1,720,986 research outputs found
Copeptin for risk stratification in acute illness: beyond cardiological problems.
No full textCopeptin for risk stratification in acute illness: beyond cardiological problems
Practicing appropriateness: the case of troponin.
No full textLaboratory testing significantly contributes to the clinical decision making, and the number of tests that a modern clinical laboratory can now perform is considerable. The impact of Laboratory Medicine in Cardiology has substantially evolved and increased over the past years. The cardiac troponin I and T (cTnI and cTnT) are universally regarded as the reference biomarkers for detection of myocardial injury and, understandably, for the diagnosis of myocardial infarction. Novel immunoassays for measurement of cTns have been recently introduced, which are characterized by a considerable improvement of analytical sensitivity and lower imprecision at low concentrations of the proteins. This assays, defined as last generation or high-sensitivity, allow to detect cTn concentrations that were virtually undetectable with the previous methods. On the one hand this has remarkably improved the diagnostic sensitivity for diagnosing myocardial infarction but, on the other, this has reduced the diagnostic specificity. A potential solution of this problem entails diagnostic algorithm based on the serial evaluation of these biomarkers, although the crucial issue still remains the appropriateness of the request. In conclusion, as often occurred in Laboratory Medicine, the leading problem with the use of highly-sensitivity cTn assays is the inappropriateness of ordering and interpretation of test results, and not the biomarker in itself
Blood cells characteristics as determinants of acute myocardial infarction.
No full textBackground: The aim of this study is to analyse the relation between red blood cells, platelets morphology and acute myocardial infarction (AMI), and to assess whether they could supplement the role of traditional cardiac biomarkers in the early identification of patients with AMI. Methods: All consecutive patients admitted to our emergency department between the 1st January and the 31st August 2009 due to chest pain of suspected cardiac origin were included in the study. All the patients underwent physical examination, a 12-lead ECG, blood sampling for determination of cardiac troponin I and a complete blood count. Results: A percentage of 6.7% of the 1971 patients had a confirmed diagnosis of AMI. Mean corpuscular volume (MCV), red blood cells distribution width (RDW) and platelets count (Plt) did not differ between patients with and without AMI. However, the mean platelet volume (MPV) was significantly higher in AMI patients (7.9 vs. 7.7 fL; p=0.0457). After stratification for gender, men with AMI displayed a lower RDW (p=0.0464) and a higher MPV (p=0.0062) as compared with those without AMI. The MCV and Plt were not significantly different. Women with AMI had a higher RDW (p=0.0079) as compared with those without AMI, while the MCV, Plt and MPV were not significantly different. Conclusions: Our study partially confirms previous data on the association between MPV or RDW and AMI. The inclusion of these parameters along with other conventional cardiac biomarkers might be a valuable perspective when evaluating patients with suspected AMI, although gender differences should be taken in account. © 2011 by Walter de Gruyter Berlin Boston
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
Interference of medical contrast media on laboratory testing
Full text linkThe use of contrast media such as organic iodine molecules and gadolinium contrast agents is commonplace in diagnostic imaging. Although there is widespread perception that side effects and drug interactions may be the leading problems caused by these compounds, various degrees of interference with some laboratory tests have been clearly demonstrated. Overall, the described interference for iodinate contrast media include inappropriate gel barrier formation in blood tubes, the appearance of abnormal peaks in capillary zone electrophoresis of serum proteins, and a positive bias in assessment of cardiac troponin I with one immunoassay. The interference for gadolinium contrast agents include negative bias in calcium assessment with ortho-cresolphthalein colorimetric assays and occasional positive bias using some Arsenazo reagents, negative bias in measurement of angiotensin converting enzyme (ACE) and zinc (colorimetric assay), as well as positive bias in creatinine (Jaffe reaction), total iron binding capacity (TIBC, ferrozine method), magnesium (calmagite reagent) and selenium (mass spectrometry) measurement. Interference has also been reported in assessment of serum indices, pulse oximetry and methaemoglobin in samples of patients receiving Patent Blue V. Under several circumstances the interference was absent from manufacturer-supplied information and limited to certain type of reagents and/or analytes, so that local verification may be advisable to establish whether or not the test in use may be biased. Since the elimination half-life of these compounds is typically lower than 2 h, blood collection after this period may be a safer alternative in patients who have received contrast media for diagnostic purposes
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
Evaluation of hematocrit bias on blood glucose measurement with six different portable glucose meters.
No full textINTRODUCTION:
Measurement and monitoring of blood glucose levels in hospitalized patients with portable glucose meters (PGMs) is performed widely and is an essential part of diabetes monitoring, despite the increasing evidence of several interferences which can negatively bias the accuracy of measurements. The purpose of this study was to evaluate the effect of the hematocrit on the analytical performances of different PGMs as compared with a reference laboratory assay.
MATERIALS AND METHODS:
The effect of various hematocrit values (approximiately 0.20, approximiately 0.45 and approximiately 0.63 L/L) were assessed in three whole blood specimens with different glucose concentration (approximiately 1.1, approximiately 13.3, and approximiately 25 mmol/L) by using six different commercial PGMs. The identical samples were also tested with the laboratory reference assay (i.e., hexokinase). The percentage difference from the laboratory assay (%Diff) was calculated as follows: % Diff = average PGM value - value from laboratory assay x 100 / value from laboratory assay.
RESULTS:
The %Diff of the six different PGMs were rather broad, and comprised between 56.5% and -34.8% in the sample with low glucose concentration (approximiately 1.1 mmol/L), between 40% and -32% in the sample with high glucose concentration (approximiately 13.3 mmol/L), and between -50% and 15% in the sample with very high glucose concentration (approximiately 25 mmol/L), respectively. It is also noteworthy that a very high hematocrit value (up to 0.63 L/L) generated a remarkable negative bias in blood glucose (-35%) as measured with the laboratory assay, when compared with the reference sample (hematocrit 0.45 L/L).
CONCLUSION:
The results of this analytical evaluation clearly confirm that hematocrit produces a strong and almost unpredictable bias on PGMs performances, which is mainly dependent on the different type of devices. As such, the healthcare staff and the patients must be aware of this limitation, especially in the presence of extreme hematocrit levels, when plasma glucose assessment with the reference laboratory technique might be advisable
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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