Maternal Physical Activity and Cardiorespiratory Fitness During Pregnancy and its Relation to Infant Size

Recent evidence indicates that U.S.-born infants are larger today compared to 20 years ago. A strong determinant of neonatal size is maternal body mass, where larger mothers deliver larger infants. Consistent evidence indicates that higher levels of maternal physical activity (PA) during pregnancy reduce the risk of delivering a larger infant. However, this protective effect has only been demonstrated in normal weight pregnant women. Little is known about the relationship between maternal PA and neonatal size in overweight or obese pregnant women. Moreover, no studies have examined the association between maternal cardiorespiratory fitness (CRF), an indicator of habitual PA, on infant size in this pregnant subpopulation. Thus, the overall purpose of this dissertation was to determine if maternal PA moderates the association between maternal body mass and infant size and whether maternal PA and/or CRF are associated with neonatal size in overweight or obese pregnant women. In study one, logistic regression analyses were performed to evaluate the moderating roles of maternal PA in the preconception and prenatal periods on the association between maternal body mass index (BMI) and the risk of delivering a macrosomic infant. Maternal BMI and physical activity served as the main predictor variables. Regression models were adjusted for maternal age and race/ethnicity, gestational age and weight gain, smoking and alcohol use, and infant sex. Overweight or obese pregnant women had increased odds of delivering a macrosomic infant (OR = 1.69, p=0.34; OR=1.00, p=0.13, respectively), after adjusting for covariates. The present study does not support the hypothesis that maternal PA prior to or during pregnancy alters the relationship between maternal BMI and infant size. In study two, multiple linear regression models were constructed to determine the independent and joint associations of maternal PA and CRF with infant birthweight. Maternal PA and CRF were the main predictors and regression models were adjusted for gestational age, maternal age and weight gain, and group allocation. After adjusting for covariates, multiple linear regression analyses showed that maternal PA (steps.day-1.month-1) (β= 0.03 g, 95% CI: -0.03, 0.08g) and CRF (ml O2.kg-1.min-1) (β= -8.83 g, 95%CI: -42.2, 24.5 g) were not independently nor jointly (β= 0.006 g, 95%CI: -0.005, 0.005 g) associated with offspring birthweight. Contrary to hypotheses, maternal PA and CRF during pregnancy were not related to infant birthweight in overweight or obese pregnant women. In study three, individual trajectories for maternal PA in the prenatal period were estimated via repeated measures analyses to represent the change in PA from mid (4th month) to late (8th month) pregnancy. Multiple linear regression models were then performed to determine the association between change in prenatal PA and birthweight. Change in maternal PA was the main predictor and regression models were adjusted for gestational age, weight gain, maternal age and group allocation. PA declined from the 4th to the 8th month of pregnancy (- 399.73 ± 371.38 steps.day-1.month-1). After adjusting for covariates, multiple linear regression analyses showed that the decline in prenatal PA (β= -0.28 g, 95%CI: -0.70, 0.25 g, p=0.35) was not associated with birthweight. In addition, CRF (β= 0.04 g, 95%CI: -0.06 g, 0.14 g, p=0.697) did not exhibit a moderating effect. Maternal physical activity declined in mid-to-late pregnancy, and contrary to hypotheses, the observed decrement was found to be unrelated to infant birthweight. Overall, the findings from these studies demonstrate that higher levels of maternal physical activity prior to and during pregnancy do not modify the relationship between maternal body mass and neonatal size. In addition, these findings indicate that maternal physical activity and cardiorespiratory fitness do not independently or jointly associate with neonatal birthweight. These studies provide information about these relationships in an understudied subpopulation and contribute to this rapidly growing area of research. Several recommendations are suggested to address the limitations of these studies including sampling strategies that will increase variability in PA and CRF levels, more rigorous and precise measures of PA and infant anthropometry and the inclusion of metabolic biomarker assessments

The effects of a S.M.A.R.T. goal setting and self-monitoring intervention on physical activity and fitness in middle school students

