first event was lower when the 2 defects were associated (46v52 years). No increase in risk of venous thromboembolism could be demonstrated when the HR2 haplotype was associated with inherited thrombophilic defects other than factor V R506Q. Because both factor V R506Q and the HR2 haplotype are very frequent, the effect of their coinheritance on the risk of venous thromboembolism might represent a clinically relevant issue, and screening for HR2 in carriers of factor V R506Q should be considered.

According to strict clinical, hematological and morphological criteria, the Philadelphia (Ph) chromosome negative chronic myeloproliferative disorders essential thrombocythemia (ET), polycythemia vera (PV), and agnogenic myeloid (megakaryocytic/granulocytic) metaplasia (AMM) or idiopathic myelofibrosis (IMF) are three distinct disease entities with regard to clinical manifestations, natural history and outcome in terms of life expectancy. As clonality studies have clearly demonstrated that fibroblast proliferation in AMM, as well as in many other conditions such as advanced stages of Ph+-essential thrombocythemia, Ph+-granulocytic leukemia, and Ph−-polycythemia vera, is polyclonal indicating that myelofibrosis is secondary to the megakaryocytic granulocytic metaplasia in these various conditions, AMM is illogically labeled as IMF. As abnormal megakaryocytic granulocytic metaplasia is the essential feature preceding the early prefibrotic stage of AMM, the term essential megakaryocytic granulocytic metaplasia (EMGM) can readily be used to characterize this condition more appropriately at the biological level.

Essential thrombocytemia (ET) is a clonal myeloproliferative disorder of unknown cause, characterized by an increased number of apparently normal platelets.

In seven patients with acquired von Willebrand's disease (AvWD) associated with lymphoproliferative disorders or benign monoclonal gammopathies, the platelet contents of von Willebrand factor antigen and ristocetin cofactor (vWF:Ag and vWF:RiCof, respectively) were normal. All the multimers of vWF:Ag could be seen in the 1.6% SDS- agarose gel electrophoresis patterns of plasma and platelet lysates. Infusion of 1-deamino-8-D-arginine vasopressin (DDAVP) augmented plasma levels of vWF:Ag and vWF:RiCof of all patients and corrected prolonged bleeding times (BT). However, compared with patients with congenital vWD type I and comparable degrees of baseline abnormalities treated in the same way, vWF:Ag and vWF:RiCof were increased less and cleared more rapidly from plasma and the BT remained normal for a shorter period of time. These studies provide evidence that these AvWD patients have qualitatively normal vWF in plasma, but at lower concentrations, that vWF in platelets is normal both qualitatively and quantitatively, and that cellular vWF can be rapidly released into plasma by DDAVP to correct the hemostatic abnormalities. However, vWF is removed rapidly from plasma, making the correction more transient than in congenital vWD type I.

Type 1 antithrombin III (ATIII) deficiency, which is the commonest form of inherited ATIII defect, is characterized by a quantitative reduction in both immunologically and functionally detectable protein. This condition is associated with a high incidence of thromboembolic disorder. Previous investigations have shown that the ATIII genes in the majority of cases are grossly intact, but the precise underlying molecular defects remain unknown. We have investigated the molecular basis of a type 1 ATIII deficiency in an Italian kindred by enzymatic amplification of the ATIII gene sequences in affected family members and direct sequencing of the amplified genomic DNA. A novel mutation, the deletion of a single T in the second position of codon 119, was identified in each of the affected individuals. The resulting frameshift leads to a premature termination in codon 126, effectively resulting in a null allele.

In seven patients with acquired von Willebrand's disease (AvWD) associated with lymphoproliferative disorders or benign monoclonal gammopathies. the platelet contents of von Willebrand factor antigen and ristocetin cofactor (vWF:Ag and vWF:RiCof, respectively) were normal. All the multimers of vWF:Ag could be seen in the 1.6% SDS-agarose gel electrophoresis patterns of plasma and platelet lysates. Infusion of 1-deamino-8-D-arginine vasopressin (DDAVP) augmented plasma levels of vWF:Ag and vWF:RiCof of all patients and corrected prolonged bleeding times (BT). However, compared with patients with congenital vWD type I and comparable degrees of baseline abnormalities treated in the same way, vWF:Ag and vWF:RiCof were increased less and cleared more rapidly from plasma and the BT remained normal for a shorter period of time. These studies provide evidence that these AvWD patients have qualitatively normal vWF in plasma, but at lower concentrations, that vWF in platelets is normal both qualitatively and quantitatively, and that cellular vWF can be rapidly released into plasma by DDAVP to correct the hemostatic abnormalities. However, vWF is removed rapidly from plasma, making the correction more transient than in congenital vWD type I.

