Behavioural and neuroimaging studies of food reward after bariatric surgery for obesity

BACKGROUND Roux-en-Y gastric bypass (RYGB) surgery is the most effective treatment for obesity and has greater efficacy for weight loss than gastric banding (BAND) surgery. The superior weight loss seen after RYGB may result from profoundly different effects on food hedonics and reward brought about by physiological changes secondary to the distinct manipulations of gut anatomy. AIMS To compare body mass index (BMI) matched patients after RYGB or BAND surgery and unoperated controls using comprehensive phenotyping of brain structure and function, eating behaviour and metabolism. METHODS In these cross-sectional studies, un-operated controls and patients after RYGB and BAND surgery had functional and anatomical neuroimaging of food reward systems. Reward responses to food were assessed with a functional magnetic resonance imaging (fMRI) food picture evaluation task. Anatomical differences in grey and white matter were assessed using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI). Eating behaviour, food appeal and palatability, potential mediators, and post-ingestive effects were compared between groups using questionnaires, test meals, food diaries and assay of plasma hormones and metabolites. Surgical patients were compared in both the fasted and fed state, and after administration of the somatostatin analogue, Octreotide, to suppress anorexigenic gut hormone responses after RYGB. RESULTS Obese patients after RYGB had healthier gut-brain-hedonic responses to food than patients after BAND surgery. RYGB patients had lower activation than BAND patients in brain reward systems, particularly to high-calorie foods, including the orbitofrontal cortex, amygdala, caudate nucleus, nucleus accumbens and hippocampus. This was associated with lower palatability and appeal of high-calorie foods, and healthier eating behaviour, including less fat intake, in RYGB compared to BAND patients and/or BMI-matched unoperated controls. These differences were not explicable by differences in hunger or psychological traits between the surgical groups, or by differences in brain structure as measured by VBM and DTI. However anorexigenic plasma gut hormones (GLP-1 and PYY), plasma bile acids and symptoms of dumping syndrome were increased in RYGB patients. Octreotide increased nucleus accumbens activation to food pictures, increased food appeal and decreased post-meal satiety in patients after RYGB, but not BAND surgery. The preliminary nature of this small study precludes extensive interpretation especially of the difference between surgical groups. Patients in the operated groups (RYGB and BAND) had lower grey matter density in areas involved in reward processing, including the amygdala, nucleus accumbens and hippocampus compared to BMI-matched controls. There was no difference between the groups in white matter tract integrity. CONCLUSIONS Identification of these differences in the gut-brain axis and hence food hedonic responses as a result of altered gut anatomy/physiology provides a novel explanation for the more favorable long-term weight loss seen after RYGB than BAND surgery. This supports targeting of gut-brain reward systems for future treatments of obesity.Open Acces

Obesity and bariatric surgery in adults living with severe mental illness: perceptions and clinical challenges

Overweight and obesity are twice as likely to develop in people living with severe mental illness (SMI), compared with those without. Many factors contribute to this, such as reduced physical activity and the use of certain medications that induce weight gain. Obesity contributes to the premature mortality seen in people living with SMI, as it is one of the fundamental risk factors for cardiovascular disease and diabetes. Bariatric surgery is an effective treatment option, although patients living with SMI might face stigma when being considered for surgical intervention. This article proposes a discussion around obesity and bariatric surgery in patients living with SMI. It will also reflect on the challenges faced by healthcare professionals and patients living with SMI and obesity, when considering appropriate treatments for weight loss. The paper utilises a fictional case, informed by contributions from a lived experience author, to explore bariatric surgery in people living with SMI

The changing face of tuberculosis : trends in tuberculosis-associated skeletal changes

Tuberculosis remains a major health problem in many areas of the world. Previous research suggested that the frequency of bone lesions has decreased in the modern (but pre-antibiotic) period, and that the predominantly spinal involvement have changed to affect other parts of the skeleton, in particular ribs. The purpose of this study was to investigate whether bone lesions associated with TB became more or less common in the post-antibiotic period, and if the pattern of skeletal involvement has changed. The skeletons of 147 individuals from South Africa who died from TB were assessed. These were divided into three groups – those dying before 1950 and presumed to have had no antibiotic intervention (n = 52); those dying between 1950 and 1985 presumed to have been treated with antibiotics (n = 34); and those dying after 1985 where co-infection with HIV and drug-resistant disease emerged (n = 61). Overall, 33.3% of all individuals showed signs that could be associated with TB, with corresponding figures in each of the three groups being 21.1%, 38.2% and 41.0%. The increase from group 1 to 3 was statistically significant. Rib lesions are becoming more common, while spinal lesions are decreasing. It may be suggested that patients are surviving for longer due to antibiotic treatment, allowing more time for the development of lesions.National Research Foundation (NRF) of South Africa.http://www.journals.elsevier.com/tuberculosis/hb201

