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Methylmercury (MeHg) is a global pollutant that can bioaccumulate and biomagnify along the aquatic food chain, causing adverse outcomes in humans and wildlife. Effective biomonitoring programs are needed to identify high exposure populations and to develop proper mitigation strategies. However, biomonitoring results showed high inter-individual variability in the relationship between MeHg exposure and body burden. Moreover, the gut microbiota can potentially play a role in MeHg transformations, and it is widely believed that the gut microbiota may be the underlying reason for the variability between and within a population. However, the microbially-mediated mechanisms of Hg transformation in the gastrointestinal environment is poorly understood. The overarching goal of my thesis is to investigate the role of gut microbiota in MeHg transformation in human, and the relationship between environmental pollutants and the gut microbiota of sentinel species such as river otters (Lontra canadensis) and seabirds (Arctic Tern [Sterna paradisaea], Black Guillemot [Cepphus grille], Common Eider [Somateria mollissima], Double-crested Cormorant [Phalacrocorax auratus], and Leach’s Storm Petrel [Oceanodroma leucorhoa]). My thesis consists of four research papers. In the first paper, I discovered that the gut microbiota`s ability to demethylate MeHg is significantly enhanced by altering the diet. In my second paper, I discovered a novel MeHg degradation pathway. In the third and fourth papers, I explored the effect of Hg and other environmental contaminant exposure on river otters and seabirds gut microbial community structures and found a relationship between prey selection and diet to the gut microbial structure. In conclusion, my thesis explores the relationship between diet, prey selection, environment contaminants and the humans and wildlife gut microbiota and contributes to understanding the gut microbiota’s role in biomonitoring of ecosystem and human health.

The only treatment for celiac disease (CeD), an autoimmune disorder triggered by the ingestion of gluten, is lifelong adherence to a gluten-free diet (GFD). CeD and the GFD have been shown to be associated with low quality of life (QoL). In some individuals, such a strict diet can lead to disordered eating attitudes and behaviors. The purpose of this study was to better understand the extent to which disordered eating attitudes and behaviors may be common in a sample of adults diagnosed with CeD, as well as the relationship with various factors and QoL measures, including anxiety and depression. The study is a cross sectional pilot study of 50 individuals with CeD. Patients between the ages of 18 to 45 years old (mean=29.56, SD=7.40) with a biopsy-proven CeD diagnosis, following a GFD for at least a year (mean=7.20, SD=5.31) with no previous or current eating disorder diagnosis were recruited. In this study, suggestive ED (based on EDDS) and DE (based on EPSI) were present, but low (2% suggestive diagnosis of BED, 12% suggestive diagnosis of OSFED as per DSM-V). The distribution of the self-reported food attitudes and behaviors measures (CD-FAB scores) were spread out around the mean 36.96 (15.30) with a maximum score of 66 out of a possible 77. The CD-FAB may have utility in identifying adults with CeD that may be at risk for disordered eating attitudes and behaviors, particularly those in the first few years after diagnosis. It likely has limited utility in identifying suggestive EDs (as per EDDS) and DE (as per EPSI). The main factors that were associated with higher CD-FAB scores were BMI, number of symptoms, years since diagnosis, diet adherence and personality characteristics. Seven years after diagnosis seems to be an important cut-point in how participants rated food attitudes, fear responses and adaptive responses on the CDFAB scales. Higher CD-FAB scores had a significant and meaningful association with QoL scores. Participants recruited during the COVID-19 pandemic had significantly lower CD-FAB scores and higher QoL scores compared to those recruited pre-pandemic; despite not having significant differences in any other demographic characteristics.

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Objective: To describe the intention for healthy eating and its correlates among southern Appalachian teens. Methods: Four hundred sixteen adolescents 14 to 16 years old were surveyed with self-administered questionnaires. Results: About 30% of the adolescents surveyed had definite intentions to eat healthfully during the next 2 weeks. The scales for perceived behavior control, attitude, perceived eating habits of significant others, and social support were shown to be fairly reliable (Cronbach's α=0.60 to 0.88). Perceived behavior control and attitude were positively associated with the intention for healthy eating. Conclusions: Better behavior control and more positive attitude may lead to a stronger intention for healthy eating.

