1,721,242 research outputs found
Substance P in pain
No full textFollowing noxious stimulation, the neuropeptide substance P is released both peripherally and in the central nervous system (CNS), binding to its NK1 receptor and contributing to nociception. However, despite the initial excitement surrounding the blockade of spinal NK1 receptors as a potential clinical analgesic, substance P is now widely considered to be more of a neuromodulator of the pain response in the CNS rather than the primary nociceptive neurotransmitter. Nonetheless, it is a critical player in neuronal sensitization to pain, as well as playing a major role in cortical processing of the pain response in the brain, including the emotional aspects of pain. The current review will summarize the historical data supporting a role for substance P in nociception, the preclinical studies examining NK1 antagonists as antinociceptive agents, attempts at clinical translation, and recent developments supporting further research into NK1 antagonists as clinical analgesics
Magnesium and stress
No full textMagnesium status is highly associated with stress levels, with both stress and hypomagnesemia potentiating each other’s negative effects. Indeed, hypomagnesemia has been associated with stressful conditions such as photosensitive headache, fibromyalgia, chronic fatigue syndrome, audiogenic stress, cold stress, and physical stress, amongst others. The role of magnesium in these conditions is unclear, although a number of potential mechanisms for magnesium’s action have been identified including via the glutamatergic, serotonergic, and adrenergic neurotransmitter systems, as well as via several neuro-‐ hormones. The current review examines the link between magnesium deficiency and stress, focusing on the association between magnesium and various stress pathologies, magnesium’s potential interaction with stress pathways, and magnesium’s effects on the brain
Magnesium transport across the blood-brain barriers
No full textThe finding that magnesium levels are reduced in acute and chronic brain diseases has led to a recent surge in interest in the role of magnesium in the normal and injured nervous system, although the mechanisms of magnesium decline in pathological conditions and its availability in the neural tissue after administration are not fully understood. The brain has two main barrier systems: (1) the blood-‐brain barrier (BBB) formed by brain capillary endothelial cells which separate the blood from the extracellular fluid in the neuropil; and (2) the blood-‐CSF barrier (BCSFB) formed by choroidal epithelial cells which separate the blood from the CSF. Genetic studies in families with hereditary hypomagnesemia have identified mutations in two genes encoding claudin-‐16 (paracellin-‐1) and claudin-‐19, both localized at tight junctions between nephron epithelial cells and providing passive paracellular conductance for magnesium in the kidney. Endothelial cells of the BBB also express claudins, although whether members of the claudin family expressed at the BBB and BCSFB have similar conductance for magnesium akin to the role of claudin-‐16 and -‐19 in the nephron remains to be confirmed. Recently, the transient receptor potential melastatin (TRPM) members TRPM6 and TRPM7 have been identified as cation channels for magnesium transport. Although it is not known if choroidal epithelial cells express TRPM6 and TRPM7, these molecules are expressed by brain endothelial cells and may play a role in magnesium transport. While it is evident that magnesium enters the CNS through the BBB and is actively transported by choroidal epithelial cells into the CSF, the mechanisms of its entry into the brain will require further investigation.Mounir N. Ghabriel and Robert Vin
Magnesium and stress
No full textMagnesium status is highly associated with stress levels, with both stress and hypomagnesemia potentiating each other’s negative effects. Indeed, hypomagnesemia has been associated with stressful conditions such as photosensitive headache, fibromyalgia, chronic fatigue syndrome, audiogenic stress, cold stress, and physical stress, amongst others. The role of magnesium in these conditions is unclear, although a number of potential mechanisms for magnesium’s action have been identified including via the glutamatergic, serotonergic, and adrenergic neurotransmitter systems, as well as via several neuro-‐ hormones. The current review examines the link between magnesium deficiency and stress, focusing on the association between magnesium and various stress pathologies, magnesium’s potential interaction with stress pathways, and magnesium’s effects on the brain.Magdalena D. Cuciureanu and Robert Vin
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
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