Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 146
Filtrar
1.
Appl Opt ; 59(26): 7994-8002, 2020 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-32976475

RESUMO

The full-beam in-tank (FBIT) diagnostic has been deployed to directly measure the target-plane beam fluence profile, when operated at high energy, of the OMEGA Laser System at the University of Rochester's Laboratory for Laser Energetics. This paper presents the results of early measurements taken with this diagnostic and discusses an improvement that has overcome performance limitations discovered during the initial testing. The diagnostic gives new insight into the ability of the OMEGA Laser System to provide uniform fluence profiles that are consistent across all 60 beams in the laser. The ultimate goal of the FBIT diagnostic is to allow accurate assessment of the fluence uniformity on a spherical target in 60-beam implosion experiments.

2.
Nature ; 565(7741): 581-586, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30700868

RESUMO

Focusing laser light onto a very small target can produce the conditions for laboratory-scale nuclear fusion of hydrogen isotopes. The lack of accurate predictive models, which are essential for the design of high-performance laser-fusion experiments, is a major obstacle to achieving thermonuclear ignition. Here we report a statistical approach that was used to design and quantitatively predict the results of implosions of solid deuterium-tritium targets carried out with the 30-kilojoule OMEGA laser system, leading to tripling of the fusion yield to its highest value so far for direct-drive laser fusion. When scaled to the laser energies of the National Ignition Facility (1.9 megajoules), these targets are predicted to produce a fusion energy output of about 500 kilojoules-several times larger than the fusion yields currently achieved at that facility. This approach could guide the exploration of the vast parameter space of thermonuclear ignition conditions and enhance our understanding of laser-fusion physics.

3.
Appl Opt ; 57(32): 9571-9583, 2018 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-30461737

RESUMO

Multibeam lasers often require an output beam balance that specifies the degree of simultaneity of the laser output energy, instantaneous power, or instantaneous irradiance (power per unit area). This work describes the general problem of balancing a multibeam laser. Specific techniques used to balance the output power of the 60-beam pulsed OMEGA Laser System are discussed along with a measured reduction of beam-to-beam imbalance. In particular, the square-pulse distortion induced by a simple saturating amplifier operating with its output at some fraction of its saturation fluence is derived, and a method to exchange gain between saturated amplifiers in a single beam that have different saturation fluences to adjust balance is described.

4.
Thromb Res ; 146: 119-125, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27354153

RESUMO

BACKGROUND: The rate of recurrent venous thromboembolism (VTE) in patients with a first unprovoked VTE who had a negative qualitative D-dimer test one month after stopping anticoagulant therapy was higher than expected in the D-dimer Optimal Duration Study (DODS). OBJECTIVES: To determine whether quantitative D-dimer levels using a low threshold, age- and sex-specific thresholds, or repeated measurements, would improve identification of patients at low risk of recurrent VTE. MATERIALS AND METHODS: D-dimer levels were quantified in banked samples from 307 patients in DODS who had a negative qualitative D-dimer test while on, and 1month after stopping, anticoagulant therapy and the rates of recurrent VTE were determined in patients with D-dimer levels below various predefined thresholds. RESULTS: The rate (per patient year) of recurrent VTE was: 5.9% with D-dimer levels<250µg/l at one month; 5.2% with D-dimer levels between 250 and 499µg/l at one month; 5.0% with D-dimer levels less than predefined age- and sex-specific thresholds at one month; and 6.3% when D-dimer levels were <500µg/l at both one and 7months after stopping anticoagulant therapy. These rates are similar to the overall event rate of 6.3% in patients who stopped treatment. CONCLUSIONS: Among unprovoked VTE patients who had a negative qualitative D-dimer test during and after anticoagulant therapy, low D-dimer thresholds, age and sex-adjusted thresholds or repeated measurements, did not identify subgroups with a very low rate of recurrence.


Assuntos
Anticoagulantes/uso terapêutico , Produtos de Degradação da Fibrina e do Fibrinogênio/metabolismo , Tromboembolia Venosa/tratamento farmacológico , Estudos de Coortes , Feminino , Humanos , Masculino , Prognóstico , Recidiva , Medição de Risco , Fatores de Risco
5.
Eur J Clin Microbiol Infect Dis ; 35(9): 1433-9, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27230510

