1,720,961 research outputs found
Prenatal Hypoxia and the Impact of Maternal Antioxidant (MitoQ) Treatment on Developmental Programming of Cardiovascular Disease
Get PDFCardiovascular disease is the primary cause of morbidity and mortality worldwide. Prenatal hypoxia (due to placental or maternal hypoxia) is an established risk factor for cardiovascular disease. Hypoxia in pregnancy can lead to intrauterine growth restriction (IUGR; defined as a fetus who does not reach its genetic growth potential) and to an increase in offspring susceptibility to develop cardiovascular disease later in life, a concept known as developmental programming of cardiovascular disease. This PhD project focusses on assessing the effect of hypoxia in pregnancy on maternal vascular function, fetal development and on offspring cardiovascular function later in life in both males and females separately. I also aimed to propose an intervention to improve offspring cardiovascular health in complicated pregnancy. As placental oxidative stress is important in the pathophysiology of many pregnancy complications including IUGR and developmental programming, the mitochondrial antioxidant MitoQ loaded onto nanoparticles (nMitoQ) was proposed herein as an intervention to prevent placental oxidative stress and optimally prevent IUGR and fetal programming of cardiovascular disease. Nanoparticles were used to prevent MitoQ from crossing the placental barrier to the fetus in order to avoid risking direct fetal exposure to the antioxidant treatment.
In this thesis, an established rat model of maternal hypoxia was used. Maternal vascular function was assessed using both in vivo and ex vivo techniques. Fetal body weight was measured after euthanizing the dams. Hypoxia in pregnancy increased maternal blood pressure and caused vascular bed-dependent alterations in maternal vascular function (mesenteric artery versus uterine artery). Furthermore, hypoxia in pregnancy caused a reduction in uterine artery resistance index and IUGR in the fetuses.
To assess the effect of maternal hypoxia and nMitoQ treatment on developmental programming, a similar animal model but with a shorter period of maternal hypoxic exposure was used (our laboratory has previously assessed the phenotype of offspring cardiovascular function in this animal model). nMitoQ (125 µM) was intravenously injected on GD 15 just before animal exposure to hypoxia and at the same day for the control (dams that stayed in normoxia all over the pregnancy period). In one set of animals, rats were euthanized near term to assess pregnancy outcome, placental oxidative stress, and fetal cardiac development. Cultured medium was prepared and used to assess the effect of placental secreted factors on normal cardiomyocyte growth in male and female fetuses separately. In another set of animals, dams were allowed to give birth and male and female offspring were assessed at 7 and 13 months of age for in vivo cardiac function and ex vivo vascular function.
Hypoxia in pregnancy led to IUGR and to an increase in placental oxidative stress and relative heart weight to body weight (cardiac hypertrophy) in both male and female fetuses. However, hypoxia led to an increased cardiomyocyte size in only male but not female fetuses. Factors released from placentas of hypoxic dams did not alter normal cardiomyocyte growth. nMitoQ treatment prevented placental oxidative stress in both male and female fetuses. nMitoQ prevented IUGR and prevented cardiac hypertrophy in only female fetuses. However, nMitoQ rescued cardiomyocyte growth, which was increased in male fetuses due to maternal hypoxia.
In young (7 months) and aged (13 months) male and female offspring, maternal hypoxia led to sex-dependent cardiovascular dysfunction. This includes changes in cardiac morphology, signs of diastolic, and systolic dysfunction and abnormal vascular responses to vasoconstriction and vasorelaxation. nMitoQ treatment partly improved cardiovascular function in offspring of both sexes. For example, in hypoxic dams nMitoQ improved systolic function in aged female offspring compared to the nMitoQ untreated controls; and increased sensitivity to vasorelaxation in aged male and female offspring from normoxic and hypoxic dams.
In conclusion, this thesis has elucidated factors that play an important role in the pathophysiology of IUGR and developmental programming of cardiovascular disease in male and female offspring. This thesis as well showed that targeting antioxidant treatment to the placenta can impact fetal body weight, fetal cardiac development and offspring cardiovascular function in adult life, suggesting that interventions do not necessarily need to target the fetus to improve fetal outcome. This project helped in setting the stage for future studies about employing nanoparticles to deliver interventions to specific targets during pregnancy to improve offspring cardiovascular function in complicated pregnancy
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
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
The psychological impact of COVID‑19 quarantine on children, and the role of parental support and physical environment design
No full textCoronavirus disease 2019 is a contagious infection that caused a global lockdown and affected children who needed to stay home. There is a lack of knowledge about the role of parental stress and physical environment design on children’s mental wellbeing in quarantine. We hypothesis that COVID-19 quarantine affected child mental health, and that paternal stress or support, and child physical environment including household space, colors, sunlight exposure, and natural views, impacted child mental wellbeing in the quarantine. To assess the effect of quarantine on a child’s mental health, an online survey was administered globally through scientific organizations and social media. Those over 18 years old, and guardians of children were asked to participate in the survey. The survey was filled by 114 guardians from 31 countries. Descriptive statistics were used to summarize the data. Most participants experienced stress in the quarantine and reported child anxiety symptoms including focus reduction, sleeping difficulties, and appetite changes. Family fun activities and encouraging words, were mostly successful in reducing child anxiety. Reporting anxiety symptoms in children were more common in parents who had mental hardships compared to those who did not experience mental problems or had an improved mental status. Physical environment assessment showed that households with bright walls associated with fewer reports of child mental problems compared to households with neutral wall colors, and that most guardians thought that their children’s living space was not sufficient to play and study. Architects can provide evidence-based recommendations for customers to support children’s mental health
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