1,721,088 research outputs found
Lead and cadmium at very low doses affect in vitro immune response of human lynphocytes
No full textThe effect of lead chloride and cadmium chloride on in vitro immunoglobulin (Ig) production by human lymphocytes was investigated. After 7 days in culture, lead added in the range of human exposure (207-1035 micrograms/liter) significantly enhanced Ig production either when cells were activated by pokeweed mitogen (PWM) or not. The effect was dose-dependent and was related to the Pb we measured in the extracellular medium and in the cells. Independently of the mitogen addition, about 2% of the Pb added was accumulated in the cells, most being associated with the nuclear fraction. Those findings suggest that the Pb effects could depend on its uptake and distribution in the cells. Cadmium added in the 50-500 nM range exhibited a dose-independent mitogenic activity in unstimulated cells, whereas the Ig secretion was not significantly affected by Cd when cells were PWM-activated. A considerable intraindividual variability, however, was observed when blood donors were separately examined, with both an increase, a decrease, or no variation on Ig production. Furthermore, higher percentages of Cd were accumulated in the nuclear fraction, and lower in the cytosol and precipitate, in PWM-activated compared to resting lymphocytes. Genetic factors could be of importance for the observed variability of the immune response to cadmium, and we support the hypothesis that differences in the metallothionein (MT) inducibility could play a role
Indagine alimentare in un gruppo di sportivi con particolare riferimento agli introiti di magnesio, zinco e rame ed ai relativi livelli intra ed extracellulari
No full textThe aim of the present study was to evaluate the dietary habits in a group of athletes (footballers) compared with sedentary subjects matched for sex, age and body mass index. All subjects kept a record of food eaten for seven consecutive days using various models for portion sizes. Daily nutrient intake was then computed and was expressed as either total intake, or percent of the recommended daily dietary allowances (LARN). For each subject, a 20-ml blood sample and a 24h urine sample was collected for analysis of magnesium, zinc and copper. The three elements were measured both in plasma and in erythrocytes, monocytes and neutrophils. The athletes eat significantly more sheets than controls (22.5% of total kcal vs 15.2%, p less than 0.01) and significantly less cereals (22.5% vs 31.7%, p less than 0.01). Concerning the nutrient composition, in both groups the lipid intake was higher than that recommended and this trend was more pronounced in the athletes (+ 43.2% vs + 16.1% in the controls). In addition, the diet was particularly rich in animal fats with a mean intake of 21.0% of total kcal in the athletes and 20.9% in the sedentary group (recommended value was 12.5% and 14%, respectively). A parallel reduction in vegetal protein intake was observed in the trained group, and the difference was significant (4.3% of kcal in the athletes and 5.2% in the controls, p less than 0.01). Furthermore, in the athletes the soluble carbohydrate intake was higher than the recommended levels (+ 110%) and significantly higher than that eaten by the controls (21.0% vs 16.4% of kcal, p less than 0.01), with parallel decrease of polysaccharides intake
Cadmium, nickel, chromium and lead accumulate in human lymphocytes and interfere with PHA-induced proliferation
No full textThe in vitro effect of five toxic metals (cadmium, lead, nickel, barium, chromium III and VI) on PHA-induced blastogenesis in human lymphocytes was investigated by [3H]-thymidine incorporation. With the exception of hexavalent chromium, the metals tested were in the chloride forms. The levels of metals associated with lymphocytes were measured under our experimental procedure. An inhibitory effect was found when cadmium was added at doses which closely approximate those of occupationally exposed subjects. Hexavalent chromium and nickel showed a biphasic pattern, with a stimulatory effect at the lowest concentrations tested (10(-8)-10(-6) mol/L) and an inhibitory effect on thymidine incorporation at concentrations higher than 10(-6) and 10(-4) mol/L, respectively. No effect was observed when lead, barium, and trivalent chromium were added to the culture medium. All metals showed the ability to enter the lymphocytes or to adhere to their surface, and the interaction appeared to be quite stable, with the exception of barium. The relationship between metal accumulation and [3H]-thymidine incorporation in the cells is discusse
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
Il trattamento delle II classi border-line: quando il compenso ortodontico e quando la correzione chirurgico-ortodontica?
No full textDispelling 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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