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Evidence For The Involvement Of Peripheral β -adrenoceptors In Delayed Liquid Gastric Emptying Induced By Dipyrone, 4-aminoantipyrine, And Antipyrine In Rats
No full textDipyrone (Dp), 4-aminoantipyrine (AA), and antipyrine (At) delay liquid gastric emptying (GE) in rats. We evaluated adrenergic participation in this phenomenon in a study in male Wistar rats (250-300 g) pretreated subcutaneously with guanethidine (GUA), 100 mg?kg-1?day-1, or vehicle (V) for 2 days before experimental treatments. Other groups of animals were pretreated intravenously (iv) 15 min before treatment with V, prazosin (PRA; 1 mg/kg), yohimbine (YOH; 3 mg/kg), or propranolol (PRO; 4 mg/kg), or with intracerebroventricular (icv) administration of 25 mg PRO or V. The groups were treated iv with saline or with 240 mmol/kg Dp, AA, or At. GE was determined 10 min later by measuring the percentage of gastric retention (%GR) of saline labeled with phenol red 10 min after gavage. %GR (mean±SE, n=8) indicated that GUA abolished the effect of Dp (GUA vs V=31.7±1.6 vs 47.1±2.3%) and of At (33.2±2.3 vs 54.7±3.6%) on GE and significantly reduced the effect of AA (48.1±3.2 vs 67.2±3.1%). PRA and YOH did not modify the effect of the drugs. %GR (mean±SE, n=8) indicated that iv, but not icv, PRO abolished the effect of Dp (PRO vs V=29.1±1.7 vs 46.9±2.7%) and At (30.5±1.7 vs 49±3.2%) and significantly reduced the effect of AA (48.4±2.6 vs 59.5±3.1%). These data suggest activation of peripheral b-adrenoceptors in the delayed GE induced by phenylpyrazolone derivatives.469735738Collares, E.F., Vinagre, A.M., Evidence of the effect of dipyrone on the central nervous system as a determinant of delayed gastric emptying observed in rats after its administration (2003) Braz J Med Biol Res, 36, pp. 1375-1382. , doi: 10.1590/ S0100-879X2003001000014Collares, E.F., Vinagre, A.M., Effect of the GABAB agonist baclofen on dipyrone-induced delayed gastric emptying in rats (2005) Braz J Med Biol Res, 38, pp. 99-104. , doi: 10.1590/ S0100-879X2005000100015Soares, A.C., Vinagre, A.M., Collares, E.F., Effect of antipyrine on the gastric emptying of liquid in rats (2006) Braz J Med Biol Res, , 39: 1507-1512doi: 10.1590/S0100-879X2006001100015Vinagre, A.M., Collares, E.F., Effect of 4-aminoantipyrine on gastric compliance and liquid emptying in rats (2007) Braz J Med Biol Res, 40, pp. 903-909. , doi: 10.1590/S0100-879X2006005000119Vinagre, A.M., Collares, E.F., Phenylpyrazolone derivatives inhibit gastric emptying in rats by a capsaicin-sensitive afferent pathway (2009) Braz J Med Biol Res, 42, pp. 1086-1089. , doi: 10.1590/S0100-879X2009001100014Barrett, K.E., Neurohumoral regulation of gastrointestinal function (2006) Gastrointestinal Physiology, pp. 18-36. , In: Barrett KE (Editor), New York: Lange Medical Books/McGraw-HillSzurszewski, J.H., Linden, D.R., Physiology of prevertebral sympathetic ganglia (2012) Physiology of the Gastrointestinal Tract, pp. 583-627. , In: Johnson LR (Editor), 5th edn. Oxford: Elsevier IncFulop, K., Zadori, Z., Ronai, A.Z., Gyires, K., Characterisation of alpha2-adrenoceptor subtypes involved in gastric emptying, gastric motility and gastric mucosal defence (2005) Eur J Pharmacol, 528, pp. 150-157. , doi: 10.1016/j.ejphar.2005.10.025Yu, O., Ouyang, A., Distribution of beta-adrenoceptor subtypes in gastrointestinal tract of nondiabetic and diabetic BB rats (1997) A longitudinal study Dig Dis Sci, 42, pp. 1146-1153. , doi: 10.1023/A:1018877318101Ozakca, I., Arioglu, E., Guner, S., Altan, V.M., Ozcelikay, A.T., Role of beta-3-adrenoceptor in catecholamine-induced relaxations in gastric fundus from control and diabetic rats (2007) Pharmacology, 80, pp. 227-238. , doi: 10.1159/000104876Gondim, F.A., Rodrigues, C.L., da