1,721,041 research outputs found
Uterine fibroids and non-informative cell-free DNA screening results
No full textObjective: Uterine fibroids are monoclonal tumors, which are often genetically abnormal and associated with false-positive genome-wide cell-free DNA (cfDNA) screening results, particularly when large. It is plausible that fibroids may also increase the risk of cfDNA failure by affecting fetal fraction or due to their genetic anomalies confounding cfDNA algorithms. We aimed to investigate a possible association between fibroids and cfDNA non-informative results. Methods: This was a retrospective cohort study of women undergoing cfDNA screening for fetal chromosomal abnormalities between 2013 and 2020, comparing pregnancies with vs without uterine fibroids recorded on any obstetric ultrasound before 24 weeks' gestation. Univariable and multivariable logistic regression models were used to investigate the association between fibroids and cfDNA failure, adjusting for gestational age, maternal age, weight and height at blood sampling, mode of conception, multiple gestation and test platform (chromosome-selective or genome-wide). Analyses were stratified according to the number of fibroids and total fibroid volume. The impact of fibroids on fetal fraction was assessed using linear regression, adjusting for the same covariates. Results: Among 19 818 pregnancies undergoing cfDNA screening, fibroids were reported in 2038 (10.28%) and cfDNA failure at the first screening attempt occurred in 228 (1.15%) pregnancies. Non-informative results occurred in 1.96% of pregnancies with fibroids and 1.06% of pregnancies without fibroids (adjusted odds ratio (aOR), 2.40 (95% CI, 1.65–3.48)). The risk of failure in the first screening attempt increased progressively with the number of fibroids (aOR, 5.05 (95% CI, 2.29–11.13) in women with four or more fibroids) and total fibroid volume, with greater than a 5-fold and 14-fold increase in risk among women with fibroid volumes of 100.1–400 mL (aOR, 5.52 (95% CI, 2.30–13.25)) and > 400 mL (aOR, 14.80 (95% CI, 4.50–48.69)), respectively. Although test failure was more common with chromosome-selective than genome-wide screening, fibroids similarly increased the risk of failure of both screening platforms. Compared to pregnancies without fibroids, those with fibroids had a fetal fraction on average 0.61% lower (adjusted mean difference, −0.61% (95% CI, −0.77% to −0.45%)). Conclusion: Uterine fibroids are associated with lower fetal fraction and an increased risk of cfDNA screening failure. The strength of this association increases with increasing fibroid number and volume. © 2024 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.Full Tex
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
Second and third trimester serum levels of HtrA1 in pregnancies affected by pre-eclampsia
No full textIntroduction: Altered placental expression of high temperature requirement factor A1 (HtrA1) is implicated in abnormal trophoblastic invasion and endothelial dysfunction in pre-eclampsia (PE). Serum levels of HtrA1 have been proposed as a novel biomarker to improve the prediction of PE. This study assesses serum HtrA1 levels in prospectively collected samples of women who developed PE compared to normotensive pregnancies. Methods: This was a case-control study of serum HtrA1 levels in second and third trimester samples in women who later developed preterm or term PE compared to controls. Overall, 300 serum samples were drawn from a prospective observational study of adverse pregnancy outcomes in three different gestational age windows (19–24, 30-34 and 35–37 weeks) at the Fetal Medicine Research Institute, King's College Hospital, London. Serum HtrA1 levels were determined by enzyme-linked immunosorbent assay (ELISA) by a blinded laboratory professional. Median HtrA1 MoM values, adjusted for gestational age and maternal characteristics, were compared between cases and controls at each gestational age group. Results: Women who later developed PE, compared to controls, had significantly higher maternal weight and more frequently had chronic hypertension or a history of PE in a previous pregnancy. In normotensive pregnancies, serum HtrA1 increased with increasing gestational age, whereas, in PE pregnancies HtrA1 levels remained stable, but were not significantly different from control pregnancies at any gestational age. Discussion: Serum HtrA1 levels are not significantly different in women who develop PE compared to controls.No Full Tex
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Serum leukotriene B4 and hydroxyeicosatetraenoic acid in the prediction of pre-eclampsia
No full textIntroduction: Pre-eclampsia (PE) affects 2–8% of pregnancies worldwide. Despite identification of numerous possible biomarkers, accurate prediction and early diagnosis of PE remain challenging. We examined the potential of leukotriene B4 (LTB4) and 15-hydroxyeicosatetraenoic acid (15(S)-HETE) as biomarkers of PE by comparing serum levels at three gestational age (GA) groups between normotensive pregnancies and asymptomatic women who subsequently developed preterm or term-PE. Methods: This is a case-control study drawn from a prospective study of adverse pregnancy outcomes with serum samples collected at 19–24 weeks (n = 48), 30–34 weeks (n = 101) and 35–37 weeks (n = 54) GA. LTB4 and 15(S)-HETE levels were determined by ELISA. Serum level multiples of the median (MoM) were compared between normal and PE-pregnancies. Association between LTB4 and 15(S)-HETE and GA at delivery was investigated with Cox proportional-hazards models. Results: Serum LTB4 levels were lower in women of East-Asian ethnicity, higher in women with PE history, and increased with GA in normotensive pregnancies, but not in PE. LTB4 was elevated at 19–24 weeks in women who developed preterm-PE. There was a negative association between LTB4 MoM and interval between sampling and delivery with PE at 19–24 weeks only. Serum 15(S)-HETE levels were not influenced by GA at testing and were elevated in women of South-Asian ethnicity. Median 15(S)-HETE levels were unchanged in preterm and term-PE at any GA. Discussion: LTB4 was higher at 19–24 weeks in pregnancies that developed preterm-PE versus unaffected pregnancies, suggesting it is a potentially useful predictive marker of preterm PE in the second trimester.No Full Tex
- …
