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Using image analysis on the ventral colour pattern in Salamandrina perspicillata (Amphibia: Salamandridae) to discriminate among populations
No full textThe ventral colour pattern in Salamandrina perspicillata is characteristic of each individual and remains invariant throughout the salamanders' life. The present study aimed to determine, using statistical methods applied to quantitative image analysis, whether the coloration pattern is population-specific. The images of ventral colour pattern of 180 salamanders belonging to five populations were analysed. The images were previously warped by geometric morphometry. To our knowledge, this is the first study to use an approach based on geometric morphometrics to standardize ventral shapes. This technique is useful for eliminating form distortions. The results of an analysis of similarities recognized more coloration similarity among individuals of the same population than among individuals from different populations. Analysis by partial least squares correctly classified the 88.88% of individuals into the correct population. The similarities or differences among individuals of different populations are not related to the geographical distances. The results obtained showed that the coloration of the ventral side of the head of the salamanders can be used for discriminating among populations. (C) 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 35-43
Vagus nerve stimulation induces cell proliferation and changes in neuronal morphology in the rat hippocampus
No full textPurpose of study: Vagus nerve stimulation (VNS) is used to treat pharmacotherapy-resistant epilepsy. Observations of mood elevation during VNS therapy for epilepsy suggested that such treatment might also show efficacy for refractory major depression. The molecular mechanism(s) underlying its therapeutic action remains unclear, however. By using a rat model of VNS we previously showed that acute VNS increases the gene expression of growth factors in the rat brain as well as the release of norepinephrine. We have now examined the effects of chronic VNS on hippocampal cell proliferation as well as on the expression of DCX and BDNF in rat brain and whether such effects might be associated with behavioral changes similar to those induced by chronic antidepressant drugs.
Methods: Male Sprague-Dawley rats were used and a VNS therapy stimulator (Cyberonics, Houston, TX) was implanted. Cell proliferation in the hippocampus of rats subjected to acute (3h) or chronic (1 month) VNS was examined by injection of bromodeoxyuridine (BrdU) and immunohistochemistry. Expression of doublecortin (DCX) and brain-derived neurotrophic factor (BDNF) was evaluated by immunofluorescence staining. Behavioral effects were studied in the forced swim and elevated plus- maze tests.
Results: Acute VNS induced an increase in the number of BrdU+ cells in the dentate gyrus that was apparent 24 h (2200±159; P < 0.05) and 3 weeks (2448±129; P < 0.01) after treatment compared with that apparent in sham-operated controls (1760±74). It also induced long- lasting increases in the amount of DCX immunoreactivity (+39%; P < 0.05) and in the number of DCX+ neurons (+57%; P<0.01). Neither the number of BrdU+ cells nor the amount of DCX immunoreactivity was increased 3 weeks after the cessation of chronic VNS. Moreover, VNS induced long-lasting increases in the amount of BDNF immunoreactivity and the number of BDNF+ cells (+104% and +40% respectively; P < 0.001). VNS also affected the dendritic complexity of DCX+ neurons in the hippocampus. Nevertheless, in contrast to chronic imipramine, chronic VNS had no effect on the behavior ofratsintheforcedswimorelevatedplus-mazetests.
Conclusions: In the hippocampus VNS induced cell proliferation and persistent changes in morphology ofDCX+ neurons. These effects were accompanied by a robust increase in the expression of BDNF, which may play an important role in consolidating the changes in neuronal connections as suggested by the increased complexity of the dendritic arborization. Thus, some of the effects of chronic VNS appear to be similar to those induced by chronic treatment with antidepressant drugs but do not correlate with corresponding behavioral changes. Although further clinical and experimental studies are necessary to better understand the mechanisms of VNS, our results show that the promotion of neurogenesis and the expression of growth factors are rapidly induced by VNS differently from antidepressant. Whether such early newly generated neurons contribute to existing or de novo networks that might mediate antiepileptic or antidepressant effects remains to be determined
Vagus nerve stimulation induces cells proliferation and changes in neuronal morphology in the rat hippocampus
No full textEFFECTS OF WITHDRAWAL OF LOW ETHANOL CONCENTRATIONS ON GABA(A) RECEPTOR GENE EXPRESSION IN RAT CEREBELLAR GRANULE NEURONS IN CULTURE
No full textOne of the most likely targets of ethanol (EtOH) in the central nervous system (CNS) is the GABAA receptor (GABAAR). While the effects of EtOH have been the subject of study on most common CNS GABAAR composition, many other subunit combinations have only recently been tested for their EtOH responses. The a4b2d GABAARs are very sensitive to alcohol, with a concentration of 1 mM EtOH signifcantly enhancing GABAergic currents. Moreover, a6 and a4, when combined with b3 and d-containing subunits were associated with EtOH enhancement of function. Nevertheless, other studies were not able to obtain functional effects of low (1–30 mM) concentrations of EtOH. A plethora of studies both ‘‘in vivo’’ and ‘‘in vitro’’ show that chronic EtOH and EtOH withdrawal, can modify the gene expression of the GABAAR, but in these studies large concentrations of EtOH (50–200 mM) were used. A key question is whether GABAAR gene expression can be altered also by lower concentrations (e.g., 1–50 mM) of EtOH. In order to address this question we here used rat cerebellar granule cells in culture chronically treated with EtOH (1–100 mM). We then measured the GABAAR gene expression by RNase protection assay in two experimental conditions: After chronic EtOH (5 days) or its withdrawal (3 hours). Our results demonstrated that the only subunit affected by chronic EtOH treatment was the c2, the mRNA of which resulted decreased ()20%; p < 0.01) only at concentrations of 50 mM or higher. Neither low nor high concentrations of EtOH were able to change the gene expression of the other subunits of the GABAAR (a1, a4, a6 and d). On the contrary, EtOH withdrawal at the lowest concentration
(1 mM) significantly decreased the abundance of the a1, a6 and d subunits ()36; )26 and )16% respectively; p < 0.05), but did not change the a4 subunit mRNA abundance. Similar results were observed using 10 mM EtOH for a1, a6 and d subunits ()37; )38 and 22% respectively; p < 0.05). The a4 subunit was up-regulated only by withdrawal of 100 mM EtOH (+31%; p < 0.01). This is the first report showing that low concentrations of EtOH, such as
1 mM, can modify GABAAR gene expression. These effects were subunit specific and more evident after withdrawal, suggesting that even such low EtOH concentrations when removed may disrupt neuronal excitability controlled by GABAAR; nevertheless, the key question of whether specific GABAAR subunits are more selectively sensitive to low EtOH remains still unanswered
Effects of withdrawal of low ethanol concentrations on GABAA receptor gene expression in rat cerebellar granule neurons in colture
No full textVoluntary ethanol consumption alters hippocampal GABAA receptor gene expression in C57BL/6J mice
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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
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