1,721,022 research outputs found
Rubidium shows effects different from lithium on phosphatidylinositol metabolism in a cell line of human neuroblastoma
No full text[No abstract available
HIV coating gp 120 glycoprotein-dependent prostaglandin E2 release by human cultured astrocytoma cells is regulated by nitric oxide formation
No full textCentral cardiovascular effects of clonidine and another imidazoline derivative ST [600] in adult fowls
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Nitric oxide inhibition aggravates ischemic damage of hippocampal but not of NADPH neurons in gerbils
No full textBackground and Purpose Nitric oxide may influence pathophysiology of brain ischemia in a complex way depending on the sources of its production either from neurons or endothelial cells. We investigated whether inhibition of nitric oxide synthesis affects postischemic neuronal death in hippocampus. Moreover, we evaluated whether the presence of nitric oxide synthase activity in specific neurons protects these against ischemia in the hippocampus, striatum, and sensorimotor cortex. Methods To inhibit nitric oxide synthase, several dosing regimens of N-G-nitro-L-arginine methyl ester (L-NAME) were used (5 or 50 mg/kg IP, twice a day for 4 days, or 30 mg/kg IV) in gerbils. Control animals received either the isomer N-G-nitro-D-arginine methyl ester or the vehicle. The gerbils underwent 10-minute occlusion of carotid arteries under ether anesthesia and controlled body temperature while physiological parameters were monitored. Neuronal damage was assessed 5 days after ischemia using Nissl-stained sections of hippocampus. Nitric oxide synthase neurons were histochemically stained for reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase activity. Results L-NAME treatments, but not the chronic one at 5 mg/kg, induced elevation of blood pressure (30% to 80% greater than the control level, P<.01), as observed shortly before and after bilateral carotid occlusion. Postischemic neuronal loss in the CA1 through CA4 sectors was worsened by chronic pretreatment with L-NAME at 50 mg/kg leg, CA1 neuronal counts per 100-mu m length: 3.2+/-2.74, mean+/-SD; n=19; P<.01). After the acute (30 mg/kg) or chronic pretreatment at lower dosage (5 mg/kg) with L-NAME, neuronal loss was comparable to that of animals treated with the D-isomer or the vehicle (CA1 counts in vehicle-treated animals: 7.65+/-6.51, mean+/-SD; n=14). None of the L-NAME treatments affected postischemic survival of NADPH diaphorase-positive neurons in hippocampus, striatum, and sensorimotor cortex. Conclusions These observations demonstrate that inhibition of endothelial and neuronal nitric oxide synthase activity does not modify resistance of nitric oxide-producing neurons to transient ischemia. The severe inhibition of nitric oxide production aggravates postischemic neuronal death in the hippocampus, whereas the mild inhibition is ineffective
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
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