The connection between mental and physical health : investigating the associations between psychosocial well-being, sleep and cardio-metabolic health in European children and adolescents

Background The high prevalence of overweight and obesity and related cardio-metabolic disorders such as insulin resistance and hypertension in European children and adolescents is a matter of concern. Aspects of mental health have been suggested to be determinants of cardio-metabolic health and it has been hypothesised that lifestyle factors such as sleep may be part of the underlying mechanism. However, studies in young populations investigating the role of mental health for sleep or cardio-metabolic markers have mainly focussed on a psychopathological view of mental health. Further, studies on the association between sleep and specific cardio-metabolic markers are either limited or suffer from methodological limitations with respect to the measurement of sleep. Aims The present cumulative thesis consists of four original papers that aim to shed light on the associations between psychosocial well-being as one aspect of positive mental health and cardio-metabolic markers. A special focus was put on the role of sleep as a potential mediating factor. Methods Analyses were carried out based on data of children and adolescents from 8 European countries participating in the IDEFICS/I.Family study. The IDEFICS/I.Family study was set up to identify risk and protective factors for chronic non-communicable diseases and to develop and evaluate a community-based intervention for the prevention of childhood obesity. The data that were used for this thesis were collected during three examination waves with intervals of approximately 2 and 4 years in between them (Wave 1: 2007/2008, Wave 2: 2009/2010, Wave 3: 2013/2014). In 2015, these examination waves were complemented by an in depth examination of a subsample in which children with overweight were overrepresented. The samples on which the analyses for the different papers were based varied in size between 559 and 6,519 subjects depending on the available data for the respective research question. Psychosocial well-being comprised items on emotional well-being, self-esteem and social relationships. Sleep characteristics included questionnaire-based and objective measurements of sleep duration, sleep disturbances, sleep quality and sleep timing. Cardio-metabolic markers encompassed waist circumference, blood pressure, the homeostasis model assessment for insulin resistance (HOMA-IR), high-density lipoprotein cholesterol (HDL-C) and triglycerides. Associations were examined applying a variety of statistical methods including multilevel regression analysis, quantile regression and path analysis. Results Higher psychosocial well-being was found to be cross-sectionally associated with longer sleep duration and fewer sleep disturbances (N=6,336). However, well-being at the second examination wave did not predict sleep characteristics 4 years later (N=3,379). Using actigraphy- and sleep diary-derived sleep characteristics (sleep duration, sleep latency, sleep efficiency, bed- and wake time), the following distinct sleep subtypes were identified in a sample of 559 participants from whom detailed information on sleep was collected in 2015: (i) early birds, (ii) short sleep duration, (iii) optimal sleep and (iv) poor sleep quality. Neither sleep subtype nor the single sleep characteristics were found to be statistically significantly associated with body mass index. In contrast, an analysis conducted in 3,900 children and adolescents participating in the second and third examination wave revealed a cross-sectional inverse association between parent- or self-reported sleep duration and waist circumference. Longer sleep duration was also found to be indirectly associated with lower HOMA-IR through lower waist circumference. This indirect pathway was also observed longitudinally, i.e. longer sleep duration at the second examination wave was indirectly associated with lower HOMA-IR four years later following the pathway through waist circumference at the second and waist circumference at the third examination wave. After the associations (i) between psychosocial well-being and sleep and (ii) between sleep and cardio-metabolic markers were investigated in-depth, the associations between psychosocial well-being and cardio-metabolic markers considering sleep duration and other lifestyle factors as potential mediators were analysed in one cross-sectional (N=6,519) and one longitudinal path model (N=1,393). Cross-sectionally, higher psychosocial well-being was found to be indirectly associated with (i) lower waist circumference through a healthier lifestyle and with (ii) lower blood pressure, lower HOMA-IR, lower triglycerides and higher HDL-C through both a healthier lifestyle and lower waist circumference. These indirect effects were also shown in the longitudinal model where changes in psychosocial well-being over the 2- and 4-year-intervals, respectively, were investigated in relation to cardio-metabolic markers measured at the 6-year follow-up (third examination wave). Direct associations were observed between higher levels of psychosocial well-being and lower waist circumference, lower HOMA-IR and higher HDL-C independent of potential confounders and mediators. However, direct associations were less consistent across analyses, i.e. they were partially only observed in the cross-sectional or longitudinal analysis. Discussion and conclusions The results of the present thesis support the hypothesis that psychosocial well-being may be linked to cardio-metabolic health through sleep and other lifestyle factors in children and adolescents. One strategy to improve cardio-metabolic health of children and adolescents may therefore be to promote psychosocial well-being and a healthy sleep, e.g. through resilience training programs and mindfulness-based interventions. However, because of the scarcity of research more longitudinal studies designed for gaining further knowledge on the temporal relationships between positive mental health, lifestyle factors and cardio-metabolic health are needed