RESUMO

Currently, in vitro synergy with colistin has not translated into improved clinical outcomes. This study aimed to compare colistin combination therapy to colistin monotherapy in critically ill patients with multi-drug resistant gram-negative (MDR-GN) pneumonia. This was a retrospective analysis of critically ill adult patients receiving intravenous colistin for MDR-GN pneumonia comparing colistin combination therapy to colistin monotherapy with a primary endpoint of clinical cure. Combination therapy was defined by administration of another antibiotic to which the MDR-GN pathogen was reported as susceptible or intermediate. Ninety patients were included for evaluation (41 combination therapy and 49 monotherapy). Baseline characteristics were similar between groups. No difference in clinical cure was observed between combination therapy and monotherapy in univariate analysis, nor when adjusted for APACHE II score and time to appropriate antibiotic therapy (57.1 vs. 63.4 %, adjusted OR 1.15, p = 0.78). Microbiological cure was significantly higher for combination therapy (87 vs. 35.5 %, p < 0.001). Colistin combination therapy was associated with a significant improvement in microbiological cure, without improvement in clinical cure. Based on the in vitro synergy and improvement in microbiological clearance, colistin combination therapy should be prescribed for MDR-GN pneumonia. Further research is warranted to determine if in vitro synergy with colistin translates into improved clinical outcomes.


Assuntos
Antibacterianos/uso terapêutico , Colistina/uso terapêutico , Estado Terminal , Farmacorresistência Bacteriana Múltipla , Bactérias Gram-Negativas/efeitos dos fármacos , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Pneumonia Bacteriana/tratamento farmacológico , Administração Intravenosa , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Quimioterapia Combinada/métodos , Feminino , Bactérias Gram-Negativas/isolamento & purificação , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Pneumonia Bacteriana/microbiologia , Pneumonia Bacteriana/patologia , Estudos Retrospectivos , Resultado do Tratamento , Adulto Jovem
6.
J Thromb Haemost ; 14(1): 3-27, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26439670

RESUMO

UNLABELLED: Essentials The priority of ISTH was to establish a global core curriculum in thrombosis and hemostasis. International survey to determine competencies required for clinical specialists was carried out in the field. Competency framework provides a reference point for mapping and developing regional curricula. Core curriculum informs and links to a variety of ISTH educational materials. SUMMARY: Background The International Society on Thrombosis and Haemostasis (ISTH) identified the need for an international core curriculum on thrombosis and hemostasis for its society members and the larger thrombosis and hemostasis community. Aims The current research sought consensus on the core competencies required by medical doctors who are ready to practise as independent clinical specialists in thrombosis and hemostasis with the aim of developing a core clinical curriculum for specialists in the field. Method A draft list of competencies was developed by the Working Group and formed the basis of an online survey. ISTH members and the larger thrombosis and hemostasis community were asked to rate the importance of each competency, on a Likert scale, for clinical specialists in thrombosis and hemostasis. Results There were a total of 644 responses to the online survey with broad geographical representation. There was general agreement on what level of competency would be required for clinical specialists in thrombosis and hemostasis at the specified level of training. Conclusions Using the survey to gain consensus on the level of competency required by clinical specialists in the field of thrombosis and hemostasis enabled the development of a core clinical curriculum that has been endorsed by the ISTH Council. The curriculum will offer a framework and international reference that will be used by the society, by national and regional organizations, and for further research.


Assuntos
Cardiologia/educação , Competência Clínica , Currículo , Hematologia/educação , Hemostasia , Trombose/terapia , Cardiologia/métodos , Geografia , Hematologia/métodos , Humanos , Cooperação Internacional , Sociedades Médicas , Inquéritos e Questionários
7.
BMJ ; 345: e4944, 2012 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-22872710

RESUMO

OBJECTIVES: To evaluate the risk of venous thromboembolic events associated with the use of progestin-only contraception and whether that risk differs with the mode of drug delivery (oral, intrauterine, or depot injection). DESIGN: Systematic review and meta-analysis of randomised controlled trials and observational studies. DATA SOURCES: Pubmed, Embase, Cochrane Library, and reference lists of relevant reviews. STUDY SELECTION: Randomised controlled trials and case-control, cohort, and cross sectional studies with venous thromboembolic outcome for progestin-only contraception reported relative to a non-hormone comparator group. DATA EXTRACTION: Data were extracted by two independent investigators, and consensus for inclusion was reached after assessment by additional investigators. RESULTS: Among the 2022 unique references identified by all searches, eight observational studies fulfilled inclusion criteria. A total of 147 women across all studies were diagnosed with a venous thromboembolic event while taking progestin-only contraception, and the summary measure for the adjusted relative risk of a venous thromboembolic episode for users versus non-users of a progestin-only contraceptive was, based on the random effects model, 1.03 (95% CI 0.76 to 1.39). Subgroup analysis confirmed there was no association between venous thromboembolic risk and progestin-only pills (relative risk 0.90 (0.57 to 1.45)) or a progestin intrauterine device (0.61 (0.24 to 1.53)). The relative risk of a venous thromboembolic event for users of an injectable progestin versus non-users was 2.67 (1.29 to 5.53). CONCLUSIONS: Published data assessing the risk of venous thromboembolism in women prescribed progestin-only contraception are limited. In this meta-analysis of eight observational studies, the use of progestin-only contraception was not associated with an increased risk of venous thromboembolism compared with non-users of hormonal contraception. The potential association between injectable progestins and thrombosis requires further study.


