1,721,063 research outputs found
Direct bone effects of calcimimetics in chronic kidney disease?
No full textCalcimimetics are widely used in patients on dialysis to treat secondary hyperparathyroidism. Our current view is that bone effects are only indirect through parathyroid hormone suppression. However, because bone cells express the calcium-sensing receptor, direct calcium-sensing receptor–mediated effects are also possible. New experimental data demonstrate direct anabolic bone actions of calcimimetics, independent of parathyroid hormone suppression. Because these effects could be clinically useful, further studies are necessary to confirm the validity of this observation
Calciphylaxis: a conundrum for patients and nephrologists?
No full textIn 1961 Selye actively induced soft tissues calcification and necrotic eschars in rats using first “sensitizing agents” (injections of parathyroid glands extract, high dose vitamin D, high phosphate diets) and then “challenging agents” (local trauma or injection of egg white or ferric dextran). The resulting phenomenon, reproduced also in nephrectomised rats, was interpreted as hypersensitivity reaction and thus named “calciphylaxis” (from calcium and anaphylaxis) [1]. Years later, similar cutaneous lesions were described in patients with chronic renal failure (CRF) and, since then, a huge number of cases have been recorded. Nowadays calciphylaxis is defined as a condition of small arterioles calcification with eventual micro-vessels occlusion resulting in thrombus formation and tissue necrosis. As such, calciphylaxis is a rare (registered in orphan.net as ORPHA280062) and possibly underdiagnosed disease
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
Dialysate calcium concentration during calcimimetic treatment: a neglected issue
No full textHypocalcaemia is a well-known effect of the treatment of
secondary hyperparathyroidism when using calcimimetics.
In a retrospective, observational, study, which was published
recently in this Journal [1], Louie et al. investigated
the frequency, predictors, and consequences of cinacalcetinduced
hypocalcaemia in a cohort of over one thousand
haemodialysis patients. They found that hypocalcaemia
occurred in more than two third of the treated patients
and was mild in many cases. Nonetheless, in one third it
was moderate (1.87– < 2.0 mmol/L; 23%) or even severe
(< 1.87 mmol/L; 9%). These results coming from a “realworld”
setting raise questions on the true potentially negative
impact of hypocalcaemia per se or of its treatment,
including the increase of dialysate calcium concentration
Foreword
No full textClinical practice guidelines serve many purposes. First and
foremost, guidelines help clinicians and other caregivers deal
with the exponential growth in medical literature. It is
impossible for most busy practitioners to read, understand,
and apply a rapidly changing knowledge base to daily clinical
practice. Guidelines can help fill this important need
Interaction between Vitamin D and calcimimetics in chronic kidney disease
No full textFor many years vitamin D has been the only available drug to suppress parathyroid hormone (PTH) hypersecretion in patients with renal insufficiency. This effect is accomplished directly through activation of the vitamin D receptor (VDR) on parathyroid cells. However, vitamin D also stimulates intestinal absorption of calcium and phosphate, thus often resulting in hypercalcemia and hyperphosphatemia, both undesirable in renal patients. For this reason vitamin D analogs with less calcemic effects have been developed, with some improvement of this problematic effect. The discovery of calcium sensing receptor (CaSR) and the subsequent production of drugs capable of stimulating it, has allowed the introduction of calcimimetics as an alternative therapy to vitamin D. Cinacalcet, the first to be available for clinical uses, has been successfully employed to reduce serum PTH levels in patients with end stage renal disease. At variance with vitamin D, calcimimetics, while decreasing PTH, also decrease serum levels of calcium and phosphate. The effect on serum calcium is of such entity that symptomatic hypocalcemia may occur. As a consequence, vitamin D is frequently associated and instead of becoming an alternative, cinacalcet is mostly prescribed together with vitamin D. Importantly, we have clear experimental evidence that vitamin D administration increases the expression of CaSR on target cells and that, reciprocally, calcimimetics increase VDR expression. This interaction allows presuming potential clinical advantages to control secondary hyperparathyroidism. Further, since both VDR and CaSR are expressed also in tissues not involved with mineral metabolism, other still unpredicted clinical effects are possible
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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