1,721,002 research outputs found
Purkinje cell compartmentation in the cerebellum of the lysosomal Acid phosphatase 2 mutant mouse (nax - naked-ataxia mutant mouse).
No full textThe Acp2 gene encodes the beta subunit of lysosomal acid phosphatase, which is an isoenzyme that hydrolyzes orthophosphoric monoesters. In mice, a spontaneous mutation in Acp2 results in severe cerebellar defects. These include a reduced size, abnormal lobulation, and an apparent anterior cerebellar disorder with an absent or hypoplastic vermis. Based on differential gene expression in the cerebellum, the mouse cerebellar cortex can normally be compartmentalized anteroposteriorly into four transverse zones and mediolaterally into parasagittal stripes. In this study, immunohistochemistry was performed using various Purkinje cell compartmentation markers to examine their expression patterns in the Acp2 mutant. Despite the abnormal lobulation and anterior cerebellar defects, zebrin II and PLCβ4 showed similar expression patterns in the nax mutant and wild type cerebellum. However, fewer stripes were found in the anterior zone of the nax mutant, which could be due to a lack of Purkinje cells or altered expression of the stripe markers. HSP25 expression was uniform in the central zone of the nax mutant cerebellum at around postnatal day (P) 18-19, suggesting that HSP25 immunonegative Purkinje cells are absent or delayed in stripe pattern expression compared to the wild type. HSP25 expression became heterogeneous around P22-23, with twice the number of parasagittal stripes in the nax mutant compared to the wild type. Aside from reduced size and cortical disorganization, both the posterior zone and nodular zone in the nax mutant appeared less abnormal than the rest of the cerebellum. From these results, it is evident that the anterior zone of the nax mutant cerebellum is the most severely affected, and this extends beyond the primary fissure into the rostral central zone/vermis. This suggests that ACP2 has critical roles in the development of the anterior cerebellum and it may regulate anterior and central zone compartmentation
INSL5 is a novel marker for human enteroendocrine cells of the large intestine and neuroendocrine tumours
No full textWe report for the first time the distribution of human INSL5 and its cognate leucine rich G-protein coupled receptor RXFP4 in the large intestine and in neuroendocrine/carcinoid tissues. Immunoreactive INSL5 was uniquely expressed by enteroendocrine cells (EECs) located within the colonic mucosa, whereas colonocytes were immunopositive for RXFP4. INSL5(+) and RXFP4(+) cells were also detected in human neuroendocrine/carcinoid tissues. We employed a recently described Insl5 knockout mouse model and 2 mouse models of induced colitis to address the relevance of Insl5 in EEC development and in acute inflammation of the colon. We identified INSL5 as a specific marker for synaptophysin(+) EECs in the mucosa of the normal human and mouse colon. Insl5 was not essential for the development of mouse synaptophysin(+) EECs. The mouse models of chemically induced colitis (dextran sulfate sodium and dinitrobenzene-sulfonic acid) failed to show changes in the numbers of Insl5(+) EECs at inflammatory sites during the acute phase of colitis. In conclusion, we showed that INSL5 is a novel marker of colorectal EECs and provide first evidence for the presence of a potentially autocrine/paracrine INSL5-RXFP4 signaling system in the normal human and mouse colon and in rare human neuroendocrine tumours
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
Brain pericyte calcium signaling during vasomotion and neurovascular coupling in murine models.
No full textPericytes, which are mural cells located on the external surface of blood vessels in the brain, play a role in various processes such as vasomotion and neurovascular coupling (NVC), which control the flow of blood to the brain. These cells possess contractile abilities, but recent research has identified different types of pericytes with varying morphology and protein expression, leading to a debate regarding their functional roles in regulating cerebral blood flow (CBF).
The objective of this study is to examine the impact of different pericyte types on vasomotion and NVC by investigating specific calcium channels that could generate intracellular calcium events and influence their capacity to constrict or dilate. By utilizing in vivo two-photon microscopy, we assessed the calcium signaling of distinct pericyte populations—ensheathing pericytes (EP) and capillary pericytes (CP)—in transgenic mice expressing genetically encoded calcium indicators (RCaMP1.07 and GCaMP6s). Concurrently, we measured the hemodynamic properties of nearby blood vessels. We also studied the effects of calcium channel blockers, namely nimodipine and Pyr3, on pericyte calcium signals and vessel hemodynamics.
Our findings revealed differential impacts of specific calcium pathways in brain pericytes on local hemodynamic behavior. Nimodipine and Pyr3 reduced calcium activity in both pericyte types, and this reduction was different in distinct pericyte sub-cellular compartments (somata vs. processes). Nimodipine increased the diameter of vessels covered by EP, reduced their CBF and diminished the response to NVC. Likewise, nimodipine reduced CBF and NVC response of blood vessels covered by CP. Interestingly, Pyr3 caused vasodilation in both EP and CP, and it solely decreased the response to NVC in EP.
Our data provide fresh insights into the mechanisms of calcium signaling in brain pericytes, shedding light on the role of these cells in regulating CBF. This knowledge holds potential for advancing our understanding of cerebrovascular and neurodegenerative diseases, where the full understanding of their development is yet to be determined.Brain Canada, Azreili Foundation, Research Manitoba, Mitacs Globalink Research.October 202
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