1,720,976 research outputs found
Disturbed proprioceptive weighting during postural control in pregnant women compared to non-pregnant controls
No full textBACKGROUND AND AIM: Falling during pregnancy can seriously harm mother and child, and should thus be avoided. However, 1/4 women report falling during pregnancy. Pregnant women show a decreased postural balance (i.e., greater sway variability and velocity), particularly during the second part of pregnancy. Unfortunately, the underlying mechanisms are poorly understood. Postural balance depends greatly on proprioceptive inputs from e.g., ankle and lumbar muscles. Depending on the postural condition, the brain will adjust the weight assigned to these inputs. For example during standing on unstable support surfaces, healthy individuals up-weight lumbar proprioception and down-weight ankle proprioception. So far, it remains unclear whether the weighting of ankle and lumbar proprioception during postural control differs in pregnant compared to non-pregnant women. METHODS: We recruited 12 pregnant, multiparous women in the third trimester, and 20 non-pregnant women. Exclusion criteria were a history of surgery/major trauma to spine, pelvis or lower limbs; specific balance or neurological disorders; and acute ankle problems. All women stood on a force plate (AMTI), with the heels 20 cm apart and vision occluded. After 20 s, muscle vibration (60 Hz, 15 s) was applied to the ankle or lumbar muscles. A stable and unstable support surface was used. Center-of-pressure (COP) displacements during vibration, and the Relative Proprioceptive Weighting (RPW) ratio, a measure of ankle vs. lumbar proprioceptive dominance, were calculated. Group differences in age, and pre-pregnancy BMI were determined with Mann-Whitney U tests, differences in COP displacement during vibration, and RPW ratio with mixed-design ANOVAs with "Surface" as the within-subjects factor, and "Pregnant" as the between-subjects factor. RESULTS: Pregnant women were significantly older (31 (30-34) vs. 28 (27-30) years, p= 0.004), and reported lumbopelvic pain more often (7/12 vs. 1/20, p= 0.002) than the non-pregnant controls. Pre-pregnancy BMI did not differ between groups (23.3 (21.4-27.2) vs. 22.4 (21.1-23.8), p= 0.219). For COP displacement during lumbar muscle vibration, a significant interaction effect of "Pregnant x Surface" was found (F= 8.157, p= 0.009). Post-hoc tests showed a significantly larger COP displacement during lumbar muscle vibration on the unstable compared to the stable support surface in the non-pregnant women (p< 0.001), but not in the pregnant group (p= 0.065). CONCLUSIONS: While non-pregnant women adequately up-weighted lumbar proprioception when switching from the stable to the unstable support surface, pregnant women did not show this increase in reliance on lumbar proprioception when needed. Future research must determine whether this decreased ability for proprioceptive re-weighting in pregnant women is already present in early pregnancy or even before conception, and whether it correlates to the presence of lumbopelvic pain and an increased risk of falling. ACKNOWLEDGEMENTS AND FUNDING: The authors wish to thank all participants. Nina Goossens is a beneficiary of an AXA Research Fund Postdoctoral Grant
Disturbed proprioceptive weighting during postural control in pregnant women compared to non-pregnant controls
No full textBACKGROUND AND AIM: Falling during pregnancy can seriously harm mother and child, and should thus be avoided. However, 1/4 women report falling during pregnancy. Pregnant women show a decreased postural balance (i.e., greater sway variability and velocity), particularly during the second part of pregnancy. Unfortunately, the underlying mechanisms are poorly understood. Postural balance depends greatly on proprioceptive inputs from e.g., ankle and lumbar muscles. Depending on the postural condition, the brain will adjust the weight assigned to these inputs. For example during standing on unstable support surfaces, healthy individuals up-weight lumbar proprioception and down-weight ankle proprioception. So far, it remains unclear whether the weighting of ankle and lumbar proprioception during postural control differs in pregnant compared to non-pregnant women. METHODS: We recruited 12 pregnant, multiparous women in the third trimester, and 20 non-pregnant women. Exclusion criteria were a history of surgery/major trauma to spine, pelvis or lower limbs; specific balance or neurological disorders; and acute ankle problems. All women stood on a force plate (AMTI), with the heels 20 cm apart and vision occluded. After 20 s, muscle vibration (60 Hz, 15 s) was applied to the ankle or lumbar muscles. A stable and unstable support surface was used. Center-of-pressure (COP) displacements during vibration, and the Relative Proprioceptive Weighting (RPW) ratio, a measure of ankle vs. lumbar proprioceptive dominance, were calculated. Group differences in age, and pre-pregnancy BMI were determined with Mann-Whitney U tests, differences in COP displacement during vibration, and RPW ratio with mixed-design ANOVAs with "Surface" as the within-subjects factor, and "Pregnant" as the between-subjects factor. RESULTS: Pregnant women were significantly older (31 (30-34) vs. 28 (27-30) years, p= 0.004), and reported lumbopelvic pain more often (7/12 vs. 1/20, p= 0.002) than the non-pregnant controls. Pre-pregnancy BMI did not differ between groups (23.3 (21.4-27.2) vs. 22.4 (21.1-23.8), p= 0.219). For COP displacement during lumbar muscle vibration, a significant interaction effect of "Pregnant x Surface" was found (F= 8.157, p= 0.009). Post-hoc tests showed a significantly larger COP displacement during lumbar muscle vibration on the unstable compared to the stable support surface in the non-pregnant women (p< 0.001), but not in the pregnant group (p= 0.065). CONCLUSIONS: While non-pregnant women adequately up-weighted lumbar proprioception when switching from the stable to the unstable support surface, pregnant women did not show this increase in reliance on lumbar proprioception when needed. Future research must determine whether this decreased ability for proprioceptive re-weighting in pregnant women is already present in early pregnancy or even before conception, and whether it correlates to the presence of lumbopelvic pain and an increased risk of falling. ACKNOWLEDGEMENTS AND FUNDING: The authors wish to thank all participants. Nina Goossens is a beneficiary of an AXA Research Fund Postdoctoral Grant
De invloed van maternaal prenataal emotioneel welzijn en maternaal cortisol op de ontwikkeling van de foetus en het kind - een epigenetische studie
