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PGE2 reduces net water and chloride absorption from the rat colon by targeting the Na+-H+ exchanger and the Na+K+2Cl- cotransporter
No full textAn effect of PGE2 on water and chloride absorption was already established in a previous work. This study is an attempt to find the mechanism of action of the prostaglandin by investigating the involvement of three major transporters namely the Na+-K+ATPase, the Na+-H+ exchanger and the Na+K+2Cl- cotransporter. Rats were injected with PGE2 and 15 min later, the colon was perfused in situ with Krebs Ringer buffer, and net water and chloride absorption were determined. When the involvement of the cotransporter and-or the exchanger was investigated, animals were injected with, respectively, furosemide and amiloride 10 min before PGE2. Superficial and crypt colonocytes were then isolated and the protein expression of the Na+-K+ ATPase and the Na+K+2Cl- was determined by western blot analysis. The effect of PGE2 on the pump activity in presence or absence of the transporters' inhibitors was also studied. PGE2 decreased net water and chloride absorption from the colon, increased the Na+-K+ ATPase activity in superficial cells and reduced it in crypt cells. The prostaglandin was found to stimulate secretion in superficial cells by targeting the Na+K+2Cl- symporter, and reduce absorption in crypt cells by targeting the Na+-H+ antiporter. Changes in the activity of the pump are secondary to changes in the activity of the other transporters. © 2007 Elsevier Ltd. All rights reserved.Abramovitz M, 2000, BBA-MOL CELL BIOL L, V1483, P285, DOI 10.1016-S1388-1981(99)00164-X; ANDERSON RJ, 1976, KIDNEY INT, V10, P205, DOI 10.1038-ki.1976.99; Bachmann O, 2004, AM J PHYSIOL-GASTR L, V287, pG125, DOI 10.1152-ajpgi.00332.2003; Benos DJ, 1982, AM J PHYSIOL, V242, P131; BERTRAND B, 1994, J BIOL CHEM, V269, P13703; BINDER HJ, 1973, AM J PHYSIOL, V225, P1232; Bos CL, 2004, INT J BIOCHEM CELL B, V36, P1187, DOI 10.1016-j.biocel.2003.08.006; CHU J, 2002, AM J PHYSIOL-CELL PH, V283, P358; CORDINA J, 1999, J BIOL CHEM, V274, P19693; CROOK RB, 1992, J CELL PHYSIOL, V153, P214, DOI 10.1002-jcp.1041530126; CURRAN PF, 1960, J GEN PHYSIOL, V43, P555, DOI 10.1085-jgp.43.3.555; DAWSON DC, 1991, ANNU REV PHYSIOL, V53, P321; DELCASTILLO JR, 1991, AM J PHYSIOL, V261, pG1005; DONG J, 1994, AM J PHYSIOL-CELL PH, V267, pC1553; FLIEGEL L, 1993, BIOCHEM J, V296, P273; Gawenis LR, 2004, AM J PHYSIOL-GASTR L, V287, pG1140, DOI 10.1152-ajpgi.00177.2004; Geibel JP, 2001, GASTROENTEROLOGY, V120, P144, DOI 10.1053-gast.2001.20890; Greger R, 1997, NEWS PHYSIOL SCI, V12, P62; HARGIS L, 1988, ANAL CHEM PRINCIPLES, P314; HEBERT RL, 1990, AM J PHYSIOL, V259, P318; HEBERT RL, 1993, AM J PHYSIOL, V265, pF643; Heitzmann D, 2000, PFLUG ARCH EUR J PHY, V439, P378, DOI 10.1007-s004240050953; Kaji DM, 1996, AM J PHYSIOL-CELL PH, V271, pC354; KOCKERLING A, 1993, AM J PHYSIOL, V264, pC1285; KOEFOEDJOHNSEN V, 1958, ACTA PHYSIOL SCAND, V42, P298, DOI 10.1111-j.1748-1716.1958.tb01563.x; Kreydiyyeh SI, 2006, PROSTAG OTH LIPID M, V79, P43, DOI 10.1016-j.prostaglandins.2005.07.004; Kunzelmann K, 2002, PHYSIOL REV, V82, P245; LOMAX RB, 1994, AM J PHYSIOL, V266, pG71; Maly K, 2002, FEBS LETT, V521, P205, DOI 10.1016-S0014-5793(02)02867-3; MOOLENAAR WH, 1983, NATURE, V304, P645, DOI 10.1038-304645a0; Nielsen MS, 1998, PFLUG ARCH EUR J PHY, V435, P267; Rask-Madsen J, 1990, J Intern Med Suppl, V732, P137; SERNKA TJ, 1982, PROSTAGLANDINS, V23, P411, DOI 10.1016-0090-6980(82)90086-7; SIDOROV JJ, 1976, CLIN BIOCHEM, V9, P117, DOI 10.1016-S0009-9120(76)80032-X; SINGH SK, 1995, J CLIN INVEST, V96, P2373, DOI 10.1172-JCI118294; TAUSSKY HH, 1953, J BIOL CHEM, V202, P675; Thiagarajah JR, 2001, J PHYSIOL-LONDON, V536, P541, DOI 10.1111-j.1469-7793.2001.0541c.xd; TRAYNOR TR, 1993, J PHARMACOL EXP THER, V264, P61; Wakabayashi S, 1997, PHYSIOL REV, V77, P51; YUN CHC, 1995, AM J PHYSIOL-GASTR L, V269, pG122
