1,721,008 research outputs found
Sleep as a behavioral model of neuro-immune interactions
No full textThe central nervous system, by a variety of mechanisms engages in constant surveillance of the peripheral immune system. Alterations in the status of the peripheral immune system induced by an invading pathogen for example, are quickly detected by the central nervous system, which then responds by altering physiological processes and behavior in an attempt to support the immune system in its efforts to eliminate the pathogen. Sleep is one of several behaviors that are dramatically altered in response to infection. Immune-active substances such as the pro-inflammatory cytokines interleukin-1 and tumor necrosis factor, either directly or indirectly via interactions with neurotransmitters or neurohormones are involved in the regulation of sleep. Because these cytokines increase during infection, they are likely candidates for mediating the profound alterations in sleep that occur during infection. Since regulation of behavior is the function of the central nervous system, infection-induced alterations in behavior provide a unique model for the study of neuro-immune interactions
Blockade of 5-hydroxytryptamine (serotonin)-2 receptors alters interleukin-1-induced changes in rat sleep
No full textRecent data suggest that interleukin-1-induced enhancement of non-rapid eye movement sleep is mediated, in part, by the serotonergic system. To determine if sleep changes induced by interleukin-1 are mediated by a specific serotonergic receptor subtype, we evaluated interleukin-1 effects on sleep in rats pretreated with the 5-hydroxytryptamine (serotonin)-2 receptor antagonist ritanserin. Ritanserin (0.63 mg/kg, intraperitoneally) by itself did not alter sleep-wake behavior, although it did reduce cortical brain temperature. Interleukin-1 (5 ng, intracerebroventricularly) enhanced non-rapid eye movement sleep, suppressed rapid eye movement sleep, and induced a moderate febrile response. Pretreatment with ritanserin completely blocked the febrile response to interleukin-1 and abolished the interleukin-1-induced enhancement in non-rapid eye movement sleep that occurred during postinjection hours 3-4, without altering interleukin-1 effects on rapid eye movement sleep. The present data suggest that serotonin may partially mediate interleukin-1 effects on sleep by interacting with 5-hydroxytryptamine (serotonin)-2 receptors. These results also suggest that interactions between the serotonergic system and interleukin-1 may be important in regulating sleep-wake behavior. (C) 1999 IBRO. Published by Elsevier Science Ltd
AN IL-1 RECEPTOR AND AN IL-1 RECEPTOR ANTAGONIST ATTENUATE MURAMYL DIPEPTIDE- AND IL-1-INDUCED SLEEP AND FEVER
No full textIt is hypothesized that the somnogenic and pyrogenic effects of muramyl dipeptide (MDP) are mediated via enhanced interleukin-1 (IL-1) production. To test this hypothesis the effects of intracerebroventricular (icv) administration of a recombinant human soluble type I IL-1 receptor (sIL-1r) and of the IL-1 receptor antagonist (IL-1ra) on MDP-induced sleep and fever were evaluated in rabbits. The sIL-1r recognized rabbit IL-1beta, but it did not affect sleep or brain temperature across the dose range tested (1-50 mug) when injected icv into normal rabbits. Pretreatment of rabbits with 50 mug sIL-1r or 10 mug IL-1ra blocked human recombinant IL-1-enhanced non-rapid eye movement (NREM) sleep and fever. Thus both the sIL-1r and the IL-1ra were effective antagonists of IL-1 actions. When the animals were pretreated with either 50 mug sIL-1r or with 10 or 100 mug of the IL-1ra, the somnogenic effects of 150 pmol MDP were attenuated. However, the sIL-1r had little effect on MDP-induced febrile responses. These results suggest that the sIL-1r and the IL-1ra can function as antagonists of IL-1 actions in vivo and that MDP-induced sleep and fever are partially mediated by IL-1
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
5-hydroxytryptophan, but not L-tryptophan, alters sleep and brain temperature in rats
No full textThe precise role of serotonin (5-hydroxytryptamine) in the regulation of sleep is not fully understood. To further clarify this role for 5-hydroxytryptamine, the 5-hydroxytryptamine precursors L-tryptophan (40 and 80 mg/kg) and L-5-hydroxytryptophan (25-, 50-, 75-, 100 mg/kg) were injected intraperitoneally into freely behaving rats 15 min prior to dark onset, and subsequent effects on sleep-wake activity and cortical brain temperature were determined. L-5-hydroxytryptophan, but not L-tryptophan, induced dose-dependent changes in sleep-wake activity. During the 12-h dark period, non-rapid eye movement sleep was inhibited in post-injection hours 1-2 by the two lowest L-5-hydroxytryptophan doses tested, while the two highest doses induced a delayed increase in non-rapid eye movement sleep in post-injection hours 3-12. These highest doses inhibited non-rapid eye movement sleep during the subsequent 12-h light period. The finding that L-5-hydroxytryptophan, but not L-tryptophan, induced a dose-dependent and long-lasting decrease in cortical brain temperature regardless of whether or not non-rapid eye movement sleep was suppressed or enhanced contributes to a growing list of conditions showing that sleep-wake activity and thermoregulation, although normally tightly coupled, may be dissociated. The initial non-rapid eye movement sleep inhibition observed following low doses of L-5-hydroxytryptophan may be attributable to increased serotonergic activity since 5-hydroxytryptamine may promote wakefulness per se, whereas the delayed non-rapid eye movement sleep enhancement after higher doses may be due to the induction by 5-hydroxytryptamine of sleep-inducing factor(s), as previously hypothesized. The period of non-rapid eye movement sleep inhibition beginning 12 h after administration of L-5-hydroxytryptophan doses that increase non-rapid eye movement sleep is characteristic of physiological manipulations in which non-rapid eye movement sleep is enhanced. The results of the present study suggest that the complex effects of 5-HT on sleep depend on the degree and time course of activation of the serotonergic system such that 5-HT may directly inhibit sleep, yet induce a cascade of physiological processes that enhance subsequent sleep. (C) 1999 IBRO. Published by Elsevier Science Ltd
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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