The impact of a variety of factors on the obesity associated gut microbiota

The obesity pandemic has become perhaps the most prevalent health issue of our time, with more than 10% of the world’s population now being obese. Obesity can be defined as abnormal or excess fat accumulation that may impair health and results from an imbalance between energy intake and energy expenditure. A decrease in physical activity due to an increase in sedentary forms of work, changing modes of transport and increasing urbanization is likely a major contributory factor. Diet is another major factor with the increased availability and intake of calorie dense, high fat foods being of global concern. Notably, with respect to this thesis, over the last decade advances in the field of next generation sequencing (NGS) have facilitated investigations to determine the relationship between the gut microbiota and obesity. This thesis examines the impact of a variety of factors on the obesity associated gut microbiota. Overall the results presented in this thesis highlight that microbial diversity is influenced by diet, exercise, antibiotics and disease state, however it is only through further understanding of the structure and function that we can identify targets that can impact on health.

Using parent report to assess early lexical production in children exposed to more than one language

Limited expressive vocabulary skills in young children are considered to be the first warning signs of a potential Specific Language Impairment (SLI) (Ellis & Thal, 2008). In bilingual language learning environments, the expressive vocabulary size in each of the child’s developing languages is usually smaller compared to the number of words produced by monolingual peers (e.g. De Houwer, 2009). Nonetheless, evidence shows children’s total productive lexicon size across both languages to be comparable to monolingual peers’ vocabularies (e.g. Pearson et al., 1993; Pearson & Fernandez, 1994). Since there is limited knowledge as to which level of bilingual vocabulary size should be considered as a risk factor for SLI, the effects of bilingualism and language-learning difficulties on early lexical production are often confounded. The compilation of profiles for early vocabulary production in children exposed to more than one language, and their comparison across language pairs, should enable more accurate identification of vocabulary delays that signal a risk for SLI in bilingual populations. These considerations prompted the design of a methodology for assessing early expressive vocabulary in children exposed to more than one language, which is described in the present chapter. The implementation of this methodological framework is then outlined by presenting the design of a study that measured the productive lexicons of children aged 24-36 months who were exposed to different language pairs, namely Maltese and English, Irish and English, Polish and English, French and Portuguese, Turkish and German as well as English and Hebrew. These studies were designed and coordinated in COST Action IS0804 Working Group 3 (WG3) and will be described in detail in a series of subsequent publications. Expressive vocabulary size was measured through parental report, by employing the vocabulary checklist of the MacArthur-Bates Communicative Development Inventory: Words and Sentences (CDI: WS) (Fenson et al., 1993, 2007) and its adaptations to the participants’ languages. Here we describe the novelty of the study’s methodological design, which lies in its attempt to harmonize the use of vocabulary checklist adaptations, together with parental questionnaires addressing language exposure and developmental history, across participant groups characterized by different language exposure variables. This chapter outlines the various methodological considerations that paved the way for meaningful cross-linguistic comparison of the participants’ expressive lexicon sizes. In so doing, it hopes to provide a template for and encourage further research directed at establishing a threshold for SLI risk in children exposed to more than one language.