1,720,967 research outputs found
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
Failure of acute ethanol administration to alter cerebral cortical and hippocampal allopregnanolone levels in C57BL/6J and DBA/2J mice
No full textAcute ethanol administration to rats stimulates the hypothalamic-pituitary-adrenal (HPA) axis and increases brain and plasma levels of the potent neurosteroid allopregnanolone. Increased allopregnanolone levels contribute to the anxiolytic, anticonvulsant, sedative and pro-aggressive actions of ethanol. It is not yet known if ethanol’s effects on allopregnanolone levels generalize across species. Indeed, studies in mice have reported that ethanol does not always alter brain and plasma allopregnanolone levels We thus explored the effects of ethanol administration on brain levels of allopregnanolone and its precursor progesterone in C57BL/6J and DBA/2J mice, two inbred strains with different sensitivity to behavioral effects of alcohol.
Male C57BL/6J and DBA/2J mice were injected with ethanol (1, 2, 3 or 4 g/kg, i.p.) or saline and were sacrificed 1 hour later or 15, 30, 60 and 120 minutes later for the time course studies. Allopregnanolone, progesterone and corticosterone levels were measured by radioimmunoassay in cerebral cortex and hippocampus.
Acute ethanol administration did not alter cerebral cortical and hippocampal levels of allopregnanolone and progesterone in both C57BL/6J and DBA/2J mice at any of the doses examined. Cerebral cortical levels of allopregnanolone and progesterone were also not altered at any of the time points examined in either strain. Acute ethanol administration dose-dependently increased corticosterone levels in the cerebral cortex and the hippocampus of both mouse strains. In C57BL/6J mice, corticosterone levels were increased by 319%, 352% and 448% in the cerebral cortex and by 284%, 218% and 368% in the hippocampus at the doses of 2, 3 and 4 g/kg, respectively, p<0.001. In DBA/2J mice, corticosterone levels were increased by 354%, 417%, 447% and 574% in the cerebral cortex and by 259%, 434%, 567% and 629% in the hippocampus at the doses of 1, 2, 3 and 4 g/kg, respectively, p<0.001. The effect of ethanol on cerebral cortical corticosterone levels was also time-dependent: in C57BL/6J mice it was apparent at 15 min (+155%), reached a peak at 60 min (+306%) and remained elevated at 120 min (+217%) from ethanol administration (p<0.001); in DBA/2J mice it was apparent at 30 min (+546%), reached a peak at 60 min (+1002%) and remained elevated at 120 min (+822%) from ethanol administration (p<0.001). These results suggest that ethanol administration is activating the HPA axis, as expected, and that ethanol might directly impair brain neurosteroid synthesis. Moreover, to evaluate if the effect of ethanol on allopregnanolone levels was specific to ethanol or not, we tested whether administration of morphine, which also increases cerebral cortical levels of allopregnanolone in rats, alters allopregnanolone and progesterone levels in male C57BL/6J and DBA/2J mice. Morphine administration increased cerebral cortical allopregnanolone levels in C57BL/6J mice (+77%, +93% and +88%, at the doses of 5, 10 and 30 mg/kg, respectively, p<0.01) and DBA/2J mice (+81% at the dose of 5 mg/kg, p<0.05). Morphine administration also increased progesterone levels in both strains. These results suggest that the impairment in brain neurosteroidogenesis in C57BL/6J and DBA/2J mice appears to be specific to ethanol.
Overall, these results show important species differences in the effects of ethanol on brain neurosteroidogenesis. Given that ethanol does not alter cerebral cortical and hippocampal concentrations of allopregnanolone and progesterone in the two mouse strains examined, the differential sensitivity to some of the behavioral effects of ethanol cannot be directly correlated to hormonal changes in C57BL/6J and DBA/2J mice
Decreased allopregnanolone induced by hormonal contraceptives is associated with a reduction in social behavior and sexual motivation in female rats
No full textRATIONALE:
Allopregnanolone is a neurosteroid involved in depression, memory, social, and sexual behavior. We have previously demonstrated that treatment with a combination of ethinylestradiol (EE) and levonorgestrel (LNG), two compounds frequently used in hormonal contraception, decreased brain allopregnanolone concentrations. These changes may contribute to some of the emotional and sexual disorders observed in hormonal contraceptive users.
OBJECTIVES:
We thus examined whether the reduction in allopregnanolone concentrations induced by long-term EE/LNG administration was associated with altered emotional, learning, social, and sexual behaviors.
METHODS:
Rats were orally treated with a combination of EE (0.030 mg) and LNG (0.125 mg) once a day for 4 weeks and were subjected to behavioral tests 24 h after the last administration.