The nutritional ecology of the black carpenter ant, Camponotus pennsylvanicus (De Geer) was investigated by examining macronutrient preference and particle consumption in foraging workers. The crops of foragers collected in the field were analyzed for macronutrient content at two-week intervals through the active season. Choice tests were conducted at similar intervals during the active season to determine preference within and between macronutrient groups. Isolated individuals and small social groups were fed fluorescent microspheres in the laboratory to establish the fate of particles ingested by workers of both castes. Under natural conditions, foragers chiefly collected carbohydrate and nitrogenous material. Carbohydrate predominated in the crop and consisted largely of simple sugars. A small amount of glycogen was present. Carbohydrate levels did not vary with time. Lipid levels in the crop were quite low. The level of nitrogen compounds in the crop was approximately half that of carbohydrate, and exhibited seasonal dependence. Peaks in nitrogen foraging occurred in June and September, months associated with the completion of brood rearing in Camponotus. In choice tests, foragers demonstrated a preference for sucrose, fructose, and glucose, the most common honeydew sugars. Sucrose was preferred over other sugars in laboratory and field tests. Consumption rates peaked at a concentration of 20%. Casein hydrolysate and processed fish products stimulated the most feeding in choice tests of protein foods. Though a variety of lipids of plant and animal origin were offered in both field and laboratory tests, they were generally ignored. No effect of time was observed during choice tests of macronutrient preference. Overall, nitrogenous food was collected four-fold more intensively than carbohydrate, in contrast to the results obtained from examinations of the crop contents. These data suggest that accessible nitrogen is limited in the environment. Workers readily consumed fluorescent microspheres 0.5 - 45 μm diameter. Forty-five μm microspheres were excluded from the crop. Particles 3 - 10 μm reached the crop, but were never seen in the mid- or hindguts of either major or minor workers. They also filled the infrabuccal pocket, where they were compacted into pellets. It is thought that the proventriculus contains such particles in the foregut, where they are eventually filtered from the ingluvium. Microspheres 1 μm or less were difficult to observe in the infrabuccal pocket, suggesting that they are not as effectively sequestered as larger particles. Microspheres smaller than 1 μm were seen in the mid- and hindgut of both worker castes, indicating that particles of this size are immune to the proventricular filter. Caste exerted an effect at one μm diameter, the threshold of filtering efficiency. One μm microspheres consumed by minor workers were detected in the mid- and hindgut, whereas one μm microspheres were never detected beyond the proventriculus in major workers. / Ph. D.

Background and purpose: The purpose of this study was to identify whether or not sleep behaviors mediated bioecological predictors of weight-related behaviors among college students. Methods: This descriptive, quantitative, cross-sectional study, guided by Bronfenbrenner's bioecological model, examined bioecological characteristics and path analysis to assess model fit. Conclusions: The fit indices indicated excellent fit of the final model to the data (x2 (24) = 30.33, p =.17, root-mean-square error approximation = 0.04, comparative fit index = 0.96, standardized root-mean-square residual = 0.03). Sleep duration mediated significant bioecological predictors of weight-related behaviors, but sleep quality did not. Having children significantly predicted increased sugar-sweetened beverage (SSB) consumption and decreased physical activity (PA) among college students. Conversely, eating the majority of meals at home significantly predicted decreased consumption of SSBs and increased PA. Implications for practice: Findings support inclusion of sleep duration and use of the bioecological model, when providing patient-centered healthcare focused on weight-related behaviors and weight management in college students.

