1,721,146 research outputs found
Glucagon-like peptide-2 modulates neurally evoked mucosal chloride secretion in guinea pig small intestine in vitro
Get PDFGlucagon-like peptide-2 (GLP-2) is
an important neuroendocrine peptide in intestinal physiology. It influences
digestion, absorption, epithelial growth, motility, and blood
flow. We studied involvement of GLP-2 in intestinal mucosal secretory
behavior. Submucosal-mucosal preparations from guinea pig
ileum were mounted in Ussing chambers for measurement of shortcircuit
current (Isc) as a surrogate for chloride secretion. GLP-2 action
on neuronal release of acetylcholine was determined with ELISA.
Enteric neuronal expression of the GLP-2 receptor (GLP-2R) was
studied with immunohistochemical methods. Application of GLP-2
(0.1–100 nM) to the serosal or mucosal side of the preparations
evoked no change in baseline Isc and did not alter transepithelial ionic
conductance. Transmural electrical field stimulation (EFS) evoked
characteristic biphasic increases in Isc, with an initially rapid rising
phase followed by a sustained phase. Application of GLP-2 reduced
the EFS-evoked biphasic responses in a concentration-dependent
manner. The GLP-2R antagonist GLP-2-(3-33) significantly reversed
suppression of the EFS-evoked responses by GLP-2. Tetrodotoxin,
scopolamine, and hexamethonium, but not vasoactive intestinal peptide
type 1 receptor (VPAC1) antagonist abolished or reduced to near
zero the EFS-evoked responses. GLP-2 suppressed EFS-evoked acetylcholine
release as measured by ELISA. Pretreatment with GLP-2-
(3-33) offset this action of GLP-2. In the submucosal plexus, GLP-2R
immunoreactivity (-IR) was expressed in choline acetyltransferase-IR
neurons, somatostatin-IR neurons, neuropeptide Y-IR neurons, and
vasoactive intestinal peptide-IR neurons. We conclude that submucosal
neurons in the guinea pig ileum express GLP-2R. Activation of
GLP-2R decreases neuronally evoked epithelial chloride secretion by
suppressing acetylcholine release from secretomotor neurons
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Glucagon-Like Peptide-1 Modulates Neurally-Evoked Mucosal Chloride Secretion in Guinea Pig Small Intestine In Vitro.
Get PDFGlucagon-like peptide-1 (GLP-1)
acts at the G protein-coupled receptor, GLP-1R, to stimulate secretion
of insulin and to inhibit secretion of glucagon and gastric acid.
Involvement in mucosal secretory physiology has received negligible
attention. We aimed to study involvement of GLP-1 in mucosal
chloride secretion in the small intestine. Ussing chamber methods, in
concert with transmural electrical field stimulation (EFS), were used
to study actions on neurogenic chloride secretion. ELISA was used to
study GLP-1R effects on neural release of acetylcholine (ACh).
Intramural localization of GLP-1R was assessed with immunohistochemistry.
Application of GLP-1 to serosal or mucosal sides of
flat-sheet preparations in Ussing chambers did not change baseline
short-circuit current (Isc), which served as a marker for chloride
secretion. Transmural EFS evoked neurally mediated biphasic increases
in Isc that had an initial spike-like rising phase followed by a
sustained plateau-like phase. Blockade of the EFS-evoked responses
by tetrodotoxin indicated that the responses were neurally mediated.
Application of GLP-1 reduced the EFS-evoked biphasic responses in
a concentration-dependent manner. The GLP-1 receptor antagonist
exendin-(9 –39) suppressed this action of GLP-1. The GLP-1 inhibitory
action on EFS-evoked responses persisted in the presence of
nicotinic or vasoactive intestinal peptide receptor antagonists but not
in the presence of a muscarinic receptor antagonist. GLP-1 significantly
reduced EFS-evoked ACh release. In the submucosal plexus,
GLP-1R immunoreactivity (IR) was expressed by choline acetyltransferase-
IR neurons, neuropeptide Y-IR neurons, somatostatin-IR neurons,
and vasoactive intestinal peptide-IR neurons. Our results suggest
that GLP-1R is expressed in guinea pig submucosal neurons and that
its activation leads to a decrease in neurally evoked chloride secretion
by suppressing release of ACh at neuroepithelial junctions in the
enteric neural networks that control secretomotor functions
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Mast Cell Proteases Stimulate Neurogenic and Non-Neurogenic Mucosal Chloride Secretion in Guinea Pig Distal Ileum.
No full textDispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Activation of the Glucagon-Like Peptide-2 Receptor Inhibits Neurally-Evoked Mucosal Chloride Secretion in the Guinea Pig Ileum In Vitro.
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