Graca, J.R., Camurca, F.D., de Alencar, H.M., dos, S.A.A., Neural mechanisms involved in the delay of gastric emptying and gastrointestinal transit of liquid after thoracic spinal cord transection in awake rats (2001) Auton Neurosci, 87, pp. 52-58. , doi: 10.1016/ S1566-0702(00)00261-7Gupta, Y.K., Chaudhary, G., Effect of antiemetic drugs on decrease in gastric emptying in experimental model of motion sickness in rats (2003) Acta Pharmacol Sin, 24, pp. 296-300Nakade, Y., Tsuchida, D., Fukuda, H., Iwa, M., Pappas, T.N., Takahashi, T., Restraint stress delays solid gastric emptying via a central CRF and peripheral sympathetic neuron in rats (2005) Am J Physiol Regul Integr Comp Physiol, 288, pp. R427-R432. , doi: 10.1152/ajpregu.00499.2004Tsukada, F., Nagura, Y., Abe, S., Sato, N., Ohkubo, Y., Effect of restraint and footshock stress and norepinephrine treatment on gastric emptying in rats (2003) Biol Pharm Bull, 26, pp. 368-370. , doi: 10.1248/bpb.26.368Navegantes, L.C., Resano, N.M., Migliorini, R.H., Kettelhut, I.C., Effect of guanethidine-induced adrenergic blockade on the different proteolytic systems in rat skeletal muscle (1999) Am J Physiol, 277, pp. E883-E889Zadori, Z.S., Shujaa, N., Fulop, K., Dunkel, P., Gyires, K., Pre and postsynaptic mechanisms in the clonidine and oxymetazoline induced inhibition of gastric motility in the rat (2007) Neurochem Int, 51, pp. 297-305. , doi: 10.1016/j.neuint.2007.06.027Bucaretchi, F., Collares, E.F., Effect of Phoneutria nigriventer spider venom on gastric emptying in rats (1996) Braz J Med Biol Res, 29, pp. 205-211Ursino, M.G., Vasina, V., Raschi, E., Crema, F., de Ponti, F., The b3-adrenoceptor as a therapeutic target: Current perspectives (2009) Pharmacol Res, 59, pp. 221-234. , doi: 10.1016/ j.phrs.2009.01.002McAinsh, J., Cruickshank, J.M., Beta-blockers and central nervous system side effects (1990) Pharmacol Ther, 46, pp. 163-197. , doi: 10.1016/0163-7258(90)90092-GNicholas, A.P., Hokfelt, T., Pieribone, V.A., The distribution and significance of CNS adrenoceptors examined with in situ hybridization (1996) Trends Pharmacol Sci, 17, pp. 245-255. , doi: 10.1016/0165-6147(96)10022-
The Effect Of Bacterial Lipopolysaccharide On The Gastric Emptying Of Rats: A Pretreatment Evaluation Using N W-nitro-l-arginine Methyl Ester (l-name) [efeito Do Lipopolissacarídio Bacteriano Sobre O Esvaziamento Gástrico De Ratos: Avaliação Do Pré-tratamento Com N W-nitro-l-arginine Methyl Ester (l-name)]
No full textBackground - There is evidence that nitric oxide plays a role in the decrease in gastric emptying induced by bacterial lipopolysaccharide. Aim - To evaluate the effect of pretreatment with N w-nitro-L-arginine methyl to ester, one competitive inhibitor of the nitric oxide syntases, on the gastric emptying delay induced by lipopolysaccharide. Material and Methods - Male Wistar rats, SPF, were used after 24 h fast and 1 h-water withdrawn. The pretreatment was done intravenously with vehicle (saline) or N w-nitro-L-arginine methyl to ester in the doses of 0.5, 1, 2.5 e 5 mg/kg. After 10 min, the animals were treated iv with lipopolysaccharide (50 μg/kg) or received vehicle (saline). The gastric emptying was evaluated 1 h after the lipopolysaccharide administration. A saline solution containing phenol red was used as the test meal. The gastric emptying was indirectly assessed by the determination of percent gastric retention of the test meal 10 min after orogastric administration. Results - The animals pretreated with vehicle and treatment with lipopolysaccharide have significant rise of the gastric retention (average = 57%) in comparison with the controls receiving only vehicle (38.1%). The pretreatment with the different doses of N w-nitro-L-arginine methyl