Assuntos
Anticoncepcionais Femininos/efeitos adversos , Progestinas/efeitos adversos , Tromboembolia Venosa/induzido quimicamente , Administração Oral , Anticoncepcionais Femininos/administração & dosagem , Preparações de Ação Retardada , Métodos Epidemiológicos , Feminino , Humanos , Dispositivos Intrauterinos Medicados , Progestinas/administração & dosagem
8.
J Thromb Haemost ; 9 Suppl 1: 12-9, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21781237

RESUMO

While parenteral anticoagulants such as unfractionated and low molecular weight heparins and the oral vitamin K antagonists are effective for the prevention and treatment of thrombosis, they have a number of limitations. Up until recently, vitamin K antagonists (e.g. warfarin) have been the only available oral anticoagulants. These drugs have a delayed onset of action, food and drug interactions, and variable pharmacokinetics/pharmacodynamics such that regular laboratory monitoring and dose adjustments are required to maintain the International Normalized Ratio (INR) in the therapeutic range. New oral anticoagulants that selectively inhibit either thrombin (dabigatran etexilate) or factor Xa (rivaroxaban, apixaban) have now gained approval in many countries for some clinical indications. Unlike warfarin, these drugs have a rapid onset of action and a relatively wide therapeutic range such that coagulation monitoring is not required. These agents are more convenient for patients and health care providers, but also have potential for improving clinical outcomes and being more cost-effective than existing agents. This will result in major changes in the way that thrombosis is managed, both with respect to prevention and treatment. The new oral inhibitors of thrombin and factor Xa, however, have limitations and the absence of a need for regular laboratory monitoring makes medication compliance extremely important for maintaining efficacy given their relatively short half-lives. Furthermore there will be challenges in managing patients on these agents who develop recurrent thrombosis or major bleeding until methods to monitor and assess the levels of the new agents are readily available and specific antidotes are developed.


Assuntos
Anticoagulantes/uso terapêutico , Inibidores do Fator Xa , Trombina/antagonistas & inibidores , Tromboembolia/tratamento farmacológico , Tromboembolia/prevenção & controle , Administração Oral , Anticoagulantes/administração & dosagem , Anticoagulantes/farmacocinética , Disponibilidade Biológica , Humanos
9.
Hematol Oncol Clin North Am ; 25(2): 323-33, viii, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21444033

RESUMO

Thrombophilic conditions are associated with an increased risk of venous thromboembolic events (VTE) during pregnancy. Thrombophilic disorders are either acquired, as in antiphospholipid syndrome, or inherited, as in factor V Leiden. Both are associated with VTE but acquired disorders can also increase the risk of arterial events. However, there is controversy as to whether they may adversely affect other pregnancy outcomes including pregnancy loss, placental abruption, severe preeclampsia, and stillbirth. This article discusses the effect of thrombophilias on pregnancy.


Assuntos
Complicações Hematológicas na Gravidez , Tromboembolia Venosa , Aborto Espontâneo/sangue , Aborto Espontâneo/epidemiologia , Aborto Espontâneo/etiologia , Aborto Espontâneo/genética , Aborto Espontâneo/terapia , Descolamento Prematuro da Placenta/sangue , Descolamento Prematuro da Placenta/epidemiologia , Descolamento Prematuro da Placenta/etiologia , Descolamento Prematuro da Placenta/genética , Descolamento Prematuro da Placenta/terapia , Síndrome Antifosfolipídica/complicações , Síndrome Antifosfolipídica/epidemiologia , Síndrome Antifosfolipídica/genética , Síndrome Antifosfolipídica/terapia , Fator V/análise , Fator V/genética , Feminino , Humanos , Pré-Eclâmpsia/sangue , Pré-Eclâmpsia/epidemiologia , Pré-Eclâmpsia/etiologia , Pré-Eclâmpsia/genética , Pré-Eclâmpsia/terapia , Gravidez , Complicações Hematológicas na Gravidez/sangue , Complicações Hematológicas na Gravidez/epidemiologia , Complicações Hematológicas na Gravidez/genética , Complicações Hematológicas na Gravidez/terapia , Natimorto/epidemiologia , Natimorto/genética , Tromboembolia Venosa/sangue , Tromboembolia Venosa/epidemiologia , Tromboembolia Venosa/etiologia , Tromboembolia Venosa/genética , Tromboembolia Venosa/terapia
10.
J Thromb Haemost ; 8(11): 2394-403, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20735728

