1,720,986 research outputs found
Review of prevalence of Simian Virus 40 (SV40) genomic infection in healthy subjects
No full textBecause of the carcinogenicity of SV40 in rodents, and its possible distribution through the polio vaccine, many studies have been conducted to determine if there is an association between SV40 genomic infection and different types of cancer; sometimes, these studies included data on the prevalence of genomic infection in healthy subjects as secondary information. We reviewed all the studies that reported the prevalence of SV40 genomic infection in healthy subjects, tested by PCR based methods. The 20 articles considered here included 1103 samples from healthy subjects, with a prevalence of infection ranging from 0 to 25.6%, with high heterogeneity, and no association with the type of sample analyzed (Mantel-Haenszel OR: 0.74; 95% CI: 0.44-1.23). The wide variation in frequency pose problems in terms of study design; in fact, the representativeness of the samples used as controls in the published studies may be very limited. Larger studies on healthy subjects, tested for SV40 genomic infection at various genomic regions, conducted in different geographic areas, are needed
Genetics of leptin and obesity : a HuGE review
No full textLeptin is an important regulator of the mass of adipose tissue and of body weight; it operates by inhibiting food intake and stimulating energy expenditure. Some polymorphic genes involved in the regulation of leptin-the leptin gene (LEP A19G), the leptin receptor gene (LEPR Q223R, K109R, and K656N), and the peroxisome proliferator-activated receptor-gamma gene (PPARG P12A and C161T)--have been investigated as possible factors associated with obesity. Allelic frequencies of these polymorphisms show ethnic variation. The authors performed a meta-analysis of the available data on the association between these polymorphisms and obesity based on case-control studies. Odds ratios and 95% confidence intervals for obesity associated with leptin polymorphisms were calculated by using both fixed- and random-effects models. Results suggest no evidence of association between the genes under study and obesity. The lack of association could be due to the complex pathogenesis of obesity, which involves a number of genetic and environmental factors. Large studies including testing of multiple genes in both obese and lean subjects, with epidemiologic data on dietary habits in different ethnic groups, are necessary to better understand the role of leptin in regulating weight in human populations
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
Human amnion-derived cells : prospects for the treatment of lung diseases
No full textLung diseases represent a significant burden of morbidity and mortality worldwide. Current therapies have not proven adequate in the long term and are often associated with significant side effects. There has been recent interest in the regenerative/reparative potential of cell-based therapies, including cells derived from the placental tissues. Amnion-derived cells are fetal-derived and characterized by expression profile and differentiative capacity of pluripotent cells. Moreover, because placenta is discarded after delivery, they represent an ethical source for the purposes of regenerative medicine. Amnion-derived cells are endowed with immunomodulatory, anti-inflammatory, anti-scarring and antibacterial properties, which may explain many of the beneficial effects observed with administration of the cells in animal models for a large number of inflammatory diseases. Both human amniotic epithelial cells (hAEC) and mesenchymal stromal cells (hAMSC) have been shown to acquire in vitro and in vivo some characteristics of epithelial cells, i.e. CFTR (cystic fibrosis transmembrane conductance regulator) and surfactant proteins. Administration of hAEC or hAMSC in vivo in the bleomycin-induced lung injury model has proven their therapeutic effects in term of reduction of pulmonary fibrosis and inflammation, as well as recovery of lung mechanical function. Many biological and clinical information have to be gathered before proposing amnion-derived cells in the clinic for the treatment of acute and chronic lung diseases
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
Molecular identification of simian virus 40 infection in healthy Italian subjects by birth cohort
No full textSimian virus SV40, an oncogenic virus in rodents, was accidentally transmitted to humans through the Poliovirus vaccine during the years 1955 to 1963. If the vaccination program were the major source of human infection, then differences in SV40 infection rates by cohort of birth should be observed. The aim of this study was to address this issue. In 134 healthy Italian Caucasian subjects, 15 DNA samples were positive for SV40 by nested polymerase chain reaction and DNA sequencing. The prevalence of genomic infection did not differ across cohorts of birth from 1924 to 1983, however DNA sequencing revealed viral strain differences in individuals born before 1947 and after 1958. While horizontal transmission following the introduction of the polio vaccine could explain the presence of SV40 DNA in younger people, our results also suggest the possibility that other sources of the virus may also be involved in human SV40 infection
A common CYP1B1 polymorphism is associated with 2-OHE1/16-OHE1 urinary estrone ratio
No full textCytochrome P450 (CYP) is a multigene family of enzymes involved in important life functions; some of these genes are inducible and are implicated in the oxidative metabolic activation and detoxification of many endogenous and exogenous compounds. CYP1B1 codes for an enzyme that catalyses the production of a 2- and 4-hydroxyl group in estrone and estradiol, while CYP1A1 catalyzes the 2-hydroxylation of estradiol in endometrium. The two genes were evaluated in a cohort of 150 subjects: African-American women had significantly lower 2-hydroxyl estrone/16-hydroxyl estrone (2-OHE1/16-OHE1) urinary metabolite ratios than Caucasian women (2.06+/-1.05 vs. 1.43+/-0.56; p=0.0002). A common polymorphism in the CYP1B1 gene (leucine to valineat codon 432) was associated with changes in urinary estrogen levels: both Caucasian and African-American women carrying the variant allele showed higher urinary metabolite ratios than women with the wild-type allele. No effect of the CYP1A1 MspI was observed. The 4-OHE1/2-OHE1 ratio was lower in subjects carrying the variant allele (Leu). The percentage change in 2-OHE1/16-OHE1 urinary ratio after indole treatment was significant in both Caucasian and African-American women carrying the wild-type CYP1B1 genotype, although it was more evident in African-Americans than in Caucasians. These results suggest that the Leu/Val CYP1B1 polymorphism may modify estradiol metabolism
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