The relevance of muscle fibre typology in sports

The human skeletal muscle consists of two major cell types, slow-twitch fibers (also called type I fibers) and fast-twitch fibers (or type II fibers). These fibers have distinct characteristics, as fast-twitch fibers are able to generate a large amount of power at high shortening velocities, while slow-twitch fibers have a better energy efficiency, a higher resistance to fatigue and a more robust structural integrity. On average, most humans will dispose of a 50% slow-twitch and a 50% fast-twitch distribution. However a big heterogeneity exists, what results in people with predominantly slow or fast muscle fibers. The typology of a person is mostly genetically determined and is present across most muscles of the body. Taken together, the fact that muscle fibers have distinct characteristics and that muscle typologies range over the whole continuum from predominantly slow to fast in human, will have important implications for sports performance. Nevertheless, these typologies are currently not used in the daily coaching practice. This is probably due to the invasiveness of the current ‘gold’ standard to measure the muscle typology: a muscle biopsy, which is a labor intensive method and harbors a low generalizability. In 2011, our group introduced a non-invasive way to estimate the muscle fiber type composition through the measurement of carnosine – a metabolite which is abundantly available in fast-twitch fibers – using proton magnetic resonance spectroscopy (1H-MRS). The non-invasiveness of this technique enables the use in both the sports practice and science, and renews the interest of the muscle typology in sports. In the first study, the 1H-MRS method to determine the muscle typology was further optimized with the ultimate goal to make it applicable on various scanner systems of multiple vendors. 1H-MRS was found to be a reliable method to quantify carnosine in the muscle. Furthermore, best practices were proposed to prevent often encountered methodological problems and step by step guidelines were developed to allow broader utilization of this technique. Secondly, we investigated if pre-puberty carnosine measurements could give insights in the post-puberty carnosine concentrations, which would allow application of this technique in early specialization sports (study 2). Carnosine was shown to be a trackable metabolite through the disruptive puberty period (R2=0.249-0.670), which confirms the potential of the current technique to scan both future talents and elite athletes. Next to the methodological optimization, the relevance of the muscle typology for talent identification was examined. Before the start of the thesis, the construct validity of our method was already confirmed in athletics, in which clear differences were determined in the muscle typology of either sprint or endurance disciplines. Despite the fact that a comparable distribution of the muscle typologies could be expected in other cyclic sports such as cycling and swimming, this was not yet investigated in elite athletes. Therefore, study 3 established the muscle typologies of 80 world-class cyclists. Clear differences were found in the muscle typology between cycling events. Keirin, bicycle motocross racing (BMX), sprint and 500 m to 1 km time trial cyclists can be considered as fast typology athletes. Time trial, points race, scratch, and omnium consist of intermediate typology athletes, while most individual pursuit, single-stage, cyclo-cross, mountain bike, and multistage cyclists have a slow typology. Nevertheless, this distribution was not present in 73 elite swimmers (study 4), as no clear differences in the muscle typology were detected between short and long distance swimming events in the different strokes. However, there was some evidence to suggest that truly world-class sprint swimmers had a faster muscle fiber type composition when compared to elite swimmers competing at the international level. Moreover, breaststroke swimmers were identified to have a faster muscle typology in comparison to the either freestyle, backstroke or butterfly swimmers. Elite soccer players (n=118) were found to have an on average intermediate typology, which matches with the intermittent nature of this sport (study 6). In contrary to our hypothesis, no differences in the muscle typology were detected between different positions (keeper, defender, midfielder and striker). A big heterogeneity was established over all positions, indicating that the muscle typology is not of major importance for talent identification in soccer. To determine the influence of the muscle typology on individualized training and recovery cycles, we investigated if fatigue and recovery were different when both slow and fast typology subjects were exposed to the same high-intensity training (study 5). Fatigue during three Wingate tests, determined by the power drop, was 20% higher in fast typology athletes. Even though the same work was done during these Wingate tests, also the recovery from these Wingate tests was found to be 15 times slower in fast typology athletes (20 min in slow typology vs. longer than 5 h in fast typology). If a training plan would be composed with a minimum of recovery in between the training sessions, recovery might be insufficient for fast typology athletes, possibly rendering them with a higher risk for muscle strains. In study 6, we studied if the muscle typology is a risk factor for muscle strains in elite soccer players. We discovered that fast typology soccer players had a 5.3 times higher chance to get a hamstring injury, when compared to slow typology soccer players during a prospective longitudinal follow-up study over three seasons. Next to a higher accumulation of fatigue, a higher vulnerability in fast typology players could be expected due to the lower structural integrity in fast fibers. Bringing together, the muscle typology is an important characteristic, which could be non-invasively monitored using 1H-MRS. This technique could help athletes to make a scientific based decision on their ideal discipline during talent orientation. Moreover, it could help coaches tailoring training to enlarge the athletes’ muscle potential and to prevent fatigue accumulation. This endeavor might partly prevent fast typology athletes to be at a higher risk for strain injuries. Consequently, we believe that measuring the muscle fiber typology of athletes should be considered as a valuable procedure to help athletes to fully develop their potential based on the smart use of muscle profiling