to ester did not modify per se the gastric retention in comparison with the animals pretreated with vehicle. Pretreatment with N w-nitro-L- arginine methyl to ester with the dose of 1 mg/kg determined a discrete but significant reduction in the gastric retention (52%) of animals treated with lipopolysaccharide in comparison with vehicle-pretreated rats. Paradoxically, animals pretreated with 2.5 or 5 mg of N w-nitro-L-arginine methyl to ester/kg followed by treatment with lipopolysaccharide displayed a significantly higher gastric retention (74.7% and 80.5%, respectively) as compared to their controls, pretreated with the same doses of the inhibitor and treated with vehicle (40.5% and 38.7%, respectively) and to those pretreated with vehicle and treated with the same toxin. Conclusion - The pretreatment with N w-nitro-L-arginine methyl to ester at low dose (1 mg/kg) resulted in a discrete inhibition of the gastric emptying delay induced by lipopolysaccharide. Nevertheless, N w-nitro-L-arginine methyl to ester at higher doses (2.5 and 5 mg/kg) induced an enhancement of the lipopolysaccharide effect on gastric emptying, despite not interfering with the gastric emptying per se.433229232Allescher, H.-D., Daniel, E.E., Role of NO in pyloric, antral, and duodenal motility and its interaction with other inhibitory mediators (1994) Dig Dis Sci, 39, pp. 73s-5sBaykal, A., Kavuklu, B., Iskit, A.B., Guc, M.O., Hascelik, G., Sayek, I., Experimental study of the effect of nitric oxide inhibition on mesenteric blood flow and interleukin-10 levels with lipopolysaccharide challenge (2000) World J Surg, 24, pp. 1116-1120Belangero, V.M.S., Collares, E.F., Esvaziamento gástrico e acidose metabólica. I Estudo de um modelo experimental em ratos, empregando uma solução de cloreto de amônio por via orogástrica (1991) Arq Gastroenterol, 28, pp. 145-150Boughton-Smith, N.K., Evans, S.M., Laszlo, F., Whittle, B.J.R., Moncada, S., The induction of nitric oxide synthase and intestinal vascular permeability by endotoxin in rat (1993) Br J Pharmacol, 110, pp. 1189-1195Bucaretchi, F., Collares, E.F., Effect of Phonetria nigriventer spider venom on gastric emptying in rats (1996) Braz J Med Biol Res, 29, pp. 205-211Ceregrzyn, M., Kamata, T., Yajima, T., Kuwahara, A., Biphasic alterations in gastrointestinal transit following endotoxaemia in mice (2001) Neurogastroenterol Mot, 13, pp. 605-613Ceregrzyn, M., Kuwahara, A., Involvement of nitric oxide in lipopolysaccharide-induced gastric relaxation in mice (2002) Biomed Res, 23, pp. 263-272Chou, C.C., Relationship between intestinal blood flow and motility (1982) Ann Rev Physiol, 44, pp. 29-42Collares, E.F., Effect of bacterial lipopolysaccharide on gastric emptying of liquids in rats (1997) Braz J Med Biol Res, 30, pp. 207-211Collares, E.F., Effect of tolerance to bacterial lipopolysaccharide on gastric emptying in rats (1997) Arq Gastroenterol, 34, pp. 227-230Collares, E.F., Vinagre, A.M., Efeito do lipopolissarídio bacteriano sobre o esvaziamento gástrico de ratos: Avaliação do pré-tratamento com dexametasona e azul de metileno (2003) Arq Gastroenterol, 40, pp. 104-109Fan, Y.-P., Chakder, S., Gao, F., Rattan, S., Inducible and neuronal nitric oxide synthase involvement in lipopolysaccharide-induced sphincteric dysfunction (2001) Am J Physiol Gastrointest Liver Physiol, 280, pp. G32-G42Förstermann, U., Gath, I., Schwarz, P., Closs, E.I., Kleinert, H., Isoforms of nitric oxide synthase. Properties, cellular distribution and expressional control (1995) Biochem Pharmacol, 50, pp. 1321-1332Hayes, J.K., Havaleshko, D.M., Plachinta, R.V., Rich, G.F., Isoflurane pretreatment supports hemodynamics and leukocyte rolling velocities in rat mesentery during lipopolysaccharide-induced inflammation (2004) Anesth