PGE2 exerts dose-dependent opposite effects on net water and chloride absorption from the rat colon
No full textThis work investigated the effect of different doses of PGE2 on net water and Cl- absorption from the rat colon, using an in situ perfusion technique. PGE2 exerted opposite effects at different concentrations. Net water and Cl- absorption was significantly reduced at low doses with a minimum at 0.4 μg-100 g BW, and significantly elevated at high doses with an observed maximal effect at 21 μg-100 g BW. At low doses, PGE2 increased in superficial cells, the activity of the Na+-K+ ATPase and the protein expression of the Na+K+2Cl- cotransporter, but reduced them in crypt cells. Thus, the reduction in net water and Cl- absorption was ascribed to an increase in secretion by surface cells that masked absorptive processes. At high doses, PGE2 increased significantly the activity of the Na+-K+ ATPase in superficial cells only, and was without any effect on the protein expression of the cotransporter and the pump in both surface and crypt cells. The observed increase in net water and Cl- absorption was attributed in this case to an increase in absorptive processes with no effect on secretion. © 2005 Elsevier Inc. All rights reserved.Abramovitz M, 2000, BBA-MOL CELL BIOL L, V1483, P285, DOI 10.1016-S1388-1981(99)00164-X; ANDRES H, 1985, J PHYSIOL-LONDON, V364, P301; Bachmann O, 2004, AM J PHYSIOL-GASTR L, V287, pG125, DOI 10.1152-ajpgi.00332.2003; BINDER HJ, 1987, GASTROENTEROLOGY, V93, P449; Bos CL, 2004, INT J BIOCHEM CELL B, V36, P1187, DOI 10.1016-j.biocel.2003.08.006; CURRAN PF, 1960, J GEN PHYSIOL, V43, P555, DOI 10.1085-jgp.43.3.555; DAndrea L, 1996, J BIOL CHEM, V271, P28969; Dudeja PK, 1996, AM J PHYSIOL-GASTR L, V271, pG483; FISONE G, 1994, J BIOL CHEM, V269, P9368; FRIELING T, 1994, NEUROGASTROENT MOTIL, V6, P95; Frieling T, 1999, N-S ARCH PHARMACOL, V359, P71, DOI 10.1007-PL00005327; Greger R, 1997, COMP BIOCHEM PHYS A, V118, P271, DOI 10.1016-S0300-9629(96)00304-0; HARGIS L, 1988, ANAL CHEM PRINCIPLES, P314; Hata AN, 2004, PHARMACOL THERAPEUT, V103, P147, DOI 10.1016-j.pharmthera.2004.06.003; Hatae N, 2002, J BIOCHEM, V131, P781; HEBERT RL, 1990, AM J PHYSIOL, V259, P318; HOMAIDAN FR, 1995, ANAL BIOCHEM, V224, P134, DOI 10.1006-abio.1995.1018; Janecki AJ, 1998, J BIOL CHEM, V273, P8790, DOI 10.1074-jbc.273.15.8790; JORGENSEN PL, 1980, PHYSIOL REV, V60, P864; KANDASAMY RK, 1995, J BIOL CHEM, V270, P29209; Kunzelmann K, 2002, PHYSIOL REV, V82, P245; Layne J, 2001, EXP EYE RES, V72, P371, DOI 10.1006-exer.2000.0966; Narumiya S, 1999, PHYSIOL REV, V79, P1193; PETERSON JW, 1989, SCIENCE, V245, P857, DOI 10.1126-science.2549637; Russell JM, 2000, PHYSIOL REV, V80, P211; SARDET C, 1989, CELL, V56, P271, DOI 10.1016-0092-8674(89)90901-X; Schmitz H, 1996, AM J PHYSIOL-GASTR L, V271, pG669; SERNKA TJ, 1982, PROSTAGLANDINS, V23, P411, DOI 10.1016-0090-6980(82)90086-7; SINGH SK, 1995, J CLIN INVEST, V96, P2373, DOI 10.1172-JCI118294; Stewart WC, 1998, GLIA, V23, P349, DOI 10.1002-(SICI)1098-1136(199808)23:4349::AID-GLIA73.0.CO;2-Y; TAUSSKY HH, 1953, J BIOL CHEM, V202, P675; Therien AG, 2000, AM J PHYSIOL-CELL PH, V279, pC541; TRAYNOR TR, 1993, J PHARMACOL EXP THER, V264, P61; TSE CM, 1991, EMBO J, V10, P1957; TSE M, 1993, J MEMBRANE BIOL, V135, P93; Tyagi S, 2000, DIGEST DIS SCI, V45, P2282, DOI 10.1023-A:100567040445655
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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