CONSULTANCY: Human Health & Nutrition
Brain image analysis
- PET scanner in action.
Diets with different composition in terms of protein, fat and carbohydrate are known both to have important physiological effects and to vary in how well they can be adhered to. Recent research at the Rowett Institute and Medical Sciences Institute at the University of Aberdeen, has used PET (positron emission tomography) scanning to study the differences in brain activity in volunteers following diets with different carbohydrate content. The technology produces 3D images at a number of time points. BioSS has been involved in analysing the images to assess where there is evidence that glucose uptake might be related to appetite or diet.
Brain scan slices of a volunteer on separate occasions when following diets differing in carbohydrate content.
Microarray studies of weight regulation
The Siberian hamster, which is used as a model for weight regulation in humans, is known to adapt its body weight according to season, and shows big weight changes between in summer-like long day (LD) and winterlike short day (SD) photoperiods. Identification of genes contributing to the seasonal-appropriate body weight of the Siberian hamsters may provide an insight into how body weight is regulated in other mammals including humans. BioSS helped with normalisation of cDNA microarrays and analyses based on significance tests, controlling the false discovery rate, to find genes that were differentially expressed in hypothalamic samples from animals living under LD and SD conditions.
Plot of estimated expression ratios (LD to SD). Horizontal lines indicate 0 (solid) and 2-fold (dashed) expression ratios. Coloured spots indicate genes with strongest evidence for differential expression. Vertical line indicates cut-off for background noise.
Studying the bacterial composition of the digestive system
Atkins-type diets have been demonstrated to result in body weight loss. To investigate concerns about the impacts of such diets on other aspects of health, we have been involved in experiments on the effect of the low carbohydrate (CHO) content on microbial populations in the gut. The results show that the compositions of bacteria and their metabolic products have changed substantially. In particular, the butyrate producing bacterial group Roseburia rectale is reduced by a factor of three. We have begun developing mathematical models to further investigate the interactions between diet, bacteria, and their metabolic products such as butyrate which are thought to play a role in the prevention of colon cancer.
Average bacterial composition of faecal samples from 7 subjects. bac = Bacteroides fpr = Faecalibacterium prausnitzii rum = Ruminococcus bif = Bifidobacteria prop = Clostridial cluster IX rrec = Roseburia rectale erec - rrec = Clostridial clusters XIVa and XIVb excluding Roseburia rectale