Background: Fractures are a major health concern for older adults, especially for those with osteoporosis or low bone mineral density (BMD). Physical activity and exercise can be important self-management strategies for older adults with osteoporosis or low BMD to prevent fractures. Objectives: This study examined the physical activity and exercise levels of older adults with low BMD and determined the proportion of individuals meeting the Canadian Physical Activity Guidelines. As well, this study characterized perceived individuals’ barriers to exercise and their willingness to pay for different methods of delivering exercise information. Secondary goals of this study were to investigate correlates of aerobic exercise and factors associated with meeting moderate- to vigorous-intensity aerobic physical activity guidelines. Methods: Individuals aged 50 years or older with a self-reported diagnosis of low BMD were recruited from the Canadian Osteoporosis Patient Network (COPN) and an osteoporosis public education event. Questionnaires were distributed online and through mail to individuals interested in participating. Participants were asked about the amount of time they spent doing moderate- and vigorous-intensity physical activity (MVPA) and the frequency at which they did strength and balance training per week. Also, participants were asked about potential barriers to exercise that they perceive, the strength at which they perceived those barriers at, and their interest in and willingness to pay (WTP) for different methods of delivering exercise information. Information about different factors affecting exercise behaviour such as risk perception, intention to exercise, and exercise self-efficacy were collected as well. Results: The total number of participants included in this study was 130 (mean [SD] age 66.32 [8.81] years). The mean (SD) time spent doing MVPA per week reported by participants was 831.35 (1065.43) minutes. The mean (SD) days per week that participants reported doing strength and balance training were 1.90 (1.66) and 1.36 (1.84), respectively. Sixteen individuals (12.3%) did not meet the guideline of engaging in at least 150 minutes of MVPA per week. Forty-one participants (31.5%) did not report doing any strength training and sixty-five individuals (50%) did not report doing any balance training. The most prevalent barriers to exercise that were reported was having no enjoyment for exercise (51.2%) , having no company to exercise with (47.2%), and health-related problems (37.5%). Although a majority of participants expressed interest in all methods of delivering exercise information, the mean WTP for a group exercise class and for training one-on-one with a certified personal trainer was lower than the suggested amounts that they would normally cost. Factors associated with meeting MVPA recommendations were intention to exercise (p = 0.03), exercise self-efficacy (p = 0.03), and strength of perceived barriers (p = 0.02). Conclusion: Many older adults with low bone mineral density are not meeting established physical activity guidelines. Greater measures need to be taken in promoting strength and balance training among these individuals. Addressing barriers to exercise may be an effective strategy to encourage individuals with low bone mineral density to become more active.

No description available.

Osteoporosis is caused by loss of bone mineral content, which leads to bone fractures or structural deformations of bone. Osteoporosis usually occurs when people get older, after menopause in women, or it can be caused by a lack in the intake of a sufficient amount of calcium and vitamin D. Until recently, osteoporosis was considered to be an unavoidable part of aging, but today, approved and effective treatments can be used to deal with the consequences. At present, determination of risk of bone abnormalities is done by measuring the density of bone (largely determined by calcium content). Dual energy X-ray Absorptiometry (DXA) is the gold standard technique for measuring bone mineral density (BMD). Even though BMD is one of the principal determinants of bone strength, BMD measurements do not give information about variation of trabecular structure of bone. That's why DXA alone has limited ability to predict who will sustain an osteoporotic fracture. To predict fracture risk of patients, the texture analysis of the DXA images is of interest as a measure to predict fracture in addition to BMD. This thesis focuses on the application of texture analysis to digital images of bone scans of patients at risk of fracture and osteoporosis. Texture analysis was performed by analyzing the variation of grey level patterns of pixels of DXA images. Texture analysis of such images will give an idea of the variation of grey scale patterns of pixels between normal and osteoporotic DXA images of bone. Existing texture analysis measures such as contrast measures of co-occurrence matrices and mean slope value of fractal dimension based measure are used to analyze the texture of DXA images. An alternative partitioning technique is proposed as a measure of the texture analysis.