The aim of this thesis is to investigate different methods of improving the glycaemic control of diabetic out-patients, within the scope of the author's training both as a therapeutic dietitian and as a teacher. Evidence is presented from the literature, which indicates that high-carbohydrate, high-fibre diets are of benefit in diabetes, that supplements of viscous fibre improve glycaemic control, and that education of the diabetic patient may help to achieve good diabetic control, provided that the patient also complies with all parameters of therapy. Three main studies have been undertaken: - (1) An educational project, to investigate the effect of a mass-education programme on compliance and control in diabetic out-patients. (2) An investigation of the effect of long-term high-fibre diets in diabetic out-patients. (3) A study of the use of guar gum in the diabetic diet. In Study 1, a large random sample of patients attending a diabetes outpatient clinic were tested by means of a detailed questionnaire, in order to assess their existing knowledge of the disease. A suitable education programme was then devised and patients were exposed to this in the clinic situation. Another sample of patients was then re-tested with the same questionnaire and statistical analysis was used to assess the effect of this programme on knowledge, compliance and control. Results indicate that, while patients' knowledge scores improved, there was no improvement in dietary compliance and also no significant change in the standard of diabetic control in the clinic population. In Study 2 we investigated the practical aspects of administering a high-fibre diet to diabetic out-patients in Cape Town, in the light of the reported benefits of diets containing large amounts of dietary fibre (OF) in the control of diabetes. Readily-available, low-cost foodstuffs with a high OF content, were incorporated into suitable, individualised high-fibre meal plans for 10 selected diabetic out-patients. Patients were closely monitored over a period of 9 months, for 3 months of which the high-fibre diet was prescribed. Various parameters of glycaemic control were recorded and analysed, and the patients' compliance to the new regimen was assessed. Only 3 patients approached the projected fibre intake, but significant negative correlations were found between the dietary fibre increments and both mean plasma glucose and mean serum triglyceride changes. These findings suggest that, were it not for poor dietary compliance, a high-fibre diet might result in significant improvement in diabetic control, and that education and motivation are of prime importance when making major changes to patients' eating habits. Study 3 investigates the use of guar gum, when incorporated into the diabetic diet in both short- and medium-term studies. This viscous fibre has been shown by workers overseas to be effective in lowering postprandial glycaemia. In this study a palatable vehicle for the gum, a digestive-type biscuit, was tested for its effect on glycaemic control when incorporated into the usual meal plans of diabetic out-patients, and also against an oral glucose load as a reference standard. It was found to be effective in reducing the post-prandial rise in blood glucose, and in improving glycaemic control, as shown by reduced fasting blood glucose values and decreased 24-hour urinary glucose excretion. The biscuit proved to be palatable and acceptable to patients, and the guar gum was effective in much smaller quantities than have previously been tested. It may therefore prove a valuable adjunct to diabetes therapy. Results of these studies indicate that compliance to therapeutic recommendations is the crux of achieving good diabetic control. Increased diabetic knowledge alone does not lead to improved diabetic control, and compliance to altered eating habits is difficult to achieve unless prior education and motivation has taken place. The simplest means of achieving better glycaemic control of diabetes appears to be the use of a supplement of viscous fibre, which will improve the glycaemic response to the patients' usual meals.

Indiana University-Purdue University Indianapolis (IUPUI) / Chronic consumption of a high-fat diet is a lifestyle factor that increases the risk for cognitive impairment (Granholm et al., 2008; Greenwood & Winocur, 2005; Mattson, 2004; Winocur & Greenwood, 2005). A high-fat diet appears to facilitate cognitive impairment through the promotion of insulin resistance (Greenwood & Winocur, 2005; Stranahan et al., 2008; Winocur & Greenwood, 2005). A gap in the literature is an established timeframe of the progression and underlying mechanism, which study in animals would better afford. Furthermore, A limited number of studies have investigated the relationship between a high-fat diet and behavioral dysregulation such as anxiety and depression. The 1st aim of the study was to determine if consumption of a high-fat diet leads to cognitive impairment and behavioral dysfunction at 3, 8, or 13 weeks of consumption. The 2nd aim was to determine if cholesterol levels and HBP activity are aberrantly increased in specific regions in mice that display feeding induced cognitive/behavioral dysfunction. Consumption of the experimental specialty diets produced a number of significant behavioral effects. These significant effects began to emerge after only 3 weeks of low-and high-fat feeding with increased anxiety-like behavior displayed higher in the high-fat diet group for the Elevated Plus Maze and Open Field Test. There was increased thigmotactic behavior and floating in the low-fat diet group in the Morris Water Maze (MWM) task, therefore making cognitive assessment uninterpretable. This pattern in the behavioral tasks were more robust in the 8 week group and alleviated in the 13 week group. There was only a significant difference in depression-like symptoms in the Forced Swim (FS) Task in the 3 week group. Cholesterol analysis is still under review in Dr. Elmendorf’s lab to correlate cholesterol levels and cognitive/behavioral impairment.

A decline in the density of zoobenthos has taken place in Lake Abiskojaure in the northern Swedish mountains between 1988 and 2019 but no response can be seen in the abundance (CPUE) of Arctic charr (Salvelinus alpinus) that feed mainly on benthic invertebrates. To evaluate if possible shifts in resource use of charr explain this lack of change in population abundance, stomach contents (i.e. diet) of charr between 1985 and 2020 were analyzed. Charr diets changed during the study period, with decreasing contributions to the diet of larger sized prey and increasing contribution of smaller sized prey and zooplankton. A corresponding recent decline in charr growth, size, and condition factor was observed. The proportion of large prey in diets and charr growth both show a hump-shaped relationship with time before the recent decline, indicating consumption of large prey had a positive effect on charr growth. Densities of zooplankton in the lake did not change with time, meaning increases in diet proportions are driven by something else. Declines in nitrogen and phosphorous over time may have contributed to the decline in zoobenthos densities through nutrient limitation of primary production. The results from this study suggest charr has changed diet towards smaller, less energetically efficient prey as a response to declining zoobenthos levels, and that this has had a negative effect on charr growth, size, and condition factor. Additional declines in nutrients and zoobenthos abundance may further worsen charr performance and eventually be manifested as declining charr abundance.