RESUMO

BACKGROUND: Evidence for the associations of single nucleotide polymorphisms (SNPs) in the F7 gene and factor (F)VII levels and with risk of coronary heart disease (CHD) is inconsistent. We examined whether F7 tagging SNPs (tSNPs) and haplotypes were associated with FVII levels, coagulation activation markers (CAMs) and CHD risk in two cohorts of UK men. METHODS: Genotypes for eight SNPs and baseline levels of FVIIc, FVIIag and CAMs (including FVIIa) were determined in 2773 healthy men from the Second Northwick Park Heart Study (NPHS-II). A second cohort, Whitehall II study (WH-II, n = 4055), was used for replication analysis of FVIIc levels and CHD risk. RESULTS: In NPHS-II the minor alleles of three SNPs (rs555212, rs762635 and rs510317; haplotype H2) were associated with higher levels of FVIIag, FVIIc and FVIIa, whereas the minor allele for two SNPs (I/D323 and rs6046; haplotype H5) was associated with lower levels. Adjusted for classic risk factors, H2 carriers had a CHD hazard ratio of 1.34 [95% confidence interval (CI): 1.12-1.59; independent of FVIIc], whereas H5 carriers had a CHD risk of 1.29 (95% CI: 1.01-1.56; not independent of FVIIc) and significantly lower CAMs. Effects of haplotypes on FVIIc levels were replicated in WH-II, as was the association of H5 with higher CHD risk [pooled-estimate odds ratio (OR) 1.16 (1.00-1.36), P = 0.05], but surprisingly, H2 exhibited a reduced risk for CHD. CONCLUSION: tSNPs in the F7 gene strongly influence FVII levels. The haplotype associated with low FVIIc level, with particularly reduced functional activity, was consistently associated with increased risk for CHD, whereas the haplotype associated with high FVIIc level was not.


Assuntos
Doença das Coronárias/sangue , Doença das Coronárias/genética , Fator VII/genética , Genótipo , Haplótipos , Polimorfismo de Nucleotídeo Único , Alelos , Coagulação Sanguínea , Estudos de Coortes , Humanos , Masculino , Pessoa de Meia-Idade , Razão de Chances , Estudos Prospectivos , Fatores de Risco , Reino Unido
11.
J Thromb Haemost ; 8(2): 263-8, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19912516

RESUMO

BACKGROUND: The management of recurrent pregnancy loss is uncertain. Some cohort studies have identified an association between inherited thrombophilias and recurrent or late non-recurrent pregnancy loss, which has prompted investigators to evaluate the benefit of low molecular weight heparin (LWMH) to achieve live birth. A similar benefit for LMWH has also been proposed independent of thrombophilia status. OBJECTIVE AND METHODS: We conducted a systematic review of randomized controlled trials to assess the benefit of LMWH in achieving live birth for women with a history of recurrent or late non-recurrent pregnancy loss in the absence of antiphospholipid antibodies. RESULTS: For the five studies that satisfied the eligibility criteria, the risk ratio of live birth for women with a history of pregnancy loss treated with LWMH compared with control ranged from 0.95 to 3.00. There was considerable heterogeneity among studies in terms of treatment effect (Q-value was 41.7, P=0.000, and I2=90.4%) independent of thrombophilia status. There was also a wide variation among all studies in terms of definition of early or late pregnancy loss, thrombophilic risk factors, and number of prior pregnancy losses. CONCLUSION: There is a trend for increased live births when using LWMH for the prevention of recurrent pregnancy loss. Currently, there is insufficient evidence to support the routine use of LWMH to improve pregnancy outcomes in women with a history of pregnancy loss. Not only are additional studies necessary but standardized criteria for trials evaluating the benefit of an intervention in recurrent pregnancy loss should be established.


