1,721,101 research outputs found
Comment: Does L-thyroxine prevent or cause stroke in hypothyroidism?
No full textThe association between overt hypothyroidism and atherosclerotic risk factors, especially hypertension and dyslipidemia, is clear. To date, only a few small and methodologically flawed epidemiologic studies have investigated the relationship between hypothyroidism and stroke, precluding definitive conclusions. In the current issue of Neurology®, Karch and Thomas(1) present a large well-designed case-control study investigating this relationship. They compared 34,907 patients with autoimmune thyroiditis on treatment with l-thyroxine and 149,632 matched individuals without autoimmune thyroiditis from a UK primary care electronic health record system. They found a slight increase in the risk of stroke in patients with autoimmune thyroiditis (adjusted relative risk = 1.10, 95% confidence interval: 1.01-1.20) compared with controls. Some of this increased risk of stroke was independent of cardiovascular risk factors
Thyroid Disorders and Hemostasis
No full textLower levels of free thyroxine (whether this is endogenous or exogenous) lead to a hypocoagulable state, and higher levels of free thyroxine lead to a hypercoagulable state. In this narrative review, the effects of different levels of thyroid hormones on clinical end points are described. Hypothyroidism is associated with an increased bleeding risk, whereas hyperthyroidism leads to an increased risk of venous thrombosis. Besides, effects of thyroid hormone on the heart may indirectly influence hemostasis. Hyperthyroidism leads to a higher incidence of atrial fibrillation and atrial flutter, and, at least partly by that mechanism, a higher risk of cerebral arterial thrombosis. In addition, compression effects of goiter on developing venous thrombosis are described. This is caused by local stasis of blood due to tumor expansion
Thrombosis Associated with Viral Hepatitis
No full textViral hepatitis may promote the development of venous thromboembolism (VTE) and, more specifically, portal vein thrombosis (PVT). In this narrative review, we summarize the clinical data and discuss the possible pathogenetic roles of cytomegalovirus (CMV), Epstein-Barr virus (EBV), and hepatitis A, B, and C viruses (HAV, HBV, HCV) in the occurrence of VTE. CMV is the first qualified candidate to enter the list of VTE minor risk factors, and in the rare case of fulminant infection, both EBV and CMV, like any severe infection or inflammatory disease, increase risk for thrombosis. In chronic hepatitis B and C, it remains controversial whether antiphospholipid antibodies are important for thrombotic complications or merely an epiphenomenon. Retinal vein occlusion described in chronic hepatitis C is usually attributed to the treatment with interferon. Eltrombopag, used for HCV-related thrombocytopenia, has been associated with increased thrombotic risk. The imbalance between procoagulant and anticoagulant factors associated with chronic liver disease may have clinical implications. This may help to explain why these patients are not protected from clinical events such as VTE, PVT, and the progression of liver fibrosis
Point-of-care ultrasound in the diagnosis of pulmonary embolism
No full textThe best diagnostic strategy to confirm or exclude pulmonary embolism (PE) suspicion needs an appropriate combination of clinical assessment, plasma D-dimer measurement, and computed tomographic pulmonary angiography (CTPA). CTPA should be used with caution in some patient groups, such as patients with known allergy to contrast media, those with severe renal insufficiency, and pregnant women, and could be not immediately available in case of unstable patients. In the emergency setting, alternative diagnostic strategies should be implemented to overcome CTPA limitations. Ultrasonography is certainly a valuable alternative diagnostic tool. In addition to echocardiography and lower limb compressive venous ultrasonography, lung ultrasound (US) may play an important role in selected patients’ subgroups. Recent data on the diagnostic performance of a triple point-of-care US (lung, heart, and leg vein US) are discussed in the present paper, and pros and cons of triple point-of-care US are compared with those of standard diagnostic approaches
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
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