1,721,008 research outputs found
Histamine H3 and H4 receptors are expressed on distinct endocrine cell types in the rat fundic mucosa
No full textThe present study was designed to explore the expression and distribution of histamine H3 and H4
receptors within the rat gastric fundus by immunohistochemistry using our unique immunological
probes. Groups of rats were either fed ad libitum or fasted for 24h before the sacrifice. Tissue
samples from the fundic region of the stomach were removed, fixed and processed for
immunohistochemistry, using our validated anti-H3 (349-358) and anti–H4 (374-390) antibodies.
The results showed that cells immunoreactive for H3R and H4R are located in the fundic epithelium.
The vast majority of H3R immunopositive cells occupied the lower half of the glands, and were
absent in the superficial portion. Their number per gland was 5.38 ± 0.19 in freely fed rats and 3.21
± 0.40 in fasted rats. Conversely, cells immunoreactive for H4R were dispersed throughout the
glands. Their number per gland was 0.75 ± 0.03 in fed rats and 0.90 ± 0.05 in fasted rats. Double
immunostaining revealed that the H3R is not colocalized with the H4R, while both H3R and H4R
positive cells were immunoreactive for chromogranin A, suggesting that these immunopositive cells
are endocrine cells. Because five different endocrine cell types have been identified in the rat fundic
epithelium, we used double immunostaining to identify the cell types expressing H3R and H4R,
respectively. Approximately 90% of cells positive for H3R were also immunoreactive for histidine
decarboxylase, demonstrating that the H3R is located on ECL cells. Cells positive for H4R were
immunoreactive for ghrelin, originating from A-like cells.
These findings may imply that histamine, via a balanced interaction with H3R and H4R expressed
on ECL and A-like cells respectively, regulates not only acid secretion and mucosal protection but
could also have a role in feeding behaviour and growth hormone release
Immunolocalization of histamine H3 receptors on endocrine cells in the rat gastrointestinal tract
No full textThe histamine H3 receptor (H3R) has been identified in the gastrointestinal tract of the rat by immunohistochemistry, using the first validated anti-H3 receptor antibody. Immunoreactivity to H3R was exclusively localized to the endocrine cells scattered in the gastrointestinal mucosa, with positive cells being prominently abundant in the gastric fundus, while they were rarely found in the other regions. In the fundus, positive cells were distributed in the lower half of the mucosa and their number significantly decreased after a 24 h-fasting period. Double-labeling studies were undertaken to identify the H3R-immunoreactive cell types in the fundic and antral mucosa. The H3R-immunoreactive cells were positive for chromogranin A. In the fundus, approximately 90% of cells positive to H3R were also positive to the histamine-forming enzyme, histidine decarboxylase. None of the cells expressing H3R displayed immunoreactivity for gastrin, somatostatin or ghrelin. Location, the influence of food deprivation and colocalization with histidine decarboxylase indicate that H3R positive cells correspond to the enterochromaffin-like cells (ECL)
Influence of (R)-alpha-Methylhistamine on the histamine H3 receptor in the rat gastrointestinal tract
No full text
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
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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