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dc.contributor.authorCreamer, Kyle Williamen
dc.date.accessioned2016-02-26T07:00:14Zen
dc.date.available2016-02-26T07:00:14Zen
dc.date.issued2014-09-03en
dc.identifier.othervt_gsexam:3374en
dc.identifier.urihttp://hdl.handle.net/10919/64865en
dc.description.abstractBone health in the context of two common maladies, osteoporosis and obesity, has spurred research in the area of physical activity (PA) and bariatric surgery (BarS). Objectives: To examine: 1) relationships between PA and the skeleton utilizing the peripheral Quantitative Computed Tomography (pQCT) and Dual-energy X-ray Absorptiometry (DXA) in pre-menopausal women; 2) effects of adjustable gastric banding (AGB) vs. Roux-en-Y gastric bypass (RYGB) surgeries on pQCT and DXA measures; 3) 6-month time course changes on serum biomarkers of bone turnover and associated adipokines induced by AGB vs. RYGB. Methods: Standard DXA and pQCT measurements were taken for all subjects. PA tertiles (PA-L, PA-M, PA-H) were based on a calculated average MET-min/day determined from 4-d self-reported PA and pedometer step counts. For BarS subjects, bone measurements were taken pre-surgery, 3- and 6-months post-surgery along with serum (or plasma) from fasting blood draws, with ELISA assays for total OC, undercarboxylated OC, CTx, adiponectin, and leptin. Results: Minimal DXA differences between the highest and lowest PA tertiles were seen, while pQCT tibial measures and polar strength-strain index (SSIp) indicated differences along the tibial shaft. Comparing the two instruments and adjusting for BMI, the DXA leg and hip BMD and BMC showed differences (p<0.05) between PA-M and PA-L as well as PA-H and PA-L. Similarly, the pQCT tibial cortical area, BMC, and SSIp were progressively greater for the different levels of PA (p<0.05). 3- and 6-months post-BarS weight, fat-free mass, fat mass, central body fat, tibial and radial subcutaneous fat, and radial MCSA decreased (p<0.05). Comparing the AGB and RYGB and adjusting for weight, DXA BMC showed decreases (p<0.01) at both time points for RYGB. RYGB demonstrated differences (p<0.05) in bone measures at 3- and 6-months post-surgery along the tibial shaft that are indicative of increases in bone strength, and at 6-months, total OC, undercarboxylated OC, and HMW adiponectin increased, while leptin decreased. Conclusions: PA is associated with increases in bone, but pQCT data are more discriminatory and sensitive. 6-months post-RYGB, pQCT measures indicate increases in bone strength parameters, and greater bone adaptation was evidenced by biomarkers of increased osteoblastic activity.en
dc.format.mediumETDen
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectPhysical Activityen
dc.subjectBariatric Surgeryen
dc.subjectBoneen
dc.subjectperipheral Quantitative Computed Tomographyen
dc.subjectpQCTen
dc.titleUtilizing pQCT and Biomarkers of Bone Turnover to Study Influences of Physical Activity or Bariatric Surgery on Structural and Metabolic Status of Boneen
dc.typeDissertationen
dc.contributor.departmentHuman Nutrition, Foods, and Exerciseen
dc.description.degreePh. D.en
thesis.degree.namePh. D.en
thesis.degree.leveldoctoralen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.disciplineHuman Nutrition, Foods, and Exerciseen
dc.contributor.committeechairHerbert, William G.en
dc.contributor.committeememberDe Vita, Raffaellaen
dc.contributor.committeememberNickols, Sharon M.en
dc.contributor.committeememberRamp, Warrenen
dc.contributor.committeememberHulver, Matthew W.en
dc.contributor.committeememberHosig, Kathryn W.en
dc.contributor.committeememberWilliams, Jay H.en


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