1,721,144 research outputs found
Correction to: Can novel CT-and MR-based neuroimaging biomarkers further improve the etiological diagnosis of lobar intra-cerebral hemorrhage?
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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
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
Caractérisation intégrative radio-histologique, génomique et épigénétique des tumeurs glioneuronales pédiatriques
No full textPas de résuméThe large-scale genomic studies performed recently has enabled the objective identification of numerous novel genomic alterations and highlighted that pediatric brain tumors often harbor quiet cancer genomes, with a single driver genomic alteration. This characteristic is of special interest in the current context of precision medicine development. Low-grade glioneuronal tumor group is highly heterogeneous and remains particularly challenging since it includes a broad spectrum of tumors, often poorly discriminated by their histopathological features and not completely molecularly characterized. We used targeted methods (IHC, FISH, targeted sequencing), and large scale genomic and epigenetic methodologies to perform an integrative analysis to further characterized papillary glioneuronal tumors (PGNT), midline gangliogliomas and dysembryoplastic neuroepithelial tumors (DNT). We demonstrated that PGNT is a distinct entity characterized by a PRKCA fusion. We highlighted that H3 K27M mutation can occur in association with BRAF V600E mutation in midline grade I glioneuronal tumors, showing that despite the presence of H3 K27M mutations, these cases should not be graded and treated as grade IV tumors because they have a better spontaneous outcome than classic diffuse midline H3 K27M-mutant glioma. The DNT study enable us 1) to specify that non-specific DNT corresponds to a clinico-histological tumor group encompassing diverse molecularly distinct entities and 2) to demonstrate that specific DNTs can be progressive tumors and harbored a distinct DNA methylation profile. Diagnosis and genomic profiling that can guide precision medicine require tissue acquisition by neurosurgical procedures that are often difficult or not possible. We validated a sample collection procedure and we developed methodologies to detect circulating tumor DNA (ctDNA) in CSF, plasma and urine to identify clinically relevant genomic alterations from a cohort of 235 pediatric patients with brain tumors. We optimized a method to process ctDNA and performed ultra-low pass whole genome sequencing (ULP-WGS) using unique molecular identifiers, confirming we can reliably construct sequencing libraries from CSF-, plasma- and urine-derived ctDNA. ULP-WGS has also been used to assess sequencing library quality, copy number variations (CNVs) and tumor fraction. The vast majority of samples undergoing ULPWGS exhibited no CNVs, consistent with either absence in the tumor or low levels of tumorderived cfDNA. To distinguish between these, we developed a hybrid capture sequencing panel allowing identification of specific mutations and fusions more common in pediatric brain tumors
Multi-omics characterization of glial and glioneuronal tumors with altered FGFR1-3 genes
No full textLes fusions des gènes FGFR1-3 sont rares dans les tumeurs primitives du système nerveux (SNC). Les tumeurs gliales et glioneuronales avec fusion FGFR1-3 ont des caractéristiques cliniques et histologiques communes cependant elles peuvent correspondre à des types tumoraux bénins, tels que : les tumeurs dysembryoplasiques neuroépithéliales (DNET), les astrocytomes pilocytiques (PA), les gangliogliomes (GG), les tumeurs polymorphes de bas grade neuroépithéliale du sujet jeune (PLNTY) ; comme à des types tumoraux malins tels que le glioblastome IDH non muté (GBM IDH WT) ou l'astrocytome de haut grade avec aspects piloïdes (HGAP). Cela pose un problème de diagnostic différentiel lourd de conséquences en termes de décision thérapeutique. Les critères de la classification de l'OMS des tumeurs du SNC manquent de précision pour distinguer certains types tumoraux, en particulier pour les tumeurs glioneuronales et les nouveaux types tumoraux comme la PLNTY ou l'HGAP. Dans ce contexte, il a été réalisé un travail de caractérisation fine des tumeurs gliales/glioneuronales avec fusion FGFR1-3 en intégrant des données, cliniques, radiologiques, histologiques, immunophénotypiques, moléculaires, et épigénétiques. Les résultats montrent qu'il existe différents spectres tumoraux en fonction du type de fusion et de l'âge de survenue des tumeurs. Les tumeurs avec fusion de FGFR2 sont plutôt restreintes aux enfants et aux adultes jeunes et correspondent à des tumeurs glioneuronales associées à l'épilepsie chronique telles que les PLNTY ou les GG dont le diagnostic différentiel pourrait être facilité par l'adjonction de critères radiologiques. Les tumeurs FGFR3-TACC3 et FGFR1-TACC1 ont un spectre tumoral plus large définit par l'âge. Avant 40 ans pour les tumeurs