- ItemEmbargoHow are driving licensure status, delay in driving licensure, and driving exposure associated with alcohol and drug use, parental monitoring knowledge, peer alcohol and drug use, and health, education, and employment of emerging adults?(Colorado State University. Libraries, 2023) Gao, Xiang, author; Li, Kaigang, advisor; Vaca, Federico E., committee member; Sharp, Julia, committee member; DeYoung, Wendy, committee memberIndependence and mobility facilitated by driving privileges could have a major impact on alcohol and drug use, parental monitoring knowledge, peer alcohol and drug use, and health, education, and employment of emerging adults. Driving privileges may provide emerging adults with the ability to move more freely, and that mobility may affect their access to drugs and alcohol. It may also mean that emerging adults with driving privileges were more likely to be in environments where alcohol and drugs were available. Parents of emerging adults with driving privileges may be more involved in monitoring their child's driving activities, resulting in higher levels of parental monitoring knowledge. Emerging adults with driving privileges were more likely to report a higher level of peer alcohol and drug use because having access to a car allowed them to spend more time with their peers and engage in alcohol and drug use. On the other hand, driving privileges may have positive impacts on the health, education, and employment of emerging adults. Having the ability to travel to places of employment and educational institutions may open more opportunities and allow for greater access to resources. This could lead to improved academic and professional outcomes. Overall, driving privileges may have both positive and negative impacts on alcohol and drug use, parental monitoring knowledge, peer alcohol and drug use, and health, education, and employment of emerging adults. It was important to consider these trade-off impacts when considering how to best support emerging adults in their development. My dissertation explored how were driving licensure status, delay in driving licensure, and driving exposure associated with alcohol and drug use, parental monitoring knowledge, peer alcohol and drug use, and health, education, and employment of emerging adults. Data was collected from a nationally representative sample of U.S. emerging adults starting at grade 10th for a seven-year longitudinal assessment. Having driving licensure in high school, no delay in driving licensure, and higher driving exposure were associated with higher levels of alcohol and drug use, higher levels of parental monitoring knowledge, higher levels of peer alcohol and drug use, better health, higher levels of education attainment, and more working hours in emerging adulthood. My dissertation could inform policymakers and practitioners on the importance of driving privileges in promoting the well-being of emerging adults.
- ItemEmbargoIdentifying novel molecular mechanisms of healthspan using multi-omics(Colorado State University. Libraries, 2023) Smith, Meghan Elizabeth, author; LaRocca, Tom, advisor; Hamilton, Karyn, committee member; Broussard, Josiane, committee member; Ehrhart, Nicole, committee memberAn important goal in research on aging is to extend healthspan, the period of life spent healthy and disease-free. Next-generation sequencing and other emerging bioinformatics technologies (e.g., RNA-seq/transcriptomics, epigenetic profiling, and proteomics) have made it possible to broadly profile potential molecular mediators of aging, and perhaps identify therapeutic targets. The studies in this dissertation focus on using transcriptomics and complementary "multi-omics" strategies to characterize novel cellular mechanisms of aging, and to determine their relevance to systemic/functional health in humans. With the guidance of my mentoring team, I completed three studies in which I identified novel mediators of healthspan-related exercise training responsiveness, age-related inflammation, and cognitive/motor function decline in middle-aged and older adults. One particularly novel focus among these studies was the role of non-coding repetitive RNAs (derived from transposable elements) in healthspan. Transposable elements have been linked to known mechanisms of aging, and this topic is reviewed at the start of this dissertation to provide perspective on their role in the context of research on aging biology. Collectively, my findings represent new ideas for targetable genes and proteins that may influence human healthspan.
- ItemOpen AccessThe transcallosal highway: the ipsilateral silent period as a neural biomarker for impaired corpus callosum communication and gait asymmetry in people with multiple sclerosis(Colorado State University. Libraries, 2023) Acosta, Jordan, author; Fling, Brett, advisor; Rudolph, Alan, committee member; Miravalle, Augusto, committee member; Schmid, Arlene, committee memberMultiple sclerosis is a neurodegenerative disease that damages the myelin sheath within the central nervous system. Axonal demyelination, particularly in the corpus callosum, impacts communication between the brain's hemispheres in persons with multiple sclerosis (PwMS). Changes in transcallosal communication impairs the coordination of gait which requires constant communication across the corpus callosum to excite and inhibit specific muscle groups. To further evaluate the functional role of transcallosal communication in gait and mobility, this study assessed the ipsilateral silent period (iSP), an indirect marker of transcallosal inhibition in PwMS. This study utilizes transcranial magnetic stimulation (TMS) to assess the inhibitory capacity between the brain's hemispheres. There is a lack of research analyzing directionality data between the more and less affected hemisphere in PwMS. Therefore, we evaluated outcome metrics dependent upon the individual's more affected hemisphere calculated from the subject's more affected limb observed during walking assessments and self-report. We hypothesize that the iSP may serve as a neural biomarker for transcallosal impairments evaluated by directionality differences between the hemispheres and highlight transcallosal inhibition as an underlying neural mechanism for gait asymmetries in PwMS. From twenty-nine PwMS, metrics such as depth iSP% average, duration, depth iSP% max, and onset latency were collected. No statistically significant differences were found between the two hemispheres. This suggests that PwMS may be able to preserve their interhemispheric inhibitory capacity irrespective of their more affected hemisphere. Additionally, another component of the study investigated gait coordination utilizing a split-belt treadmill training paradigm. Limb excursion asymmetry (LEA) measures, pre and post-training, were analyzed for spatial coordination and as a measurement of locomotor adaptability in PwMS. The relationship between LEA change and dSP% average highlighted a significant correlation (r=0.46, p= 0.02). Thus, showing that less interhemispheric inhibition corresponds with more spatial adaptability leading to a more symmetric gait. These findings may help determine the potential of iSPs as a neural biomarker to address gait asymmetries and stratify participants into mobility rehabilitation protocols.