The work contained in this thesis explores the economic issues of screening women, and the subsequent use of hormone replacement therapy (HRT), for the prevention of osteoporosis. The thesis is divided into five sections. In the first section the background to the problem is described as are the relevant economic evaluation techniques. In addition, the relevant economic literature is reviewed. The second section of the thesis, contains the results of research aimed at estimating the costs of population screening followed by treating the women at highest risk. The three chapters in this section address the following issues: estimating total screening costs; developing an economic definition of at risk status; and describing the HRT compliance rate after screening and its associated costs. In the third section the consequences of screening are examined. Hence, the osteoporosis risk profile of non attenders is described and the effects of HRT on women's quality of life is explored. Finally, this section is completed with a study looking at the predictive value of bone density screening. The fourth section is a synthesis of all the costs and consequences described in the preceding sections with relevant additional information from the literature. This section shows that screening perimenopausal women will be very expensive in terms of cost per quality adjusted life years (QALY) gained. In contrast, screening women and treating them when they are aged 70 appears to generate a relatively low cost per QALY. The final, fifth section, of the thesis describes outstanding research issues which need to be addressed before any screening programme is implemented.

Osteoporosis is caused by loss of bone mineral content, which leads to bone fractures or structural deformations of bone. Osteoporosis usually occurs when people get older, after menopause in women, or it can be caused by a lack in the intake of a sufficient amount of calcium and vitamin D. Until recently, osteoporosis was considered to be an unavoidable part of aging, but today, approved and effective treatments can be used to deal with the consequences. At present, determination of risk of bone abnormalities is done by measuring the density of bone (largely determined by calcium content). Dual energy X-ray Absorptiometry (DXA) is the gold standard technique for measuring bone mineral density (BMD). Even though BMD is one of the principal determinants of bone strength, BMD measurements do not give information about variation of trabecular structure of bone. That's why DXA alone has limited ability to predict who will sustain an osteoporotic fracture. To predict fracture risk of patients, the texture analysis of the DXA images is of interest as a measure to predict fracture in addition to BMD. This thesis focuses on the application of texture analysis to digital images of bone scans of patients at risk of fracture and osteoporosis. Texture analysis was performed by analyzing the variation of grey level patterns of pixels of DXA images. Texture analysis of such images will give an idea of the variation of grey scale patterns of pixels between normal and osteoporotic DXA images of bone. Existing texture analysis measures such as contrast measures of co-occurrence matrices and mean slope value of fractal dimension based measure are used to analyze the texture of DXA images. An alternative partitioning technique is proposed as a measure of the texture analysis.

No description available.

Osteoporosis is a skeletal disorder that affects millions of people worldwide, and is characterized by the accelerated loss of bone mass. Current anti-resorptive drug approaches such as bisphosphonates and salmon calcitonin exhibit severe side effects and very low bioavailability, respectively. In this study, we have designed, synthesized, and performed preliminary tests on a novel conjugate that targets the RANK receptor on bone resorbing cells (osteoclasts) in vitro with one arm, while delivering a specific effector molecule, calcitonin, to osteoclasts with the other arm. First, we successfully generated osteoclasts from precursor RAW 264.7 cells and confirmed that they were functional. We also designed a resorption assay that can be used to test the efficacy of new and existing anti-resorptive drugs. RAW 264.7 cells were then treated with an antibody to RANK to prove that anti-RANK could be used as a targeting mechanism. We then showed that delivery of calcitonin-loaded anti-Calcitonin antibodies onto osteoclasts results in the association of calcitonin onto its receptors on osteoclasts. Finally, we constructed a novel conjugate: calcitonin–Streptavidin–anti-RANK, and showed that it can be used to introduce calcitonin into an osteoclast-like microenvironment.

Thesis (M. Res. (Med.))--University of Hong Kong, 2007.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Also available in print.

Diss. (sammanfattning) Uppsala : Univ., 2004. / Härtill 4 uppsatser.