Analg, 98, pp. 999-1006Helmer, K.S., West, S.D., Shipley, G.L., Ghang, L., Cui, Y., Mailman, D., Mercer, D.W., Gastric nitric oxide synthase expression during endotoxemia: Implications in mucosal defense in rats (2002) Gastroenterology, 123, pp. 173-186Hunt, J.N., Mechanisms and disorders of gastric emptying (1983) Ann Rev Med, 34, pp. 219-229Hutcheson, I.R., Whittle, B.J.R., Boughton-Smith, N.K., Role of nitric oxide in maintaining vascular integrity in endotoxin-induced acute intestinal damage in the rat (1990) Br J Pharmacol, 101, pp. 815-820Lohse, M.J., Förstermann, U., Schmidt, H.H.H.W., Pharmacology of NO: CGMP signal transduction (1998) Naunyn Schmiedebergs Arch Pharmacol, 358, pp. 111-112Martin, M.J., Jiménez, M.D., Motilva, V., New issues about nitric oxide and its effects on the gastrointestinal tract (2001) Curr Pharm des, 7, pp. 881-908Mateo, A.O., De-Artiñano, A.A., Highlights on endothelins: A review (1997) Pharmacol Res, 36, pp. 339-351Moncada, S., Higgs, A., The L-arginine-nitric oxide pathway (1993) N Engl J Med, 329, pp. 2002-2012Read, N.W., Houghton, L.A., Physiology of gastric emptying and pathophysiology of gastroparesis (1989) Gastroenterol Clin North Am, 18, pp. 359-404Szabo, J.S., Stonestreet, B.S., Oh, W., Effects of hypoxemia on gastrointestinal blood flow and gastric emptying in the newborn piglet (1985) Pediatr Res, 19, pp. 466-471Walus, K.M., Jacobson, E.D., Relation between small intestinal motility and circulation (1981) Am J Physiol, 241, pp. G1-G1
Effect Of The Gabab Agonist Baclofen On Dipyrone-induced Delayed Gastric Emptying In Rats
Full text linkDipyrone administered intravenously (iv) or intracerebroventricularly (icv) delays gastric emptying (GE) in rats. Gamma-aminobutyric acid (GABA) is the most potent inhibitory neurotransmitter of the central nervous system. The objective of the present study was to determine the effect of icv baclofen, a GABAB receptor agonist, on delayed GE induced by dipyrone. Adult male Wistar rats received a saline test meal containing phenol red as a marker. GE was indirectly evaluated by determining the percent of gastric retention (%GR) of the meal 10 min after orogastric administration. In the first experiment, the animals were injected iv with vehicle (Civ) or 80 mg/kg (240 μmol/kg) dipyrone (Dpiv), followed by icv injection of 10 μl vehicle (bac0), or 0.5 (bac0.5), 1 (bac1) or 2 μg (bac2) baclofen. In the second experiment, the animals were injected icv with 5 μl vehicle (Cicv) or an equal volume of a solution containing 4 μmol (1333.2 μg) dipyrone (Dpicv), followed by 5 μl vehicle (bac0) or 1 μg baclofen (bac1). GE was determined 10 min after icv injection. There was no significant difference between control animals from one experiment to another concerning GR values. Baclofen at the doses of 1 and 2 μg significantly reduced mean %GR induced by iv dipyrone (Dpivbac1 = 35.9% and Dpivbac2 = 26.9% vs Dpivbac0 = 51.8%). Similarly, baclofen significantly reduced the effect of dipyrone injected icv (mean %GR: Dpicvbac1 = 30.4% vs Dpicvbac0 = 54.2%). The present results suggest that dipyrone induces delayed GE through a route in the central nervous system that is blocked by the activation of GABAB receptors.38199104Weisbrodt, N.W., Gastric emptying (1997) Gastrointestinal Physiology, pp. 33-42. , Johnson LR (Editor), 5th edn. 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Effect Of Toxin-g From Tityus Serrulatus Scorpion Venom On Gastric Emptying In Rats
