1,721,049 research outputs found
A surprising link with unexplained infertility: a possible Covid-19 paradox?
No full textUnexplained infertility represents about 22–28 percent of infertility causes.The diagnosis is based on the exclusion of common causes
using standard fertility investigation. Over the years, the causes of unexplained infertility or subfertility have been identified in pre-existing associated pathologies, such as alterations of the immune system, thyroid dysfunctions, and coagulopathies.Studies regarding the influence of psychological factors on the development of infertility highlighted that spontaneous pregnancies following adoption or the decision to remain childless are absolute exceptions. The link between stress and infertility in humans is still unclear. For many women, the effect of infertility and the subsequent medical therapy represents a considerable emotional stress
PTPN22 1858C>T (R620W) functional polymorphism and human longevity
No full textThe PTPN22 gene, located on chromosome 1p13, encoding lymphoid protein tyrosine phosphatase (LYP), plays a crucial role in the negative control of T lymphocyte activation. Since the age-related change in T-cell signal transduction may be one of the most important causes of cell-mediated immune response decline with ageing, we performed a population-based association study to test whether the PTPN22 1858C>T (R620W) functional polymorphism affects the ability to survive to old age and to reach even exceptional life expectancy. 892 unrelated healthy individuals (age range 8-106 years, 403 males and 489 females) from central Italy were studied. For both gender, the frequency of PTPN22*T1858 carriers does not differ significantly in nona/centenarians and in octogenarians respect to young group. Allele and genotype frequencies of age groups were compared to those reported in previously published studied carried out on control individuals with Italic ancestry (N = 1393), further confirming results obtained from our sample population. Overall, our study suggests that PTPN22*T1858 allele is not negatively selected at oldest ages and we speculate that its increased ability to protect individuals against development of infectious diseases may counteract its deleterious effect on immune system leading to autoimmunity. © Springer Science+Business Media B.V. 2010
Further Observations on Associations Between the ADA Gene and Past Malaria Morbidity in Sardinia.
No full textObjectives: Adenosine Deaminase (ADA) contributes to the regulation of adenosine concentration and in turn to T cell activation. Genetic variability of ADA activity may have, therefore, an important role in resistance to malaria.
Indeed, previous studies in Sardinia have shown a lower frequency of ADA1*2 allele (associated with low ADA activity)
in areas, where malaria was heavily endemic compared to areas where malaria was not endemic. We have now studied
the ADA2 locus, another polymorphic site with two alleles ADA2 *1 and ADA2 *2 within the ADA gene.
Methods: In the area of Oristano (where malaria was endemic in the past) 51 consecutive newborns and in the area
of Nuoro (where malaria was not as endemic) 48 consecutive newborns were examined.
ADA1 and ADA2 genotypes were determined by DNA analysis.
Results: The low frequency of the ADA1*2 allele in the area where malaria was endemic is confirmed. The frequency
of the ADA2*2 allele is higher in Oristano than in Nuoro resulting in a higher frequency of the ADA1*1/ADA2*2 haplotype
in Oristano as compared to Nuoro. This suggests a selective advantage of this haplotype in a malarial
environment.
Conclusions: The ADA gene shows other polymorphic sites further studies on their role in human adaptation to
malaria could be rewarding
Esame di tre polimorfismi del DNA presenti nel locus strutturale dell’adenosindeaminasi in sei campioni italiani
No full text
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
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