- ItemOpen AccessThe effects of sleep extension on physical and cognitive performance in AROTC cadets(Colorado State University. Libraries, 2023) Wedderburn, J'Michael, author; Broussard, Josiane, advisor; Lipsey, Tiffany, committee member; Eakman, Aaron, committee member; Brager, Allison, committee memberCollege students and military personnel have limited sleep opportunities; Reserve Officer Training Corps (ROTC) cadets belong to both groups. Thus, cadets are at a heightened risk of insufficient sleep. Sleep loss can have deleterious effects on physical and cognitive health (Halson et al., 2014). In military professions, these impairments have potentially fatal consequences, as decreased performance will result in diminished operational readiness. Recent evidence suggests that sleep extension is a valid intervention to increase sleep duration (Bonnar et al., 2018). Thus, we aim to identify if sleep extension improves performance in chronically sleep-deprived ROTC cadets. This study examines the impact of 1-week of sleep extension on physical and cognitive performance in Army ROTC cadets. We recruited 16 healthy, active male and female participants aged 18-35 from Colorado State University's ROTC program. Participants were equipped with Actiwatches and completed daily sleep questionnaires and diaries during the habitual and sleep extension periods. Sleep extension was achieved by asking participants to spend 10 hours in bed to increase sleep by at least 1 hour per night. Cadets then completed a series of physical and cognitive tests to measure performance on tactically relevant tasks. The physical testing consisted of a vertical jump, 3-repetition maximal hexagon deadlift, 300-meter shuttle, and a 1-mile run; and cognitive test consisted of a psychomotor vigilance test, the Purdue pegboard test Tiffin (1948), the STROOP color-word test Jensen (1965), and a simulated shooting exercise. Wilcoxon Signed rank-test and two samples paired t-test statistical analysis compared baseline, physical, and cognitive testing data to post-intervention testing data. Cognitive and physical testing occurred after 1-week of habitual sleep and 1-week of sleep extension. The mean objective Total Sleep Time (TST) was 6.07 ± 0.15 hours during the baseline period and 7.03 ± 0.17 hours during the sleep extension period (P=<0.0001). The mean Epworth Sleepiness Scale (ESS) rating was outside of normal limits at 10.47 ± 1.16 during the habitual sleep period; it decreased to fall within the normal limits during the sleep extension period at 7.10 ± 0.79 (P <0.005) (Shattuck & Matsangas. 2014). There were statistically significant differences found on 2 of the 4 Purdue pegboard tests and deadlift performance from habitual sleep to the sleep extension period. The mean hands and assembly scores significantly improved (P = 0.038 and P=0.003, respectively). Performance on the 3-repetition maximal hexagon deadlift increased significantly during the habitual sleep period and sleep extension period (p = .007). The limited sleep opportunities ROTC cadets encounter have negative implications on physical and cognitive performance; based on our findings in the current study, it is plausible that sleep was not extended to an adequate duration to elicit cognitive and physical performance improvements in all of the tested cognitive and physical measure. Thus, more research is needed to investigate the relationship between sleep duration and sleep quality and their effect on cognitive and physical performance in tactical population.
- ItemOpen AccessThe effect of circadian regulation and sleep disruption on metabolic homeostasis(Colorado State University. Libraries, 2022) Morton, Sarah J., author; Broussard, Josiane L., advisor; Hickey, Matthew S., committee member; Dinenno, Frank A., committee member; Bergman, Bryan C., committee member; Prenni, Jessica E., committee memberSleep and circadian disruption are ubiquitous in modern society. While the National Sleep Foundation recommends adults sleep 7-9 hours per night, the average sleep duration of American adults has decreased from ~8.8 hours to ~6.8 hours over the last century, with 1 in 3 people report sleeping fewer than 6.5 hours per night during the work week. People who sleep fewer than 6 hours per night have a three-fold risk of impaired fasting glucose than those sleeping at least 8 hours per night. Laboratory studies report that as little as one night of insufficient sleep impairs insulin sensitivity, which is a common risk factor for obesity and diabetes. Circadian misalignment is common in people who work non-standard hours, including evening, night, or rotating shifts, and is associated with increased fasting glucose and insulin concentrations, as well as impaired insulin sensitivity. Moreover, circadian misalignment can also occur as a consequence of insufficient sleep. With more than 35% of adults reporting insufficient amounts of sleep, chronic and acute circadian misalignment are likely even more prevalent than commonly recognized. Sleep and circadian disruption are associated with increased mortality rates and health problems, including obesity and diabetes. However, the molecular mechanisms by which these impairments occur are not known. Thus, the overall goal of this dissertation was to determine the circadian rhythms of substrate oxidation and hormonal regulators of energy balance as well as to identify molecular alterations associated with insufficient sleep, including skeletal muscle lipid accumulation and altered gene expression, and their relation with insulin sensitivity. The primary findings are that in healthy, young, lean participants 1) carbohydrate and lipid oxidation as well as ghrelin and peptide YY have circadian rhythms as identified by a constant routine protocol and 2) insufficient sleep induces skeletal muscle lipid accumulation and altered gene expression as well as impaired insulin sensitivity. Together, these studies indicate that sleep and circadian disruption may impair insulin sensitivity via dysregulated lipid metabolism.