No full textThe effect of toxin-γ from Tityus serrulatus scorpion venom on the gastric emptying of liquids was studied in 176 young adult male Wistar rats (2-3 months of age) divided into subgroups of 8 animals each. Toxin-γ was injected iv at doses of 25, 37.5, 50 or 100 μg/kg and the effect on gastric emptying was assessed 30 min and 8 h later. A time-course study was also performed by injecting 50 μg of toxin-γ/kg and measuring the effect on gastric emptying at times 0.25, 0.5, 1, 2, 4, 8, 24 and 48 h post-venom. Each envenomed animal was paired with its saline control and all received a saline test meal solution containing phenol red (60 μg/ml) as a marker. Ten minutes after administering the test meal by gavage the animals were sacrificed and gastric retention was determined by measuring the residual marker concentration of the test meal. A significant delay in gastric emptying, at 30 min and 8 h post-venom, was observed only after 50 and 100 μg of toxin- γ/kg compared to control values. The responses to these two doses were significantly different after 8 h post-venom. Toxin-γ (50 μg/kg) significantly delayed the gastric emptying of liquids at all times studied, with a peak response at 4 h after toxin administration compared to control values. These results indicate that the iv injection of toxin-γ may induce a rapid, intense and sustained inhibition of gastric emptying 0.25 to 48 h after envenomation.324431434Freire-Maia, L., Campos, J.A., Pathophysiology and treatment of scorpion poisoning (1989) Natural Toxins, pp. 139-159. , Ownby CH & Odell GV (Editors), Pergamon Press, OxfordBucaretchi, F., Baracat, E.C.E., Nogueira, R.J.N., Chaves, A., Zambrone, F.A.D., Fonseca, M.R.C., Tourinho, F.S., A comparative study of severe scorpion envenomation in children caused by Tityus bahiensis and tityus serrulatus (1995) Revista Do Instituto de Medicina Tropical de Sāo Paulo, 37, pp. 331-336Andrade, S.P., Santos, R.A.S., Beraldo, W.T., Comparative study of the action of purified scorpion toxin (tityustoxin) on the submandibular and parotid glands of the rat (1981) Toxicon, 19, pp. 255-261Cunha-Melo, J.R., Gonzaga, H.M.S., Alzamora, F., Freire-Maia, L., Effects of purified scorpion toxin (tityustoxin) on gastric secretion in the rat (1983) Toxicon, 21, pp. 843-848Cunha-Melo, J.R., Almeida, A.P., Gonzaga, H.M.S., Gomez, M.V., Freire-Maia, L., Effect of scorpion toxin on gastric histamine and acetylcholine content in the rat (1987) Brazilian Journal of Medical and Biological Research, 20, pp. 393-401Novaes, G., Cabral, A.P.G., Falco, C.N.M.L., Queiroz, A.C., Acute pancreatitis induced by scorpion toxin, tityustoxin. Histopathological study in rats (1989) Arquivos de Gastroenterologia de Sāo Paulo, 26, pp. 9-12Cunha-Melo, J.R., Toppa, N.H., Martins, P., Colares, C.N., Castro, C.N., Freire-Maia, L., Acute gastric injury induced by toxins from Tityus serrulatus scorpion venom: A novel experimental model in the rat (1991) Toxicon, 29, pp. 1395-1401Hunt, J.N., Mechanisms and disorders of gastric emptying (1983) Annual Review in Medicine, 34, pp. 219-229Roman, C., Gonella, J., Extrinsic control of the stomach (1987) Physiology of the Gastrointestinal Tract. 2nd Edn., pp. 522-532. , Johnson LR (Editor), Raven Press, New YorkSampaio, S.V., Laure, C.J., Giglio, J.R., Isolation and characterization of toxic proteins from the venom of the Brazilian scorpion Tityus serrulatus (1983) Toxicon, 21, pp. 265-277Belangero, V.M.S., Collares, E.F., Estudo do esvaziamento gástrico e acidose metabólica. I. Estudo de um modelo experimental em ratos, empregando uma soluçāo de cloreto de amônio por via orogástrica (1991) Arquivos de Gastroenterologia de Sāo Paulo, 28, pp. 145-150Bucaretchi, F., Collares, E.F., Effect of Phoneutria nigriventer spider venom on gastric emptying in rats (1996) Brazilian Journal of Medical and Biological Research, 29, pp. 205-211Burks, T.F., Actions of drugs on gastrointestinal motility (1987) Physiology of the Gastrointestinal Tract. 