1,720,956 research outputs found
Hydrogen Breath Test - Diet and Basal H-2 Excretion: A Technical Note
No full textBackground: Hydrogen breath tests are widely used in clinical practice. For a correct evaluation of data, low basal H 2 excretion is required, thus, 12-hour fasting is usually prescribed. An additional reduction in the intake of complex carbohydrates in the preceding 24 h is suggested in some centers. The issue, however, has never been directly investigated. Aim: The aim of the present study was to analyze the effect of the pretest diet on the basal H 2 excretion and the number of subjects excluded from the test due to high basal H 2 excretion. Methods: Two cohorts of 500 consecutive patients undergoing a lactose tolerance test in the years 19971998 (when 12-hour fasting was required) and in 2007-2008 (when a low-carbohydrate diet in the preceding 24 h was also prescribed) were retrospectively reviewed. Results: The mean basal H 2 excretion was significantly lower (p < 0.0001) in the low-carbohydrate diet group (2.46 +/- 6.8 vs. 4.73 +/- 3.3 ppm). In 1997-1998, 46/500 patients (9.2%) were excluded from the test due to basal H 2 values as compared to 7/500 (1.4%) in the period 2007-2008. Discussion: To the best of our knowledge, ours is the first study to provide objective data on the advantage offered by reducing the intake of complex carbohydrates before H 2 breath tests. Copyright (C) 2010 S. Karger AG, Base
Hydrogen breath test for the diagnosis of lactose intolerance, is the routine sugar load the best one?
No full textAIM: To evaluate the prevalence of lactose intolerance (LI) following a load of 12.5 g in patients diagnosed as high-grade malabsorbers using the hydrogen breath test (HBT)-25. METHODS: Ninety patients showing high-grade malabsorption at HBT-25 were submitted to a second HBT with a lactose load of 12.5 g. Peak hydrogen production, area under the curve of hydrogen excretion and occurrence of symptoms were recorded. RESULTS: Only 16 patients (17.77%) with positive HBT-25 proved positive at HBT-12.5. Hydrogen production was lower as compared to HBT-25 (peak value 21.55 parts per million (ppm) +/- 29.54 SD vs 99.43 ppm +/- 40.01 SD; P < 0.001). Symptoms were present in only 13 patients. The absence of symptoms during the high-dose test has a high negative predictive value (0.84) for a negative low-dose test. The presence of symptoms during the first test was not useful for predicting a positive low-dose test (positive predictive value 0.06-0.31). CONCLUSION: Most patients with a positive HBT-25 normally absorb a lower dose of lactose and a strict lactose restriction on the basis of a "standard" HBT is, in most instances, unnecessary. Thus, the 25 g lactose tolerance test should probably be substituted by the 12.5 g test in the diagnosis of LI, and in providing dietary guidelines to patients with suspected lactose malabsorption/intolerance. (C) 2008 The WJG Press. All rights reserved
254 Diagnosis of lactose intolerance and the "nocebo" effect: The role of negative expectations.
No full textBACKGROUND: Diagnosis of lactose intolerance is based on a "positive" H(2) breath test associated with abdominal symptoms. The present study established to what extent the occurrence of symptoms during a "negative" H(2) breath test may result from a "nocebo effect" instead of lack of sensitivity of the procedure. METHODS: Between 2005 and 2007, 636 outpatients performed a standard 4-h 25g lactose tolerance test. The test was positive in 254, negative in 325, and 57 patients were H(2) "non-producers". Twenty-seven patients reporting symptoms despite a negative H(2) breath test underwent a "sham" breath test following ingestion of 1g of glucose. Fifty-four patients presenting with documented lactose intolerance were used as controls. RESULTS: Twelve out of 27 patients (44.4%), and unexpectedly also 14 (25.9%) controls presented abdominal symptoms during the sham test. The difference between the two groups was not significant (P0.15) OR 2.28; C.I. 0.77-6.78. CONCLUSION: In most instances, symptoms reported by patients during a negative lactose H(2)BT cannot be attributed to a false-negative test. Instead, a non-organic component, resulting from negative expectations ("nocebo effect") is likely implicated. Moreover, also in patients diagnosed as lactose intolerant, the need for restricting the primary source of dietary calcium should be critically reconsidered
Extraintestinal manifestations in a large series of Italian inflammatory bowel disease patients
No full textAIM:
To investigate prevalence, type and time of onset of extraintestinal manifestations (EIMs) in a series of Italian inflammatory bowel disease (IBD) patients.
METHODS:
Data of 811 IBD consecutive patients, first referred to our Centre from 2000 to 2011, were retrospectively evaluated.
RESULTS:
Eight hundred and eleven IBD patients (437 M, 374 F) were studied: 595 ulcerative colitis (UC) (73.4%) and 216 Crohn's disease (CD) (26.6%). Among these, 329 (40.6%) showed EIMs: 210 UC (35.3%) and 119 CD (55.1%) (P < 0.0001). Considering the time of the diagnosis of IBD, 37 EIMs (11.2%) were developed before, 229 (69.6%) after and 63 (19.2%) were simultaneous. The type of EIM were as follows: 240 musculoskeletal (29.6%), in 72 CD patients and in 168 UC (P < 0.0001); 47 mucocutaneous (5.8%), in 26 CD and in 21 UC (P = 0.0049); 26 ocular (3.2%), in 16 CD and in 10 UC (CD 7.4% vs UC 1.7%, P = 0.0093); 6 hepatobiliary (0.8%); 10 endocrinological (1.2%). In particular, with regards to the involvement of the musculoskeletal system, arthritis Type 1 was found in 41 CD (19%) and in 61 UC (10.2%) (P = 0.0012) and Type 2 in 25 CD (11.6%) and in 100 UC (16.8%) (P = 0.0012).
CONCLUSION:
Mucocutaneous manifestations, arthritis Type 1 and uveitis were significantly more frequent in CD than UC. The complications of the musculoskeletal system were the mostly observed ones, often with symptoms more severe than intestinal ones, confirming the need for close cooperation with rheumatologists
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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