Obese patients after gastric bypass surgery have lower brain-hedonic responses to food than after gastric banding

Objectives Roux-en-Y gastric bypass (RYGB) has greater efficacy for weight loss in obese patients than gastric banding (BAND) surgery. We hypothesise that this may result from different effects on food hedonics via physiological changes secondary to distinct gut anatomy manipulations. Design We used functional MRI, eating behaviour and hormonal phenotyping to compare body mass index (BMI)-matched unoperated controls and patients after RYGB and BAND surgery for obesity. Results Obese patients after RYGB had lower brain-hedonic responses to food than patients after BAND surgery. RYGB patients had lower activation than BAND patients in brain reward systems, particularly to high-calorie foods, including the orbitofrontal cortex, amygdala, caudate nucleus, nucleus accumbens and hippocampus. This was associated with lower palatability and appeal of high-calorie foods and healthier eating behaviour, including less fat intake, in RYGB compared with BAND patients and/or BMI-matched unoperated controls. These differences were not explicable by differences in hunger or psychological traits between the surgical groups, but anorexigenic plasma gut hormones (GLP-1 and PYY), plasma bile acids and symptoms of dumping syndrome were increased in RYGB patients. Conclusions The identification of these differences in food hedonic responses as a result of altered gut anatomy/physiology provides a novel explanation for the more favourable long-term weight loss seen after RYGB than after BAND surgery, highlighting the importance of the gut–brain axis in the control of reward-based eating behaviour

The perceptions and attitudes of general practitioners and final-year medical interns in central Johannesburg hospitals toward chiropractic

Abstract : Please refer to full text to view abstract.M.Tech. (Chiropractic

Generalist bird exhibits site-dependent resource selection

Quantifying resource selection (an organism\u27s disproportionate use of available resources) is essential to infer habitat requirements of a species, develop management recommendations, predict species responses to changing conditions, and improve our understanding of the processes that underlie ecological patterns. Because study sites, even within the same region, can differ in both the amount and the arrangement of cover types, our objective was to determine whether proximal sites can yield markedly different resource selection results for a generalist bird, northern bobwhite (Colinus virginianus). We used 5 years of telemetry locations and newly developed land cover data at two, geographically distinct but relatively close sites in the south-central semi-arid prairies of North America. We fit a series of generalized linear mixed models and used an information-theoretic model comparison approach to identify and compare resource selection patterns at each site. We determined that the importance of different cover types to northern bobwhite is site-dependent on relatively similar and nearby sites. Specifically, whether bobwhite selected for shrub cover and whether they strongly avoided trees, depended on the study site in focus. Additionally, the spatial scale of selection was nearly an order of magnitude different between the cover types. Our study demonstrates that—even for one of the most intensively studied species in the world—we may oversimplify resource selection by using a single study site approach. Managing the trade-offs between practical, generalized conclusions and precise but complex conclusions is one of the central challenges in applied ecology. However, we caution against setting recommendations for broad extents based on information gathered at small extents, even for a generalist species at adjacent sites. Before extrapolating information to areas beyond the data collected, managers should account for local differences in the availability, arrangement, and scaling of resources

Quantified-self for obesity: Physical activity behaviour sensing to improve health outcomes

