1,721,027 research outputs found
Angiotensin II binding sites in the rat pancreas and their modulation after sodium loading and depletion
No full textSpecific 125I angiotensin II binding sites were identified in the rat pancreas by radioreceptor assay, autoradiography and immunohistochemistry. Scatchard analysis of the binding in normal rats yielded a Kd of 0.51 ± 0.23 nM with a Bmax of 15 ± 3.5 fmol/mg protein (means ± SD, n = 6). Changed plasma sodium concentration resulted in modifications in the binding affinity and capacity. Sodium loading depressed both Kd (0.36 ± 0.1 nM) and Bmax (6.4 ± 0.1 fmol/mg protein), while sodium depletion elevated both Kd (2.03 ± 0.3 nM) and Bmax (45 ± 3.5 fmol/mg protein) (means ± SD, n = 6). Autoradiography using 125I Ang II and immunohistochemistry of the binding sites saturated with unlabeled Ang II and incubated with Ab-Ile5 Ang II, revealed localization of the binding sites on the islet cell membranes and in the exocrine pancreas
Key enzymes of the kallikrein-kinin system in antarctic teleosts
No full textIn this study, some of the mammalian kallikrein-kinin system (KKS)-like components were identified in two species of Antarctic notothenioid [Chionodraco hamatus (Channichthydae) and 1remato- mus bernacchii (Nothothenidae)]. The kidney and heart were assayed for kallikrein-like activity using the syn- thetic substrate D-Val-Leu-Arg-paranitroanilide. Values expressed as nmol p-nitroanilide/mg proteins, were in C. hamatus 15.51.4 in kidney and heart, respectively, and 15.81 in kid- ney and heart of 1. bernacchii. Kallikrein-like activity was inhibited by aprotinin and phenylmethylsulfonyl fluoride (PMSF). The assay was stable at 20°C. Kininase II-like activity was performed on kidney, gills and heart using the substrate hippuryl-L-histidyl-L- leucine. The activity was inhibited by captopril, and in kidney and gills by high temperatures (20°C and 37°C); in the heart the enzymatic activity was measurable also at 20°C. Bradykinin-like immunoreactive cells were localized by immunohistochemistry in the nephron, in the gills, and in the arterial walls of the heart. These results show that Antarctic teleosts possess elements comparable to those of the KKS, including kallikrein- like, and kininase II-like activities, and the end product of the enzymatic cascade, bradykinin. The enzymatic cascade appears to be fully active only at low temper- atures
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
Angiotensin II vascular receptors in fetal and neonatal rats
No full textSpecific binding sites for angiotensin II in aorta and renal arteries have been studied in rat fetuses (18th day of pregnancy) and 1-day-old newborn rats by binding studies in arterial membranes using [125I] ileu-5-angiotensin II. One type of angiotensin receptor was found both in fetuses and in the newborns; the capacity of this (RT) decreased immediately after birth (from 0•06 ± 0•01 nM to 0•02 ± 0•005 nM; ± SEM) and the affinity (Kd) increased at birth (from 3•5 ± 0•6 nM to 19•5 ± 1•2 nM; ± SEM). Localization of the specific binding sites was studied by autoradiography on arteries from fetal and newborn rats either perfused with iodinated angiotensin II by cannulation of the aorta or in vitro on cryostat sections incubated with the radioactive angiotensin II. Both in fetuses and in the newborn the binding sites were located in the tunica media of the arteries
Osmotic stress, plasma renin activity, and spermatogenesis in Vipera aspis.
No full textCirculating electrolytes (Na+, K+), plasmarenin-like activity, testosterone, and testis morphology were investigated in early summer during the spermatogenic progressive phase in Viperaaspis subjected to sodium loading and sodium depletion. After sodium loading, plasma sodium and plasma testosterone levels were significantly elevated compared with those of controls, while plasmarenin-like activity was depressed, spermiogenesis was increased, the epithelium lining the epididymis was very thick, and the Leydig cells were hypertrophied. After sodium depletion, plasma sodium and plasma testosterone levels were significantly depressed and plasmarenin-like activity was significantly elevated. Spermiogenesis seemed to be slightly regressed: the epithelium lining the epididymis was very thin, and the lumen was devoid of spermatozoa. The Leydig cells were hardly visible. All the data strongly suggest that osmoticstress affects gonadal activity in the snake. V. aspis
Immunoreactive localization of vasoactive hormones (Atrial natriuretic peptide and endothelin) in the heart of Protopterus annectens, an African lungfish
No full textThe present study demonstrated, by immuno- histochemistry and Western blotting, the presence of im- munoreacting atrial natriuretic peptide (ANP) and endo- thelin in the heart of Protopterus annectens by both light and electron microscopy. The distribution of ANP gran- ules was investigated. ANP granules were localised in myocytes from the atrium, ventricle and conus arterio- sus; endothelin-1 (ET-1) was demonstrated in subendo- cardial myocytes of the atrium and the conus. No ET-1 immunoreactivity was observed in the ventricle wall. At the light-microscopical level, ET-1 appeared to occur in the endocardium, but at the electron-microscopical level no immunogold labelling was seen on the granules of the endocardial cells. It is suggested that ET-1 is pro- duced and stored in the subendocardial cells and re- leased into the subendocardial space to reach the ANP- producing myocytes and the endothelial cells
Renin-like activity, angiotensin I converting enzyme-like activity and osmoregulatory peptides in the dogfish rectal gland
No full textRenin-like activity (RLA) and angiotensin I-converting enzyme-like activity (ACELA), two key enzymes of the renin-angiotensin cascade (RAS), were sought in the dogfish rectal gland. RLA was 1.1 +/- 0.2 ng Ang I/mg protein/hr after incubation with porcine angiotensinogen and 0.8 +/- 0.1 ng Ang I/mg protein/hr after incubation with homologous plasma. ACELA was 7.22 +/- 1.08 and 8.87 +/- 1.9 nmol hippurate generated/min/mg protein respectively, at 0 and 37 degrees. The presence of these enzymes may indicate the presence of an endogenous RAS-like system in the rectal gland. Angiotensin II (Ang II) and atrial natriuretic peptide (ANP) binding sites were demonstrated autoradiographically in the subcapsular region of the gland, suggesting a possible interaction of the two hormones in the blind outer ends of the rectal gland tubules. Immunoreactivities toward Ang II, ANP, bombesin, vasoactive intestinal polypeptide (VIP), glucagon, and somatostatin were differentially localized in the rectal gland within three concentric zones with potentially different functional activities. In the capsule, there was a strong positive ir-glucagon reaction and a slightly weaker reaction for ir-somatostatin and VIP. In the blind outer ends of the tubules (in the subcapsular zone), strong immunoreactivity was present toward all the tested peptides except glucagon and somatostatin. In the inner zone and in the central canal, only a weak immunoreactivity toward Ang II and glucagon was observed
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