Analysis of metabolic profiles underlying surrogates for obesity and insulin resistance in young adults from the Western Australian Pregnancy Cohort (Raine) Study

Objectives The prevalence of non-communicable disorders and diseases such as insulin resistance and obesity are currently on the rise worldwide in adults and children. However, the underlying metabolic mechanisms are not fully understood yet. Therefore, the methods of metabolomics are a good tool to analyse these mechanisms. Metabolomics analyses small molecules (MW<1.5kDa) in biological samples. The results collected can then be used for basic research, epidemiological studies or in the clinic in the form of biomarker. In the field of metabolomics, sex differences and underlying non-communicable disease development, are highly underrepresented. The aim of this thesis was to find potential markers for obesity and insulin resistance, as well as to analyse sex differences with respect to females taking hormonal contraceptives. The group of females taking hormonal contraceptives was taken into account, as the majority of the women are at least taking the pill, since its development in the 1960s and hormones are known to influence the metabolism. The overall aim was to set the foundation for future biomarker studies for obesity, insulin resistance and the metabolic syndrome, as well as to sensitise future biomarker studies and clinical application of those to sex differences. Methods Blood plasma samples together with anthropometric, sociodemographic and biological data from the 20 year follow-up of the Western Australian Pregnancy Cohort (Raine) Study have been analysed with the aim to find potential biomarkers for obesity and insulin resistance, as well as variables being associated with the metabolome. Firstly, metabolomics data coming from the laboratory underwent quality control. Following, was an analysis strategy, which has been developed for the metabolomics data set containing more than 200 individual metabolites, in association with obesity and insulin resistance. Further, markers for the metabolic syndrome, namely HDL-C, triacylglycerol and glucose concentrations as well as systolic blood pressure and waist circumference, have been analysed with respect to sex differences. To analyse the association between the metabolomics data and waist circumference/BMI and HOMA-Index as a marker for insulin resistance, multiple linear regression analysis has been performed, as it was possible to analyse single metabolites and their associations with the aforementioned obesity and insulin resistance marker. For sex differences, principal components analysis, analysis of variance and post-hoc regression analysis have been performed. All models have been corrected for multiple testing. Principal component analysis was used to depict the general variance in the data, by that the data was reduced to its principal components. These components contain a loading factor for every metabolite resulting from the laboratory analysis based on the variance, which this metabolite explains in relation to the general data set. By plotting the two components, that explain the biggest part of the variance, one can see if there are cluster, which, in the case of sex group analysis, explain the grouping. Results Sphingomyelin (SM), and phosphatidylcholine (PC) patterns have been identified as potential markers for waist circumference, while lyso-phosphatidylcholine C14:0 was associated with HOMA-IR. The results suggest weight status-dependent mechanisms for the development of IR with the respective lyso-phosphatidylcholine C14:0 as a key metabolite in non-obese IR. Further, an analysis according to sex showed significant differences, not only in general, but also disease specific. More than 100 metabolites have been significantly differently associated with sex and hormonal contraceptive use, 43 were significantly different in their effect size on disease markers for the metabolic syndrome and highlighted the importance and need for sex specific analysis in metabolomics and interventional as well as biomarker studies that also take hormonal contraceptive-usage in females into account. Conclusion In conclusion, this thesis showed that metabolomics seems to be valid for cross sectional analyses, showing potential marker for obesity and insulin resistance. Furthermore, the importance of sex sensitive or stratified analysis in the field of metabolomics biomarker studies was shown.Ziele Die Prävalenz nicht-übertragbarer Krankheiten wie Insulinresistenz und Adipositas steigt weltweit unter Erwachsenen und Kindern. Die zugrundeliegenden metabolischen Mechanismen sind nicht vollständig geklärt. Für dieses Forschungsfeld