1,720,968 research outputs found
A Novel Precursor Ion Discovery Method on a Q-TOF Mass Spectrometer for GnRH Detection in Complex Biological Mixtures
No full textD-aspartate modulates transcriptional activity in Harderian gland of frog, Rana esculenta: Morphological and molecular evidence
No full textIn the green frog, Rana esculenta, a substantial amount Of D-aspartate (D-Asp) is found enclogenously within the Harderian gland (HG) following its synthesis from (L)-aspartate ((L)-Asp) by an aspartate racemase. The frog HG is an orbital seromucoid gland that displays seasonal changes in secretory activity. Our in vivo experiments, consisting of i.p. injection of 2.0 mu mol/g.b.w. (D)-Asp in frogs collected during two periods of differing glandular activity (high or medium-low secretory activity), revealed that HG can to take up and accumulate D-Asp and that this amino acid may modulate the exocrine secretion through a kinase pathway. Atatirnewhenthe gland shows relatively low secretory activity, i.p. administration of (D)-Asp rapidly induced activation of ERK1 and an increase in cells active in RNA synthesis. This increase in transcriptional activity was followed by a significant increase in Mucous secretion. By contrast, administration of exogenous (D)-Asp when HG was showing high activity rapidly induced inhibition of both ERK1 and transcriptional activity. Since D-Asp is known to be recognized by receptors for N-methyl-(D)-aspartic acid (NMDA), it is possible that in the HG, D-Asp mediated NMDA activation may enhance the kinase pathway. The above activation of opposing stimulatory and inhibitory processes could reflect different levels of NMDA-receptor activity, which could vary as a function of the level of gland activity. This study provides the first evidence of a role for this excitatory amino acid in exocrine secretion. The effects of (D)-Asp in HG appear to be specific since they were not seen in frogs treated with other (D)- or (L)-amino acids with known excitatory effects on neurosecretion. (c) 2005 Wiley-Liss, Inc
Occurrence of D-aspartate in the Harderian gland of Podarcis s. sicula and its effect on gland secretion
No full textHigh concentrations of free D-aspartate (D-Asp), an amino acid well known for its neuroexcitatory activity, are endogeneously present in the Harderian gland (HG) of the lizard Podarcis s. sicula. This orbital gland consists of two different parts: the medial part, which is prevalently a mucous acinar gland, and the lateral part, which is a serous tubulo-acinar gland. To determine the physiological effect of D-Asp on exocrine secretion in HG, D-Asp (2.0 μmol/g b.w.) was injected intraperitoneally into lizards. We found that highest accumulations of exogenous D-Asp in HGs occurred 15 hr after the injection. Specifically, exogenous D-Asp prevalently stimulated serous secretion from the lateral portion of the gland, where immunohistochemical analysis revealed a major accumulation. Similarly, in the medial part of the gland, highly sulfated mucosubstances were observed after D-Asp injection. Further, in both parts of the HG, the electron microscope revealed euchromatic nuclei, a prominent rough endoplasmic reticulum, as well as numerous secretory granules within the acinar cells. Thus, following D-Asp injection, a 60% increase in HG total protein was detected. In addition, exogenous D-Asp induced changes in the electrophoretic pattern of HG. In conclusion, although further investigations are still needed to clarify the molecular pathway induced by D-Asp in exocrine secretion, this study does indicate that free D-Asp plays a significant role in the secretory activity of this gland. © 2006 Wiley-Liss, Inc
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
D-Aspartate binding sites in rat Harderian gland
No full textRadioligand binding of d-[3H]aspartic and l-[ 3H]glutamic acids to plasma membranes from rat Harderian gland was evaluated. Binding was optimal under physiological conditions of pH and temperature, and equilibrium was reached within 50 min. Specific binding for d-Asp and l-Glu was saturable, and Eadie-Hofstee analysis revealed interaction with a single population of binding sites (for d-Asp K d = 860 ± 28 nM, B max = 27.2 ± 0.5 pmol/mg protein; for l-Glu, K d = 580 ± 15 nM and B max = 51.3 ± 0.8 pmol/mg protein). l-[3H]glutamate had higher affinity and a greater percentage of specific binding than did d-[3H]aspartate. The pharmacological binding specificity of l-[3H]glutamate indicated an interaction with NMDA-type receptors. Specifically, the order of potency of the displacing compound tested was l-Glu > d-Asp > NMDA > MK801 > d-AP5 > glycine. For d-[3H]aspartate, the data revealed an interaction of d-Asp with either NMDA-type receptors or putative specific binding sites. © 2009 Springer-Verlag
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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