avec fusion FGFR3, il s'agit principalement de DNET et de GG tandis qu'après 40 ans il s'agit de GBM IDH WT. Pour FGFR1-TACC1, les enfants ( 18 ans) ont plutôt des neurocytomes extraventriculaires. Ces travaux et ces résultats s'intègrent dans les perspectives futures en neuro-oncologie de thérapie ciblée, d'intégration de l'intelligence artificielle aux pratiques médicales et de techniques chirurgicales ou de prélèvements moins invasives.FGFR1-3 gene fusions are rare in primary tumors of the nervous system (CNS). Glial and glioneuronal tumors with FGFR1-3 fusion have common clinical and histological features, but may correspond to benign tumor types, such as: neuroepithelial dysembryoplastic tumors (DNET), pilocytic astrocytomas (PA), gangliogliomas (GG), polymorphic low-grade neuroepithelial tumors of the young (PLNTY); as well as malignant tumor types such as: glioblastoma IDH wildtype (GBM IDH WT) or high grade astrocytoma with piloid features (HGAP). This poses a problem of differential diagnosis with heavy consequences in terms of therapeutic decisions. The criteria from the WHO classification of CNS tumors lack precision in distinguishing certain tumor types, in particular glioneuronal tumors and new tumor types such as PLNTY or HGAP. Against this backdrop, a detailed characterization of glial/glioneuronal tumors with FGFR1-3 fusion was carried out, integrating clinical, radiological, histological, immunophenotypic, molecular and epigenetic data. The results show that there are different tumor spectra depending on the type of fusion and the age of onset. Tumors with FGFR2 fusion are rather restricted to children and young adults and correspond to glioneuronal tumors associated with chronic epilepsy, such as PLNTY or GG, whose differential diagnosis could be facilitated by the addition of radiological criteria. FGFR3-TACC3 and FGFR1-TACC1 tumors have a broader tumor spectrum defined by age. Before the age of 40, tumors with FGFR3 fusion are mainly DNET and GG, whereas after the age of 40 they are GBM IDH WT. For FGFR1-TACC1, children (18 years) tend to have extraventricular neurocytomas. This work and these results fit in with future prospects in neuro-oncology for targeted therapy, the integration of artificial intelligence into medical practices, and less invasive surgical or sampling techniques
A histopathological and epigenetic comparison of central nervous system mesenchymal tumors to their soft tissue counterparts
No full textCes dernières années, la classification des tumeurs du système nerveux central (SNC) s'est considérablement étoffée avec la description de nouveaux types tumoraux, et ce, grâce aux découvertes liées au profil de méthylation des tumeurs. Parmi ces nouvelles entités, des tumeurs présentant des aspects morphologiques ou génétiques communs avec des types tumoraux décrits précédemment dans les tissus mous. Ce chevauchement histo-moléculaire pose la question de la cellule d'origine de ces tumeurs primitives du SNC. Dans ce travail, cinq axes d'étude ont permis d'aborder cette problématique : les tumeurs du SNC avec altérations du gène BCOR, les tumeurs mésenchymateuses intracrâniennes avec fusions FET::CREB, les angioléiomyomes de la dure-mère, les tumeurs avec fusions du gène PATZ1 et les tumeurs mésenchymateuses avec fusions NTRK1/2/3. Parmi les tumeurs avec altération de BCOR, l'anomalie moléculaire la plus fréquente est la duplication en tandem. Dans ce travail, une cohorte incluant des tumeurs du SNC et extra-SNC ont été incluses. D'un point de vue morphologique, immunophénotypique et épigénétique, les formes du SNC étaient distinctes des tissus mous et des viscères. En outre, dans un second travail, nous avons décrit des tumeurs du SNC avec fusion EP300:BCOR qui montraient des similitudes morphologiques, immunophénotypiques et épigénétiques avec les tumeurs du SNC avec duplication en tandem de BCOR. Puis, nous avons étudié des cas présentant des altérations décrites dans les tissus mous du spectre BCOR (comprenant des fusions alternatives impliquant les gènes YWHAE, NUTM2 et KDM2B). Contrairement aux tumeurs avec duplication en tandem de BCOR et celles avec fusion EP300::BCOR, ces tumeurs avec fusions alternatives étaient morphologiquement et d'un point de vue épigénétique plus proches des sarcomes des tissus mous avec altérations BCOR que des tumeurs du SNC. La question du chevauchement histomoléculaire entre des tumeurs du SNC avec des fusions des familles de gènes FET et CRB s'est posée également avec les histiocytomes fibreux angiomatoïdes des tissus mous qui présentent les mêmes fusions. D'un point de vue ultrastructural et épigénétique, nous avons mis en évidence que la majorité de ces tumeurs du SNC se rapprochent de tumeurs mésenchymateuses d'origine arachnoïdienne que des tumeurs des tissus mous (dont la nature histiocytaire ou fibroblastique est encore débattue). Ensuite, à partir de la caractérisation histo-radiologique d'une série de 202 lésions vasculaires du SNC, nous avons isolé