1,720,980 research outputs found
Both the neuronal and inducible isoforms contribute to upregulation of retinal nitric oxide synthase activity by brain-derived neurotrophic factor
No full textAlthough neurotrophins are best known for their trophic functions, growing evidence suggests that neurotrophins can also be neurotoxic, for instance by enhancing excitotoxic insults. We have shown recently that brain-derived neurotrophic factor (BDNF) limits its neuroprotective action on axotomized rat retinal ganglion cells (RGCs) by upregulating nitric oxide synthase (NOS) activity (Klocker et al., 1998). The aim of the present study was to investigate this interaction of BDNF and NOS in the lesioned adult rat retina in more detail. We used NOS immunohistochemistry and NADPH-diaphorase (NADPH-d) reaction to characterize morphologically retinal NOS expression and activity. Using reverse transcription-PCR and Western blot analysis, we were able to identify the NOS isoforms being regulated. Six days after optic nerve lesion, we observed an increase in neuronal NOS (NOS-I) mRNA and protein expression in the inner retina. This did not lead to a marked increase in overall retinal NOS activity. Only RGC axons displayed strong de novo NADPH-d reactivity. In contrast, intraocular injection of BDNF resulted in a marked upregulation of NOS activity in NOS-I-immunoreactive structures, leaving the level of NOS-I expression unchanged. In addition, an induction of inducible NOS (NOS-II) was found after BDNF treatment. We identified microglial cells increasing in number and being activated by BDNF, which could serve as the cellular source of NOS-II. In summary, our data suggest that BDNF upregulates retinal NOS activity by both a post-translational regulation of NOS-I activity and an induction of NOS-II. These findings might be useful for developing pharmacological strategies to improve BDNF-mediated neuroprotection
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
Expression of neurotrophins and neurotrophin receptors in the cerebellum of mutant weaver and lurcher mice
No full textTo test the hypothesis whether a failure to express neurotrophins or a neurotrophin receptor might underlie the pathology observed in mutant mice with degeneration of regionally distinct subpopulations of neurons, the expression of BDNF, NT-3, TrkB, TrkC and synaptophysin mRNA. was examined in the cerebellum of mutant lurcher (lc/+) and weaver (wv/+)/(wv/wv) mice. To identify the expression patterns of individual neurons, we used in situ hybridization with digoxigenin labeled ribonucleotide probes. RT-PCR of cerebellar mRNA for BDNF, NT-3, TrkB and TrkC (GAPDH as internal standard) was performed in parallel. Although especially in homozygous (wv/wv) weaver mice the normal anatomical order and number of the cerebellar neurons is grossly disturbed, residual Purkinje and granule neurons of both mutants displayed a normal expression pattern of the neurotrophins examined. Thus, the affected animals showed no significant signal decrease compared to healthy littermates or C3H mice. Our results suggest that the loss of specific neuron populations in the cerebellum of either mutant occurs via mechanisms either independent or downstream of the neurotrophins examined in this study. (C) 1998 Elsevier Science B.V. All rights reserved
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
STUDY OF THE LIHG EXCIMER - BLUE-GREEN BANDS
No full textWe report for the first time the production of the LiHg excimer by a photochemical reaction of excited Li-2 molecules with Hg(6s(2 1)S(0)) Excitation energy was provided by a cw ultraviolet (UV)-argon ion laser operating in single-line and in multi-line mode or by pulsed XeCl excimer laser at 3080 Angstrom. We observed bound-free emission of LiHg in the form of diffuse bands peaking at 4450 and at 4670 Angstrom. The latter was structured by bound-bound emission lines. Relativistic ab initio calculations for the potential energy curves of LiHg and for the relevant dipole transition moments were performed. Using these results, an interpretation of the observed emission is presented
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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