Assuntos
Aborto Habitual/prevenção & controle , Aborto Espontâneo/prevenção & controle , Anticoagulantes/uso terapêutico , Heparina de Baixo Peso Molecular/uso terapêutico , Nascido Vivo , Aborto Habitual/sangue , Aborto Espontâneo/sangue , Medicina Baseada em Evidências , Feminino , Humanos , Guias de Prática Clínica como Assunto , Gravidez , Medição de Risco , Fatores de Risco
12.
J Thromb Haemost ; 6(2): 259-67, 2008 02.
Artigo em Inglês | MEDLINE | ID: mdl-17973650

RESUMO

OBJECTIVE: To determine whether activation of coagulation increases in parallel with inflammation and whether coagulation activation markers (CAMs) are independently associated with coronary heart disease (CHD), in the prospective study, NPHSII. METHODS: Surveillance of 2997 men between 50 and 63 years yielded 314 first CHD events during 36507 person-years of observation. The plasma levels of activated factor XII (FXIIa), the peptides released upon activation of factor X (FXpep) and factor IX (FIXpep), activated factor VII (FVIIa), prothrombin fragment 1 + 2 (F1 + 2) and fibrinopeptide A (FpA) served as indices of activity along the coagulation pathway. C reactive protein (CRP) provided a marker of inflammatory activity. RESULTS: While borderline or significant correlations were identified for each CAM with inflammation, as determined by CRP levels, these did not reach as high a numerical value as was shown for fibrinogen with CRP. FVIIa and FIXpep possessed independent associations with CHD: a one SD increase in adjusted FIXpep and FVIIa level was associated with a relative hazard of 1.20 (95% CI 1.00-1.43) and 0.70 (CI 0.58-0.86), respectively, using a group including all CHD events, compared with 'no-event'. CONCLUSIONS: Inflammation has significant but minimal impact upon CAMs of the extrinsic coagulation pathway. Reduced FVIIa and increased FIXpep levels were found to be significant, independent, predictors of CHD.


Assuntos
Fatores de Coagulação Sanguínea/análise , Coagulação Sanguínea/fisiologia , Doença das Coronárias/epidemiologia , Inflamação/sangue , Biomarcadores , Proteína C-Reativa/análise , Estudos de Coortes , Comorbidade , Doença da Artéria Coronariana/sangue , Doença da Artéria Coronariana/epidemiologia , Doença das Coronárias/sangue , Gorduras na Dieta/farmacologia , Suscetibilidade a Doenças , Ativação Enzimática/efeitos dos fármacos , Fator IX/análise , Fator VIIa/análise , Hemofilia B/epidemiologia , Humanos , Inflamação/epidemiologia , Londres/epidemiologia , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos Prospectivos , Fatores de Risco
14.
J Thromb Haemost ; 5(9): 1854-61, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17723125

RESUMO

BACKGROUND: The benefit of combined mechanical and pharmacologic methods for venous thromboembolism prevention after abdominal surgery has not been clearly established. OBJECTIVES: To compare the efficacy and safety of fondaparinux in conjunction with intermittent pneumatic compression vs. intermittent pneumatic compression alone in this context. PATIENTS AND METHODS: This was a randomized, double-blind, placebo-controlled superiority trial. Patients aged at least 40 years undergoing abdominal surgery were randomized to receive either fondaparinux 2.5 mg or placebo s.c. for 5-9 days, starting 6-8 h postoperatively. All patients received intermittent pneumatic compression. The primary efficacy outcome was venous thromboembolism up to day 10. The main safety outcomes were major bleeding and all-cause mortality. Follow-up lasted 32 days. RESULTS: Of the 1309 patients randomized, 842 (64.3%) were evaluable for efficacy. The venous thromboembolism rate was 1.7% (7/424) in the fondaparinux-treated patients and 5.3% (22/418) in the placebo-treated patients (odds ratio reduction 69.8%; 95% confidence interval 27.9-87.3; P = 0.004). Fondaparinux significantly reduced the proximal deep vein thrombosis rate from 1.7% (7/417) to 0.2% (1/424; P = 0.037). Major bleeds occurred in 1.6% (10/635) and 0.2% (1/650) of fondaparinux-treated and placebo-treated patients, respectively (P = 0.006), none being fatal or involving a critical organ. By day 32, eight patients (1.3%) receiving fondaparinux and five (0.8%) receiving placebo had died. CONCLUSIONS: In patients undergoing abdominal surgery and receiving intermittent pneumatic compression, fondaparinux 2.5 mg reduced the venous thromboembolism rate by 69.8% as compared to pneumatic compression alone, with a low bleeding risk as compared to placebo.


