1,720,956 research outputs found
Neuronal biomarkers associated with recovery of motor function in a mouse model of stroke
Get PDFIschemic stroke, a major cause of adult disability, is characterized by an occlusion of cerebral blood vessels, leading to neurological impairment. After a stroke, the neural circuits in the peri-infarct zone undergo plastic changes to allow a spontaneous restoration of the neurological function. However, the extent of spontaneous recovery is highly variable among patients, underscoring the need for identifying neurophysiological biomarkers that can predict recovery outcomes, thus aiding effective treatment strategies.
In this thesis work, I employed a well-established model of ischemic stroke in mice, the distal middle cerebral artery occlusion (dMCAO), to investigate the relationship between motor deficits and cortical changes after stroke in the peri-infarct area. Behavioral tests (rotarod, grip strength, and gridwalk) were conducted at various intervals post-stroke (D02, D09, D30) to evaluate the evolution of motor performance.
I observed that dMCAO does not significantly impact muscle force or motor coordination and balance, as assessed by the grip strength and the rotarod test, but does induce deficits in fine motor behavior, unmasked by the gridwalk test. After determining the extent of the behavioral impairment with the gridwalk test, subjects were classified as either good or poor recoverers.
To explore the potential correlations between behavioral impairments and neural changes, I performed both spontaneous and evoked in vivo local field potential (LFP) recordings in anesthetized Thy1-ChR2-YFP transgenic mice, at D30, the chronic phase of stroke. I found that stroke mice displayed a substantial reduction of the total frequency power in comparison to the control group, and mice with poor recovery outcomes demonstrated decreased excitability in response to ipsilesional premotor cortex stimulation, contrasted by heightened responses to contralateral primary motor cortex stimulation. Altogether my data shed light on potential mechanisms about the ‘good’ and ‘poor’ recovery outcomes of the motor function, thus opening new perspectives for further preclinical investigations
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
Hypoxic Human Microglia Promote Angiogenesis Through Extracellular Vesicle Release
Get PDFMicroglia, the brain-resident immune cells, orchestrate neuroinflammatory responses and are crucial in the progression of neurological diseases, including ischemic stroke (IS), which accounts for approximately 85% of all strokes worldwide. Initially deemed detrimental, microglial activation has been shown to perform protective functions in the ischemic brain. Besides their effects on neurons, microglia play a role in promoting post-ischemic angiogenesis, a pivotal step for restoring oxygen and nutrient supply. However, the molecular mechanisms underlying microglia–endothelial cell interactions remain largely unresolved, particularly in humans. Using both in vitro and in vivo models, we investigated the angiogenic signature and properties of extracellular vesicles (EVs) released by human microglia upon hypoxia–reperfusion stimulation. EVs were isolated and characterized in terms of their size, concentration, and protein content. Their angiogenic potential was evaluated using endothelial cell assays and a zebrafish xenograft model. The in vivo effects were further assessed in a mouse model of ischemic stroke. Our findings identified key proteins orchestrating the pro-angiogenic functions of human microglial EVs under hypoxic conditions. In vitro assays demonstrated that hypoxic EVs (hypEVs) promoted endothelial cell migration and tube formation. In vivo, hypEVs induced vessel sprouting in zebrafish and increased microvessel density in the perilesional area of mice following ischemic stroke
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
The role of parvalbumin positive interneurons in stroke recovery: combination of optogenetic and robotic approaches in a mouse model.
No full textThis work focalizes on the study of the GABAergic parvalbumin positive interneurons (PV+) in a mouse model of motor cortical stroke. First, I investigated the connectivity of PV+ interneurons through a specific labelling of the efferent cells using an EnvA pseudotyped Rabies virus (RV) in collaboration with Prof. Pasqualetti and his group of the Department of Biology. Mice expressing Cre recombinase in PV+ (PV::Cre) has been injected in Rostral Forelimb Area, premotor cortex with an adeno-associated virus expressing the TVA receptor for RV. After two weeks the RV has been injected in the same site. With this approach it has been possible to carry out a monosynaptic tracing of the PV+ afferences. I then quantified the PV+ target cells and the only RV expressing cells with immunohistochemistry. I found retrogradely labelled neurons in ipsilesional cortex and thalamus in healthy animals and started to study the differences between sham and ictus mice was done.
A second experiment had evaluated the effects of the PV+ optogenetic stimulation associated with robotic rehabilitation. With this system, I was able to use intrinsic properties of PV+ to synchronise brain oscillations in gamma frequencies as a neuromodulatory treatment to couple with robotic rehabilitation. In PV::Cre transgenic animals injected with ChR2 virus the activation is restricted to PV+ interneurons allowing to deepen their role in the rehabilitation process. This experiment focuses on the effects of the gamma band synchronization induced by the PV+ stimulation
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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