1,721,151 research outputs found
Oligodendrocytes in a dish for the drug discovery pipeline: The risk of oversimplification
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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
Thyroid hormone activates oligodendrocyte precursors, increases a myelin forming protein and NGF content in the spinal cord during experimental allergic encephalomyelitis
No full textRemyelination in the adult central nervous system has been demonstrated in different experimental models of demyelinating diseases. However, there is no clear evidence that remyelination occurs in multiple sclerosis, the most diffuse demyelinating disease. In this article, we explore the possibility of promoting myelination in experimental allergic encephalomyelitis, a widely used experimental model of multiple sclerosis, by recruiting progenitors and channeling them into oligodendroglial lineage through administration of thyroid hormone (T4). A large number of proliferating cells (BrdUrd uptake and Ki67-IR) and the expression of markers for undifferentiated precursors (nestin) increased in the subventricular zone and spinal cord of experimental allergic encephalomyelitis animals. T4 administration reduces proliferation and nestin-immunoreactivity and up-regulates expression of markers for oligodendrocyte progenitors [polysialylated-neural cell adhesion molecule (PSA-NCAM), O4, A2B5] and mature oligodendrocytes (myelin basic protein) in the spinal cord, olfactory bulb, and subventricular zone
Vulnerability of primary neurons derived from Tg2576 Alzheimer mice to oxygen and glucose deprivation: role of intraneuronal amyloid-β accumulation and astrocytes.
Full text linkMicrovascular dysfunction is considered an integral part of Alzheimer disease (AD) pathogenesis, but the possible relationship between amyloid pathology, microvascular dysfunction and cell death is still unclear. In order to investigate the influence of intraneuronal amyloid-β (Aβ) accumulation on vulnerability to hypoxia, we isolated primary cortical neurons from Tg2576 (carrying the amyloid precursor protein APPSwe mutation) and wild-type fetal mice. We first demonstrated that neurons isolated from Tg2576 newborn mice show an increase in VEGFa mRNA expression and a decrease in the expression of the two VEGF receptors, Flt1 and Kdr, compared with wild-type cells. Moreover, APPSwe primary neurons displayed higher spontaneous and glutamate-induced cell death. We then deprived the cultures of oxygen and glucose (OGD) as an in vitro model of hypoxia. After OGD, APPSwe neurons display higher levels of cell death in terms of percentage of pyknotic/fragmented nuclei and mitochondrial depolarization, accompanied by an increase in the intraneuronal Aβ content. To explore the influence of intraneuronal Aβ peptide accumulation, we used the γ-secretase inhibitor LY450139, which showed that the reduction of the intracellular amyloid fully protects APPSwe neurons from OGD-induced degeneration. Conditioned medium from OGD-exposed APPSwe or wild-type astrocytes protected APPswe neurons but not wild-type neurons, during OGD. In conclusion, the presence of the mutated human APP gene, leading to the intracellular accumulation of APP and Aβ fragments, worsens OGD toxicity. Protection of APPSwe neurons can be obtained either using a γ-secretase inhibitor or astrocyte conditioned medium
Nerve Growth Factor: The First Molecule of the Neurotrophin Family
No full textNeurotrophins (NTs) are molecules regulating differentiation, maintenance, and functional plasticity of vertebrate nervous systems. Nerve growth factor (NGF) was the first to be identified in the neurotrophin family. The long scientific history of NTs provided not only advancement in the neuroscience field but opened new scenarios involving different body districts in physiological and pathological conditions, which include the immune, endocrine, and skeletal system, vascular districts, inflammation, etc. To date, many biological aspects of NTs have been clarified, but the new discoveries are still opening new insights on molecular and cellular mechanisms and systemic effects, also affecting the possible therapeutic application of NTs. This short review summarizes the main aspects of NGF biology and biochemistry, including the role of the NGF precursor molecule, high- and low-affinity receptors and related intracellular pathways, and target cells
Effetto antimicrobico di due nuovi irriganti nei confronti dell'Enterococcus faecalis: studio comparativo in vitro
Full text linkIntroduction: the antibacteric action of irri- gants in the endodontic therapy could be in- hibited by many factors. The most important one is the presence of bacterial strain (e.g. En- terococcus faecalis) resistant to irrigants and intracanal dressing action. Two new irrigants, based on antibiotics, Tetraclean and Bio Pure MTAD have been recently proposed to face this problem. The aim of this study is to com- pare the antibiotic action of these new irrig- ants.
Methodology: according to NCCLS guide- lines the MIC of Tetraclean and MTAD against Enterococcus faecalis ATCC 29212 strain were determined, using dilutions from 1:2 to 1:2048.
Results: Bio Pure MTAD killed all bacteria until a dilution of 1:256; Tetraclean has shown better results, until 1:1024.
Conclusions: both Bio Pure MTAD and Tetr- aclean proved effective antibacteric action as compared to the Enterococcus faecalis strain examined. Tetraclean was better than MTAD. Other in vitro and in vivo studies should be performed to confirm these data
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