Assuntos
Abdome/cirurgia , Anticoagulantes/uso terapêutico , Dispositivos de Compressão Pneumática Intermitente , Polissacarídeos/uso terapêutico , Procedimentos Cirúrgicos Operatórios/efeitos adversos , Tromboembolia/prevenção & controle , Adulto , Idoso , Idoso de 80 Anos ou mais , Anticoagulantes/efeitos adversos , Método Duplo-Cego , Feminino , Fondaparinux , Humanos , Masculino , Pessoa de Meia-Idade , Placebos , Polissacarídeos/efeitos adversos , Resultado do Tratamento
15.
J Thromb Haemost ; 5(9): 1896-903, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17723129

RESUMO

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.


Assuntos
Doenças Cardiovasculares/epidemiologia , Sistema Calicreína-Cinina , Doenças Cardiovasculares/sangue , Estudos de Casos e Controles , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Risco
16.
J Thromb Haemost ; 4(10): 2199-203, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16869933

RESUMO

BACKGROUND: In some but not all studies, men with venous thrombosis had a higher risk of recurrence than women. Information on women with initial hormone-related thrombosis is scant. OBJECTIVE: We assessed the incidence of recurrent thrombosis by gender, and among women using exogenous hormones or pregnant/postpartum at the time of index thrombosis. PATIENTS/METHODS: A total of 508 men and women with one or more previous venous thrombosis episodes were observed while participating in a randomized trial of low-intensity warfarin or placebo for 2.1 years. Index thrombosis events during treatment with postmenopausal hormones, oral contraceptives, or during pregnancy, or the puerperium were considered to be hormone-related events. RESULTS: Among 268 men the 3-year probability of recurrent thrombosis was 18.4% (95% confidence intervals; CI 12.3-24.4). Among 109 women without hormone-related thrombosis, the rate was 15.0% (95% CI 6.3-23.8). Among 129 women with hormone-related thrombosis, the rate was 5.0% (95% CI 1.1-8.9). Adjusting for other risk factors and treatment assignment, women had a 39% lower thrombosis recurrence risk than men: hazard ratio (HR) 0.61 (95% CI 0.34-1.08). Women with hormone-related thrombosis had a 58% lower risk than men: HR 0.42 (95% CI 0.19-0.97); and a 46% lower recurrence risk than other women; HR 0.54 (95% CI 0.19-1.54). Women without hormone-related index events had a recurrence rate similar to men; HR 0.83 (95% CI 0.42-1.66). CONCLUSIONS: In this trial population, women had a lower risk of recurrent venous thrombosis than men. This difference was explained by a low risk of recurrence among women with hormone-related index thrombosis.


Assuntos
Anticoagulantes/uso terapêutico , Hormônios/metabolismo , Tromboembolia/metabolismo , Tromboembolia/patologia , Trombose Venosa/metabolismo , Trombose Venosa/patologia , Varfarina/uso terapêutico , Idoso , Feminino , Humanos , Coeficiente Internacional Normatizado , Masculino , Pessoa de Meia-Idade , Modelos Estatísticos , Placebos , Recidiva , Risco , Fatores de Risco , Fatores Sexuais , Tromboembolia/epidemiologia , Trombose Venosa/epidemiologia
17.
J Thromb Haemost ; 4(6): 1208-14, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16706961

RESUMO

BACKGROUND: Elevated plasma D-dimer and factor VIII coagulant activity (FVIIIc) may be associated with the risk of recurrent venous thromboembolism (VTE). OBJECTIVES: To evaluate D-dimer and FVIIIc as risk factors for recurrent VTE and assess the efficacy of extended low-intensity warfarin (target International Normalized Ratio 1.5-2.0) in preventing recurrence by biomarker level. PATIENTS AND METHODS: In the Prevention of Recurrent Venous Thromboembolism trial, 508 idiopathic VTE patients treated for > or = 3 months with full-intensity warfarin, and who had stopped warfarin for 7 weeks on average, were randomized to low-intensity warfarin or placebo and followed for 2.1 years for recurrent VTE. Prerandomization blood samples were analysed for D-dimer and FVIIIc. RESULTS: One-third of participants had elevated baseline D-dimer (> or = 500 ng mL(-1)) and one-fourth, elevated FVIIIc (> or = 150 IU dL(-1)). Adjusting for other risk factors, the hazard ratios (HRs) for recurrent VTE with elevated D-dimer or FVIIIc were 2.0 [95% confidence interval (CI) 1.2-3.4] and 1.5 (95% CI 0.8-2.8), respectively. The association of elevated D-dimer with recurrence was larger among patients with one prior VTE (HR 3.2, 95% CI 1.3-8.0) than in patients with more than one event (HR 1.4, 95% CI 0.7-2.2). For patients with one prior VTE on placebo, the annual recurrence incidence was 10.9% with elevated D-dimer and 2.9% with normal values. Low-intensity warfarin was equally effective in recurrence risk reduction in those with normal or elevated biomarkers. CONCLUSIONS: Among patients with idiopathic VTE, measurement of D-dimer, but not FVIIIc, might be useful for risk stratification. The efficacy of extended low-intensity warfarin therapy did not vary by biomarker level.


