Filtering by
- All Subjects: Biology
- All Subjects: Metabolism
- Creators: Sweazea, Karen
- Resource Type: Text
Urbanization is characterized by profound environmental changes, and urban animals must adjust to an environment vastly different from that of their non-urban conspecifics. Evidence suggests that birds adjust to urban areas by advancing the timing of seasonal breeding and gonad development, compared to their non-urban conspecifics. A leading hypothesis to account for this phenomenon is that food availability is elevated in urban areas, which improves the energetic status of urban birds and enables them to initiate gonad development earlier than their non-urban conspecifics. However, this hypothesis remains largely untested.
My dissertation dovetailed comparative studies and experimental approaches conducted in field and captive settings to examine the physiological mechanisms by which food availability modulates gonad growth and to investigate whether elevated food availability in urban areas advances the phenology of gonad growth in urban birds. My captive study demonstrated that energetic status modulates reproductive hormone secretion, but not gonad growth. By contrast, free-ranging urban and non-urban birds did not differ in energetic status or plasma levels of reproductive hormones either in years in which urban birds had advanced phenology of gonad growth or in a year that had no habitat-related disparity in seasonal gonad growth. Therefore, my dissertation provides no support for the hypothesis that urban birds begin seasonal gonad growth because they are in better energetic status and increase the secretion of reproductive hormones earlier than non-urban birds. My studies do suggest, however, that the phenology of key food items and the endocrine responsiveness of the reproductive system may contribute to habitat-related disparities in the phenology of gonad growth.
Depression is a worldwide public health problem that affects millions of people every year. Due to recent reports that depressed individuals have an altered gut microbiome composition, there is speculation that treatments that influence microorganisms in the gut could potentially lead to alleviation of depressive symptoms. Apple cider vinegar has been studied extensively for its health-promoting properties and benefits. Apple cider vinegar’s main ingredient is the short chain fatty acid, acetic acid. Short chain fatty acids have been shown to improve mood state and depressive symptoms, as well as amplify the effect of prebiotics in restoring the gut microbiome. This experimental design study examined the effects of ingesting 2 tbsp. apple cider vinegar (1 g acetic acid) twice daily with a meal on the levels of urinary metabolites in 14 college students compared to a control group of 11 college students that took one vinegar supplement tablet (0.015 g of acetic acid) daily for 28 days. All participants were healthy, normal to underactive (< 300 minutes of moderate exercise a week), and free of chronic or acute illnesses. Urinary metabolite analysis revealed a significant production of enzymes involved in the hexosamine pathway in the liquid vinegar group compared to baseline levels. However, anticipation of an alteration in tryptophan metabolites, a possible consequence of altered metabolism of gut microflora, was not observed. These data suggest that apple cider vinegar might be a potential treatment for depression through the production of hexosamine pathway enzymes.
This feasibility study explored the use of an evolutionary mismatch narrative in nutritional education intervention aiming to reduce ultra-processed foods in the diets of veterans with type 2 diabetes and improve diabetic outcomes. Ultra-processed foods are foods that are primarily manufactured through industrial processes. These foods are high in calories but low in nutritional content. Diets high in these foods have been linked to increased health risks. One of the major health risks is type 2 diabetes. Type 2 diabetes is a chronic disease that is developed when cells become unable to properly utilize insulin. Over time this may lead to additional health conditions such as nerve damage, cardiovascular disease, and renal disease. Evolutionary mismatch narrative nutritional intervention offers a different approach to nutritional education to help reduce ultra-processed foods in diets. This study was a randomized controlled feasibility study at the Phoenix VA. Eleven participants were enrolled and randomly selected to be given either an evolutionary mismatch narrative education intervention or general nutritional education about ultra-processed foods. 24-hour diet recalls and blood chemistry were collected and analyzed. Blood chemistry provided diabetes related measurements which included glucose, HbA1c, insulin, HOMA-IR, and C-reactive protein. Statistically significant findings in this study included percentage of ultra-processed foods decreasing for both control and experimental groups from week 0 to week 4 (p=0.014), and C-reactive protein levels between the control and experimental groups (p=0.042). However, baseline C-reactive protein concentrations were lower in the experimental group such that normalizing for group differences at baseline revealed no significant difference in C-reactive protein change between interventions (p = 1.000). There were no other statistically significant values regarding diabetes related measurements. The results from this study suggest that nutritional education in general may help decrease ultra-processed food consumption.