1,720,998 research outputs found
Dynamic Contrast-Enhanced MRI in the Study of Brain Tumors. Comparison Between the Extended Tofts-Kety Model and a Phenomenological Universalities (PUN) Algorithm
No full textDynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a well-established technique for studying bloodâbrain barrier (BBB) permeability that allows measurements to be made for a wide range of brain pathologies, including multiple sclerosis and brain tumors (BT). This latter application is particularly interesting, because high-grade gliomas are characterized by increased microvascular permeability and a loss of BBB function due to the structural abnormalities of the endothelial layer. In this study, we compared the extended Tofts-Kety (ETK) model and an extended derivate class from phenomenological universalities called EU1 in 30 adult patients with different BT grades. A total of 75 regions of interest were manually drawn on the MRI and subsequently analyzed using the ETK and EU1 algorithms. Significant linear correlations were found among the parameters obtained by these two algorithms. The means of R2 obtained using ETK and EU1 models for high-grade tumors were 0.81 and 0.91, while those for low-grade tumors were 0.82 and 0.85, respectively; therefore, these two models are equivalent. In conclusion, we can confirm that the application of the EU1 model to the DCE-MRI experimental data might be a useful alternative to pharmacokinetic models in the study of BT, because the analytic results can be generated more quickly and easily than with the ETK model
Ecological impact of isolated cognitive relapses in MS
No full textIsolated cognitive relapses (ICRs) are transient deficits in cognitive performance that are the only presentation of a multiple sclerosis (MS) relapse. Here, we evaluated the impact of ICRs on cognitive difficulties in daily activities (assessed with the Multiple Sclerosis Neuropsychological Screening Questionnaire, Informant Version (MSNQ-I)) to characterize ICRs’ clinical relevance. We used 2-year-long retrospective data to compare 15 relapsing-remitting MS (RRMS) patients with ICRs with 57 RRMS patients presenting an asymptomatic gadolinium enhancing lesion (and no-ICRs). ICRs were associated not only with neuropsychological performance decline but also with an increase in the daily cognitive difficulties. These findings support the ecological relevance of ICRs
Human mesenchymal stem cells target adhesion molecules and receptors involved in T cell extravasation
Full text linkIntroduction: Systemic delivery of bone marrow-derived mesenchymal stem cells (MSC) seems to be of benefit in
the treatment of multiple sclerosis (MS), an autoimmune disease of the central nervous system (CNS) sustained by
migration of T cells across the brain blood barrier (BBB) and subsequent induction of inflammatory lesions into CNS.
MSC have been found to modulate several effector functions of T cells. In this study, we investigated the effects of
MSC on adhesion molecules and receptors on T cell surface that sustain their transendothelial migration.
Methods: We used different co-culture methods combined with real-time PCR and flow cytometry to evaluate the
expression both at the mRNA and at the plasma-membrane level of α4 integrin, β2 integrin, ICAM-1 and CXCR3. In
parallel, we assessed if MSC are able to modulate expression of adhesion molecules on the endothelial cells that
interact with T cells during their transendothelial migration.
Results: Our in vitro analyses revealed that MSC: (i) inhibit proliferation and activation of both peripheral blood
mononuclear cells (PBMC) and CD3+-selected lymphocytes through the release of soluble factors; (ii) exert suppressive
effects on those surface molecules highly expressed by activated lymphocytes and involved in transendothelial migration;
(iii) inhibit CXCL10-driven chemotaxis of CD3+ cells; (iv) down-regulated expression of adhesion molecules on
endothelial cells.
Conclusions: Taken together, these data demonstrate that the immunosuppressive effect of MSC does not exclusively
depends on their anti-proliferative activity on T cells, but also on the impairment of leukocyte migratory potential
through the inhibition of the adhesion molecules and receptors that are responsible for T cell trafficking across
BBB. This could suggest a new mechanism through which MSC modulate T cell responses
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
Intense immunosuppression followed by autologous haematopoietic stem cell transplantation as a therapeutic strategy in aggressive forms of multiple sclerosis
Full text linkIn the majority of relapsing multiple sclerosis patients, the disease can be quite easily controlled by already available, approved therapies. There are, however, some aggressive cases who continue to have clinical and magnetic resonance imaging (MRI) activity in spite of the treatment. These are the cases who may now receive benefit from intense immunosuppression followed by autologous haematopoietic stem cell transplantation (aHSCT). In this review, we describe the method and the rationale of aHSCT, the more recently published studies that demonstrate its efficacy in selected multiple sclerosis cases, the problems related to safety and the transplant-related mortality risk of the procedure. A description of the ideal patient who can take advantage of aHSCT is outlined and, finally, the ongoing studies which are near to completion or are close to starting are briefly reported
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
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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