A large body of evidence suggests physical activity is inversely associated with several cardio-metabolic risk factors among children and adolescents. Despite these health benefits, a majority of youth are not meeting the physical activity guidelines set forth by the USDHHS. Schools have been identified as an ideal vehicle for interventions; however, research evidence indicates school-based interventions are not effective at increasing outside of school physical activity. Goal setting may be a potential effective strategy for increasing physical activity among youth; however no previous studies have examined the effects of goal setting on cardiorespiratory fitness and physical activity in middle school students. Therefore, the purpose of this study is to evaluate the effects of a S.M.A.R.T. goal setting and self-monitoring intervention on fitness and physical activity in middle school students. Two middle schools in Tallahassee, FL participated in this study. One school served as the intervention and the other served as a delayed intervention measurement only control. The students in the intervention school completed a one-time S.M.A.R.T. goal setting lesson. During the lesson, students were taught the definition of a goal, the importance of goal setting, and how to set S.M.A.R.T. goals. As part of the lesson, students completed a S.M.A.R.T. goal setting worksheet. The objectives of the worksheet activity were to teach students the concepts of S.M.A.R.T. goal setting and to apply this knowledge by creating personal fitness goals. Student fitness goals were entered into an interactive website that acted as a self-monitoring tool. Before and after the intervention, participating students completed a survey assessing student demographics, physical activity, and physical activity self-efficacy. Cardiorespiratory fitness levels, assessed by the PACER test, were also measured pre and post. Betweengroup differences in post-test scores, adjusted for baseline levels, were assessed for statistical significance using ANCOVA. Additional covariates included gender, race/ethnicity, grade level and weight status. After adjustment for baseline levels, students in the intervention school exhibited significantly higher PACER laps in comparison to the control school ((F[subscript (1,257)] = 58.0) p<0.0001)). The PACER scores in intervention school increased from 40.6 laps to 45.9 laps while the PACER scores in the comparison school decreased. There were no significant between-group differences for physical activity or self-efficacy Although these results require replication in larger studies using a group randomized study design and objective measures of physical activity, the results suggest that teaching students about S.M.A.R.T. goal setting may be a potentially effective strategy for increasing fitness in middle school students and worthy of further investigatio

Differential Relationships Between Waist Circumference and Cardiorespiratory Fitness Among People With and Without Type 2 Diabetes

Adults with type 2 diabetes mellitus tend to exhibit an increased level of central adiposity, augmenting their risk of further non-communicable diseases (NCDs). Importantly, consistent evidence demonstrates a significant, negative association between cardiorespiratory fitness (CRF) and waist circumference (WC). However, no previous studies have investigated differences in these CRF-related reductions in WC between adults with and without diabetes. This study used data from the Aerobic Center for Longitudinal Studies, conducted between 1970 and 2006 among predominately Non-Hispanic White, middle-to-upper class adults in Texas. Quantile regression models were used to estimate CRF-related differences in WC between persons with and without diabetes. Age, height, smoking status and birth cohort served as covariates. The analytic sample included 45901 adults. Significantly larger reductions in WC were observed among adults with diabetes as compared to without diabetes across all WC percentiles. Among males, high CRF levels were associated with significant reductions, as compared to their low-fit counterparts, in WC as large as 21.9 cm for adults without diabetes and as large as 27 cm for adults with diabetes. Among females, high CRF levels were associated with significant reductions, as compared to their low-fit counterparts, in WC as large as 22.3 and 30.0 cm for adults without and with diabetes, respectively. This study demonstrated that higher CRF is associated with significant reductions in WC, with greater magnitudes found among adults with diabetes, especially among the most centrally obese, highlighting the necessity of exercise prescription in this clinical population potentially leading to lower risks of future NCDs

Maternal Weight Gain in Pregnancy and Risk of Obesity among Offspring: A Systematic Review

Objectives. To systematically review the evidence from prospective and retrospective cohort studies on the association between gestational weight gain (GWG) and offspring’s body weight. Methods. Electronic databases PubMed, Web of Science, CINAHL, and Academic Search Premiere were searched from inception through March 18, 2013. Included studies (n=23) were English articles that examined the independent associations of GWG with body mass index (BMI) and/or overweight status in the offspring aged 2 to 18.9 years. Two authors independently extracted the data and assessed methodological quality of the included studies. Results. Evidence from cohort studies supports that total GWG and exceeding the Institute of Medicine maternal weight gain recommendation were associated with higher BMI z-score and elevated risk of overweight or obesity in offspring. The evidence of high rate of GWG during early- and mid-pregnancy is suggestive. Additionally, the evidence on inadequate GWG and net GWG in relation to body weight outcomes in offspring is insufficient to draw conclusions. Conclusions. These findings suggest that GWG is a potential risk factor for childhood obesity. However, findings should be interpreted with caution due to measurement issues of GWG and potential confounding effects of shared familial characteristics (i.e., genetics and maternal and child’s lifestyle factors)

Neuroactivational and Behavioral Correlates of Psychosocial Stress-Induced Cocaine Seeking in Rats