bietet sich daher die Analyse von Humanproben mit Hilfe von Metabolomics an. Metabolomics beruht auf der Erfassung und Erforschung der kleinsten Moleküle im Stoffwechsel (MW<1.5kDa). Die Ergebnisse können dann für Grundlagenforschung, epidemiologische Studien oder in der Klinik in Form von Biomarkern verwendet werden. In den oben genannten Krankheiten sind Geschlechterunterschiede bekannt, die auf der metabolischen Ebene so gut wie nicht erforscht sind, obwohl es etliche Hinweise auf deren Bestehen gibt. Aus diesem Grund war das Ziel dieser Arbeit, frühe Marker für Adipositas und Insulinresistenz, sowie deren zugrunde liegenden Geschlechterunterschiede mit Berücksichtigung der Gruppe von Frauen, die Hormonkontrazeptiva verwenden, zu finden. Die Gruppe der Kontrazeptiva wurde deshalb berücksichtigt, weil ein Großteil der Frauen zumindest die Pille verwendet, seit diese in den 60ern eingeführt wurde und Hormone bekanntermaßen den Stoffwechsel beeinflussen. Das übergeordnete Ziel war es, die Grundlage für zukünftige Biomarker für Adipositas, Insulinresistenz und das Metabolische Syndrom zu schaffen, sowie zukünftige Biomarker- und Metabolomics-Studien und deren Anwendung für Geschlechterunterschiede zu sensibilisieren. Methoden In dieser Arbeit wurden Blutplasmaproben sowie anthropometrische, soziodemographische und biologische Daten der Western Australian Pregnancy Cohort (Raine) Study mit dem Ziel analysiert, einerseits potentielle Biomarker für Adipositas und Insulinresistenz zu finden und andererseits potentielle Geschlechterunterschiede im Metabolom zu untersuchen. Zuerst musste eine Qualitätskontrolle der aus dem Labor kommenden Metabolomics Daten durchgeführt werden. Im Anschluss wurde eine Analysestrategie für den Datensatz mit mehr als 200 individuellen Metaboliten entwickelt, die diesen zusammen mit Markern für Adipositas und Insulinresistenz untersucht. Im Weiteren wurden Marker für das metabolische Syndrom, namentlich HDL-C, Triacylglycerol und Glukose-Konzentrationen, sowie systolischer Blutdruck und Hüftumfang, unter Berücksichtigung von Geschlechterunterschieden analysiert. Um die Assoziationen zwischen den Metabolomics Daten und Hüftumfang bzw. BMI und dem HOMA-Index als Marker für Insulinresistenz zu analysieren, wurde die Methodik der multiplen linearen Regression verwendet, da hierbei einzelne Metaboliten und deren Assoziation mit BMI und HOMA untersucht werden konnten. Für die Geschlechterunterschiede wurde die Hauptkomponentenanalyse (principal components analysis, PCA), Varianzanalyse (ANOVA) und post-hoc Regressionsanalyse verwendet. Alle Modelle wurden für multiples testen korrigiert. Die PCA wurde zur Untersuchung der generellen Varianz in den Daten herangezogen, indem hierbei der Datensatz auf seine Hauptkomponenten reduziert wurde. Diese Hauptkomponenten enthalten, basierend auf der Varianz, die dieser Analyt in den Gesamtdaten erklärt, für jeden aus der Laboranalyse resultierenden Analyten einen Gewichtungsfaktor. Indem man die beiden Komponenten die die meiste Varianz erklären plottet, erkennt man, ob sich Cluster bilden, die in diesem Fall die Geschlechtergruppen erklären. Ergebnisse Es konnten sowohl Sphingomyelin- und Phosphatidylcholine-Muster als potentielle Marker für Hüftumfang identifiziert werden, als auch Lyso-Phosphatidylcholine C14:0 als Marker für Insulinresistenz in nicht-adpösen Patienten. Diese Ergebnisse suggerieren einen gewichtsabhängigen Mechanismus welcher der Entwicklung von Insulinresistenz zugrunde liegt, mit dem Lyso-Phosphatidylcholine C14:0 als Schlüsselmetaboliten in nicht-adipösen Insulinresistenzpatienten. Des Weiteren konnten nicht nur generelle, sondern auch krankheitsbildspezifische, signifikante Geschlechterunterschiede gezeigt werden. Mehr als 100 Metaboliten waren signifikant Unterschiedlich mit dem Geschlecht oder der Hormonkontrazeptiva Gruppe assoziiert, während 43 signifikant unterschiedliche Effektgrößen in Assoziation mit Markern für das Metabolische Syndrom zeigten. Dieses Ergebnis zeigt die Bedeutung und den Bedarf an geschlechtsspezifischer Analyse in Biomarker Studien in Metabolomics, die auch die Gruppe der Frauen, die hormonelle Kontrazeptiva einnehmen, berücksichtigt. Schlussfolgerungen Zusammenfassend konnte diese Arbeit zeigen, dass Metabolomics ein valides Instrument zur Querschnittsanalyse darstellt, welches potentielle Biomarker für Adipositas und Insulinresistenz aufzeigen konnte. Außerdem zeigte sich die Wichtigkeit Geschlechtersensitiver oder –stratifizierter Analysen im Bereich der Biomarkersuche und –Forschung in Metabolomics. Es kann empfohlen werden, dass in zukünftigen Studien das Geschlecht der Studienteilnehmer stärkere Berücksichtigung finden sollte

