No description available.

No description available.

No description available.

The purpose of this study was to develop a personalized step test and a valid regression model that used non-exercise data and data collected during the step test to estimate VO2max in males and females 18 to 30 years of age. All participants (N= 80) successfully completed a step test with the starting step rate and step height being determined by the self-reported perceived functional ability (PFA) score and participant's height, respectively. All participants completed a maximal graded exercise test (GXT) to measure VO2max. Multiple linear regression analysis yielded the following equation (R = 0.90, SEE = 3.43 mL/kg/min): 45.938 + 9.253(G) - 0.140(KG) + 0.670(PFA) + 0.429(FSR) - 0.149(45sRHR) to predict VO2max (mL/kg/min) where: G is gender (0=female;1=male), KG is body mass in kg, PFA is the sum of the two PFA questions, FSR is the final step rate (step-ups/min), and 45sRHR is the recovery heart rate 45 seconds following the conclusion of the step test. Each independent variable was significant (p < 0.05) in predicting VO2max and the resulting regression equation accounted for roughly 83% (R2=0.8281) of the shared variance of measured VO2max. Based on the standardized B-weights, gender (0.606) explained the largest proportion of variance in VO2max values followed by PFA (0.315), body mass (-0.256), FSR (-0.248), and the 45sRHR (-0.238). The cross validation statistics (RPRESS = 0.88, SEEPRESS = 3.57 (mL/kg/min-1) show minimal shrinkage in the accuracy of the regression model. This study presents a relatively accurate model to predict VO2max from a submaximal step test that is convenient, easy to administer, and individualized.

No / Motion at the midfoot joints can contribute significantly to overall foot motion during gait. However, there is little information regarding the kinematic coupling relationship at the midfoot. The purpose of the present study was to determine whether the coupling relationship at the midfoot and subtalar joints was affected when step width was manipulated during running. Twelve subjects ran over-ground at self-selected speeds using three different step widths (normal, wide, cross-over). Coupling at the midfoot (forefoot relative to rearfoot) and subtalar (rearfoot relative to shank) joints was assessed using cross-correlation techniques. Rearfoot kinematics were significantly different from normal running in cross-over running (P < 0.05) but not in wide running. However, coupling between rearfoot eversion/inversion and shank rotation was consistently high (r > 0.917), regardless of step width. This was also the case for coupling between rearfoot frontal plane motion and forefoot sagittal plane (r < 0.852) and forefoot transverse plane (r > 0.946) motion. There was little evidence of coupling between rearfoot frontal plane motion and forefoot frontal plane motion in any of the conditions. Forefoot frontal plane motion appeared to have little effect on rearfoot frontal plane motion and thus, had no effect on motion at the subtalar joint. The strong coupling of forefoot sagittal and transverse plane motions with rearfoot frontal plane motion suggests that forefoot motion exerts an important influence on subtalar joint kinematics.

New strategies for integrating sample pretreatment with chemical analyses under a single format is required for rapid, sensitive and enantioselective analyses of low abundance metabolites in complex biological samples. Capillary electrophoresis (CE) offers a unique environment for controlling analyte/reagent band dispersion and electromigration properties using a discontinuous electrolyte system allowing for highly efficient separations to be achieved. A fundamental study of the thermodynamic and electrokinetic parameters influencing enantioselectivity in chiral CE separation is first examined. A new strategy for single-step analysis of low abundance metabolites via online sample preconcentration with chemical derivatization by CE (SPCD-CE) is then detailed within. In-capillary sample preconcentration serves to enhance concentration sensitivity via electrokinetic focusing of long sample injection volumes for lower detection limits, whereas chemical derivatization by zone passing of single or multiple reagents is used to expand detectability and selectivity, notably for enantiomeric resolution of metabolites lacking intrinsic chromophores. Together, on-line SPCD-CE can provide over a 100-fold improvement in concentration sensitivity, shorter total analysis times, reduced sample handling and improved reliability for a variety of biologically relevant amino acid and amino sugar metabolites, which is also amenable to automated high-throughput screening. The basic method development and optimization parameters relevant to SPCD-CE, including applications to bacterial metabolite flux and biomarker analyses are discussed. Insight into the mechanism of analyte focusing and labelling during electromigration by SPCD-CE is also presented, as well as future directions for continued research using this unique integrated analytical platform. / Thesis / Doctor of Philosophy (PhD)

