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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
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
Effects of atrial natriuretic factor on blood pressure and the renin-angiotensin-aldosterone system.
No full textAtrial natriuretic factor (ANF) antagonizes vasoconstriction induced by numerous smooth muscle agonists and also lowers blood pressure in intact animals. ANF has particularly marked relaxant effects on angiotensin II-contracted vessels in vitro. Sensitivity to the blood pressure-lowering effect of ANF in vivo appears to be enhanced in renin-dependent models of renovascular hypertension compared with other experimental hypertensive models. The depressor action of low, possibly physiological doses of ANF in two-kidney, one-clip Goldblatt rats is due to a decrease in total peripheral resistance. On the other hand, high doses of ANF can lower cardiac output, particularly in volume-expanded models such as deoxycorticosterone-salt hypertension. ANF markedly inhibits renin secretion in intact animals, probably via increased glomerular filtration rate and load of sodium chloride to the macula densa. This effect is masked when renal perfusion is impaired (e.g., via unilateral renal artery constriction), in which case ANF may stimulate renin secretion slightly. ANF also reduces plasma aldosterone in vivo and inhibits basal and agonist-induced aldosterone release from isolated adrenal cortical cells. This effect appears to be especially marked for angiotensin-induced aldosterone production in vivo and in vitro. These findings indicate that ANF has potentially important interactions with the renin-angiotensin-aldosterone system and suggest a role for ANF in the homeostatic control of blood pressure as well as of extracellular fluid volume
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
CLEARANCE RECEPTOR AND NEUTRAL ENDOPEPTIDASE-MEDIATED METABOLISM OF ATRIAL-NATRIURETIC-FACTOR
No full textA novel small linear C-atrial natriuretic factor receptor ligand [C-ANF-(11-15)] and phosphoramidon (PHO) were used to determine the effects of C-ANF receptor blockade alone, or in combination with inhibition of neutral endopeptidase (NEP), on the pharmacokinetics and-metabolism of ANF in the rat. C-ANF-(11-15) infusion decreased apparent volume of distribution (V(ss)) and metabolic clearance rate (MCR) of administered I-125-ANF-(1-28) to one-third of their control values, whereas PHO alone was without effect on these parameters. In combination with C-ANF(11-15), however, PHO further decreased MCR of I-125-ANF(1-28) and increased plasma half time by more than threefold. High-performance liquid chromatography analysis revealed that C-ANF-(11-15) inhibited the delayed appearance of free I-125 and [I-125] monoiodotyrosine but had no effect on the small proportion of NEP metabolites in plasma. The combination of C-ANF-(11-15) and PHO further delayed the appearance of small metabolites, abolished the appearance of NEP metabolites, and markedly prolonged the permanence of intact I-125-ANF-(1-28) in plasma. The results demonstrate that C-ANF receptor blockade by C-ANF-(11-15) impairs clearance and metabolism of ANF, an effect which is synergistically potentiated by concomitant inhibition of NEP. C-ANF-(11-15) alone or in combination with NEP inhibitors may be a potentially useful therapeutic tool in the treatment of cardiovascular and renal diseases
DYNAMICS OF ATRIAL NATRIURETIC FACTOR-GUANYLATE CYCLASE RECEPTORS AND RECEPTOR-LIGAND COMPLEXES IN CULTURED GLOMERULAR MESANGIAL AND RENOMEDULLARY INTERSTITIAL-CELLS
No full textThe dynamics of the guanylate cyclase receptor of atrial natriuretic factor (GC(A)-ANF receptor) were investigated in cultured glomerular mesangial and renomedullary interstitial cells from the rat. In these cells, the GC(A)-ANF receptor did not mediate internalization and lysosomal hydrolysis of I-125-ANF1-28 and did not undergo ligand-induced endocytosis. Glomerular mesangial cells were able, however, to mediate internalization and lysosomal hydrolysis of I-125-ANF1-28 via clearance ANF (C-ANF) receptors and to promote rapid receptor-mediated internalization and lysosomal hydrolysis of I-125-(Sar1) angiotensin II. Radioligand specifically bound to surface GC(A)-ANF receptors was rapidly dissociated at 37-degrees-C (k(off) > 0.8 min-1), with a Q10(30-37-degrees-C) > 6. The dissociation was markedly slower at subphysiological temperatures (Q10(4-30-degrees-C), 2-3) or in the presence of 0.5 mM amiloride. The results demonstrate that the GC(A)-ANF receptor, contrary to C-ANF receptors and most other polypeptide hormone receptors, is a membrane resident protein that does not mediate internalization and lysosomal hydrolysis of ligand. The termination of the interaction of ANF with GC(A)-ANF receptors results from a physiological process that leads to rapid dissociation of receptor-ligand complexes. The unique dynamics of GC(A)-ANF receptor-ligand complexes are likely to contribute importantly to stimulus-response homeostasis of ANF
Cardiovascular effects of atrial natriuretic factor in anesthetized and conscious dogs.
