1,720,958 research outputs found
Renal involvement in subjects with peripheral atherosclerosis
No full textBackground: Ischemic nephropathy is an important cause of renal failure in western countries. Subclinical renal function abnormalities may exist in patients wi[th extrarenal atherosclerosis, and may precede the onset of overt ischemic nephropathy.
Methods: To assess the impact of extrarenal atherosclerosis on the kidney, we evaluated renal function in 89 subjects with differing degrees of peripheral atherosclerosis, without manifest clinical or laboratory signs of ischemic nephropathy and renovascular hypertension. All laboratory testing, ultrasonography with Doppler analysis for the localization of peripheral vascular disease (carotid and lower limb arteries), and non-invasive evaluation of renal function by radionuclide studies of renal plasma flow (MAG(3) clearance) and glomerular filtration (DTPA clearance), as well as total, LDL and HDL cholesterol, and triglycerides were determined; smoking habit was recorded. By combining sonographic data on arterial tree stenosis (ATS), the subjects were grouped according to the atherosclerotic vascular damage (ATS involvement).
Results: Despite no change in plasma creatinine and DTPA clearance (from 91.58 +/- 26.53 mL/min /1.73 m(2) to 93.47 +/- 24.82), MAG(3) clearance progressively declined with the severity of vascular damage (from 244.86 +/- 60.60 mL/min/1.73 m(2) to 173.59+/-58.74). Stepwise multiple regression analysis indicated that MAG(3) clearance was best explained by ATS involvement (standardized beta coefficient -0.40; p<0.001), smoking habit (-0.34; p= 0.004), and scrum LDI-cholesterol (-0.24; p<0.035).
Conclusions: The renal hemodynamic profile in atherosclerotic patients might constitute functional evidence of the silent phase of ischemic renal disease. The findings suggest that renal function should be carefully assessed in patients with extrarenal atherosclerosis, particularly in those with classic cardiovascular risk factors
Dietary fatty acid supplementation modulates the urinary excretion of calcium and oxalate in the rat. Insight into calcium lithogenesis
No full textAn anomalous plasma phospholipid polyunsaturated fatty acid composition has been reported in calcium nephrolithiasis, and was proposed to play a crucial role in the pathogenesis of hypercalciuria and hyperoxaluria, well-known risk factors for lithogenesis. Methods: To confirm this hypothesis, we administered rats three different diets rich in coconut, soybean and fish oils, and evaluated their effect on plasma urinary calcium and oxalate excretion, since the quality of fatty acids represents an important factor able to influence the activity of delta-6-desaturase, the rate-limiting enzyme in the biosynthetic pathway of highly unsaturated fatty acids. Results: In comparison with coconut and fish oil, dietary supplementation with soybean oil increased plasma phospholipid arachidonic acid and serum 1,25-vitamin D-3 values, as well as renal tissue calcium content and urinary excretion of sodium, oxalate and calcium. Conclusions: Our findings demonstrate that the quality of fatty acids may modify the urine excretion of calcium and oxalate, confirming our previous hypothesis of a pathogenetic link between cellular membrane phospholipid polyunsaturated fatty acid composition and calcium nephrolithiasis. In addition, our study provides new in-sights into the relationship between dietary, environmental factors and renal stone diseas
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
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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