Assuntos
Anticoagulantes/uso terapêutico , Produtos de Degradação da Fibrina e do Fibrinogênio/metabolismo , Tromboembolia/prevenção & controle , Trombose Venosa/prevenção & controle , Varfarina/uso terapêutico , Adulto , Idoso , Anticoagulantes/administração & dosagem , Biomarcadores/sangue , Método Duplo-Cego , Esquema de Medicação , Fator VIII/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Prevenção Secundária , Tromboembolia/sangue , Tromboembolia/tratamento farmacológico , Trombose Venosa/sangue , Trombose Venosa/tratamento farmacológico , Varfarina/administração & dosagem
18.
J Thromb Haemost ; 3(11): 2479-86, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16241946

RESUMO

BACKGROUND: BAY 59-7939, a novel, oral, direct factor Xa inhibitor, is in clinical development for the prevention of venous thromboembolism (VTE), a frequent complication following orthopaedic surgery. METHODS: In a multicenter, parallel-group, double-blind, double-dummy study, 621 patients undergoing elective total knee replacement were randomly assigned to oral BAY 59-7939 (2.5, 5, 10, 20, and 30 mg b.i.d., initiated 6-8 h postsurgery), or subcutaneous enoxaparin (30 mg b.i.d., initiated 12-24 h postsurgery). Treatment was continued until mandatory bilateral venography 5-9 days after surgery. The primary efficacy endpoint was a composite of any deep vein thrombosis (proximal and/or distal), confirmed non-fatal pulmonary embolism and all-cause mortality during treatment. The primary safety endpoint was major, postoperative bleeding during treatment. RESULTS: Of the 613 patients treated, 366 (59.7%) were evaluable for the primary efficacy analysis. The primary efficacy endpoint occurred in 31.7%, 40.4%, 23.3%, 35.1%, and 25.4% of patients receiving 2.5, 5, 10, 20 and 30 mg b.i.d. doses of BAY 59-7939, respectively (test for trend, P = 0.29), compared with 44.3% in the enoxaparin group. The frequency of major, postoperative bleeding increased with increasing doses of BAY 59-7939 (test for trend, P = 0.0007), with no significant difference between any dose group compared with enoxaparin. Bleeding endpoints were lower for the 2.5-10 mg b.i.d. doses compared with higher doses of BAY 59-7939. CONCLUSIONS: Oral administration of 2.5-10 mg b.i.d. of BAY 59-7939, early in the postoperative period, showed potential efficacy and an acceptable safety profile, similar to enoxaparin, for the prevention of VTE in patients undergoing elective total knee replacement.


Assuntos
Antitrombina III/uso terapêutico , Artroplastia do Joelho/efeitos adversos , Hemorragia/epidemiologia , Morfolinas/uso terapêutico , Tiofenos/uso terapêutico , Tromboembolia/etiologia , Tromboembolia/prevenção & controle , Trombose Venosa/etiologia , Trombose Venosa/prevenção & controle , Administração Oral , Adulto , Idoso , Idoso de 80 Anos ou mais , Anticoagulantes/administração & dosagem , Anticoagulantes/efeitos adversos , Anticoagulantes/uso terapêutico , Antitrombina III/administração & dosagem , Antitrombina III/efeitos adversos , Método Duplo-Cego , Enoxaparina/administração & dosagem , Enoxaparina/efeitos adversos , Enoxaparina/uso terapêutico , Hemorragia/etiologia , Humanos , Incidência , Injeções Subcutâneas , Masculino , Pessoa de Meia-Idade , Morfolinas/administração & dosagem , Morfolinas/efeitos adversos , Rivaroxabana , Tiofenos/administração & dosagem , Tiofenos/efeitos adversos , Tromboembolia/epidemiologia , Trombose Venosa/epidemiologia
19.
Atherosclerosis ; 183(2): 283-92, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15921688

