Estimation of whole body muscle, adipose/fat mass, validation in health and during weight loss. Development of prediction equations using MRI as reference method

Background: Body composition is affected by diseases, and affects responses to medical treatments, dosage of medicines, etc., while an abnormal body composition contributes to the causation of many chronic diseases. While we have reliable biochemical tests for certain nutritional parameters of body composition, such as iron or iodine status, and we have harnessed nuclear physics to estimate the body’s content of trace elements, the very basic quantification of body fat content and muscle mass remains highly problematic. Both body fat and muscle mass are vitally important, as they have opposing influences on chronic disease, but they have seldom been estimated as part of population health surveillance. Instead, most national surveys have merely reported BMI and waist, or sometimes the waist/hip ratio; these indices are convenient but do not have any specific biological meaning. Anthropometry offers a practical and inexpensive method for muscle and fat estimation in clinical and epidemiological settings; however, its use is imperfect due to many limitations, such as a shortage of reference data, misuse of terminology, unclear assumptions, and the absence of properly validated anthropometric equations. To date, anthropometric methods are not sensitive enough to detect muscle and fat loss. Aims: The aim of this thesis is to estimate Adipose/fat and muscle mass in health disease and during weight loss through; 1. evaluating and critiquing the literature, to identify the best-published prediction equations for adipose/fat and muscle mass estimation; 2. to derive and validate adipose tissue and muscle mass prediction equations; and 3.to evaluate the prediction equations along with anthropometric indices and the best equations retrieved from the literature in health, metabolic illness and during weight loss. Methods: a Systematic review using Cochrane Review method was used for reviewing muscle mass estimation papers that used MRI as the reference method. Fat mass estimation papers were critically reviewed. Mixed ethnic, age and body mass data that underwent whole body magnetic resonance imaging to quantify adipose tissue and muscle mass (dependent variable) and anthropometry (independent variable) were used in the derivation/validation analysis. Multiple regression and Bland-Altman plot were applied to evaluate the prediction equations. To determine how well the equations identify metabolic illness, English and Scottish health surveys were studied. Statistical analysis using multiple regression and binary logistic regression were applied to assess model fit and associations. Also, populations were divided into quintiles and relative risk was analysed. Finally, the prediction equations were evaluated by applying them to a pilot study of 10 subjects who underwent whole-body MRI, anthropometric measurements and muscle strength before and after weight loss to determine how well the equations identify adipose/fat mass and muscle mass change. Results: The estimation of fat mass has serious problems. Despite advances in technology and science, prediction equations for the estimation of fat mass depend on limited historical reference data and remain dependent upon assumptions that have not yet been properly validated for different population groups. Muscle mass does not have the same conceptual problems; however, its measurement is still problematic and reference data are scarce. The derivation and validation analysis in this thesis was satisfactory, compared to prediction equations in the literature they were similar or even better. Applying the prediction equations in metabolic illness and during weight loss presented an understanding on how well the equations identify metabolic illness showing significant associations with diabetes, hypertension, HbA1c and blood pressure. And moderate to high correlations with MRI-measured adipose tissue and muscle mass before and after weight loss. Conclusion: Adipose tissue mass and to an extent muscle mass can now be estimated for many purposes as population or groups means. However, these equations must not be used for assessing fatness and categorising individuals. Further exploration in different populations and health surveys would be valuable.

Landscape strategies in Bronze Age Southwestern Cyprus (2500-1100 B.C.)

This thesis concerns the analysis of the socio-economic transformation of communities in Bronze Age southwestern Cyprus. Through the adoption of a dialectical perspective of analysis, individuals and environment are considered part of the same unity: they are cooperating agents in shaping society and culture. The Bronze Age is a period of intense transformation in the organization of local communities, made of a continuous renegotiation of the socio-economic roles and interactions. The archaeological record from this portion of the island allows one to go beyond the investigation of the complex and articulated transition from the EBA-MBA agro-pastoral and self-sufficient communities to the LBA centralized and trade-oriented urban-centres. Through a shifting of analytical scales, the emerging picture suggests major transformations in the individual-community-territory dialectical relations. A profound change in the materials conditions of social life, as well as in the superstructural realm, was particularly entailed by the dissolution of the relation to the earth, due to the emergence of new forms of land exploitation/ownership and to the shift of the settlement pattern in previously unknown areas. One of the key points of this thesis is the methodological challenge of working with legacy survey data as I re-analysed a diverse archaeological legacy, which is the result of more than fifty years of survey projects, rescue and research-oriented excavations, as well as casual discoveries. Source critique and data evaluation are essential requirements in an integrative and cross-disciplinary regional perspective, in the comprehensive processing of heterogeneous archaeological and environmental datasets. Through the estimation of data precision and certainty, I developed an effective - but simple - method to critically evaluate existing datasets and to inter-correlate them without losing their original complexity. This powerful method for data integration can be applied to similar datasets belonging to other regions and other periods as it originates from the evaluation of larger methodological and theoretical issues that are not limited to my spatial and temporal focus. As I argue in this thesis, diverse archaeological legacies can be efficiently re-analysed through an integrative and regional methodology. The adoption of a regional scale of analysis can provide an excellent perspective on the complexity of transformations in ancient societies, thus creating a fundamental bridge between the local stories and grand landscape narratives.