1,720,974 research outputs found
Venous thromboembolism, oral contraceptives and high prothrombin levels
No full textTheG20210A prothrombin mutation, associated with elevated prothrombin levels, is a risk factor for venous thromboembolism (VTE) and displays a strong interaction with oral contraceptives (OC). Nodata are available onVTE risk ofOCuse in women with high prothrombin levels, either associated or not with themutation. The aim of this study was to evaluate the risk of VTE in OC users with high prothrombin levels, either including or excluding carriers of the prothrombin mutation. Prothrombin levels were measured by a chromogenic assay in 152 women who suffered from VTE in reproductive age and in 296 healthy women. Subjects carrying thrombophilic alterations other than the G20210A prothrombin mutation were excluded. Prothrombin levels were stratified into quartiles. The OR of subjects in the upper quartile were 3.10[95%confidence interval (CI)1.73-5.55] and2.07(95%CI1.11-3.85)in all women and in those not carrying the prothrombin mutation, respectively. Among the 152 patients, 88 had experienced VTE during OC; in the control group we considered as OC users the women who had used OC for at least 6 months in the 2 years before presentation but had stopped the treatment at least 3 months before the time of blood sampling (n=127).For the interaction betweenOCand prothrombin levels only the two extreme strata of prothrombin were considered. Women with the lowest prothrombin levels and who did not use OC were used as reference category. The VTE risk of using OC in subjects with prothrombin levels in the upper quartile was increased5.4-fold (95%CI2.38-12.3) and3.5-fold (95%CI1.48-8.22) in all women and in those not carrying the prothrombin mutation, respectively. We conclude that elevated prothrombin levels, even in women without the G20210A prothrombin mutation, are associated with an increased risk for venous thromboembolism and that oral contraceptive use potentiates such association. © 2003 International Society on Thrombosis and Haemostasis
Predictive value of D-dimer test for recurrent venous thromboembolism after anticoagulation withdrawal in subjects with a previous idiopathic event and in carriers of congenital thrombophilia
No full textBackground - We have shown that normal D-dimer levels obtained after the discontinuation of oral anticoagulant treatment (OAT) has a high negative predictive value for recurrent venous thromboembolism (VTE). The aim of the present study was to assess the predictive value of D-dimer for recurrent VTE in subjects with a previous unprovoked event who are either carriers of inherited thrombophilia or not. Methods and Results - We prospectively evaluated 599 patients (301 males) with a previous VTE episode. They were repeatedly examined for D-dimer levels after OAT withdrawal and were screened for inherited thrombophilic alterations. Alterations were detected in 130 patients (21.7%), factor V Leiden (70 patients; 2 of whom were homozygotes) and prothrombin mutation (38 patients) were the most prevalent ones. Recurrent events were recorded in 58 subjects (9.7%) during a follow-up of 870.7 patient-years. Altered D-dimer levels at 1 month after OAT withdrawal were associated with a higher rate of subsequent recurrence in all subjects investigated, especially in those with an unprovoked qualifying VTE event (hazard ratio, 2.43; 95% confidence interval, 1.18 to 4.61) and in those with thrombophilia (hazard ratio, 8.34; 95% confidence interval, 2.72 to 17.43). The higher relative risk for recurrence of altered D-dimer was confirmed by multivariate analysis after adjustment for other risk factors. The negative predictive value of D-dimer was 92.9% and 95.8% in subjects with an unprovoked qualifying event or with thrombophilia, respectively. Conclusions - D-dimer levels measured 1 month after OAT withdrawal have a high negative predictive value for recurrence in subjects with unprovoked VTE who are either carriers or not carriers of congenital thrombophilia
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Low molecular weight heparin treatment for superficial vein thrombosis and the risk of heparin-induced thrombocytopenia
No full textnot availabl
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Interleukin-4 downregulates nuclear factor-erythroid 2 (NF-E2) expression in primary megakaryocytes and in megakaryoblastic cell lines
No full textThe trascriptional factor nuclear factor-erythroid 2 (NF-E2) is one of the few transcription factors known to be functionally linked to the megakaryocytic lineage, where it regulates terminal megakaryocyte maturation and platelet formation. However, the regulation of NF-E2 expression in megakaryocytic cells has not been extensively evaluated. In particular, no data have been reported on the effect of negative regulators of megakaryocytopoiesis on NF-E2 expression. This study investigated the in vitro effects of two negative regulators of megakaryocytopoiesis, such as interleukin-4 (IL-4) and transforming growth factor-β1 (TGF-β1) on the expression of NF-E2 transcription factor in megakaryoblastic cell lines (Hel and MK1) and in normal CD34-derived megakaryocytic cells. For this purpose, we used quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) to detect mRNA NF-E2 isoforms (a and f) and flow-cytometry analysis to evaluate NF-E2 protein expression. Our results demonstrated that TGFβ1 did not inhibit NF-E2 mRNA and protein expression of either maturating or fully mature normal megakaryocytic cells as well as that of the two cell lines. By contrast, IL-4 downmodulates the expression of NF-E2 transcription factor at both mRNA and protein levels in normal maturating megakaryocytic cells and in the megakaryoblastic cell lines. NF-E2 expression of normal mature megakaryocytes was not affected by IL-4. Thus, the results of the present investigation demonstrate that NF-E2 transcription factor is involved not only in terminal megakaryocyte maturation but also in the negative regulation of the early phase of megakaryocyte development
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