RESUMO

We have progressively analysed three studies of coronary heart disease (CHD) for a variant in EPCR (Ser219Gly). Initially, in a prospective study, NPHSII, while no overall CHD-risk was identified in heterozygotes, homozygotes for 219Gly exhibited a three-fold elevated risk (HR 3.3, CI 1.22-8.96). In diabetics within NPHSII, there was a suggestion that 219Gly+ was associated with elevated CHD-risk (HR 1.89, CI 0.39-9.06) although numbers were small. To further assess the effect of the variant in diabetes, a case-control study of MI, HIFMECH, was used, in which previous analysis had defined a group with metabolic syndrome, by factor analysis. A significant CHD-risk interaction was identified between genotype and the 'metabolic syndrome' factor (interaction p=0.009). To further assess CHD-risk for this variant in type-2 diabetes and to assess the effect of the variant upon thrombin generation and plasma levels of soluble EPCR, a cross-sectional study of type-2 diabetes was used. A significant CHD-risk was identified for European Whites (OR 2.84, CI 1.38-5.85) and Indian Asians in this study (OR 1.6, CI 1.00-2.57) and the frequency of 219Gly was two-fold higher in Indian Asians. Soluble EPCR levels were strongly associated with genotype, with homozygotes for 219Gly having four-fold higher levels (p<0.0001). In vitro studies of EPCR-transfected cells suggested increased basal release of sEPCR from cells expressing the 219Gly EPCR phenotype. Furthermore, in base-line samples from NPHSII and in the diabetic study, a significant increase in prothrombin F1+2 level was observed for 219Gly. The increased CHD-risk and thrombin generation appears to be acting through increased shedding of the Gly allele from the cell surface.


Assuntos
Antígenos/sangue , Doença das Coronárias/sangue , Glicoproteínas/sangue , Fragmentos de Peptídeos/sangue , Receptores de Superfície Celular/sangue , Animais , Antígenos/genética , Antígenos CD , Fatores de Coagulação Sanguínea/genética , Doença das Coronárias/etiologia , Doença das Coronárias/genética , Cricetinae , Estudos Transversais , DNA/genética , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/genética , Receptor de Proteína C Endotelial , Endotélio Vascular/metabolismo , Endotélio Vascular/patologia , Feminino , Citometria de Fluxo , Seguimentos , Expressão Gênica , Genótipo , Glicoproteínas/genética , Humanos , Imunoensaio , Técnicas In Vitro , Masculino , Pessoa de Meia-Idade , Fragmentos de Peptídeos/genética , Prognóstico , Estudos Prospectivos , Protrombina/genética , Receptores de Superfície Celular/genética , Fatores de Risco , Transfecção
20.
J Thromb Haemost ; 2(12): 2107-14, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15613014

RESUMO

BACKGROUND: Thrombin promotes angiogenesis and cell proliferation in cancer. Whether thrombin turnover influences cancer incidence is unknown. OBJECTIVES: To explore the relation between the status of the coagulant pathway and cancer incidence by population survey. METHODS: Of 4,009 middle-aged men clinically free of malignancy, 3052 (76.1%) were recruited. Measurements of hemostatic status were made annually for 4 years, and follow-up for morbidity and mortality was maintained thereafter. Persistent activation of the coagulant pathway was diagnosed when prothrombin fragment 1+2 and fibrinopeptide A concentrations exceeded the upper quartiles of the population distribution in two consecutive annual examinations. Cancer incidence rates in men developing persistent activation (taking the time of onset of activation as baseline) were compared with those in men remaining free of this condition. RESULTS: Persistent activation of the hemostatic pathway was a distinct entity found in 111 men [43 expected by chance alone (P <0.001)], and associated with activation throughout the coagulation pathway. Total mortality (/1000 person-years) was higher in those with persistent activation than in others (17.1 and 9.7, respectively, P=0.015), owing to a higher mortality from all cancers (11.3 and 5.1, respectively, P=0.01), due in turn largely to a higher mortality from cancers of the digestive tract (6.3 and 1.9, respectively, P=0.004). Trends were similar for non-fatal cancers. CONCLUSIONS: Persistent activation of the coagulant pathway plays a role in the preclinical phase of cancer and is associated with an increased incidence of clinical malignancy, especially of the digestive tract.


Assuntos
Coagulantes/metabolismo , Neoplasias do Sistema Digestório/complicações , Neoplasias do Sistema Digestório/epidemiologia , Ensaio de Imunoadsorção Enzimática , Fator IX/biossíntese , Fator VII/biossíntese , Fibrinopeptídeo A/biossíntese , Seguimentos , Hemostasia , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Protrombina/biossíntese , Trombina/metabolismo , Fatores de Tempo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...