Type 1 antithrombin III (ATIII) deficiency, which is the commonest form of inherited ATIII defect, is characterized by a quantitative reduction in both immunologically and functionally detectable protein. This condition is associated with a high incidence of thromboembolic disorder. Previous investigations have shown that the ATIII genes in the majority of cases are grossly intact, but the precise underlying molecular defects remain unknown. We have investigated the molecular basis of a type 1 ATIII deficiency in an Italian kindred by enzymatic amplification of the ATIII gene sequences in affected family members and direct sequencing of the amplified genomic DNA. A novel mutation, the deletion of a single T in the second position of codon 119, was identified in each of the affected individuals. The resulting frameshift leads to a premature termination in codon 126, effectively resulting in a null allele.

Antiphospholipid (aPL) antibodies include anticardiolipin (aCL) and lupus anticoagulant (LA) antibodies. LA antibodies recognize the complex of lipid-bound (human) prothrombin, in this way inhibiting the phospholipid-dependent coagulation reactions, whereas aCL antibodies are directed towards beta 2-glycoprotein I (beta 2-GPI) bound to an anionic lipid surface. According to their behavior in coagulation reactions, we have divided aCL antibodies into two groups: aCL-type A, which inhibit the phospholipid-dependent coagulation reactions because they enhance the binding of beta 2-GPI to the procoagulant phospholipid surface; and aCL-type B antibodies, which are devoid of anticoagulant properties. We report the distinctive laboratory and clinical profiles of 25 patients with well-characterized, phospholipid-dependent inhibitor of coagulation. Fourteen patients had LA antibodies (aCL-type B were concomitantly present in 10 cases, while in the other four, aCL titer was normal), and the other 11 had aCL-type A antibodies. The laboratory evaluation of the two groups showed the dilute Russell viper venom time (dRVVT) to be the most abnormal coagulation test in the aCL- type A-positive group, whereas the kaolin clotting time (KCT) was the most abnormal assay in the LA-positive group. In fact, the ratios of the coagulation times of patient plasma over normal pooled plasma (mean +/- standard deviation) for LA versus aCL-type A antibodies were 1.48 +/- 0.27 versus 2.20 +/- 0.42, P = .0001, and 2.22 +/- 0.42 versus 1.50 +/- 0.42, P = .0003, for the dRVVT and KCT, respectively. No differences were observed either in the ratios of the activated partial thromboplastin times and the prothrombin times or the plasma levels of beta 2-GPI and prothrombin. Conversely, aCL titers were significantly higher in aCL-type A-positive patients (147 +/- 44 U) than in the LA- positive group (61 +/- 55 U; P = .0003). We ruled out the possibility that platelet contamination of plasma could account for the observed coagulation profiles, as the two patterns were reproduced in platelet- free plasma. In addition, we performed clotting tests in plasma in the presence of phospholipids and calcium after addition of factor IXa or factor Xa. The assay performed with factor Xa was more sensitive to the presence of aCL-type A antibodies, while the assay performed with factor IXa was preferentially sensitive to LA-containing plasmas, supporting the earlier findings with the dRVVT and KCT assays.(ABSTRACT TRUNCATED AT 400 WORDS)

Congenital protein S deficiency is an important risk factor for venous and, more rarely, arterial thrombosis.

The purpose of this study was to estimate the incidence and to establish which factors were associated with an increased risk of hemorrhagic complications in an historic cohort of 117 consecutive and unselected patients with chronic idiopathic thrombocytopenic purpura (ITP). Sixty-eight patients (58%) underwent medical treatment and/or splenectomy and 33 (48% of treated) achieved a complete stable remission. At equivalent platelet count the incidence of major hemorrhagic complications was significantly higher in aged (greater than 60 years) than in younger (less than 40 years) patients (10.4% v 0.4%/pt-y, relative risk = 28.9, P less than .01). A previous hemorrhagic event was identified as another major risk factor for hemorrhage (relative risk = 27.5, P less than .0005), while hypertension and underlying disorders had no influence. We conclude that age more than 60 years and a previous history of bleeding are major risk factors for severe hemorrhages in adults with ITP.