RESULTS:
EE/LNG treatment reduced immobility behavior in the forced swim test, without affecting sucrose preference and spatial learning and memory. In the resident-intruder test, EE/LNG-treated rats displayed a decrease in dominant behaviors associated with a reduction in social investigation. In the paced mating test, EE/LNG treated rats showed a reduction in proceptive behaviors, while the lordosis quotient was not affected. Progesterone, but not estradiol, administration to EE/LNG-treated rats increased sexual activity and cerebrocortical allopregnanolone concentrations. Prior administration of finasteride decreased allopregnanolone concentrations and abolished the increase in proceptivity induced by progesterone administration.
CONCLUSIONS:
The decrease in brain allopregnanolone concentrations induced by EE/LNG treatment is associated with a reduction in social behavior and sexual motivation in female rats. These results might be relevant to the side effects sometimes exhibited by women taking hormonal contraceptives
Differential effects of ethanol on cerebral cortical and hippocampal allopregnanolone levels in mice and rats
No full textAcute ethanol administration to rats stimulates the hypothalamic-pituitary-adrenal (HPA) axis and increases brain and plasma levels of the potent neurosteroid allopregnanolone. Increased allopregnanolone levels contribute to the anxiolytic, anticonvulsant, sedative and pro-aggressive actions of ethanol. It is not yet known if ethanol’s effects on allopregnanolone levels generalize across species. Indeed, studies in mice have reported that ethanol does not always alter brain and plasma allopregnanolone levels. We thus explored the effects of ethanol administration on brain levels of allopregnanolone and its precursor progesterone in C57BL/6J and DBA/2J mice, two inbred strains with different sensitivity to behavioral effects of alcohol.
Male C57BL/6J and DBA/2J mice were injected with ethanol (1, 2, 3 or 4 g/kg, i.p.) or saline and were sacrificed 1 hour later or 15, 30, 60 and 120 minutes later for the time course studies. Allopregnanolone, progesterone and corticosterone levels were measured by radioimmunoassay in cerebral cortex and hippocampus.
Acute ethanol administration did not alter cerebral cortical and hippocampal levels of allopregnanolone and progesterone in both C57BL/6J and DBA/2J mice at any of the doses examined. Cerebral cortical levels of allopregnanolone and progesterone were also not altered at any of the time points examined in either strain. In contrast, as expected, acute ethanol administration dose-dependently increased cerebral cortical levels of allopregnanolone and progesterone in male Sprague-Dawley rats. Acute ethanol administration dose-dependently increased corticosterone levels in the cerebral cortex and the hippocampus of both mouse strains. In C57BL/6J mice, corticosterone levels were increased by 319%, 352% and 448% in the cerebral cortex and by 284%, 218% and 368% in the hippocampus at the doses of 2, 3 and 4 g/kg, respectively, p<0.001. In DBA/2J mice, corticosterone levels were increased by 354%, 417%, 447% and 574% in the cerebral cortex and by 259%, 434%, 567% and 629% at the doses of 1, 2, 3 and 4 g/kg, respectively, p<0.001. The effect of ethanol on cerebral cortical corticosterone levels was also time-dependent: in C57BL/6J mice it was apparent at 15 min (+155%), reached a peak at 60 min (+306%) and remained elevated at 120 min (+217%) from ethanol administration (p<0.001); in DBA/2J mice it was apparent at 30 min (+546%), reached a peak at 60 min (+1002%) and remained elevated at 120 min (+822%) from ethanol administration (p<0.001). These results suggest that ethanol administration is activating the HPA axis, as expected, and that ethanol might directly impair brain neurosteroid synthesis. Moreover, to evaluate if the effect of ethanol on allopregnanolone levels was specific to ethanol or not, we tested whether administration of morphine, which also increases cerebral cortical levels of allopregnanolone in rats, alters allopregnanolone and progesterone levels in male C57BL/6J and DBA/2J mice. Morphine administration increased cerebral cortical allopregnanolone levels in C57BL/6J mice (+77%, +93% and +88%, at the doses of 5, 10 and 30 mg/kg, respectively, p<0.01) and DBA/2J mice (+81% at the dose of 5 mg/kg, p<0.05). Morphine administration also increased progesterone levels in both strains. These results suggest that the impairment in brain neurosteroidogenesis in C57BL/6J and DBA/2J mice appears to be specific to ethanol.
Overall, these results show important species differences in the effects of ethanol on brain neurosteroidogenesis. Given that ethanol does not alter cerebral cortical and hippocampal concentrations of allopregnanolone and progesterone in the two mouse strains examined, the differential sensitivity to some of the behavioral effects of ethanol cannot be directly correlated to hormonal changes in C57BL/6J and DBA/2J mice
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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