Browsing by Author "Padilla, Jaume"

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    Normalization of flow-mediated dilation to shear stress area under the curve eliminates the impact of variable hyperemic stimulus
    (BioMed Central, 2008-09-04) Padilla, Jaume; Johnson, Blair D.; Newcomer, Sean C.; Wilhite, Daniel P.; Mickleborough, Timothy D.; Fly, Alyce D.; Mather, Kieren J.; Wallace, Janet P.; Medicine, School of Medicine
    Background Normalization of brachial artery flow-mediated dilation (FMD) to individual shear stress area under the curve (peak FMD:SSAUC ratio) has recently been proposed as an approach to control for the large inter-subject variability in reactive hyperemia-induced shear stress; however, the adoption of this approach among researchers has been slow. The present study was designed to further examine the efficacy of FMD normalization to shear stress in reducing measurement variability. Methods Five different magnitudes of reactive hyperemia-induced shear stress were applied to 20 healthy, physically active young adults (25.3 ± 0. 6 yrs; 10 men, 10 women) by manipulating forearm cuff occlusion duration: 1, 2, 3, 4, and 5 min, in a randomized order. A venous blood draw was performed for determination of baseline whole blood viscosity and hematocrit. The magnitude of occlusion-induced forearm ischemia was quantified by dual-wavelength near-infrared spectrometry (NIRS). Brachial artery diameters and velocities were obtained via high-resolution ultrasound. The SSAUC was individually calculated for the duration of time-to-peak dilation. Results One-way repeated measures ANOVA demonstrated distinct magnitudes of occlusion-induced ischemia (volume and peak), hyperemic shear stress, and peak FMD responses (all p < 0.0001) across forearm occlusion durations. Differences in peak FMD were abolished when normalizing FMD to SSAUC (p = 0.785). Conclusion Our data confirm that normalization of FMD to SSAUC eliminates the influences of variable shear stress and solidifies the utility of FMD:SSAUC ratio as an index of endothelial function.
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    Retention of sedentary obese visceral white adipose tissue phenotype with intermittent physical activity despite reduced adiposity
    (American Psychological Society, 2015-09) Wainright, Katherine S.; Fleming, Nicholas J.; Rowles, Joe L.; Welly, Rebecca J.; Zidon, Terese M.; Young-Min, Park; Gaines, T'Keaya L.; Scroggins, Rebecca J.; Anderson-Baucum, Emily K.; Hasty, Alyssa H.; Vieira-Potter, Victoria J.; Padilla, Jaume; Department of Medicine, IU School of Medicine
    Regular physical activity is effective in reducing visceral white adipose tissue (AT) inflammation and oxidative stress, and these changes are commonly associated with reduced adiposity. However, the impact of multiple periods of physical activity, intercalated by periods of inactivity, i.e., intermittent physical activity, on markers of AT inflammation and oxidative stress is unknown. In the present study, 5-wk-old male C57BL/6 mice were randomized into three groups (n = 10/group): sedentary, regular physical activity, and intermittent physical activity, for 24 wk. All animals were singly housed and fed a diet containing 45% kcal from fat. Regularly active mice had access to voluntary running wheels throughout the study period, whereas intermittently active mice had access to running wheels for 3-wk intervals (i.e., 3 wk on/3 wk off) throughout the study. At death, regular and intermittent physical activity was associated with similar reductions in visceral AT mass (approximately −24%, P < 0.05) relative to sedentary. However, regularly, but not intermittently, active mice exhibited decreased expression of visceral AT genes related to inflammation (e.g., monocyte chemoattractant protein 1), immune cell infiltration (e.g., CD68, CD11c, F4/80, CD11b/CD18), oxidative stress (e.g., p47 phagocyte oxidase), and endoplasmic reticulum stress (e.g., CCAAT enhancer-binding protein homologous protein; all P < 0.05). Furthermore, regular, but not intermittent, physical activity was associated with a trend toward improvement in glucose tolerance (P = 0.059). Collectively, these findings suggest that intermittent physical activity over a prolonged period of time may lead to a reduction in adiposity but with retention of a sedentary obese white AT and metabolic phenotype.