1,720,965 research outputs found
Impact of vitamin D deficiency on the clinical and biochemical phenotype in women with sporadic primary hyperparathyroidism
No full textThe purpose of the study was to evaluate the relationship between serum 25(OH)D and the clinical phenotype in 215 consecutive Italian Caucasian women with sporadic primary hyperparathyroidism (PHPT) not taking vitamin D supplements. The study was performed at a single Italian tertiary center. PHPT-related manifestations, serum 25(OH)D, and other parameters of calcium metabolism and bone mineral density (BMD) by DXA were recorded. Serum 25(OH)D was negatively correlated with age (r = −0.18; P = 0.006), BMI (r = −0.20; P = 0.002), PTH (r = −0.21; P = 0.001), bone-specific alkaline phosphatase (BSAP) (r = −0.27; P < 0.001), and eGFR (r = −0.22; P = 0.01), and positively with serum creatinine and 1/3 distal radius BMD (R-BMD; r = 0.17; P = 0.015). In a multivariate regression analysis, serum 25(OH)D remained significantly correlated with age (r = −0.18; P = 0.005), BMI (r = −0.23; P = 0.049), serum PTH (r = −0.01; P = 0.023), BSAP (r = −0.01; P = 0.023) and eGFR (r = −0.09; P = 0.001), but not with R-BMD. Serum 25(OHD) was higher in patients with nephrolithiasis than in those without nephrolithiasis (18.5 ± 8.8 vs. 15.6 ± 8.0 ng/ml; P = 0.029), whereas no difference was found between fractured and unfractured patients (16.8 ± 9.3 vs. 16.0 ± 7.7; P = 0.663). There was a statistically significant inverse correlation between vitamin D status [defined by quartiles of measured values as well as commonly accepted cutoffs of serum 25(OH)D] and severity of the disease, as reflected by higher PTH and BSAP, but not by meeting the latest guidelines for parathyroidectomy. In conclusion, a low vitamin D status is associated with some features reflecting a more severe biochemical and clinical phenotype of PHPT in Italian women not taking vitamin D supplements
Calcifediol Rather Than Cholecalciferol for a Patient Submitted to Malabsortive Bariatric Surgery: A Case Report
Full text linkVitamin D deficiency following malabsorptive bariatric surgery can lead to osteomalacia. We report a patient with severe vitamin D deficiency following malabsorptive bariatric surgery successfully treated with calcifediol but not cholecalciferol. A 40-year-old woman, submitted to biliopancreatic diversion 20 years before and chronically treated with 50,000 IU cholecalciferol weekly, was admitted to our Endocrine Unit because of severe lower back pain, muscle weakness, and generalized muscular hypotrophy, associated with hypocalcemia and elevated PTH levels. Initial evaluation revealed low serum albumin, low albumin-corrected serum calcium (7.36 mg/dL), high serum PTH (240 pg/mL), bone-specific alkaline phosphatase (125 μg/L) and 1,25-dihydroxyvitamin D (112 pg/mL) concentrations, undetectable serum 25-hydroxyvitamin D (<7 ng/mL), and evidence of reduced liver function. Bone mineral density was markedly low. Normocalcemia was initially restored with intravenous albumin and calcium gluconate. Treatment with calcitriol (0.5 μg three times daily) and oral calcium carbonate (1000 mg daily) was simultaneously started and cholecalciferol was replaced with calcifediol [125 μg (5000 IU) daily)]. During follow-up the calcifediol dose was progressively tapered to 25 μg (1000 IU) daily and the calcitriol dose was progressively reduced and finally withdrawn. Serum albumin and other biochemical parameters normalized, bone mineral density significantly increased, and the patient's clinical conditions progressively improved, with a substantial recovery of autonomy. Serum vitamin D binding protein at the last observation was in the normal range. Our data suggest that calcifediol might be more efficacious than cholecalciferol for prevention and treatment of vitamin D deficiency in patients treated by malabsorptive bariatric surgery
Development of an algorithm to predict serum vitamin D levels using a simple questionnaire based on sunlight exposure
No full textSun exposure is the main determinant of vitamin D production. The aim of this study was to develop an algorithm to assess individual vitamin D status, independently of serum 25(OHD) measurement, using a simple questionnaire, mostly relying upon sunlight exposure, which might help select subjects requiring serum 25(OHD) measurement. Six hundred and twenty adult subjects living in a mountain village in Southern Italy, located at 954 m above the sea level and at a latitude of 40°50′11′′76N, were asked to fill the questionnaire in two different periods of the year: August 2010 and March 2011. Seven predictors were considered: month of investigation, age, sex, BMI, average daily sunlight exposure, beach holidays in the past 12 months, and frequency of going outdoors. The statistical model assumes four classes of serum 25(OHD) concentrations: ≤10, 10–19.9, 20–29.9, and ≥30 ng/ml. The algorithm was developed using a two-step procedure. In Step 1, the linear regression equation was defined in 385 randomly selected subjects. In Step 2, the predictive ability of the regression model was tested in the remaining 235 subjects. Seasonality, daily sunlight exposure and beach holidays in the past 12 months accounted for 27.9, 13.5, and 6.4 % of the explained variance in predicting vitamin D status, respectively. The algorithm performed extremely well: 212 of 235 (90.2 %) subjects were assigned to the correct vitamin D status. In conclusion, our pilot study demonstrates that an algorithm to estimate the vitamin D status can be developed using a simple questionnaire based on sunlight exposure
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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