In recent years, screening approaches known as two-step methods have been proposed to detect gene-environment interactions for genome-wide association studies (GWAS). Genetic and environmental factors are believed to affect disease outcome as well as various quantitative traits such as height and blood pressure. The performance of the two-step methods has not been demonstrated in the quantitative trait setting. This thesis examines the method proposed by Wang and Abbott (2008) for generating genotyped markers in linkage disequilibrium (LD) and takes this approach in simulating data pertaining to a quantitative trait. The simulation results demonstrate that the two-step methods maintain type I error and have power to detect the quantitative trait locus. In this setting, the EG method (Murcray et al., 2009) is influenced by the strength and structure of the gene-environment dependency, the sample type, and the disease model. As such, the power of the EG method can fluctuate depending on the type of data while the DG method (Kooperberg and LeBlanc, 2008) remains fairly robust across a wide range of scenarios. The performance of the combined two-step approaches (EDGE (Gauderman et al., 2013) and H2 (Murcray et al., 2011) methods) tends to favour the more powerful underlying method. The power of the EDGE method can be improved if DG and EG demonstrates similar power while the H2 method can be made more powerful by choosing the appropriate parameters. / Thesis / Master of Science (MSc)

Short-term physical inactivity in older adults has been shown to cause muscular atrophy and impaired glycemic control, however, the ability to recover remains unknown. We aimed to determine the impact of step-reduction (SR) on older adults and if they could recover simply by returning to habitual activity. Ten older adults (6 men, 4 women, 69 ± 3 yr) completed 7d of normal baseline activity (BL), subsequently underwent SR by 86 ± 9% (8568 ± 3741 to 973 ± 76 steps/d; p<0.001) for 14d and then returned to 8383 ± 4513 steps/d for 14d (RC). During an oral glucose tolerance test (OGTT), SR resulted in elevated plasma glucose concentration ([G]) area under the curve (AUC; 325 ± 126 to 375 ± 137, p = 0.13), maximum [G] (10.2 ± 2.4 to 11.9 ± 1.7 mM, p = 0.027) and 2-hr [G] (7.9 ± 1.3 to 9.1 ± 1.1 mM, p = 0.085), while all [G] indices returned to BL after RC. However, Matsuda insulin sensitivity index was reduced (3.5 ± 0.3 to 2.7 ± 0.7, p < 0.001) and homeostatic model assessment of insulin resistance was elevated (2.8 ± 0.3 to 3.6 ± 0.7, p = 0.02) with SR, remaining different than BL after RC (p < 0.005). During free-living conditions, 3-hr post-prandial [G] (PPG) AUC and peak PPG increased following SR (p > 0.05), returning to BL with RC. Body composition and physical function remained unchanged with SR. These results show that periods of physical inactivity, characterized by reduced daily stepping, do not present detectable changes in body composition or physical function yet result in reduced glycemic control in older adults. While elevations in blood [G] are abolished with 14d of normal physical activity, our findings suggest that the SR-associated reductions in insulin sensitivity are not normalized as quickly. / Thesis / Master of Science in Kinesiology / Periods of physical inactivity such as hospitalizations decrease daily steps for older adults and this inactivity can cause losses of muscle, strength, and symptoms of diabetes. It was unknown if by simply returning to normal physical activity older persons could ‘reverse’ the consequences of step-reduction so we conducted a study involving two weeks of step-reduction and two weeks of recovery. While there was no change in strength or muscle mass, we found that when older adults reduced their daily steps to fewer than 1000/day, after two weeks they became ‘resistant’ to insulin, a hormone that helps control blood sugar and is connected to the development of type II diabetes. Although these older adults resumed normal step-count levels in the recovery phase, they did not recover their insulin sensitivity such that two weeks of normal daily activity was not sufficient to overcome the consequences of two weeks of inactivity.

Design and development of novel one-step reactions that produce nitrogen-containing scaffolds is an invaluable area of chemistry due to the abundance of these moieties in natural products and biologically active molecules. Discovering novel methods using uncommon substrates and rare earth metals to access these significant scaffolds present a challenge. Over the course of my doctoral studies, I have designed, developed and optimized novel reactions by using rarely known substrates and rare earth metals that have afforded important nitrogen-containing scaffolds. The products obtained allow access to otherwise long-to-synthesize molecules and expeditious construction of biologically active molecules.

No description available.