1,721,003 research outputs found
Mast cells as effector cells of innate immunity and regulators of adaptive immunity
No full textMast cells are widely distributed in human organs and tissues and they are particularly abundant at major body interfaces with the external environment such as the skin, the lung and the gastrointestinal tract. Moreover, mast cells are located around blood vessels and are highly represented within central and peripheral lymphoid organs. The strategic distribution of mast cells closely reflects the primary role of these cells in providing first-line defense against environmental dangers, in regulating local and systemic inflammatory reactions and in shaping innate and adaptive immune responses. Human mast cells have pleiotropic and multivalent functions that make them highly versatile cells able to rapidly adapt responses to microenvironmental changes. They express a wide variety of surface receptors including immunoglobulin receptors, pathogen-associated molecular pattern receptors and danger signal receptors. The abundance of these receptors makes mast cells unique and effective surveillance cells able to detect promptly aggression by viral, bacterial and parasitic agents. In addition, mast cells express multiple receptors for cytokines and chemokines that confer them the capacity of being recruited and activated at sites of inflammation. Once activated by immunological or nonimmunological stimuli mast cells secrete a wide spectrum of preformed (early) and de novo synthesized (late) mediators. Preformed mediators are stored within granules and are rapidly released in the extracellular environment to provide a fast vascular response that promotes inflammation and local recruitment of other innate immunity cells such as neutrophils, eosinophils, basophils and monocyte/macrophages. Later on, delayed release of multiple cytokines and chemokines from mast cells further induce modulation of cells of adaptive immunity and regulates tissue injury and, eventually, resolution of inflammation. Finally, mast cells express several costimulatory and inhibitory surface molecules that can finely tune activities of T cells, B cells and regulatory cells by cognate interactions within lymphoid organs. The multivalent capacity to recognize and to react to internal and external dangers together with their ability to cross-talk with other immunocompetent cells make mast cells a unique effector cell of innate responses and a main bridge between innate and adaptive immunity
Pitfalls in anaphylaxis
No full textAnaphylaxis is an acute medical emergency characterized by sudden presentation of life-threatening respiratory and cardiovascular symptoms. Rapid diagnosis of anaphylaxis is crucial to implement an appropriate treatment and management plan. However, mistakes in the diagnosis of anaphylaxis may occur because of the limited time during which the diagnosis must be made, the stressful environment of the emergency room, the often aspecific or incomplete clinical features of early anaphylaxis and the lack of useful laboratory markers
La triptasi sierica nella diagnosi di mastocitosi sistemica in pazienti adulti senza lesioni cutanee
No full textBackground.: Mastocytosis is a rare disease characterized by clonal proliferation of mast cells in several organs, such as bone marrow, liver, spleen, skin, gastrointestinal tract and lymph nodes. The course of disease and the prognosis are variable. The typical skin lesion of mastocytosis is characterized by red to brown macules, known as urticaria pigmentosa (UP). However, in about 10–30% of patients, mastocytosis occurs in absence of typical skin lesions; in these patients, the clinical picture is mainly determined by mediator-related symptoms, such as urticaria, flushing, diarrhea and recurrent anaphylaxis. Thus, in patients without skin lesions, diagnosis of mastocytosis could be difficult. The determination of serum tryptase could be useful to improve diagnostic accuracy. Methods.: In our cohort of 67 patients (44 females and 23 males; mean age 28 years) with systemic mastocytosis (SM) we selected those without skin lesion and we evaluated their initial clinical features. The diagnosis of SM was made by bone marrow biopsy according the WHO criteria. Serum tryptase levels were determined using Phadia ImmunoCAP methodology and the analytical system Phadia 250 (Thermo Fisher Scientific, Waltham, MA, USA). Results.: Fifteen percent (10/67) of our patients with systemic mastocytosis have no skin lesions. Five of them are males (mean age: 55 years). The majority of patients (7/10) have ISM, one has a bone marrow mastocytosis (BMM), one has systemic mastocytosis associated to not clonal mast cells disorders (SM-AHNMD), and one has advanced systemic mastocytosis (ASM). The most frequent presenting symptom in these patients (4 out of 10) was pathological vertebral fracture due to severe osteoporosis. Other patients had severe anaphylaxis, progressive peripheral monocytosis and bone pain. In only one case the diagnosis was incidental, because bone marrow biopsy was done to confirm another diagnosis (essential thrombocythemia). In all cases, elevation of serum tryptase suggested the diagnosis of systemic mastocytosis. The values of tryptase in these patients ranged from 15 to 120 μg/L with a mean of 52 μg/L (normal range: up to 11.4 μg/L). Conclusions.: In patients without skin lesions, the diagnosis of mastocytosis could be challenging. The clinical presentations of mastocytosis are heterogeneous, ranging from severe clinical pictures of osteoporosis to hematologic abnormality in otherwise asymptomatic patients. Our data indicate that the diagnostic relevance of serum tryptase levels in patients without skin lesions, but with suspicious symptoms and/or signs of SM, and its utility in selecting patients who do need a bone marrow biopsy
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
Flow mediated dilation shows impaired endothelial function in patients with mastocytosis
No full textMastocytosis is a rare disease characterized by clonal proliferation of mast cells in different organs. Clinical manifestations of mastocytosis are mostly due to the release of mediators from mast cells and, in many cases such as urticaria, flushing, angioedema and anaphylaxis, are expression of biological effects of mediators on endothelial cells. Chronic secretion of mediators in patients with mastocytosis may lead to alteration of endothelial function
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