2nd Edn., pp. 723-743. , Johnson LR (Editor), Raven Press, New YorkRees, M.R., Clark, R.A., Holdsworth, C.D., The effect of beta-adrenoceptor agonists on gastric emptying in man (1980) British Journal of Clinical Pharmacology, 10, pp. 551-554Sofer, S., Cohen, R., Shapir, Y., Chen, L., Colon, A., Sharf, S.M., Scorpion venom leads to gastrointestinal ischemia despite increased oxygen delivery in pigs (1997) Critical Care Medicine, 25, pp. 834-840Gwee, M.C.E., Cheah, L.S., Gopalakrishnakone, P., Involvement of the L-arginine-nitric-oxide synthase pathway in the relaxant responses of the rat isolated anococcygeus muscle to a scorpion (Leiurus quinquestriatus quinquestriatus) venom (1985) Toxicon, 33, pp. 1141-1150Teixeira, C.E., Bento, A.C., Lopes-Martins, R.A.B., Teixeira, S.A., Von Eicstedt, V., Muscará, M.N., Arantes, E.C., De Nucci, G., Effect of Tityus serrulatus scorpion venom on the rabbit isolated corpus cavernosum and the involvement of NANC nitrergic nerve fibres (1998) British Journal of Pharmacology, 123, pp. 435-442Chou, C.C., Relationship between intestinal blood flow and motility (1982) Annual Review of Physiology, 44, pp. 29-42Stark, M.E., Szurszewski, J.H., Role of nitric oxide in gastrointestinal function and disease (1992) Gastroenterology, 103, pp. 1928-1949Troncon, L.E.A., Garbacio, V.L., Santos, A., Secaf, M., Cunha-Melo, J.R., Efeitos da toxina escorpiônica sobre o esvaziamento gástrico em ratos (1996) Annals of the XI Reuniāo da Federaçāo das Sociedades de Biologia Experimental, p. 72. , Caxambu, 21-24 August, Abstract 09.005Barhanin, J., Ildefonse, M., Rougier, O., Sampaio, S.V., Giglio, J.R., Lazdunski, M., Tityus γ toxin, a high affinity effector of the sodium channel in muscle with a selectivity for channels in the surface membrane (1982) Pflügers Archives, 400, pp. 22-2
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
Comparative Study Of The Gastric Emptying Of Disaccharides And Their Respective Monosaccharides In Rats With Ontogenic Lactase Deficiency [estudo Comparativo Do Esvaziamento Gástrico De Dissacarídios E De Seus Respectivos Monossacarídios Em Ratos Com Deficiência Ontogênica De Lactase.]
No full textIn order to evaluate the gastric emptying of disaccharides and their monosaccharides, 64 male, Wistar rats weighing approximately 180 g, were divided into the following eight groups containing eight animals each: maltose, sucrose, lactose, and lactulose, and their correspondent group of monosaccharides: glucose, fructose plus glucose, galactose plus glucose and galactose plus fructose. Each animal received, after a 20 hours fast, 2 ml/100 g weight of a test meal containing a 10% solution of the correspondent sugar and phenol red (6 mg/dl) as a marker. Gastric retention was determined at 10 minutes after orogastric infusion and expressed as a percentage of the infused volume. The observed values (mean +/- SE) of gastric retention (%) of sucrose (35.0 +/- 1.8), lactose (30.4 +/- 1.5), and lactulose (29.5 +/- 1.6) were significantly lower (t test alpha = 0.05), than those observed with their respective monosaccharides, i.e. glucose plus fructose (46.9 +/- 2.6), glucose plus galactose (48.3 +/- 2.4), galactose plus fructose (43.5 +/- 1.5). No difference was noted between gastric retention of maltose (49.9 +/- 4.7) and that of glucose (53.0 +/- 3.0). As far the disaccharides are concerned, statistical analysis (ANOVA followed by Tukey test alpha = 0.05) revealed no differences among the values of gastric retention of sucrose, lactose and lactulose. Gastric retention of maltose was significantly greater than that of the other disaccharides. No differences were found among the gastric retention of monosaccharides.(ABSTRACT TRUNCATED AT 250 WORDS)29414214
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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