1,721,012 research outputs found
Natriumphosphat enthaltende Darmreinigungsmittel – eine Gefahr für die Niere?
Get PDFThere are several well-documented cases of acute irreversible renal failure involving renal calcium phosphate deposits after the use of bowel preparations containing sodium phosphate (e.g., Colophos®).
- Neither randomised clinical nor epidemiological studies have established an
association between sodium phosphate use and renal damage in patients without preexisting renal dysfunction.
- However, it is likely that patients with preexisting renal dysfunction and other risk factors were not sufficiently represented and analysed in these studies, and may be at increased risk of (further) renal damage through sodium phosphate.
- Recommendations for clinical practice:
1. Routine determination of renal function through GFR estimation before prescription of bowel cleansing preparations containing sodium phosphate.
2. If sodium phosphate is administered, sufficient hydration is crucial: 2 L of fluids should be consumed with each 90 ml bottle of Colophos®.
3. Sodium phosphate should not be used in patients with preexisting renal dysfunction (GFR <60 ml/min), and in those with other risk factors (heart failure, concomitant use of ACE inhibitors, angiotensin receptor blockers and diuretics, preexisting dehydration and electrolyte disorders, old age). Bowel preparations containing polyethylene glycol (e.g., Cololyt®) should be given to these patients
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Low membrane protein sulfhydrils but not G6PD deficiency predict ribavirin-induced hemolysis in hepatitis C
No full textHemolysis is a frequent adverse effect of ribavirin (RBV). It has been suggested that oxidative stress plays a role, but mechanisms and predictive risk factors for severe forms remain unknown. Markers of redox status were determined in erythrocytes of 34 patients with hepatitis C-four of them with glucose-6-phosphate-dehydrogenase (G6PD) deficiency-before and during treatment with RBV and interferon (IFN) and were compared with 10 healthy control subjects. In addition, erythrocytes were incubated with RBV, and the effects of dipyridamole (DPD), diethylmaleate (DEM), and glutathione ester (GSHE) were studied in vitro. Of the 30 patients without G6PD deficiency who were treated with RBV and IFN-alpha, five developed major hemolysis (Delta hemoglobin > 6 g/dL) and 25 developed minor hemolysis (Delta hemoglobin < 2.5 g/dL). Patients with major hemolysis had lower median pretreatment values of membrane protein sulfhydrils than patients with minor hemolysis (28.4 vs. 36.7 nmol/mg, P <.001). Erythrocytes of G6PD-deficient patients were not more susceptible to RBV-induced hemolysis. In in vitro incubations of erythrocytes, DEM enhanced the RBV-induced decrease of glutathione, protein sulfhydrils, and osmotic resistance. Supplementation of GSHE and DPD prevented the RBV-induced decrease in osmotic resistance, adenosyl triphosphate (ATP), and 2,3-diphosphoglycerate (DPG), the loss of glutathione and protein sulfhydrils, and the formation of thiobarbituric acid reactive substances (TBARs). In conclusion, the data indicate that low membrane protein sulfhydrils prior to therapy but not G6PD deficiency are predictive of RBV-induced major hemolysis. In vitro, GSHE and DPD reduce the RBV-associated oxidative stress in erythrocytes and prevent the increase in osmotic fragility, suggesting that these compounds might decrease the risk of hemolysis in patient
Glutathione peroxidase, thioredoxin, and membrane protein changes in erythrocytes predict ribavirin-induced anemia
No full textOBJECTIVE:
Low erythrocyte membrane protein sulfhydril concentrations are a risk factor for ribavirin-induced anemia. We further studied the role of oxidative stress and erythrocyte membrane alterations in ribavirin-induced anemia.
METHODS:
The levels of thioredoxin, glutathione peroxidase, protein sulfhydrils, and protein-mixed disulfides, as well as the electrophoretic membrane protein pattern, were determined in freshly isolated erythrocytes from healthy control subjects, patients without severe anemia during previous ribavirin treatment (still hepatitis C virus [HCV]-positive), and patients who had had severe anemia with ribavirin (still HCV-positive or HCV-negative), 6 months after full recovery. Erythrocytes were also incubated with buffer, ribavirin, phenylhydrazine, or dehydroepiandrosterone, and concentrations of protein sulfhydrils, protein-mixed disulfides, thiobarbituric acid-reactive substances, and total and oxidized glutathione, as well as osmotic resistance, were determined.
RESULTS:
Patients with previous severe ribavirin-induced anemia had lower levels of protein sulfhydrils (30.9 nmol/mg protein versus 43.2 nmol/mg protein, P<.001) and thioredoxin (0.6 nmol/g hemoglobin versus 1.2 nmol/g hemoglobin, P<.001), higher levels of protein-mixed disulfides (1.5 nmol/g hemoglobin versus 0.5 nmol/g hemoglobin, P<.001) and glutathione peroxidase (618 mU/mg protein versus 393 mU/mg protein, P<.001), and a membrane protein pattern consistent with band 4 dimer disaggregation. These differences were independent of HCV seropositivity. There were negative correlations between levels of glutathione peroxidase and thioredoxin (r=-0.87) and between levels of protein sulfhydrils and protein-mixed disulfides (r=-0.93). In vitro studies showed that erythrocytes of patients who had had hemolysis during treatment of HCV are more susceptible to oxidative stres
Ribavirin-induced anemia: mechanisms, risk factors and related targets for future research
No full textRibavirin (RBV) is an antiviral nucleoside analogue commonly used in combination with interferon for the treatment of chronic hepatitis C. Severe anemia develops in about 10% of treated patients, and requires close monitoring of hemoglobin and often RBV dose reduction, which may compromise sustained virologic response. Anemia is likely related to extensive RBV accumulation in erythrocytes subsequent to active unidirectional transmembraneous transport. RBV exerts its toxicity through an inhibition of intracellular energy metabolism and oxidative membrane damage, leading to an accelerated extravascular hemolysis by the reticulo-endothelial system. Concentration-dependent toxicity and improvement of anemia upon dose-reduction point towards the importance of pharmacokinetic factors for RBV-induced anemia. On the other hand, pronounced variability in the correlation between RBV concentration and Hb reduction limits the prediction of anemia based on plasma or erythrocyte concentrations in individual patients and points towards additional factors determining individual susceptibility to RBV-induced anemia. Recent studies suggest that erythrocyte oxidative defense mechanisms may play an important role in RBV-induced anemia. Clinical risk factors for severe RBV-induced anemia include impaired renal function, high age, high dose per body weight and female gender. Determination of RBV concentrations has little value in the management of anemia. The only proven effective prevention of RBV-induced anemia is the concomitant administration of erythropoietin. Future research on RBV pharmacokinetics and pharmacodynamics, as well as erythrocyte antioxidant defense mechanisms may improve safety and efficacy of RBV therapy and guide the development of new treatments for RBV-induced anemia and alternative antiviral agent
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
- …
