1,721,080 research outputs found
Subclinical hyperthyroidism: The cardiovascular point of view
Full text link– OBJECTIVE: Subclinical hyperthyroidism (SHyper), defined as reduced thyrotropin with free hormones within the reference range, is a common medical finding, in particular in elderly people. In the last years has gained attention due to its health-related conditions, in particular at the cardiovascular level. MATERIALS AND METHODS: We searched electronic database (PubMed) and search engines (Google Scholar) of articles and reviews using the terms “subclinical hyperthyroidism”, “Atrial fibrillation”, Ischemic stroke”, “Hypertension”, Heart failure”, and “Mortality”. RESULTS: Subclinical hyperthyroidism was clearly associated with the onset of atrial fibrillation and, consequently, with ischemic stroke. However, the latter association is less clear. The effect on hypertension is doubtful and fair. Subclinical hyperthyroidism could increase the risk of acute heart failure, possibly by increasing heart rhythm. Data on mortality are scanty but seem to suggest a possible association, probably linked to the detrimental effect on the cardiovascular system. CONCLUSIONS: Current findings mainly described possible associations with rhythm alterations, heart failure, and stroke but the effective beneficial effects of the treatment of subclinical hyperthyroidism are still lacking
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
Elevated Serum IgG4 Levels in a Young Patient with Polyserositis and Necator americanus Infection
No full textMutations in the linker region of BvgS abolish response to environmental signals for the regulation of the virulence factors in Bordetella pertussis
No full textExpression of virulence factors of Bordetella pertussis is coordinately regulated by the products of the bvg locus, which codes for a sensory protein (BvgS) and a positive regulator of transcription (BvgA), a pair in the family of bacterial 'two-component' regulators. Transcription of the bvg-regulated promoters is repressed by modulating environmental factors such as 50 mM MgSO4, 10 mM nicotinic acid (NA) or low temperature (25°C). We have isolated a spontaneous mutant (SK170) which expresses virulence genes at either 25°C, or in the presence of 1-5 mM NA, or 10-50 mM MgSO4. Virulence factors in strain SK170 are still repressed by higher concentrations of NA (10 mM), or by a combination of low temperature (25°C) and one of the other modulating agents. From this strain, we have isolated a second mutant (SK180) that showed constitutive synthesis of the virulence factors under any growth regime. Nucleotide (nt) and deduced amino acid (aa) sequence analysis showed that SK170 contains a substitution at aa570 of BvgS and SKI80 contains an additional substitution at aa680. These substitutions are confined to a 161-aa sequence that links the transmembrane (TM) and kinase domains of BvgS. These mutations also alter the transcriptional autoregulation of the p1 and P2 promoters of the bvg locus. P1 which in the wild-type (wt) strain is repressed by modulating agents, is constitutively active in the mutant strains. On the contrary, P2, which is normally induced by all three modulating agents, is active in strain SK170 only in the presence of MgSO4 or NA, while in strain SK180 this promoter is repressed by modulating agents. The mutants exhibit elevated levels of the BvgA regulatory protein and have a virulent phenotype also in the presence of modulating agents. © 1994
Response of the bvg regulon of Bordetella pertussis to different temperatures and short-term temperature shifts
No full textBordetella pertussis produces a number of virulence factors whose expression is coordinately regulated by the bvgAS locus. Transcription of virulence genes is repressed by environmental factors such as low temperature (25°C) and chemical stimuli. Temperature shift of bacterial cultures from 25°C to 37°C activates two classes of bvg-regulated virulence genes: the early genes, which are activated within 10 min, and late genes, which require 2-4 h for activation. During the interval between the activation of the early and late genes, the intracellular concentration of BvgA increases 50-fold. It has been proposed that this increased concentration may be required for the activation of the late genes. Here we have analysed the response of the bvg locus to intermediate temperatures and to repeated temperature shifts. Temperature shifts of B. pertussis cultures from 22°C to 28°C, 32°C or 35°C resulted in the synthesis of low, intermediate, and high amounts of BvgA. This implied that the intracellular concentration of BvgA is temperature-dependent. We have also observed that the amount of virulence factors produced correlates with the BvgA concentration. When bacteria grown at 37°C were shifted to 22°C, transcription from the adenylate cyclase toxin haemolysis promoter (P(AC)) was repressed after 30 min, while transcription from the bvg (P1,) and filamentous haemagglutinin (P(FHA)) promoters was repressed after 2 h. During this time, the amount of BvgA did not decrease. A subsequent temperature shift from 22°C to 37°C induced transcription from the P1 and P(FHA) promoters after 10 min and transcription from the P(AC) promoter after 20 min. This result shows that in the presence of a high concentration of BvgA, the time lag between temperature shift and late promoter transcription is reduced from 2-4 h to 20 min. The above data support the proposal that the concentration of BvgA plays a role in activating expression of the late genes
Differential binding of BvgA to two classes of virulence genes of Bordetella pertussis directs promoter selectivity by RNA polymerase
No full textTranscription of virulence genes of Bordetella pertussis is co- ordinately regulated by the BvgA and BvgS proteins, which are members of the two-component family of bacterial signal-transduction proteins. BvgS is the transmembrane sensor and BvgA the transcriptional regulator. By get mobility shift assays we demonstrate that phosphorylated BvgA (BvgA≃P) forms distinct complexes with the filamentous haemagglutinin (P(FHA)) promoter DNA at different BvgA≃P: DNA ratios. DNase I protection analyses show that phosphorylation of BvgA not only enhances affinity of the protein for the binding sites of the P(FHA) and bVgP1 promoters, but it extends significantly the bound region towards position -35 of these promoters. Conversely, a 10-fold higher amount of BvgA≃P is required for binding to a large DNA region, from 168 to -60, of the pertussis toxin (P(tox)) promoter sequence. These findings suggest that the molecular interaction of BvgA≃P with the P(tox) promoter is different from its interaction with the P(FHA) and bvgP1 promoters. The σ70 Escherichia coli RNA polymerase (RNP) does not bind to the bvg-regulated promoters. However, following the formation of a BvgA≃P-promoter complex, the E. coli RNP specifically recognizes and binds to the bvg-regulated promoters. Thus, BvgA≃P exerts its action at the level of promoter recognition by directing promoter selectivity by RNP
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
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