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Inhibitory effect of the adenosine A1 and k-opioid systems on the expression of the μ-withdrawal response in the guinea-pig ileum: Reversal by cholecystokinin.
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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
Inhibitory Control of the Acute Mu-Withdrawal Response by Indirectly Activated Adenosine A1 and Kappa-Opioid Systems in the Guinea-Pig ileum; Reversal by Cholecystochinin
No full textIn the isolated guinea-pig ileum (GPI), the acute mu-opioid withdrawal response is inhibited by the kappa-opioid system, indirectly activated by the opioid agonist; yet, other inhibitory mechanisms are probably operating. On the other hand, cholecystokinin (CCK-8) strongly enhances the withdrawal response. In this study, we have shown that the adenosine A1 antagonist 8-cyclopenthyl-1,3-dimethylxantine (CPT) increased the withdrawal response in dermorphin/naloxone (NLX) tests but lacked any effect if the withdrawal tests were carried out in presence of CCK-8. In tissue preparations coming from a same animal both CPT and the kappa-opioid antagonist, nor-binaltorphimine (BNI), increased the intensity of the withdrawal responses; the effects of the two antagonists were additive. The intensity of withdrawal contractile responses in presence of CCK-8 was similar to those obtained in presence of the two antagonists. Tissue preparations tested with dermorphin/CCK-8/NLX and then washed out yielded contractile responses when subsequently challenged with CPT, BNI or BNI+CPT, with a percentage markedly higher than the percentage of the response to NLX challenge. BNI+CPT also increased the intensity of the response to NLX challenge. These data suggest that acute exposure of GPI to dermorphin induces the activation of both the adenosine A1 and kappa-opioid systems, which in turns inhibit the mu-withdrawal response. CCK-8 antagonises the inhibitory effect of the indirectly activated systems
EFFECTS OF INSULIN-INDUCED ACUTE HYPOGLYCEMIA AND NORMOGLYCEMIC HYPERINSULINEMIA ON THE RETINAL UPTAKE AND OCULAR METABOLISM OF GLUCOSE IN RABBITS
No full textGlucose is the principal metabolic substrate for the retina in mammals, being essential for maintaining the functional activity of the retina; it can be supplied to the tissue by both vitreous humor and blood. Yet, the impact of hypoglycemia on retinal glucose metabolism has been poorly investigated. We have therefore studied the effects of acute insulin-induced hypoglycemia on the glucose uptake and metabolism in the retina, by analyzing the hypoglycemia-induced changes in the ocular distribution and metabolic fate of [3H]-2-deoxy-D-glucose (2-DG) and [14C]-D-glucose, both injected in the vitreous body. Rabbits were rendered hypoglycemic by subcutaneous injection of insulin (0.8 and 1.2 IU/kg). Insulin-induced hypoglycemia increased both retinal [3H]-radioactivity levels and retina to vitreous humor ratio of [3H]-radioactivity levels ([3H]-[R/VH]). Radio-chromatography showed that hypoglycemia did not induce any change in the retinal conversion of 2-DG to 2-DG-6- phosphate, but increased the conversion of [14C]-D-glucose to [14C]-lactate. Normoglycemic hyperinsulinemia caused no change in either retinal [3H]-radioactivity levels or [3H]-[R/VH] while decreasing retinal [14C]-radioactivity levels and retina to vitreous ratios of 14C-radioactivity levels. These results indicate that acute hypoglycemia increases the uptake rate of glucose by the retina and suggest that normoglycemic hyperinsulinemia may decrease retinal lactate, possibly stimulating its removal from the retina. © 2004 Elsevier Inc. All rights reserved
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
Role of the cholinergic system and of apamin-sensitive Ca++-activated K+ channels on rabbit jejunum spontaneous activity and on the inhibitory effects of adrenoceptor agonists
No full textOne reason why rabbit jejunum is suitable for studying the mechanisms underlying the actions of the various neurotransmitters and their interactions is its spontaneous motility. The main regulator of spontaneous motility is the cholinergic system. How the cholinergic system regulates the spontaneous activity in the rabbit jejunum and how it affects the inhibitory action of alpha- and beta-adrenoceptor agonists remains unclear. 2. We studied the influence of the cholinergic system and apamin-sensitive Ca2+-activated K+ channels on spontaneous contractions in the rabbit jejunum and on the inhibitory effects of alpha1- and beta-adrenoceptor agonists. 3. In naïve tissues, atropine (ATR, 7.4 x 10(-8) m) and tetrodotoxin (8 x 10(-8) m) almost completely inhibited - to a similar extent - the amplitude of spontaneous activity. Despite the presence of ATR or TDX, tissue contraction gradually recovered to about 50% of the baseline amplitude within 5-10 min. When ATR or TDX, respectively, were added to the TDX- or ATR-treated tissues, the recovered activity decreased weakly but significantly. After washout and a 45-min rest the contraction amplitude returned to baseline values. A further exposure to ATR or TDX reduced the contraction to a level significantly lower than the one obtained after TDX or ATR added 5 min after ATR or TDX, respectively. In preparations prestimulated for 10 min with acetylcholine (ACh), ATR abolished the TDX-resistant recovered spontaneous activity. 4. Adrenaline (ADR, 0.5-5 x 10(-7) m) and phenylephrine (PHE, 1-10 x 10(-7) m) inhibited tissue motility in naïve and in ATR- and in TDX-exposed preparations. But whereas in naïve preparations the alpha1-adrenoceptor antagonists completely antagonized inhibition induced by both drugs, in ATR- and TDX-exposed tissues they did so only partially for ADR. Agonist-induced inhibition had a rapid onset but rapidly faded; pendular movements took significantly longer to recover in ATR- and TDX-treated tissues than in naïve tissues. In tissues exposed for 2 min to ADR (0.5-5 x 10(-7) m) or PHE (1-10 x 10(-7) m), washout or addition of alpha1-adrenoceptor antagonists caused an immediate short-lasting increase in contraction amplitude. 5. Apamin (APAM, 5 x 10(-9) m) caused a rapid and persistent increase in the amplitude of contractions. It also blocked the inhibitory responses to ADR and PHE, and removed washout-induced contractions. The APAM-induced increase in the contraction amplitude correlated with the increase obtained by washing out ADR or PHE. 6. Isoprenaline (at concentrations up to 2.8 x 10(-7) m) produced no inhibitory response in naïve tissues, but it invariably blocked (at a concentration of 0.7 x 10(-7) m) the recovered spontaneous activity (and sometimes depressed muscletone) in tissues exposed to ATR or TDX. Neither propranolol (3.4 x 10(-7) m) nor APAM (5 x 10(-9) m) counteracted these inhibitory effects. 7. These results indicate that spontaneous motility in the rabbit jejunum is predominantly mediated by neuronal release of ACh and by some other unidentified neuronal activity. Released ACh inhibits myogenic activity and strongly antagonizes beta-adrenoceptor-induced APAM-insensitive inhibition but leaves alpha1 agonist-induced APAM-sensitive inhibition unchanged
Opposite role of opioid and cholecystokinin systems on the withdrawal response to adenosine A1-receptor agonist in the guinea-pig isolated ileum
No full textExposure to the A1 agonist indirectly activates the μ- and κ-opioid systems, which in turns inhibit the expression of the A1 withdrawal response. The inhibitory effect of indirectly activated systems is partially antagonised by CCK-8
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
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