Everything that shines sees : a media-archaeological investigation into flashlight as a creative concept within contemporary artistic practice

In het praktische luik van mijn doctoraatsonderzoek Everything That Shines Sees heb ik me geconcentreerd op de concepten van zelf-ontwikkeling en mediëring in beeldende processen om tot een inzicht te komen in fotografische inscripties die veroorzaakt worden door flitslicht en haar natuurlijke straling. In samenwerking met diverse internationale onderzoekscentra (Lightning Lab in Oxfordshire (VK), CERN in Genève (CH)), heb ik speculatieve experimenten uitgevoerd met artificiële blikseminslagen, kosmische straling en radioactiviteit om voorbij de statische en traditionele aannames te kijken van wat het fotografische precies inhoudt. Door de creatieve rol van een plotse lichtflits via verschillende manifestatievormen (fulgurieten, Lichtenberg figuren, fotogrammen, geluid) te onderzoeken, leg ik de nadruk op de rol die acheiropietische en automatische factoren spelen in de totstandkoming van de foto als technisch beeld en in de mediëringsprocedures die hiermee gepaard gaan. De onderzoeksprojecten trachten op die manier de betrokkenheid naar voren te schuiven van niet-menselijke actoren in de ontwikkeling van hedendaagse beelden en hun epistemologie als een mogelijke manier om perceptie te herdenken en te herdefiniëren, wat relevant lijkt in een tijd dat we steeds meer vertrouwen op vormen van kunstmatig opgewekte visibiliteit. In mijn proefschrift bespreek ik historische en actuele case studies die flitslicht en zijn technologie linken aan drie grote concepten, namelijk licht, tijd en geest. Ik focus hierbij op de technische mediëring door middel van flitslicht en hoe dit proces zich verhoudt tot de performatieve kwaliteiten van zijn zeer specifieke esthetiek en van de vaak ambigue symboliek die ermee gepaard gaan. Ik wil hiermee aantonen dat flitslicht geen passief middel is om een onafhankelijk, al bestaand fenomeen zichtbaar te maken, maar dat het een essentieel en integraal onderdeel is van de constructie van dat fenomeen en van zijn esthetische representatie. De publicatie omvat twee volumes. Volume I presenteert een theoretisch onderzoek naar flitslicht als een creatief concept binnen hedendaagse kunstpraktijken. Volume II bevat een aantal audiovisuele werken die ik in de context van dit doctoraatsonderzoek heb gerealiseerd.For my doctoral research project Everything That Shines Sees, I take a closer look at the concepts of self-origination and mediation for a better understanding of the photographic inscription engendered by a flash of light and its natural radiation. Starting from my own artistic experiments with fulguric and cosmic rays, performed in cooperation with a lightning simulation lab in Oxfordshire (UK) and with the nuclear research centre CERN in Geneva (Switzerland), my research puts forward a speculative approach that looks beyond static and traditional assumptions about what it entails to ‘be photographic’. Through the exploration of the creative role fulfilled by a sudden burst of light across different time periods and different manifestations (fulgurites, imprints, photograms, sound), focus is laid on the part the acheiropoietic and the automatic can play in this revitalized apprehension of the photograph as a technical image and of the agencies involved in its mediation. The research projects discussed thus aim to foreground the involvement of nonhuman contributors in the formation of contemporary images and their epistemology as a possible way to re-think perception in a time increasingly shaped by a reliance on artificially induced visibility. In my dissertation I discuss historic and contemporary case studies that link the flash and its technology to three major concepts: light, time and mind. I hereby focus on the engagement proper to the technical process of mediation by flashlight, and how that is tied to the performative qualities of its distinct aesthetic and the often contradictory symbolism attached to it. In doing so, I reveal that flashlight is not merely a means of obtaining some independently given entity; it is an intrinsic part of the construction and the signification of the substance since phenomena are thoroughly constituted by its workings. The published output consists of two volumes. Volume I presents a theoretical investigation into flashlight as a creative concept within contemporary artistic practice. Volume II features a selection of my audiovisual works created in the framework of this doctoral research

