1,721,099 research outputs found
Sistemi ceramici innovativi per aumentare le caratteristiche superficiali del gres porcellanato. Parte I
No full textL'articolo riprende ed esamina a fondo I'aspetto delta macchiabilità delle superfici di gres porcellanato levigato individuando una soluzione interessante.I ricercatori dell'Universita di Modena hanno messo a punto una composizione ceramica che, applicata in strato sottile sopra ad una base di impasto di gres porcellanato, riesce a dare una superficie compatta difficilmente macchiabile
THE SEROTONIN TRANSPORTER KNOCKOUT RAT: MODELLING DEPRESSION FROM ETIOLOGY TO PHARMACOLOGICAL TREATMENT
Full text linkMajor depression is a complex disorder characterized by the interaction of genetic, biological, social and environmental factors, which play in concert to determine the development of the disease. The serotonin transporter gene is of particular relevance in the context of mood disorders because it is the target of several antidepressant drugs and, due to the presence of a functional polymorphism within its promoter region, it has been associated with different neuropsychiatric disorders (Caspi et al., 2003; Uher and McGuffin, 2008). Since the molecular mechanisms contributing to depression pathophysiology are still poorly understood, several genetic or environmental animal models of depression have been developed in order to reproduce the depressive phenotype and to characterize the molecular alterations of the disease. Among these, rodents (mice or rats) with a total deletion of the serotonin transporter represent a good model of anxiety and depression phenotypes and they have been extensively characterized at behavioral level (Holmes et al., 2003; Lira et al., 2003; Olivier et al., 2008), although a detailed analyses of the molecular phenotype associated with genetic alterations of SERT is still lacking. In particular, limited information exists on potential changes in neuronal plasticity, which is strongly associated with depression. Indeed it has been proposed that psychopathology may be associated with reduced expression and function of key mediators of neuronal plasticity, such as the neurotrophin brain-derived neurotrophic factor (BDNF), (McClung and Nestler, 2008; Pittenger and Duman, 2008).
Given all these premises, in this study, we investigated the expression of BDNF in different brain regions of adult SERT mutant rats (+/− and −/−). Moreover, since the neurotrophin has a complex genomic structure (Aid et al., 2007), we have investigated the influence of SERT deletion on its different transcripts and evaluated the involvement of several transcription factors in BDNF expression changes found in SERT mutant animals.
Moreover, considering that the depressive phenotype of SERT mutant animals appears to originate from the lack of the transporter during early life (Ansorge et al., 2004; Ansorge et al., 2008), we also assessed when the neuroplastic alteration of SERT-/- animals are established, by investigating the expression of BDNF in SERT knockout rats during postnatal development.
One system lying downstream from Npas4 and BDNF that may be relevant for the phenotype of SERT mutants is GABA. Indeed, Npas4 regulates the development of GABAergic synapses (Lin et al., 2008), while BDNF alteration can affect GABAergic cellular architecture and transmission (Sakata et al., 2009). Therefore we also established if SERT mutant rats are characterized by alterations in the expression of key GABAergic markers that may eventually contribute to the depressive phenotype of these animals.
A further aspect of the experimental work is aimed at addressing the issue of gene * environment interaction in mood disorders. Indeed, stressful experiences can exacerbate or precipitate depressive disorder in genetically-prone individuals (Caspi et al., 2003). In particular adverse events early in life may impact on brain structures that are not completely matured resulting critical for the development of psychopathology later in life. In order to establish if the molecular phenotype associated with deletion of SERT gene could be modulated by early life events, we exposed SERT mutant rats (+/− and −/−) to maternal deprivation, a strong form of stress, and we assessed the expression of the neurotrophin BDNF as marker of neuronal plasticity.
Last we investigated if pharmacological intervention in SERT mutant rats may restore neuroplastic defects associated with the vulnerable genotype. Therefore we chronically treated SERT knockout rats with the antidepressant duloxetine (a SNRI, dual blocker of the reuptake of the serotonin and norepinephrine) and we assessed its ability to normalize the expression of different neuroplastic genes that are significantly altered in mutant rats. We demosntarted that animals carrying a deletion of the SERT gene show a reduction of BDNF expression, which may contribute to their pathologic phenotype. This impairment originates early in development and is associated with reduction of transcription factors and GABAergic markers, suggesting that these defects may contribute to behavioral phenotype associated with SERT-/-, and in particular those that are relevant for anxiety and depression. Moreover these animals maintain the ability to show neuroplastic changes in response to antidepressant drugs, possibly via the blockade of the noradrenaline transporter. The molecular characterization of the SERT mutant rat may prove useful to elucidate the pathophysiology of the depressive disorder and may eventually lead to the development of new effective treatments
Analysis of concatenated Reed-Solomon encoding schemes with full and partial interleaving for short data messages
No full textA concatenation of Reed-Solomon and repetition codes with symbol interleaving is considered for applications in which the message length is limited and the probability of incorrect received symbols is high. An analysis is developed with reference to a Packet Radio Network, using Spread Spectrum modulation, simultaneously affected by random errors and burst errors. The results obtained are compared with those derived by numerical simulation. It is shown that a canonical formulation can be used for the case of full interleavers, but it cannot be applied to encoding schemes with partial interleavers. In the latter situation a modified, improved, approach is proposed
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
Reconstitution and characterization of two forms of cyclic nucleotide-gated channels from skeletal muscle
No full textA cyclic nucleotide-gated channel present in skeletal muscle plasma membrane has previously been identified as being responsible for insulin-activated sodium entry into muscle cells (J. E. M. McGeoch and G. Guidotti. J. Biol. Chem. 267:832-841, 1992). We have isolated this channel activity to further study and characterize it. The channel was solubilized from rabbit skeletal muscle sarcolemma and functionally reconstituted into phospholipid vesicles, as assayed by patch-clamp analysis of the reconstituted proteins. Channel activity was isolated by 8-bromo-guanosine 3',5'-cyclic monophosphate affinity chromatography, producing two distinct peaks of cyclic nucleotide-gated channel activity. These two types of channel activity differ in guanosine 3',5'-cyclic monophosphate affinity and in the ability to be opened by adenosine 3',5'-cyclic monophosphate. The cyclic nucleotide-gated channel from rod outer segments also forms two peaks of activity when purified in this manner. The presence of two forms of channel activity could have implications for the mechanism of insulin-activated sodium entry.</jats:p
Effect of transversal aspect ratio on natural convection inside an inclined channel with an uniformly heated bottom wall
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