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A systematic evaluation of bioelectrical impedance measurement after hemodialysis session.
No full textABSTRACT
BACKGROUND: There is still no definitive indication about the ideal point of time to perform bioimpedance analysis (BIA) in hemodialysis patients. Furthermore, the interpretation of data in this regard is difficult because there is still no comprehensive information about the fluctuations in BIA variables occurring in these subjects. The aim of this study was to assess BIA changes occurring in hemodialysis and specifically in the dry-weight state.
METHODS: We studied 27 anuric patients (20 males and 7 females; age 56.1 +/- 13.7 years) on chronic hemodialysis. Single-frequency BIA (R, resistance; Xc, reactance; and PhA, phase angle) was performed (1) before and at the end of hemodialysis (dialysis period); (2) 15, 30, 60, 90, and 120 minutes after hemodialysis (postdialysis period); and (3) 24, 48, and 68 hours after hemodialysis (interdialysis period).
RESULTS: Body weight decreased by 2.8 +/- 0.8 kg during hemodialysis, was unchanged during the postdialysis period, and progressively rose during the interdialysis period. At the same time, BIA variables significantly increased during hemodialysis (R, 453 +/- 74 and 542 +/- 98 ohm; Xc, 38 +/- 10 and 53 +/- 16 ohm; P < 0.05), remained stable over the 120-minute period after treatment (R, 538 +/- 94, 539 +/- 95, 538 +/- 94, 541 +/- 95, and 544 +/- 95 ohm; and Xc, 53 +/- 15, 53 +/- 15, 51 +/- 16, 52 +/- 16, and 52 +/- 16 ohm; NS), and subsequently declined [R, 471 +/- 79 (P= <0.05 vs. postdialysis), 449 +/- 71 (P= <0.05 vs. postdialysis), 424 +/- 68 (P= <0.05 vs. postdialysis) ohm; Xc, 42 +/- 13 (P= <0.05 vs. postdialysis), 37 +/- 10 (P= <0.05 vs. postdialysis), 34 +/- 13 (P= <0.05 vs. postdialysis) ohm]. The stability of BIA measures during postdialysis was confirmed by the constant relationship found between R/height and Xc/height. Also PhA increased after dialysis (4.8 +/- 1.1 degrees vs. 5.7 +/- 1.3 degrees, P < 0.05), was unchanged during the following 120 minutes and decreased in the interdialysis period (5.1 +/- 1.3 degrees, 4.8 +/- 1.0 degrees, and 4.5 +/- 1.1 degrees, P < 0.05). At the end of hemodialysis and during the postdialysis period total body water (TBW) estimated from BIA was similar on average to TBW calculated using Watson formulas (37.2 +/- 6.3 L vs. 36.2 +/- 5.7 L, NS). On the contrary, when patients were hyperhydrated BIA significantly overestimated the Watson's values.
CONCLUSION: In hemodialysis patients BIA variables fluctuate to a considerable extent (with the highest values immediately after hemodialysis), but remain constant and highly reproducible over the 120 minutes after the end of hemodialysis, that is, in a dry-weight state. Thus, taking into consideration that the point in time chosen for performing BIA is crucial to properly assess body composition, BIA can be appropriately performed at anytime during the postdialysis period, provided that hydration status does not change due to food or drink consumption
Inflammation and oxidative stress in chronic kidney disease—potential therapeutic role of minerals, vitamins and plant-derived metabolites
No full textChronic kidney disease (CKD) is a debilitating pathology with various causal factors, culminating in end stage renal disease (ESRD) requiring dialysis or kidney transplantation. The progression of CKD is closely associated with systemic inflammation and oxidative stress, which are responsible for the manifestation of numerous complications such as malnutrition, atherosclerosis, coronary artery calcification, heart failure, anemia and mineral and bone disorders, as well as enhanced cardiovascular mortality. In addition to conventional therapy with antiinflammatory and antioxidative agents, growing evidence has indicated that certain minerals, vitamins and plant-derived metabolites exhibit beneficial effects in these disturbances. In the current work, we review the anti-inflammatory and antioxidant properties of various agents which could be of potential benefit in CKD/ESRD. However, the related studies were limited due to small sample sizes and short-term follow‐up in many trials. Therefore, studies of several anti‐inflammatory and antioxidant agents with long-term follow-ups are necessary
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
Ketoanalogs’ effects on intestinal microbiota modulation and uremic toxins serum levels in chronic kidney disease (Medika2 study)
Full text linkNutritional therapy (NT) is a therapeutic option in the conservative treatment of chronic kidney disease (CKD) patients to delay the start of dialysis. The aim of this study was to evaluate the specific effect of ketoanalogs (KA)-supplemented diets for gut microbiota modulation. In a pre-vious study we observed that the Mediterranean diet (MD) and a KA-supplemented very-low-protein diet (VLPD) modulated beneficially gut microbiota, reducing indoxyl-and p-cresyl-sulfate (IS, PCS) serum levels, and ameliorating the intestinal permeability in CKD patients. In the current study, we added a third diet regimen consisting of KA-supplemented MD. Forty-three patients with CKD grades 3B–4 continuing the crossover clinical trial were assigned to six months of KA-supplemented MD (MD + KA). Compared to MD, KA-supplementation in MD + KA determined (i) a decrease of Clostridiaceae, Methanobacteriaceae, Prevotellaceae, and Lactobacillaceae while Bacteroidaceae and Lachnospiraceae increased; (ii) a reduction of total and free IS and PCS compared to a free diet (FD)—more than the MD, but not as effectively as the VLPD. These results further clarify the driving role of urea levels in regulating gut integrity status and demonstrating that the reduction of azotemia produced by KA-supplemented VLPD was more effective than KA-supplemented MD in gut microbiota modulation mainly due to the effect of the drastic reduction of protein intake rather than the effect of KA
Vascular calcification progression modulates the risk associated with vascular calcification burden in incident to dialysis patients
Full text linkBackground: It is estimated that chronic kidney disease (CKD) accounts globally for 5 to 10 million deaths annually, mainly due to cardiovascular (CV) diseases. Traditional as well as non-traditional CV risk factors such as vascular calcification are believed to drive this disproportionate risk burden. We aimed to investigate the association of coronary artery calcification (CAC) progression with all-cause mortality in patients new to hemodialysis (HD). Methods: Post hoc analysis of the Independent study (NCT00710788). At study inception and after 12 months of follow-up, 414 patients underwent computed tomography imaging for quantification of CAC via the Agatston methods. The square root method was used to assess CAC progression (CACP), and survival analyses were used to test its association with mortality. Results: Over a median follow-up of 36 months, 106 patients died from all causes. Expired patients were older, more likely to be diabetic or to have experienced an atherosclerotic CV event, and exhibited a significantly greater CAC burden (p = 0.002). Survival analyses confirmed an independent association of CAC burden (hazard ratio: 1.29; 95% confidence interval: 1.17-1.44) and CACP (HR: 5.16; 2.61-10.21) with all-cause mortality. CACP mitigated the risk associated with CAC burden (p = 0.002), and adjustment for calcium-free phosphate binder attenuated the strength of the link between CACP and mortality. Conclusions: CAC burden and CACP predict mortality in incident to dialysis patients. However, CACP reduced the risk associated with baseline CAC, and calcium-free phosphate binders attenuated the association of CACP and outcomes, suggesting that CACP modulation may improve survival in this population. Future endeavors are needed to confirm whether drugs or kidney transplantation may attenuate CACP and improve survival in HD patients
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