Working 'with' or 'on' Moroccan migrant mothers : mediating structure versus agency in the analysis of marriage migration, gender and integration

The main question this ethnographic research seeks to answer is how to move beyond the dominant ‘structure versus agency’ in the study or analysis of marriage migration, gender and integration in Flanders (Belgium). On an international level, this binary thinking shapes the debate on migrant women, who are regarded as passive victims of men, patriarchy, religion, and the need for them to be liberated, empowered or educated in order to better fit in to society. These representations have given rise to a consensus in the West: that Muslim women need to be rescued, which is propagated by human rights groups, liberal feminists, right-wing politics and the media. In the Belgian national context of family reunification and marriage migration, marriage migrant women are believed to be held back or constrained by their husbands, family and/or religion from integrating and partaking in (regular) citizenisation and Dutch courses, which denies their agency both as wives and citizens. Additionally, their personal choices to become mothers are believed to exacerbate their position as passive citizens. Furthermore, becoming a mother supposedly leaves them little time to invest in integration courses, especially since day-care services are an important financial and cultural threshold. As these representations and policies are often not based on rigorous research that consults these migrant women directly, this research aims to fill this knowledge gap by bringing together the gendered representations and policy views on marriage migration and the narratives of lived experiences and desires, as articulated by migrant women themselves. Another aim is to find out how exactly Moroccan migrant women navigate these structures as affective migrant mothers, and the role of religion in this. The main findings show how marriage migration as a form of migration is increasingly characterised by multiple, variable and complex processes and meanings for migrant women themselves. In contrast to class and race, gender for example was rarely referred to by the participating women as a form of inequality or constraint. Rather, a first finding is that gender-inequality was more present within the narratives of ‘mediators’ or key informants with a migration background, who contend that the legal conditions for family reunification rather maintain or reinforce gender-inequality due to migrant women’s positions of legal dependency. Secondly, the migrant mothers’ capacity to navigate and cope within their complex and often (legally) precarious situations depended mainly on previous experiences with migration, the length of their residence to date, and their socio-economic and educational level. Thirdly, and contrary to popular belief, I found that migrant women are motivated to partake in citizenisation courses segregated on the basis of gender and greatly benefit from it. An important condition, however, is the opportunity to have free and/or accessible day-care services for their children. Also, engaging with both first generation and newcomer migrant mothers’ own narratives, desires and lived experiences led to my discovery of several discrepancies between dominant discourses about integration and citizenisation, and migrant mothers’ own views and experiences. Finally, I found that becoming a mother and investing in care and mothering was experienced as a rewarding investment of migrant women’s time spent in precariousness

Phosphorylation integrates signalling under drought and high temperatures in plants

Planten passen zich voortdurend aan veranderende omgevingsomstandigheden aan om schade te voorkomen en optimale prestaties te behouden. Ze hebben poriën in hun bladepidermis, die huidmondjes worden genoemd, om de gasuitwisseling met de omgeving te reguleren en abiotische stress te verminderen. Verschillende omgevingsignalen beïnvloeden het openen en sluiten van deze huidmondjes. Warmte bevordert bijvoorbeeld het openen van huidmondjes (om af te koelen), terwijl droogte leidt tot sluiting van de huidmondjes (om waterverlies te voorkomen). Onder bepaalde omstandigheden kunnen conflicterende stressfactoren echter tegenstrijdige reacties in de huidmondjes veroorzaken, maar de exacte cellulaire mechanismen om deze conflicten op te lossen, waren tot nu toe onbekend. In dit onderzoek wordt aangetoond dat het eiwit TARGET OF TEMPERATURE 3 (TOT3), dat geassocieerd is met hoge temperaturen, rechtstreeks de activiteit van plasmamembraan H+-ATPases reguleert om de opening van de huidmondjes te bevorderen. Deze TOT3-activiteit wordt op zijn beurt tegengewerkt door OPEN STOMATA 1 (OST1), dat waterverlies tijdens droogtestress voorkomt door de huidmondjes te sluiten. Op deze manier werkt deze signaalroute samen om tegenstrijdige warmte- en droogtesignalen te harmoniseren en zo de opening van de huidmondjes te reguleren. Begrijpen hoe planten tegenstrijdige stresssignalen integreren bij het reguleren van huidmondjes biedt waardevolle inzichten voor het ontwikkelen van klimaatbestendige gewassen in het licht van de wereldwijde klimaatverandering