1,720,967 research outputs found
A robust, state-of-the-art amperometric microbiosensor for glutamate detection
No full textScientific knowledge of glutamate (GLU) neurobiology is severely hampered by the inadequacy of the available in vivo brain sampling techniques. Due to the crucial role of GLU in central nervous system function and pathology, the development of a reliable sampling device is mandatory. GLU biosensor holds potential to address many of the known issues of in vivo GLU measurement. We report here on the development and test of a labor- and cost-effective micro biosensor, suitable to be applied for measuring brain GLU. A glycerol-based cryopreservation method was also tested. Needle type Pt biosensors were coated with a permselective Nafion-Poly(o-phenylenediamine) layer and cross-linked to L-glutamate oxidase with poly(ethylene glycol) diglycidyl ether. Tested in vitro, the device shows high sensitivity and specificity for GLU, while being poorly influenced by common interfering substances such as ascorbate, dopamine and dihydroxyphenylacetic acid. Further, the cryopreservation procedure kept sensitivity unaltered for 30 days and possibly longer. We conclude that a highly efficient GLU biosensor of minimal dimensions can be consistently and affordably constructed with relative ease. Together with the possibility of cryopreservation this shall foster diffusion and exploitation of GLU biosensors technology
Antioxidants, minerals, vitamins, and herbal remedies in tinnitus therapy
No full textThe use of complementary and alternative medicine (CAM) is very popular in western countries and several CAM products are often used by individuals with tinnitus with or without medical guidance. CAM pharmacological approach to tinnitus today is mainly based on vitamins and minerals (dietary supplements), antioxidants, and herbal medications. Despite the popularity of CAM products, the evidence regarding their efficacy against tinnitus is in general scarce and their potential toxic effects are often underestimated or even neglected. In this paper the available literature on the efficacy of dietary supplements, antioxidants, and herbal medications against tinnitus is reviewed, and some of the major potential toxic effects are discussed. It is concluded that the use of CAM products in tinnitus therapy in general lack substantial scientific support, and that these substances are probably not clinically effective either. However, it is difficult to draw clear-cut conclusions regarding CAM pharmacological approach to tinnitus. In fact, the subjective nature of tinnitus and the reported variability in patient's response to therapy indicate that several non-pharmacological factors may be influencing drug effects, with the placebo effect playing a major role. Nevertheless, in view of the potential harm that may occur from inappropriate use of CAM products, physicians need to be aware of their principal characteristics with particular emphasis on toxicity and possibilities of interaction with prescription drugs
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
ETHANOL, ACETALDEHYDE AND DOPAMINE NEURONS
No full textThere has been a great deal of activity in recent years in the study of the direct effects of ethanol on the dopamine reward system originating in the ventral tegmental area (VTA). In addition, recent evidence suggests that acetaldehyde formed in the brain or periphery may be a crucial factor in the central effects of ethanol. This paper examines the actions of ethanol and acetaldehyde on neurons of the ventral tegmental area in vivo and in vitro. Ethanol has specific effects on dopamine neurons and there is recent evidence that some of the in vivo and in vitro effects of ethanol are mediated by acetaldehyde. Taken together, the evidence suggests that acetaldehyde is essential in the activating effects of ethanol on dopamine VTA neurons. The link between acetaldehyde and ethanol actions on brain reward pathways may provide a new avenue for development of agents to reduce alcohol craving
Acetaldehyde sequestering prevents ethanol-induced stimulation of mesolimbic dopamine transmission
No full textEffect of L-cysteine on acetaldehyde self-administration.
No full textAcetaldehyde (ACD), the first metabolite of ethanol, has been implicated in several behavioural actions of alcohol, including its reinforcing effects. Recently, we reported that L-cysteine, a sequestrating agent of ACD, reduced oral ethanol self-administration and that ACD was orally self-administered. This study examined the effects of L-cysteine pre-treatment during the acquisition and maintenance phases of ACD (0.2%) self-administration as well as on the deprivation effect after ACD extinction and on a progressive ratio (PR) schedule of reinforcement. In a separate PR schedule of reinforcement, the effect of L-cysteine was assessed on the break-point produced by ethanol (10%). Furthermore, we tested the effect of L-cysteine on saccharin (0.2%) reinforcement. Wistar rats were trained to self-administer ACD by nose poking on a fixed ratio (FR1) schedule in 30-min daily sessions. Responses on an active nose-poke caused delivery of ACD solution, whereas responses on an inactive nose-poke had no consequences. L-cysteine reduced the acquisition (40 mg/kg), the maintenance and the deprivation effect (100 mg/kg) of ACD self-administration. Furthermore, at the same dose, L-cysteine (120 mg/kg) decreased both ACD and ethanol break point. In addition, L-cysteine was unable to suppress the different responses for saccharin, suggesting that its effect did not relate to an unspecific decrease in a general motivational state. Compared to saline, L-cysteine did not modify responses on inactive nose-pokes, suggesting an absence of a nonspecific behavioural activation. Taken together, these results could support the hypotheses that ACD possesses reinforcing properties and L-cysteine reduces motivation to self-administer ACD
“Are the hedonistic properties of oral ethanol mediated by acetaldehyde? In vivo microdialysis study in the rat”
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