Thesis (Ph. D.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.

The effects of the rate of distraction and of local infusion of IGF-1 upon bone deposition during mandibular distraction osteogenesis was studied in a rabbit model. Five groups of rabbits were studied. All rabbits, except sham operated controls, underwent distraction to 15 mm. The variables studied were the rate of distraction (0.5 mm twice a day versus 1.5 mm twice a day) and the effects of local IGF-1 infusion via osmotic infusion pumps. Analysis by DEXA scanning and three point bending 28 days after the end of distraction demonstrated no difference in density or strength of bone between the experimental groups. Histological examination demonstrated non-union across the distraction gap to be more common in rapidly distracted rabbits. Histomorphometric analysis demonstrated higher mineral apposition rates and less un-mineralised osteoid with slow as opposed to rapid distraction (p = 0.0001). Infusion of exogenous IGF-1 also resulted in a small increase in mineral apposition rate which was significant at slow but not a rapid distraction. Bone densitometry and three point bending results did not reveal any effect of distraction rate or IGF-1 infusion other than greater stiffness associated with IGF-1 infusion during rapid distraction (p = 0.01). It seems probable that the overwhelming stimulus to new bone formation produced by distraction renders the anabolic effects of IGF-1 less significant making it detectable by only the more sensitive analysis. This may be due to maximal stimulation of IGF-1 production by slow distraction thus rendering the administration of exogenous IGF-1 relatively superfluous. Rapid distraction may produce less stimulus to growth factor synthesis or the level of production maybe insufficient to cope with a higher requirement. The complete union of rapidly distracted rabbits who received exogenous IGF-1 may be as a result of levels being restored to optimal.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Includes bibliographical references (p. 163-184) Also available in print.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: angular decorrelation function; impulse response; BUA; BMD; ultrasound; coral; trabecular bone; osteoporosis. Includes bibliographical references (p. 189-191).

Thesis (Ph. D.)--Oregon State University, 2006. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 2006. / Includes bibliographical references.

No description available.

published_or_final_version / Medicine / Doctoral / Doctor of Philosophy

To examine the potential for exercise to build bone mass during growth, objectives of this dissertation included: 1) determine the effects of 7 months of jumping followed by 7 months of detraining on hip and spine bone mass in the prepubertal children; 2) determine variables that best predict bone mineral content (BMC;g) of the hip and spine in order to develop prediction equations for healthy, Caucasian children, specific to Hologic fan-beam DXA machines; and 3) to examine the potential synergy between calcium intake and the bone response to jump training in prepubertal children. Results/Conclusions Objective 1 (Chapters 2, 3 and 4): children who performed 300 jumps/week at a load magnitude of 8 body weights had significantly greater 7-month changes for BMC at the femoral neck and lumbar spine than controls (4.5% and 3.1%, respectively), and significantly greater 7-month changes for bone area (BA; cm��) at the femoral neck than controls (2.9%). After 7- months of detraining (no box jumping exercises) the jumping group maintained 4% greater BMC and 4% greater BA at the femoral neck than controls. By contrast, at the spine, gains in BMC from the intervention were not retained after an equivalent period of detraining. These data indicate that high-impact jumping enhances growth at the hip. Results/Conclusions Objective 2 (Chapter 5): Age, height, and weight were entered as predictor variables in order to create regression models for healthy, young Caucasian boys and girls. Of these, height and weight independently predicted femoral neck and total hip BMC in both boys (femoral neck: R��=.48, total hip: R��=.63) and girls (femoral neck: R��=.49, total hip R��=.65). Height best predicted spine BMC in boys (R��=.58), but both height and weight independently predicted spine BMC in girls (R��=.54). We report that height and weight not age, best predict bone mineral content at the hip and spine. Results/Conclusions Objective 3 (Chapter 6): Children responded similarly to the jumping program regardless of calcium intake. 73% of our population had dietary intakes of calcium that met the recommended values for their age group. / Graduation date: 2002