No full textAtrial natriuretic factor lowers blood pressure in normotensive and hypertensive animal models. The present study examined the mechanism of the blood pressure-lowering effect in 10 normotensive dogs. Four awake dogs previously instrumented with electromagnetic flow probes for measurement of cardiac output and catheters for systemic hemodynamic and cardiac dynamic measurements were studied. After a 30-minute control period, a 3 micrograms/kg bolus followed by 0.3 micrograms/min/kg of a 24-residue synthetic atrial natriuretic factor was infused for 30 minutes, followed by a 1-hour recovery period. Mean arterial pressure fell significantly during infusion (control, 125 +/- 4; infusion, 108 +/- 5; recovery, 125 +/- 9 mm Hg; p less than 0.05) and was accompanied by a slight but significant bradycardia (control, 144 +/- 7; infusion, 134 +/- 5; recovery, 145 +/- 7 beats/min; p less than 0.05). Significant reductions in cardiac output (control, 2.66 +/- 0.60; infusion, 2.18 +/- 0.60; recovery, 2.74 +/- 0.60 L/min; p less than 0.05), stroke volume (control, 18.4 +/- 3.9; infusion, 16.0 +/- 4.2; recovery, 19.0 +/- 3.7 ml/beat; p less than 0.05), and maximum increase in rate of change of left ventricular systolic pressure (control, 2475 +/- 200; infusion, 2088 +/- 216; recovery, 2487 +/- 243 mm Hg/sec; p less than 0.05) were also observed during infusion. No significant changes in total peripheral resistance or central venous pressure were noted, although the latter tended to fall during infusion. A similar pattern was observed in six pentobarbital-anesthetized dogs, except that infusion of atrial natriuretic factor did not induce bradycardia.(ABSTRACT TRUNCATED AT 250 WORDS
Relationship between renal hemodynamic and natriuretic effects of atrial natriuretic factor.
No full textMolecular determinants of the clearance function of type C receptors of natriuretic peptides
No full textReceptor-mediated endocytosis is the cellular mechanism by which type C receptors of natriuretic peptides exert their clearance function. In the present work, performed in recombinant Chinese hamster ovary cells stably transfected with wild type or mutated human kidney C receptors we determined net endocytic rates (ER) of C receptor-ligand complexes, lysosomal hydrolysis of ligand (I-125-labeled native atrial natriuretic factor, ANF(1-28)), and receptor recycling, Equilibrium ligand binding, immunocytochemistry, and immunoprecipitation were performed to characterize the transfected receptors, The net ER of recombinant wild type C receptors was similar to 6% of occupied receptors internalized per min, and C receptor-mediated lysosomal hydrolysis of ligand amounted to similar to 250% of specifically bound I-125-ANF(1-28)/h, with efficient recycling of internalized C receptors to the cell surface. Hypertonic sucrose reduced net ER and lysosomal hydrolysis of I-125-ANF(1-28) more than 10-fold, indicating that endocytosis occurred via clathrin-coated pits. Total deletion of the cytoplasmic domain also reduced net ER and lysosomal hydrolysis of I-125-ANF(1-28) by almost 10-fold whereas deletion of the terminal 28 amino acids of the cytoplasmic tail led to a 4-fold reduction in these parameters, Replacement of cytoplasmic domain Tyr(508) by Ala, or Tyr(508) and Phe(538) by Ala, reduced net endocytosis and lysosomal hydrolysis of I-125-ANF(1-28) by 40-50%. Replacement of extracellular domain Cys(473) by Ala impeded the constitutive formation of homodimers and reduced by similar to 50% the net ER and lysosomal hydrolysis of I-125-ANF(1-28). These results demonstrate that the cytoplasmic domain of C receptors, Tyr(508) within this domain, and constitutive receptor dimerization are the major molecular determinants of the clearance function of C receptors
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