1,720,958 research outputs found
Daily Fluctuation of Orexin Neuron Activity and Wiring: The Challenge of “Chronoconnectivity”
Full text linkIn the heterogeneous hub represented by the lateral hypothalamus, neurons containing the orexin/hypocretin peptides play a key role in vigilance state transitions and wakefulness stability, energy homeostasis, and other functions relevant for motivated behaviors. Orexin neurons, which project widely to the neuraxis, are innervated by multiple extra- and intra-hypothalamic sources. A key property of the adaptive capacity of orexin neurons is represented by daily variations of activity, which is highest in the period of the animal’s activity and wakefulness. These sets of data are here reviewed. They concern the discharge profile during the sleep/wake cycle, spontaneous Fos induction, peptide synthesis and release reflected by immunostaining intensity and peptide levels in the cerebrospinal fluid as well as postsynaptic effects. At the synaptic level, adaptive capacity of orexin neurons subserved by remodeling of excitatory and inhibitory inputs has been shown in response to changes in the nutritional status and prolonged wakefulness. The present review wishes to highlight that synaptic plasticity in the wiring of orexin neurons also occurs in unperturbed conditions and could account for diurnal variations of orexin neuron activity. Data in zebrafish larvae have shown rhythmic changes in the density of inhibitory innervation of orexin dendrites in relation to vigilance states. Recent findings in mice have indicated a diurnal reorganization of the excitatory/inhibitory balance in the perisomatic innervation of orexin neurons. Taken together these sets of data point to “chronoconnectivity,” i.e., a synaptic rearrangement of inputs to orexin neurons over the course of the day in relation to sleep and wake states. This opens questions on the underlying circadian and homeostatic regulation and on the involved players at synaptic level, which could implicate dual transmitters, cytoskeletal rearrangements, hormonal regulation, as well as surrounding glial cells and extracellular matrix. Furthermore, the question arises of a “chronoconnectivity” in the wiring of other neuronal cell groups of the sleep-wake-regulatory network, many of which are characterized by variations of their firing rate during vigilance states
Neuroinflammatory response in chronic hydrocephalus in juvenile rats
No full textHydrocephalus is especially prevalent in countries with limited resources, where its treatment is still a challenge. However, long-term neuropathological changes in untreated hydrocephalus remain largely unexplored. The present study looks at cortical parenchyma and neuroinflammation in acquired, chronic hydrocephalus. Intracisternal kaolin injections were performed in 3 week-old rats, followed by 1, 4 and 8 week survival; matched control rats received saline injections. Ventriculomegaly has been previously reported to stabilize by the third week in this model. Single and triple immunocytochemical approaches were used to highlight neurones, astrocytes, microglia, and the pro-inflammatory cytokine interleukin (IL)-1β in the parietal cortex, utilizing cell counts and densitometry. Microglial protein ionized calcium binding adaptor molecule 1 (Iba1) and IL-1β expressions were monitored with Western blotting in the parietal cortex and hippocampus. In the parietal cortex, which showed progressive disruption of cytoarchitecture, neuronal density was significantly increased at 8 weeks post-induction but not at earlier time points, indicating on-going cortical damage in chronic hydrocephalus. Astrocyte and microglia hypertrophy, and Iba1 expression indicated glial cell activation which peaked at 4 weeks. IL-1β expression also peaked at 4 weeks and was then down-regulated. Overall the findings indicate that neuroinflammatory features build up in the first month after hydrocephalus induction implicating marked IL-1β upregulation. The data also show that astrocytes are the main source of IL-1β in this disorder
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
The ameliorative effects of a phenolic derivative of Moringa oleifera leave against vanadium-induced neurotoxicity in mice
No full textVanadium, a transition series metal released during some industrial activities, induces oxidative stress and lipid peroxidation. Ameliorative effect of a pure compound from the methanolic extract of Moringa oleifera leaves, code-named MIMO2, in 14-day old mice administered with vanadium (as sodium metavanadate 3 mg/kg) for 2 weeks was assessed. Results from body weight monitoring, muscular strength, and open field showed slight reduction in body weight and locomotion deficit in vanadium-exposed mice, ameliorated with MIMO2 co-administration. Degeneration of the Purkinje cell layer and neuronal death in the hippocampal CA1 region were observed in vanadium-exposed mice and both appeared significantly reduced with MIMO2 co-administration. Demyelination involving the midline of the corpus callosum, somatosensory and retrosplenial cortices was also reduced with MIMO2. Microglia activation and astrogliosis observed through immunohistochemistry were also alleviated. Immunohistochemistry for myelin, axons and oligodendrocyte lineage cells were also carried out and showed that in vanadium-treated mice brains, oligodendrocyte progenitor cells increased NG2 immunolabelling with hypertrophy and bushy, ramified appearance of their processes. MIMO2 displayed ameliorative and antioxidative effects in vanadium-induced neurotoxicity in experimental murine species. This is likely the first time MIMO2 is being used in vivo in an animal model
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
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