Service learning and intercultural citizenship in foreign-language education

Service Learning, a pedagogy combining formal learning with community service, has recently developed into Intercultural Service Learning (ISL). Intercultural Citizenship Education (ICE) combines foreign-language education and education for (intercultural) citizenship. They have different origins and applications but recent work in ISL is linked to foreign language education, as is ICE. A comparison of the two reveals considerable similarities and the potential for mutual enrichment. The article first explains the two types of education and their origins and theory, and examples of each are then provided. Thus the ways in which they complement each other and the potential for further coherence and enrichment are demonstrated. In particular it is argued that foreign language education can gain from the experience and rigour of ISL to give new possibilities for language teachers

Soil Characteristics Drive Ficaria verna Abundance and Reproductive Output

Lesser celandine (Ficaria verna Huds.), an invasive plant from Europe, is becoming widespread in river valleys throughout the northeastern United States and the Pacific Northwest. Its high rate of asexual bulbil and tuber production creates dense infestations threatening native spring ephemerals. Ficaria verna abundance and reproductive output (seeds, bulbils, and tubers) were examined in invaded transects spanning a disturbance gradient away from a river. Site characteristics (photosynthetically active radiation [PAR], soil pH, moisture, texture, and nutrients) were quantified to examine their roles in plant abundance and reproduction. A larger-scale study examined random transects not specifically chosen based on F. verna infestations. Soil characteristics and slope were hypothesized to drive F. verna abundance and reproduction; we also hypothesized that reproductive output and biomass would be highest at intermediate distances from rivers, where disturbances are infrequent. Ficaria verna abundance and reproductive output varied considerably by site; soil characteristics, rather than landscape placement, appeared to drive plant abundance and reproduction. Lower percent sand was associated with significantly higher F. verna stem density and bulbil and tuber production. CEC was significantly negatively related to F. verna biomass and tuber counts. In the larger-scale survey, slope and PAR were significantly negatively related to F. verna presence and percent cover, respectively. Overall, these findings suggest that soil texture and slope can help explain higher abundance and reproductive outputs. However, reproductive output and biomass were not significantly greater at intermediate distances, contrary to expectations. We did not observe any seed production in any of the plots, although we did see a few plants with seeds outside our study area in the second year, demonstrating a near-complete reliance on asexual reproduction in these populations. This study expands on the current limited understanding of F. verna and can help management by identifying areas likely to support dense infestations

Influence of Microsite Disturbance on the Establishment of Two Congeneric Invasive Thistles

The successful establishment of invasive species has been shown to depend on aspects of the invaded community, such as gap characteristics. Biotic resistance may be particularly critical for stopping invaders at early life history stages, but new species can often invade following disturbances, which may create microsites with very different characteristics than are usually present. We examine the response of two invasive thistle species, Carduus nutans L. and C. acanthoides L., to three different microsite characteristics: disturbance type, size, and water availability. The two species initially responded differently to the type of disturbance: C. acanthoides had higher emergence and survival in plots with both above- and belowground disturbance, whereas C. nutans had better early performance in large microsites with above-ground disturbance only. Later in their life cycle, C. nutans performed better in plots that had been disturbed both above- and belowground, whereas C. acanthoides was largely unaffected by disturbance type. Increased emergence and survival, larger size and a higher proportion flowering were observed in larger gaps for both species throughout the life cycle. Watering had a negative impact on C. nutans emergence and fall survival and on C. acanthoides survival to the following summer. Overall, these results suggest that disturbance-generated microsite characteristics (disturbance type and size) may have large impacts on establishment of these two Carduus species, which in turn may persist well beyond the initial stages of growth. Studying invader responses to disturbance can help us to understand under what circumstances they are likely to establish and create persistent problems; avoiding or ameliorating such situations will have significant management benefits