Out of a consecutive series of 50 young people less than 45 years old with nonhemorrhagic arterial stroke, three patients had inherited protein C deficiency. CT revealed hypodense areas consistent with the clinical picture, and angiography showed occlusion of some intracranial arterial vessels. Other possible associated causes of stroke were ruled out. One patient had a transient ischemic attack and a peripheral venous thrombosis prior to the actual stroke, whereas the others were completely asymptomatic, as were relatives with the same deficiency. We suggest determining protein C in ischemic stroke of all young adults, especially when major risk factors are excluded.

Background: Thrombosis is a common cause of morbidity in polycythemia vera (PV) and essential thrombocythemia (ET). Prior thrombosis is a major risk factor for rethrombosis; yet optimal strategy for prevention of recurrence has been scarcely addressed. Objective: To assess in PV or ET patients with prior thrombosis the rate of recurrence, the risk factors for recurrence, and the efficacy of antithrombotic or cytoreductive strategies in preventing rethrombosis. Methods: We retrospectively investigated a cohort of 470 patients (M/F 227/243, PV/ET 235/235, median age at diagnosis 62 yrs, range 19–88) with a first arterial (n=328, 69.8%) or venous thrombosis (n=142, 30.2%). First thrombosis was cerebrovascular disease (CVD) in 184 cases, acute coronary syndrome (ACS) in 102, venous thromboembolism of limbs (VTE) in 102, and venous thrombosis of unusual sites (un-VTE) in 40. Microcirculatory events were not computed. Multivariate time-dependent models were developed having first recurrence as dependent variable and putative predictive or protective factors as covariates. Results: 158 patients (33.6%) had one or more recurrences during a total time from the first thrombosis of 2,821 pt-yrs (median 5.3 yrs); the overall incidence of events was 7.54% pt-yrs (4.60% arterial and 2.94% venous recurrences). Major bleeding occurred in 25 patients (84% receiving antithrombotic prophylaxis) with an incidence of 0.88% pt-yrs. The cumulative incidence of recurrence at 10 years after the first event was 64.7% (95%CI 49.1–80.3) in VTE patients, 51.9% (95%CI 37.8–66.0) in ACS, 46.6% (95%CI 35.1–58.1) in CVD, and 30.2% (95%CI 8.8–51.6) in un-VTE. In VTE patients analysis restricted to venous recurrences showed at 10 years a rate of 49.4% (95%CI 32.8–66.1). Sex, diagnosis (PV or ET), and presence of vascular risk factors did not affect the overall probability of recurrence. Age >60 years predicted recurrence (multivariate hazard ratio 1.76, 95%CI 1.24–2.49); arterial or venous first thrombosis predicted either arterial (HR 4.43, 95%CI 1.22–16.07) or venous recurrence (HR 8.48, 95%CI 1.62–44.48), respectively. Cytoreductive treatment halved the probability of all types of recurrence in the overall cohort (HR 0.54, 95%CI 0.38–0.76). In the overall model long-term antiplatelet or anticoagulant treatment did not result as independent protective factors. However, analysis of patient groups showed that a significant efficacy in preventing rethrombosis was achieved in VTE only by long-term oral anticoagulation (HR 0.42, 95%CI 0.19–0.91), in ACS by cytoreduction (HR 0.37, 95%CI 0.17–0.78), and in CVD by antiplatelet agents (HR 0.34, 95% CI 0.16–0.69). Conclusions: In PV or ET the rate of recurrent VTE seems higher than the usually observed in patients with unprovoked first VTE. Moreover our findings suggest that strategies for preventing rethrombosis and based on cytoreduction or antithrombotic prophylaxis should be tailored according to the type of first clinical event. Further studies are needed to confirm such hypothesis.

Background: Thrombosis is a common cause of morbidity in polycythemia vera (PV) and essential thrombocythemia (ET). Prior thrombosis is a major risk factor for rethrombosis; yet optimal strategy for prevention of recurrence has been scarcely addressed.