A prominent feature of cocaine abuse is a high risk of relapse even despite prolonged periods of abstinence. Psychosocial stress is thought to be a major contributor to the onset of cocaine craving and relapse in human substance abusers, yet most preclinical models of stress-induced relapse employ physical stressors (e.g., unpredictable footshock) or pharmacological stressors (e.g., yohimbine to elicit a drug seeking response) and do not rely upon psychosocial stress per se. Importantly, social stressors are well known to activate distinct neural circuits within the brain as compared to other stressors. It is therefore possible that currently available animal models of stress-induced drug relapse do not fully engage the neuroanatomical, neurochemical, and/or molecular substrates that are recruited specifically by psychosocial stressors to produce drug-seeking behavior. Social defeat stress has been proposed as an ethologically valid psychosocial stressor in rodents that more closely models the forms of psychosocial stress that precede relapse episodes in drug abusers. We previously developed a model of psychosocial stress-induced reinstatement in rats in which cocaine seeking is elicited via exposure to a cue signaling impending social defeat stress. Using this model, we discovered that predilection towards displaying active coping behaviors during prior social defeat stress exposures was positively correlated with levels of psychosocial stress-induced cocaine seeking. The present study aimed to expand upon these initial findings by assessing and comparing patterns of neural activation in key brain areas during stress induced cocaine seeking that is triggered by psychosocial or footshock stress predictive cues

The validity of US nutritional surveillance: USDA's loss-adjusted food availability data series 1971-2010

The purpose of this study was to examine the validity of the 1971-2010 United States Department of Agriculture’s (USDA’s) loss-adjusted food availability (LAFA) per capita caloric consumption estimates. Estimated total daily energy expenditure (TEE) was calculated for nationally representative samples of US adults, 20-74 years, using the Institute of Medicine’s predictive equations with “low-active” (TEE L-ACT) and “sedentary” (TEE SED) physical activity values. TEE estimates were subtracted from LAFA estimates to create disparity values (kcal/d). A validated mathematical model was applied to calculate expected weight change in reference individuals resulting from the disparity. From 1971-2010, the disparity between LAFA and TEE L-ACT varied by 394 kcal/d—(P < 0.001), from −205 kcal/d (95% CI: −214, −196) to +189 kcal/d (95% CI: 168, 209). The disparity between LAFA and TEE SED varied by 412 kcal/d (P < 0.001), from −84 kcal/d (95% CI: −93, −76) to +328 kcal/d (95% CI: 309, 348). Our model suggests that if LAFA estimates were actually consumed, reference individuals would have lost ~1-4 kg/y from 1971-1980 (an accumulated loss of ~12 to ~36 kg), and gained ~3-7 kg/y from 1988-2010 (an accumulated gain of ~42 to ~98 kg). These estimates differed from the actual measured increments of 10 kg and 9 kg in reference men and women, respectively, over the 39-year period. The USDA LAFA data provided inconsistent, divergent estimates of per capita caloric consumption over its 39-year history. The large, variable misestimation suggests that the USDA LAFA per capita caloric intake estimates lack validity and should not be used to inform public policy

SUMOylation of nuclear actin

Actin, a major component of the cytoplasm, is also abundant in the nucleus. Nuclear actin is involved in a variety of nuclear processes including transcription, chromatin remodeling, and intranuclear transport. Nevertheless, the regulation of nuclear actin by posttranslational modifications has not been investigated. We now show that nuclear actin is modified by SUMO2 and SUMO3 and that computational modeling and site-directed mutagenesis identified K68 and K284 as critical sites for SUMOylating actin. We also present a model for the actin–SUMO complex and show that SUMOylation is required for the nuclear localization of actin

Wakeshield WSF-02 GPS Experiment

Shuttle mission STS-69 was launched on September 7, 1995, 10:09 CDT, carrying the Wake Shield Facility (WSF-02). The WSF-02 spacecraft included a set of payloads provided by the Texas Space Grant Consortium, known as TexasSat. One of the TexasSat payloads was a GPS TurboRogue receiver loaned by the University Corporation for Atmospheric Research. On September 11, the WSF-02 was unberthed from the Endeavour payload bay using the remote manipulator system. The GPS receiver was powered on prior to release and the WSF-02 remained in free-flight for three days before being retrieved on September 14. All WSF-02 GPS data, which includes dual frequency pseudorange and carrier phase, were stored in an on-board recorder for post-flight analysis, but "snap- shots" of data were transmitted for 2-3 minutes at intervals of several hours, when permitted by the telemetry band- widdl The GPS experiment goals were: (1) an evaluation of precision orbit determination in a low altitude environment (400 km) where perturbations due to atmospheric drag and the Earth's gravity field are more pronounced than for higher altitude satellites with high precision orbit requirements, such as TOPEX/POSEIDON; (2) an assessment of relative positioning using the WSF GPS receiver and the Endeavour Collins receiver; and (3) determination of atmospheric temperature profiles using GPS signals passing through the atmosphere. Analysis of snap-shot telemetry data indicate that 24 hours of continuous data were stored on board, which includes high rate (50 Hz) data for atmosphere temperature profiles. Examination of the limited number of real-time navigation solutions show that at least 7 GPS satellites were tracked simultaneously and the on-board clock corrections were at the microsec level, as expected. Furthermore, a dynamical consistency test provided a further validation of the on-board navigation solutions. Complete analysis will be conducted in post-flight using the data recorded on-board