1,720,964 research outputs found
Interleukin-1beta does not affect the energy metabolism of rat organotypic hippocampal-slice cultures
No full textThe aim of this study was to examine the effect of the archetypal pro-inflammatory cytokine, interleukin-1beta (IL-1?), on high-energy phosphate levels within an ex vivo rat organotypic hippocampal-slice culture (OHSC) preparation using phosphorus ((31)P) magnetic resonance spectroscopy (MRS). Intrastriatal microinjection of IL-1? induces a chronic reduction in the apparent diffusion coefficient (ADC) of tissue water, which may be indicative of metabolic failure as established by in vivo models of acute cerebral ischaemia. The OHSC preparation enables examination of the effects of IL-1? on brain parenchyma per se, independent of the potentially confounding effects encountered in vivo such as perfusion changes, blood-brain barrier (BBB) breakdown and leukocyte recruitment. (31)P MRS is a technique that can detect multiple high-energy phosphate metabolites within a sample non-invasively. Here, for the first time, we characterise the energy metabolism of OHSCs using (31)P MRS and demonstrate that IL-1? does not compromise high-energy phosphate metabolism. Thus, the chronic reduction in ADC observed in vivo is unlikely to be a consequence of metabolic failure
Temporal development of hippocampal cell death is dependent on tissue strain but not strain rate
No full textDeformation of brain tissue in response to mechanical loading of the head is the root-cause of traumatic brain injury (TBI). Even below ultimate failure limits, deformation activates pathophysiological cascades resulting in delayed cell death. Injury response of soft tissues, such as the chest and spinal cord, is dependent on the product of deformation and velocity, a parameter termed the viscous criterion. We set out to test if hippocampal cell death could be predicted by a similar combination of strain and strain rate and if the viscous criterion was valid for hippocampus. Quantitative prediction of the brain's biological response to mechanical stimuli is difficult to achieve in animal models of TBI, so we utilized an in vitro model of TBI based on hippocampal slice cultures. We quantified the temporal development of cell death after precisely controlled deformations for 30 combinations of strain (0.05-0.50) and strain rate (0.1-50 s(-1)) relevant to TBI. Loading conditions for a subset of cultures were verified by analysis of highspeed video. Cell death was found to be significantly dependent on time-post injury, on strain magnitude, and to a lesser extent, on anatomical region by a repeated-measures, three-way ANOVA. The responses of the CA1 and CA3 regions of the hippocampus were not statistically different in contrast to some in vivo TBI studies. Surprisingly, cell death was not dependent on strain rate leading us to conclude that the viscous criterion is not a valid predictor for hippocampal tissue injury. Given the large data set and extensive combinations of biomechanical parameters, predictive mathematical functions relating independent variables (strain, region, and time post-injury) to the resultant cell death were defined. These functions can be used as tolerance criteria to equip finite element models of TBI with the added capability to predict biological consequences
An in vitro model of traumatic brain injury utilising two-dimensional stretch of organotypic hippocampal slice cultures
No full textTraumatic brain injury (TBI) is caused by rapid deformation of the brain, resulting in a cascade of pathological events and ultimately neurodegeneration. Understanding how the biomechanics of brain deformation leads to tissue damage remains a considerable challenge. We have developed an in vitro model of TBI utilising organotypic hippocampal slice cultures on deformable silicone membranes, and an injury device, which generates tissue deformation through stretching the silicone substrate. Our injury device controls the biomechanical parameters of the stretch via feedback control, resulting in a reproducible and equi-biaxial deformation stimulus. Organotypic cultures remain well adhered to the membrane during deformation, so that tissue strain is 93 and 86% of the membrane strain in the x- and y-axis, respectively. Cell damage following injury is positively correlated with strain. In conclusion, we have developed a unique in vitro model to study the effects of mechanical stimuli within a complex cellular environment that mimics the in vivo environment. We believe this model could be a powerful tool to study the acute phases of TBI and the induced cell degeneration could provide a good platform for the development of potential therapeutic approaches and may be a useful in vitro alternative to animal models of TBI
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
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