trois cas de lésions vasculaires dont la morphologie évoquait des angioléiomyomes de sous-type caverneux. Nous avons alors colligé des observations similaires d'autres centres. L'étude morphologique et génétique a pu rapprocher ces lésions des angioléiomyomes décrits dans les tissus mous. Cependant, l'étude épigénétique a montré que leurs profils de méthylation étaient distincts, sous-tendant une origine cellulaire distincte. Puis, l'étude comparant les tumeurs mésenchymateuses avec fusions NTRK1/2/3 a permis de montrer que d'un point de vue morphologique, génétique, ultrastructural et épigénétique, les formes intracrâniennes et des tissus mous et des viscères étaient identiques. Enfin, les tumeurs avec fusions PATZ1 du SNC et des tissus mous présentent les mêmes profils morphologiques et épigénétiques, sous-tendant une même cellule d'origine. L'ensemble de ces résultats montre que des tumeurs des tissus mous et du SNC partageant des aspects morphologiques et génétiques sont originaires de la même cellule d'origine (tumeurs avec fusions NTRK, tumeurs avec fusions alternatives de BCOR et tumeurs avec fusions PATZ1), alors que d'autres sont distinctes selon l'organe concerné (tumeurs avec duplication en tandem et fusion BCOR, angioléiomyomes et tumeurs avec fusions FET::CREB). Les données de ce travail pourraient permettre d'apporter des éléments de réponse dans la classification des tumeurs du SNC et leur nosologie.In recent years, the classification of central nervous system (CNS) tumors has grown considerably, with discoveries related to the methylation profile of tumors leading to the description of new tumor types. Among these new entities, tumors presenting common morphological or genetic aspects of previously described soft tissue tumor types have been found. This histo-molecular overlap raises questions pertaining to the cell of origin for these primary CNS tumors. In this work, five lines of study have made it possible to address this conundrum: CNS tumors with alterations of the BCOR gene, intracranial mesenchymal tumors with FET::CREB fusions, angioleiomyomas of the dura mater, tumors with fusions of the PATZ1 gene and mesenchymal tumors with NTRK1/2/3 fusions. Among BCOR-altered tumors, the most common molecular abnormality is tandem duplication. In this study, a cohort including CNS and extra-CNS tumors were included. From a morphological, immunophenotypic and epigenetic perspective, the CNS formations were distinct from soft tissues and viscera. Furthermore, in a second study, we described CNS tumors with an EP300:BCOR fusion that showed morphological, immunophenotypic and epigenetic similarities to CNS tumors with BCOR tandem duplication. This was followed by a study of cases having described alterations in the soft tissues of the BCOR spectrum (including alternative fusions involving the YWHAE, NUTM2 and KDM2B genes). Unlike the tumors with a tandem duplication of BCOR and those with the EP300::BCOR fusion, these tumors with alternative fusions were morphologically and epigenetically closer to soft tissue sarcomas with BCOR alterations than to CNS tumors. The question of histomolecular overlap between CNS tumors having FET and CREB gene family fusions has also arisen for angiomatoid fibrous histiocytomas of the soft tissue which present the same fusions. From an ultrastructural and epigenetic point of view, we have demonstrated that the majority of these CNS tumors are closer to mesenchymal tumors of arachnoid origin than soft tissue tumors (whose histiocytic or fibroblastic nature is still being debated). Next, comparing the histo-radiological characterizations of a series of 202 CNS vascular lesions, we isolated three cases of vascular lesions whose morphology evoked the cavernous subtype of angioleiomyomas. We then collected similar observations from other centers. The morphological and genetic study was able to approach these lesions closer to the angioleiomyomas described in the soft tissues. However, an epigenetic study showed that their methylation profiles were distinct, revealing a distinct cellular origin. Then, the study comparing mesenchymal tumors with NTRK1/2/3 fusions made it possible to show that from a morphological, genetic, ultrastructural and epigenetic perspective, the intracranial, soft tissue and visceral formations were identical. Finally, CNS and soft tissue tumors with PATZ1 fusions show the same morphological and epigenetic profiles, underlying the same cell of origin. All of these results show that soft tissue and CNS tumors sharing morphological and genetic aspects originate from the same cell of origin (tumors with NTRK fusions, tumors with alternative BCOR fusions and tumors with PATZ1 fusions), while others are distinct depending on the organ concerned (tumors with tandem duplication and BCOR fusion, angioleiomyomas and tumors with FET::CREB fusions). This data will make it possible to expand the current classification of CNS tumors
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