No full textThe prenatal period, and therefore the uterine environment, is crucial in the development of the fetal organs and organ systems and therefore in child development. Fetal programming describes the process through which the development of a fetus is altered due to changes in its immediate environment. The effects of this environment can vary at different sensitive periods and can shape the structure and function of the brain and peripheral organ systems, with long-term or even permanent effects on subsequent child and adult physiology, behavior and health (Glover et al.2010;Gluckman and Hanson2004;Gluckman et al.2008;Van den Bergh2011;Reynolds2013b). This research paradigm is commonly referred to as Developmental Origins of Health and Disease (DOHaD) - paradigm". We formulated 4 research aims. First of all we investigated the link between maternal emotional state (more specifically depression, anxiety, pregnancy related anxiety as well as attachment) and maternal cortisol secretion on the one hand, and child development [(fetal and child growth, infant HPA axis function and infant neurodevelopment) on the other hand. Furthermore we investigated whether emotional state and/or maternal cortisol during pregnancy has an association with the methylation pattern of the NR3C1 1B, 1D, and 1F promoter regions in infant DNA of cord blood mononuclear cells at birth. Additionally the relation between the methylation state of the NR3C1 promoter regions in infant DNA at birth and child development was investigated. And finally the relation between infant HPA axis and infant neurodevelopment was explored.We conducted 2 prospective longitudinal clinical studies: a pilot project (chapter 5) and a large comprehensive study, the Prenatal Early life Stress (PELS) study (chapter 4 and chapter 6-9). In the introduction part of this thesis we first give an overview of the literature in the first chapter, this to provide the reader with a broad background. In the second chapter we formulated 4 research aims as previously mentioned. In chapter 3 the epidemiology of both studies is highlighted.In part 1 we explored whether emotional state and/or maternal cortisol during pregnancy has a relation with the methylation pattern of the NR3C1 1B, 1D, and 1F promoter regions in infant DNA of cord blood mononuclear cells at birth. These data indicate that prenatal maternal emotional state, particularly pregnancy related anxiety, are associated with the methylation state of the NR3C1 gene in the child. The results found in the PELS study are relevant since differences in methylation of CpGs in the promoter region can alter gene transcription by affecting transcription factor binding (chapter 2). In part 2, first of all we investigated the association between maternal emotional state (more specifically depression, anxiety, pregnancy related anxiety as well as attachment) and maternal cortisol secretion on the one hand, and child development [fetal and child growth, infant HPA axis function and infant neurodevelopment) on the other hand. In chapter 5 we present results of the pilot study focusing on growth during the prenatal period. This study focused on the prenatal period. Some distinct patterns were observed. First of all cortisol exerted an influence mainly in mid pregnancy and on the growth trajectory between mid and late pregnancy. Secondly in late pregnancy it was observed how emotional state, particularly depressive symptoms and attachment had an influence on growth and analysis of growth between mid and late pregnancy showed that attachment and cortisol in late pregnancy had an influence. In contrast to our pilot study the focus of the PELS study, presented in chapter 5, was not only on the prenatal IUG but also on the longer lasting effects of emotional wellbeing and maternal cortisol during the first year after birth. Growth was approached in a longitudinal way across birth. Only between general anxiety and weight a weak relation has been found. Both studies resemble the normal population, but in the pilot study, depressive symptoms were more pronounced. This might be a possible explanation for these differences in results (chapter 6). In chapter 7 it was concluded that early infant HPA axis function is influenced by both maternal cortisol secretion and depressive symptoms in late pregnancy, though very limited. In chapter 8 it was observed how depressive symptoms during early pregnancy as well as pregnancy related anxiety during pregnancy predicted mental development at 12 months, though again limited. Additionally in part 2, the association between the methylation state of the NR3C1 promoter regions in infant DNA at birth and child development was studied. As concluded in chapter 6 there was only limited evidence for a link between the methylation state of NR3C1 promoter region and growth in a population comparable to general pregnant population (Chapter 6). Early infant HPA axis function at 2 months was limited related to the degree of methylation at CpG sites: D22.24, D25.26, F19 and F20.21 in the NR3C1 promoter region (Chapter 7). And finally in chapter 8 an association between mental development and the methylation state of CpG unit F35 of the NR3C1 promoter region was found as described in chapter 8. Furthermore some borderline significant relations were found between mental neurodevelopment and CpG unit F1.5 and F10.11 as well as between psychomotor development and CpG unit D12.13 and F12.13. Again several of these sites are located in transcription factor binding sites.In the third part of this thesis we investigated the relation between infant HPA axis function and neurodevelopment. It was concluded that early postnatal HPA reactivity during the first year predicts neurodevelopment at 12 months.We must underline that the relations observed were rather weak. The results on growth were inconclusive, though the results on infant HPA axis and neurodevelopment suggest that both are at least partly caused by processes occurring in fetal life.We must underline that our sample resembles the general population. It is reassuring that in a group of mild to moderately emotionally stressed mothers the effects of maternal cortisol and maternal emotional state on infant development seem to be limited. This points out that humans have solid mechanisms to protect their unborn child when exposed to mild to moderate emotionally stressful circumstances. As a consequence we expect the weak effects seen here to enlarge in a more stressed population. We believe that our data further support the fetal programming hypothesis. Of course replication of these data is needed and cautious interpretation is important.status: Publishe
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
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
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