1,720,991 research outputs found
Glutamate, aspartate and co-localization with calbindin in the medial thalamus: An immunohistochemical study in the rat
No full textTopographical and quantitative features of medial thalamic neurons in which aspartate (ASP) or glutamate (GLU) might act as neurotransmitters were investigated in the rat. The calcium-binding protein calbindin D-28k (CB) was exploited as a marker of neuronal subsets, thus allowing us to study also the relationships between the CB-containing neurons and those immunoreactive to excitatory amino acids. Double immunocytochemistry of ASP and CB or GLU and CB was performed in 40-mu-m-thick sections. The three markers were distributed in the thalamic midline, mediodorsal, anterior intralaminar and ventromedial nuclei, with regional variations. ASP-immunoreactive neurons appeared more numerous than the GLU-immunoreactive ones throughout these structures; ASP-CB or GLU-CB double-immunostained neurons were evident. ASP-, GLU- and CB-immunoreactive cells were then quantitatively evaluated in 5-mu-mthick consecutive sections. Interindividual variations and different anti-ASP and anti-GLU antibodies did not result in significant differences. ASP and GLU were not co-localized. Single ASP- or GLU-immunoreactive neurons accounted for 60% of the total number of immunostained cells, and single ASP-immunopositive cells represented more than half of these neurons. Among the CB-immunoreactive cells (40% of the total), half were double immunostained; the proportion of double CB-ASP-immunopositive neurons was seven-fold higher than that of the CB-GLU-immunoreactive ones. These results indicate that ASP may act as excitatory neurotransmitter in a relatively high proportion of medial thalamic neurons, in which ASP frequently coexists with CB. Approximately 50% of the CB-immunoreactive cells did not contain either ASP or GLU, suggesting that some medial thalamic neurons may utilize a different neurotransmitter
PSA-NCAM in the developing and mature thalamus
No full textThe polysialylated form of the neural cell adhesion molecule (PSA-NCAM) is involved in several morphogenetic processes of the central nervous
system. In the present study the expression of PSA-NCAM has been investigated in the rat thalamus during embryonic and postnatal development
using light and electron microscopic immunocytochemical techniques. At all the examined ages, PSA-NCAM staining in the thalamus was mainly
observed along neuronal plasmatic membranes and absent in astrocytes identified by labelling with cytoskeletal (vimentin and glial fibrillary
acidic protein) and membrane (GABA transporter-3) markers. At embryonic day 14 the immunoreactivity was restricted to the dorsal thalamic
mantle and to the region of reticular thalamic migration and subsequently it extended throughout the whole thalamic primordium. PSA-NCAM
labelling remained intense and homogeneously distributed along perinatal period, but from P4 it began to decrease selectively, persisting throughout
adulthood only in the reticular nucleus, ventral lateral geniculate nucleus and midline and intralaminar nuclei. The expression of this adhesion
molecule differed in areas characterized by the presence of neurons containing distinct calcium binding proteins, as PSA-NCAM labelling was
intense around calretinin-positive neurons, whereas it decreased in some calbindin-immunoreactive regions.
These findings show evidence of a selective neuronal expression of PSA-NCAM in developing thalamus, supporting its suggested role in cell
migration and synaptogenesis as it occurs in the cerebral cortex. In adulthood PSA-NCAM could instead be a marker of thalamic nuclei that retain
a potential for synaptic plasticity
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Proliferative cells in the rat developing neocortical grey matter: new insights into gliogenesis
No full textThe postnatal brain development is characterized by a substantial gain in weight and size, ascribed to increasing neuronal size and branching, and to massive addition of glial cells. This occurs concomitantly to the shrinkage of VZ and SVZ, considered to be the main germinal zones, thus suggesting the existence of other germinative niches. The aim of this study is to characterize the cortical grey matter proliferating cells during postnatal development, providing their stereological quantification and identifying the nature of their cell lineage. We performed double immunolabeling for the proliferation marker Ki67 and three proteins which identify either astrocytes (S100β) or oligodendrocytes (Olig2 and NG2), in addition to a wider panel of markers apt to validate the former markers or to investigate other cell lineages. We found that proliferating cells increase in number during the first postnatal week until P10 and subsequently decreased until P21. Cell lineage characterization revealed that grey matter proliferating cells are prevalently oligodendrocytes and astrocytes along with endothelial and microglial cells, while no neurons have been detected. Our data showed that astrogliogenesis occurs prevalently during the first 10 days of postnatal development, whereas contrary to the expected peak of oligodendrogenesis at the second postnatal week, we found a permanent pool of proliferating oligodendrocytes enduring from birth until P21. These data support the relevance of glial proliferation within the grey matter and could be a point of departure for further investigations of this complex process
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