1,720,959 research outputs found
Data set for MCORPUS project
No full textThis data set belongs to a project which was carried out as a joint venture between Khyber Medical University, Peshawar, Pakistan, and MCORPUS SPRL, A Belgium based company that designs Mixed reality gears call Hololens for the teaching and learning of Anatomy
Spinal cord neuronal circuitry involving dorsal horn projection cells
Get PDFThe spinal cord dorsal horn is involved in the processing and transmission of sensory information to the brain. There are several distinct populations of dorsal horn projection cells that constitute the major output of the spinal cord. These cells are mostly found in lamina I and are scattered throughout the deep dorsal horn. There is a population of large lamina III projection cells that expresses the neurokinin 1 receptor (NK1r), which is the main target for substance P released by nociceptive primary afferents. These cells are densely innervated by peptidergic nociceptive afferents and more sparsely by low-threshold myelinated afferents. In addition, they also receive selective innervation from neuropeptide Y-containing inhibitory interneurons. However, not much is known about their input from glutamatergic spinal neurons. It has already been reported that the great majority of large lamina III NK1r expressing cells project to caudal ventrolateral medulla (CVLM) therefore in this study these cells were easily identified without retrograde tracer injection. Preliminary observations showed that these cells received contacts from preprodynorphin (PPD)-containing excitatory axons. The first part of the study tested the hypothesis that lamina III projection cells are selectively targeted by PPD-containing excitatory spinal neurons. Spinal cord sections from lumbar segments of the rat underwent immunocytochemical processing including combined confocal and electron microscopy to look for the presence of synapses at the sites of contact. The results showed that lamina III NK1r cells received numerous contacts from non-primary boutons that expressed vesicular glutamate transporter 2 (VGLUT2), and formed asymmetrical synapses on their dendrites and cell bodies. These synapses were significantly smaller than those formed by peptidergic afferents but provided a substantial proportion of the glutamatergic input to lamina III NK1r projection cells. Furthermore, it was observed that PPD was found to be present in ~58% of the VGLUT2 boutons that contacted these cells while a considerably smaller proportion of (5-7%) VGLUT2 boutons in laminae I-IV expressed PPD. These results indicate a highly selective targeting of the lamina III projection neurons by glutamatergic neurons that express PPD.
Fine myelinated (Aδ) nociceptors are responsible for the perception of fast, well-localised pain. Very little is known about their postsynaptic targets in the spinal cord, and therefore about their roles in the neuronal circuits that process nociceptive information. In the second part of the study, Fluorogold injections were made into the lateral parabrachial region (LPb) of the rat brain on one side and cholera toxin B subunit (CTb) was injected into the sciatic nerve on the contralateral side to assess whether Aδ nociceptors provide input to lamina I projection cells. The vast majority of lamina I projection neurons belong to the spinoparabrachial tract, and these can be divided into two major groups: those that express NK1r, and those that do not. The results suggested that CTb labelled a distinct set of Aδ nociceptors, most of which lack neuropeptides. CTb-labelled Aδ afferents formed contacts on 43% of the spinoparabrachial lamina I neurons that lacked the NK1r, but on a significantly smaller proportion (26%) of NK1r projection cells. Combined confocal and electron microscopy established that the contacts were associated with synapses. Furthermore, the contact density of CTb labelled boutons was considerably higher on the NK1r- cells than on those with the NK1r. These results provide further evidence that primary afferents input to projection cells is organized in a specialized way and that both NK1r+ and NK1r- lamina I projection neurons are directly innervated by Aδ nociceptors, thus may have an important role in the perception of fast pain.
Lamina I of the rat spinal cord dorsal horn contains a population of large spinoparabrachial projection neurons (giant cells) that receive numerous synapses from both excitatory (VGLUT2) and inhibitory (VGAT) interneurons. The giant cells are selectively innervated by GABAergic axons that express neuronal-nitric oxide synthase (nNOS) and are thought to originate from local inhibitory interneurons. In the rat, the nNOS inhibitory cells belong to a distinct functional population that differs from other inhibitory interneurons in terms of somatostatin receptor (sst2A) expression and also in responsiveness to painful stimuli. There is a population of inhibitory interneurons that express green fluorescent protein (GFP) in lamina II of mice in which GFP is under control of the prion promoter (PrP) and the great majority of these cells also express nNOS. In this part of the study, the inhibitory synaptic input from nNOS-containing GFP boutons to giant lamina I cells was investigated. The great majority of lamina I projection neurons express NK1 receptor; therefore, the possibility that lamina I NK1r-expressing projection neurons received innervation from GFP+/nNOS+ axons was also tested. Since retrograde tracing technique was not used in this part of the study, lamina I projection cells were identified based on the observations made in the previous studies in the rat. Lamina I giant cells were recognized with antibodies against glycine receptor associated protein gephyrin as well as VGLUT2 and VGAT boutons, all of which provide dense innervation to these cells while only those lamina I NK1cells were included in the sample that were large and strongly immunoreactive for NK1r. The results indicated that although GFP axons accounted for only 7-9% of the GABAergic boutons in superficial dorsal horn, they provided over 70% of the inhibitory synapses on most of the giant cells in the PrP-GFP mouse and the great majority of these boutons also contained nNOS. Moreover, a subset of large lamina I NK1r-expressing cells (18/60) received a substantial inhibitory input (> 30%) from GFP+ boutons while the majority of these neurons showed sparse (< 15%) synaptic input.
Recently, it has been reported that loss of some inhibitory interneurons in mice lacking the transcription factor Bhlhb5 results in exaggerated itch, and the cells that are lost include many of those that would normally express nNOS. Therefore, in the final set of experiments was designed to test whether there is a reduction in the inhibitory synaptic input to the giant cells in Bhlhb5-/- mouse. Spinal cord sections from Bhlhb5-/- mice and the wild type littermates were processed and analysed to determine any difference in the inhibitory nNOS input to lamina I giant cells belonging to either group. The giant cells from the knockout mice showed a substantial reduction (~80%) in their inhibitory nNOS input; with a moderate reduction in their overall GABAergic input (~35%). There was a considerable increase in nNOS-/VGAT+ boutons in the Bhlhb5-/- mouse (18 ± 4.6 and 37.7 ± 8.2/100 µm of the dendrite in WT and KO, respectively), suggesting some compensation from other nNOS-negative inhibitory interneurons. These results suggest that the loss of nNOS-containing inhibitory synaptic input to lamina I projection cells may contribute to the abnormal scratching behaviour seen in the Bhlhb5-/- mouse. This raises the possibility that the giant cells and a subset of large lamina I NK1r-expressing cells are involved in perception of itch
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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