1,720,992 research outputs found
[The hematopoietic stem cell: biology and clinical applications] La cellula staminale emopoietica: biologia e applicazioni cliniche (Editoriale)
No full textThe hematopoietic stem cells (HSCs) are defined as cells that are able of both self-renewal and multilineage reconstitution of the hematopoietic system. Their biological properties and, similarly, the gene regulation, the positive and negative factors of the hematopoietic progenitor cells and the models of the hematopoietic amplification in the murine system are described. The clinical relevance of HCS has been obtained by the characterization and function of the CD34 cell surface molecule. The methods of isolation, selection and purification of HCS, the clinical use (particularly the mobilization of peripheral CD34+ cells) are detailed. Finally the potential advantages and use of HCS in vivo expansion are described
Evaluation of thrombopoiesis kinetics by measurement of reticulated platelets and CD34+ cell subsets in patients with solid tumors following high dose chemotherapy and autologous peripheral blood progenitor cell support.
Full text linkThe transplantation of mobilised peripheral progenitor cells has resulted in shortening of neutrophil and platelet engrafment times following high-dose chemotherapy. Since reticulated platelet percentage (PR%) has been established as a measure of bone marrow platelet production, we performed this type of analysis on the thrombopoietic compartment during transplant-related chemotherapy. DESIGN AND METHODS: Kinetics of thrombopoiesis of 19 patients with solid tumors undergoing a single or double autologous peripheral blood progenitor cell transplant was characterized by evaluating the level of RP. The correlation between CD34(+) cell subsets and the time of highest percentage of RP was also evaluated. RESULTS: The percentage of RP increases since day +8 after single transplant reaching the peak (3.4%) at day +10. In the group of patients receiving double transplant, the RP value of peak observed after second transplant is not significantly different from that one observed after the first transplant (3 vs 3.7%). In a subgroup of patients both the number of CD34(+) cells/Kg infused and the percentage of CD34(+) CD61(+) cell subsets correlate with the day of RP peak. INTERPRETATION AND CONCLUSIONS: These results suggest that RP measurement is an early indicator of engraftment. Additionally, the observation that RP percentage is high at the time of platelet transfusion in 13 out of 20 cases of transfusions (the 7 cases with low RP value being transfused during the period of obligate thrombocytopenia) suggests that the evaluation of this parameter, together with the platelet count, can be used to monitor the need for platelet transfusion
Distribution of age-related thymulin titres in normal subjects through the course of life
No full textThe thymus has a dominant immunological role in utero and in early childhood, being a primary source of T lymphopoiesis, and its investigation may be particularly relevant for the immunological study of paediatric patients. Thymulin, a nonapeptide secreted by the thymus, is an essential hormone for T lymphocyte differentiation and function. As thymulin values in the normal population have not been well documented, especially for children under the age of 1 year, we detail thymic endocrine function by presenting age-related plasma thymulin levels in a large series (n = 93) of healthy individuals, ranging from birth to old age. We demonstrate that thymulin is already detectable at birth; it then gradually increases with age, reaching the highest level in children aged 5-10 years. Starting at adolescence, thymulin titres gradually start to fall, reaching the lowest value at 36 years of age and remaining steady until 80 years (the oldest person tested)
Immunological evaluation of patients with beta-thalassemia major
No full textAbnormalities in the immune system and zi nc homeostasis in patients with P-thalassemia major (TM) have been reported. Since zinc ion is essential for the efficiency of the immune system and is required to induce biological activity to thymulin (Zn-FTS), a biochemically defined thymic hormone, we investigated the plasma levels of zinc and both active thymulin (Zn-FTS) and total zinc saturable thymulin (Zn-FTS+FTS) in 18 patients with TM aged between 2 and 31 years and 22 normal controls of the same age, Inhibitory molecules anti-thymulin and the distribution of lymphocyte subsets were also analyzed. Patients with TM presented significantly lowered plasma zinc and thymulin levels when compared to normal subjects, The significant enhancement of the active form of the hormone after zinc addition in vitro suggests that low thymulin values found in TM are due not to a thymic failure in synthesizing and secreting the thymic hormone, but a defect in zinc saturation of the hormone. An impairment of cell subset distribution was also demonstrated. This study shows that zinc and thymulin deficiency contribute to the complex mechanisms underlying immune dysfunction in TM
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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