1,720,977 research outputs found
Hormonal milieu in singleton pregnancy during the first trimester of gestation: comparison between spontaneous, in vitro fertilization and eggs donation pregnancies
No full textIntroduction:
In pregnancies obtained by ART exogenous estrogens and progesterone need to be administered to ensure endometrial receptivity and to maintain pregnancy after embryo transfer. To our knowledge there are few data on estrogen and progesterone maternal blood levels either spontaneous and in ART pregnancies during the first trimester. The first aim of our study is to create 17β - Estradiol and Progesterone growth curves in spontaneous pregnancy and successively to compare them with those from autologous and oocyte donation pregnancies.
Methods
From November 2015 to June 2016 three groups of singleton pregnancies were studied: spontaneous, in vitro fertilization pregnancies with autologous oocytes (Autologous IVF) and oocyte donation (OD) pregnancies. Maternal hormonal venous concentrations were analyzed in our reference laboratory in 85 spontaneous, 23 homologous IVF from fresh cycles and 12 OD pregnancies between 4 and 13+6 weeks of gestations. Serum samples were processed and assayed for 17 β – estradiol and progesterone using the Electro Chemo Luminescence in Immunoassay (ECLIA – Elecsys/Cobas®) method.
Results
In spontaneous pregnancy, maternal venous 17β - estradiol and progesterone concentrations increase according to gestational age. There is a significant relation between progesterone growth and gestational age, with a concentration growths of 0.2ng/ml per day of gestation.
17β - Estradiol and progesterone are linked by a linear correlation expressed by the following formulation: Log (17β-estr) = 2,5933 + 0,0149 x progesterone and the correlation coefficient is equal 0.388.
Comparing the different mode of conception, maternal serum concentration of 17β - Estradiol appears lower in OD donation than in spontaneous and autologous IVF pregnancy in any weeks of pregnancy (fig 1), while progesterone values are higher in autologous IVF pregnancy than in spontaneous and OD pregnancies (fig2).
Conclusion
Estrogen level are lower in OD pregnancy in the first trimester of pregnancy. Low estrogen level may enhance an efficient and early invasion of spiral artery by the trophoblast.
In autologous IVF the higher progesterone concentration may suggest a revision of progesterone therapy after pick up. It is possible that the correlation between concentration of 17β – estradiol and progesterone could help in prescribing support therapy during the first weeks of pregnancy
Heterotopic pregnancy in HIV women
Full text linkHeterotopic pregnancy occurs when intrauterine and ectopic pregnancy are concomitant; overall rate rises from 1/30.000 to 1.5/1000 in assisted reproductive technology pregnancies. HIV (human immunodeficiency virus) patients are at increased risk of heterotopic pregnancies due to the greater frequency of assisted reproductive technology and pelvic inflammatory disease. We report the first case of heterotopic pregnancy in HIV woman
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
Analysis of endothelial progenitor cells in human healthy and pathological pregnancies
No full textIntroduction: Endothelial progenitor cells (EPCs) are bone marrow-derived cells playing a critical role in adult vasculogenesis and endothelial homeostasis, as they are recruited to sites of endothelial injury where they contribute to blood vessel formation and repair. Since their first description in 1997, EPCs have stimulated considerable interest among scientists due to the observation that variations in their number and function are associated with many pathological conditions including cardiovascular, cancer, and metabolic diseases. However, comparative interpretation of clinical studies on EPCs is still hampered by the lack of standardized methods employed for EPC quantification and analysis.
Methods: Two main approaches are currently used to study circulating EPCs. One approach consists in identifying and selecting EPCs by cell surface phenotype using fluorescently labeled antibodies and flow cytometry directly performed on peripheral blood samples. The second approach consists in isolating and expanding EPCs in vitro, starting from peripheral blood samples. Key advantages, limits and critical methodological aspects of each approach will be illustrated.
Results: EPC variations observed in pathological conditions will be shown, mainly focused on the involvement of EPCs in cardiovascular diseases. The behaviour of EPCs during particular physiologic challenges, such as systemic hypoxia exposure and physical exercise, will also be described in order to provide some insight into the role and function of EPCs in human physiopathology.
Conclusions: Changes in the number and function of circulating EPCs may be relevant to the study of a wide range of human diseases. If the methods for studying EPCs will be adequately standardized and adapted for routine use, EPC analysis will likely become a valuable diagnostic and prognostic non-invasive tool useful for patient follow-up
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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