1,721,094 research outputs found
The clinical meaning of histamine skin reactivity
Full text linkThe definition of the “atopic state”, i.e. subjects presenting at least one skin wheal with a minimum diameter of 3
mm induced by an allergen skin-prick test (ASPT), is based on the assumption that wheal size depends entirely on
the amount of histamine produced in the antigen-antibody reaction. Several epidemiological studies have, however,
demonstrated that an ASPT-elicited wheal is heavily modulated by “histamine skin reactivity” (HSR), i.e. the size of
the wheal induced by a prick test performed with a given solution of histamine. HSR not only varies widely
depending on the individual characteristics and geographical setting, but also changes over time; these differences
in HSR markedly influence the amount of specific IgE required to produce a wheal of at least 3 mm in an ASPT. We
should therefore ideally conceive the existence of two types of” atopic patients”: one type in whom “atopy” is mainly
the result of an increased level of specific IgE antibodies, and another type in whom positive ASPTs are mainly the
result of marked skin reactivity to even small amounts of histamine. If hyper-reactivity to histamine occurs not only in
the skin but in parallel also in other parts of the organism, especially at the mucosal level, “normal” histamine
production may cause chronic or recurrent clinical symptom
[Childhood asthma].
No full textThe concept of chronicity in asthma, as emphasized by recent definitions of the disease, rests on the major characteristics of inflammatory response of the airways and progressive development of irreversible structural and functional alterations, or so-called airway remodeling. In childhood, however, such characteristics as chronicity and irreversibility are debatable. Various clinical phenotypes with variable degrees of severity of persistence are found in children. Furthermore, many patients with a history of recurrent wheezing in early infancy do not develop asthma later in life. The prevalence of asthma, especially in its mild forms, has increased markedly in recent years. Although the trend has stabilized in Italy, it continues to rise in other Western countries. Our research has shown that increased cutaneous response to histamine determines a major prevalence of positive skin tests. The rise in clinical forms of the disease accompanied by gastrointestinal symptoms is partly attributable to the dietary intake of food and beverages processed from environmentally engineered products. The features of the new forms of asthma demand accurate clinical and functional assessment. In addition to pulmonary function tests, determinations for eosinophils and inflammation markers in the blood and sputum, noninvasive methods have recently become available to assess airway inflammation. Among these, particularly useful studies include test for nitric oxide in exhaled air, along with tests for other markers of allergic inflammation and oxidative stress in the droplets of the exhaled air. Because in paediatric age, prolonged use of inhaled steroids increase the risk of growth impairment, asthma therapy should be guided by clinical criteria and examinations, rather than by rigid treatment guidelines. Moreover, to secure successful treatment, the parents and the child as well should be involved in monitoring the course of the disease
La misura dell’ossido nitrico espirato: applicazioni cliniche
No full textRiassunto: La concentrazione frazionale di ossido nitrico nell’aria espirata (FENO) rispecchia il grado
d’infiamma-zione delle vie aeree, in particolare quella eosinofilica e, poiché non invasiva, la sua misurazione è
utile nell’in-quadramento clinico del bambino con sintomi respiratori ricorrenti. L’elevata sensibilità del FENO a
vari stimoli, in particolare a quelli allergenici o infettivi, cosi come alla terapia antiinfiammatoria, lo rendono
particolarmente utile nel monitoraggio del bambino asmatico con fenotipo eosinofilico. Nonostante siano
stati proposti valori soglia di FENO indicativi di presenza/assenza di infiammazione, la grande variabilità della
misura impone cautela nell’interpretazione dei risultati ottenuti dal singolo paziente. Il FENO, utilizzato come
complemento ai criteri clinici e funzionali, offre la possibilità di ottimizzare la gestione del bambino asmatico.
Ulteriori studi sono ne-cessari per stabilire l’utilità del biomarker in altre patologie respiratorie.
Parole chiave: Ossido nitrico espirato, infiammazione delle vie aeree, asma, atopia, bambini.Summary: The fractional concentration of exhaled nitric oxide (FENO) reflects the degree of airway
inflammation, especially that eosinophilic. Since non-invasive, its measurement is useful for clinical assessment
of children with recurrent respiratory symptoms. The high sensitivity of FENO to various stimuli, in particular
those allergenic or infectious, as well as to anti-inflammatory therapy, make it particularly useful in monitoring
the asthmatic child with eosinophilic phenotype. Although FENO threshold values as indicative of the
presence/absence of inflam-mation have been proposed, the great variability of its measurement requires
caution in interpreting the results obtained from the single patient. FENO, used as a complement to clinical and
functional criteria, could optimize the asthmatic child’s management. Further studies are needed to determine
the usefulness of this biomarker in other respiratory diseases
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
The prevalence of atopy in asthmatic children correlates strictly with the prevalence of atopy among nonasthmatic children
No full textBackground: Because asthma preferentially burdens persons with atopy, atopy is simplistically considered a primary 'cause' of asthma. Yet at the population level, the percentage of asthma cases 'attributable' to atopy ranges from less than 10% to more than 60%. Seeking to understand the rationale for the variability of atopy-attributable cases of asthma, we systematically reviewed the results of our own previous epidemiological studies and several studies conducted by others in children. Methods: From each of the 37 random pediatric populations selected by a Medline search combining the key words 'IgE or skin tests or hypersensitivity, immediate' with 'epidemiological studies, cross-sectional, case-control, prevalence, longitudinal, epidemiology of asthma' (12 from our previous pediatric surveys and a further 25 reported from 19 studies in children), we extracted the population prevalence of asthma and atopy among asthmatic subjects and among the nonasthmatic part of the population. Results: No correlation was found between the prevalence of asthma (range 1.8-44.1%) and atopy (range 5.8-63.9%) in these 37 populations of children (r = 0.052, p = 0.761). Nevertheless, the prevalence of atopy among asthmatics strictly correlated with the prevalence of atopy in nonasthmatics (r = 0.900, p< 0.001, slope 1.364). Conclusion: The prevalence of asthma and atopy varies worldwide and at various time points and independently undergoes the influence of powerful environmental factors. The almost perfect correlation we found between atopy in asthmatics and atopy in the nonasthmatic part of the childhood population shows that the prevalence of atopy in asthma depends on environmental factors that simultaneously induce atopy in asthmatic and nonasthmatic subjects. Copyright © 2007 S. Karger AG
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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