Soil Characteristics Drive Ficaria verna Abundance and Reproductive Output

Lesser celandine (Ficaria verna Huds.), an invasive plant from Europe, is becoming widespread in river valleys throughout the northeastern United States and the Pacific Northwest. Its high rate of asexual bulbil and tuber production creates dense infestations threatening native spring ephemerals. Ficaria verna abundance and reproductive output (seeds, bulbils, and tubers) were examined in invaded transects spanning a disturbance gradient away from a river. Site characteristics (photosynthetically active radiation [PAR], soil pH, moisture, texture, and nutrients) were quantified to examine their roles in plant abundance and reproduction. A larger-scale study examined random transects not specifically chosen based on F. verna infestations. Soil characteristics and slope were hypothesized to drive F. verna abundance and reproduction; we also hypothesized that reproductive output and biomass would be highest at intermediate distances from rivers, where disturbances are infrequent. Ficaria verna abundance and reproductive output varied considerably by site; soil characteristics, rather than landscape placement, appeared to drive plant abundance and reproduction. Lower percent sand was associated with significantly higher F. verna stem density and bulbil and tuber production. CEC was significantly negatively related to F. verna biomass and tuber counts. In the larger-scale survey, slope and PAR were significantly negatively related to F. verna presence and percent cover, respectively. Overall, these findings suggest that soil texture and slope can help explain higher abundance and reproductive outputs. However, reproductive output and biomass were not significantly greater at intermediate distances, contrary to expectations. We did not observe any seed production in any of the plots, although we did see a few plants with seeds outside our study area in the second year, demonstrating a near-complete reliance on asexual reproduction in these populations. This study expands on the current limited understanding of F. verna and can help management by identifying areas likely to support dense infestations

Invasional Interference Due to Similar Inter- and Intraspecific Competition Between Invaders May Affect Management

As the number of biological invasions increases, the potential for invader– invader interactions also rises. The effect of multiple invaders can be superadditive (invasional meltdown), additive, or subadditive (invasional interference); which of these situations occurs has critical implications for prioritization of management efforts. Carduus nutans and C. acanthoides, two congeneric invasive weeds, have a striking, segregated distribution in central Pennsylvania, USA. Possible hypotheses for this pattern include invasion history and chance, direct competition, or negative interactions mediated by other species, such as shared pollinators. To explore the role of resource competition in generating this pattern, we conducted three related experiments using a response-surface design throughout the life cycles of two cohorts. Although these species have similar niche requirements, we found no differential response to competition between conspecifics vs. congeners. The response to combined density was relatively weak for both species. While direct competitive interactions do not explain the segregated distributional patterns of these two species, we predict that invasions of either species singly, or both species together, would have similar impacts. When prioritizing which areas to target to prevent the spread of one of the species, it is better to focus on areas as yet unaffected by its congener; where the congener is already present, invasional interference makes it unlikely that the net effect will change

Extensions to the IEEE 802.11 TSF for Efficient and Reliable Network Synchronization in Large Scale MANETs

Designing new protocols for Mobile Ad hoc Networks (MANETs) is a great challenge due to their distributed and self organized nature. Though, aspects of approved algorithms for hierarchical topographies may be carried over to these flat networks. The IEEE 802.11 protocol supports ad hoc networks in small scale applications, but its performance in large scale environments is still under investigation. Besides the Distributed Coordination Function (DCF), the Timer Synchronization Function (TSF) can be significantly improved in order to increase the performance in large scale multihop networks. This article presents systematic extensions to the TSF that allow increasing the overall reliability and disburdening the network at the same time. The presented scheme may be tailored to specific applications and even supports mobile stations and herewith MANETs

Moving from Pattern to Process: Coexistence Mechanisms Under Intermediate Disturbance Regimes

Coexistence mechanisms that require environmental variation to operate contribute importantly to the maintenance of biodiversity. One famous hypothesis of diversity maintenance under disturbance is the intermediate disturbance hypothesis (IDH). The IDH proposes patterns of peaked diversity under intermediate disturbance regimes, based on a tension between competitively superior species and species which can rapidly colonize following disturbance. We review the literature, and describe recent research that suggests that more than one underlying mechanism can generate this unimodal diversity pattern in disturbed environments. Several exciting emerging research areas are identified, including interactions between disturbance types, operation of the IDH in multi-trophic systems, and changes in disturbance regimes. However, empirical work is still focussed on describing the IDH pattern, with little emphasis on identifying its mechanistic basis. We discuss how to extend methods for identifying different coexistence mechanisms, developed in the theoretical literature, to experimental research. In an attempt to operationalize these various ideas we outline a hypothetical IDH research programme. A solid understanding of the life history attributes of the component species and their responses to disturbance will facilitate identification of the coexistence mechanism(s) underlying the IDH pattern, and provide a framework by which empirical and theoretical results can be more fully integrated