Background Physical activity is effective for long-term weight loss maintenance following calorie restriction diets; however, there is a lack of research on its effects on weight loss following bariatric surgery1. Previous studies objectively measuring physical activity have shown that while there is a wide range of activity levels in bariatric patients, the majority achieve significantly less than the recommended 30min/day moderate-to-vigorous physical activity (MVPA) guidelines for health-related benefits2-5. It is important to gain a better understanding of physical activity profiles in this heterogeneous group over time and to ascertain whether increased physical activity is associated with better weight loss outcomes, improved quality of life and resolution of comorbid conditions. Aims The primary aim of this study is to assess the feasibility of continuously monitoring physical activity via a smartphone app with minimal user interaction required, and to characterise the physical activity profiles of bariatric surgery patients. Method 255 patients aged 18-65years with a BMI >35kg/m2 and who were either awaiting or had previously underwent bariatric surgery were recruited from the Imperial Weight Centre. Physical activity [i.e. step count, walk time (mins) and distance walked (km)] was recorded using the free, commercial ‘Moves’ app (Protogeo), with an adjunct app recording weight, mood and wakefulness data. Physical activity data tracked by the Moves app for at least 8 hours per day between the hours of 6am-10pm was categorised as follows: 1) Average walking time (mins) of light, moderate and vigorous intensity per day, 2) ‘Moderate to Vigorous physical activity (MVPA)’; average daily walking time with >80steps/min; 3) average light and MVPA in bouts of 10 minutes per day, and 4) average MVPA in 10 minute bouts of activity per day. Results Data from 147 participants (mean age 42.95, SD±11.50; 70.7% female) met inclusion criteria for data analysis. The average BMI of patients awaiting surgery (n=52) was 47.1kg/m2 (SD±9.53) and average weight loss percentage for post-surgery patients (n=95) at the time of recruitment was 14.62% (SD±10.71) encompassing a post-surgery period from 10 days to >2 years. Participants were tracked for a median of 26 days each (range 1-139 days, partly depending on when they were recruited). 61% of participants (n=89) achieved an average of at least 30 minutes of light and MVPA per day. 57% (n=84) achieved one or more bouts of light and MVPA for a minimum of 10 minutes per day but only averaging 15.31 minutes (SD±2.89). 66% of participants (n=97) walked at a moderate-to-vigorous pace at >80 steps/min, but only for an average of 6 minutes (SD±2.83) per day. 54% (n=80) performed MVPA in bouts of 10 minutes, but only averaging at 15 minutes (SD±3.26). Conclusions We have shown that it is possible to passively monitor physical activity in a large patient population in a cost-effective way. The results demonstrate that while two thirds of bariatric patients achieved an average of 30 minutes walking per day, this was not of sufficient intensity to gain health-related benefits. Further analysis will examine whether increased activity is associated with successful weight loss outcomes, improved mood and psychological functioning, and increased quality of life. We will also employ machine-learning techniques to identify the factors that are critical for a successful outcome following bariatric surgery. Recruitment will continue to the end of the project (April 2016) and tracking will continue into 2017

Feasibility of acceptance and commitment therapy for post-bariatric surgery patients: the FAB study protocol

Background: Bariatric surgery is an effective treatment for obesity. However, around one in five people experience significant weight regain. In the months following surgery, loss of food as a hedonic reward, increased sensitivity to food-related cues, alcohol use and depression may translate into new obesogenic behaviours which can be targeted in therapy. Acceptance and Commitment Therapy (ACT) teaches acceptance of and defusion from thoughts and feelings which influence behaviour, and commitment to act in line with personal values. We will test whether people who have had bariatric surgery over one year ago find 10 weeks of ACT group therapy an acceptable treatment and whether a larger trial to test whether ACT can improve long-term post-operative outcomes would be feasible.Methods: This will be a feasibility randomised controlled trial (RCT) with participants randomised to either ACT or a Usual Care Support Group control. Participants will be recruited at 15-18 months post-surgery and compared at baseline, 3, 6 and 12 months. The trial will provide information about recruitment and characteristics of the proposed outcome measures to inform a definitive RCT.Conclusions: Trials big enough to determine whether a treatment approach works are costly, so this small study will help determine whether the methods used, such as how people are recruited, allocated to groups, and how data are collected, are likely to work on a bigger scale. This project is the first step in testing whether ACT can help people who have had bariatric surgery.Trial Registration: Researchregistry.com, UIN: 3959 (date registered: 10 April 2018); ISRCTN registry ID: ISRCTN52074801

Rapid Diagnostic for Point-of-Care Malaria Screening

Despite significant success in therapeutic development, malaria remains a widespread and deadly infectious disease in the developing world. Given the nearly 100% efficacy of current malaria therapeutics, the primary barrier to eradication is lack of early diagnosis of the infected population. However, there are multiple strains of malaria. Although significant efforts and resources have been invested in developing antibody-based diagnostic methods for Plasmodium falciparum, a rapid and easy to use screening method capable of detecting all malaria strains has not been realized. Yet, until the entire malaria-infected population receives treatment, the disease will continue to impact society. Here, we report the development of a portable, magneto-optic technology for early stage malaria diagnosis based on the detection of the malaria pigment, hemozoin. Using β-hematin, a hemozoin mimic, we demonstrate detection limits of <0.0081 μg/mL in 500 μL of whole rabbit blood with no additional reagents required. This level corresponds to <26 parasites/μL, a full order of magnitude below clinical relevance and comparable to or less than existing technologies

Quantified-self for obesity : physical activity behaviour sensing to improve health outcomes

Physical activity levels in bariatric patients have not been well documented, despite their importance in maintaining weight loss following surgery. This study investigated the feasibility of tracking physical activity using a smartphone app with minimal user interaction. Thus far, we have obtained good quality data from 255 patients at various points in their weight loss journey. Preliminary analyses indicate little change in physical activity levels following surgery with pre-surgery patients reaching an average of 16 minutes per day and post-surgery patients achieving a daily average of 21 minutes. Further analyses using machine-learning techniques will be conducted to determine whether physical activity is a critical factor in distinguishing between successful and unsuccessful weight loss outcomes and in the resolution of comorbid conditions in patients with similar clinical profiles