The effect of restricting energy intake (ad libitim vs. 75% ad libitum) elevation of vitamin and mineral levels (150% NRC vs 100% NRC) and the effects of aging on bone growth, histological lesioning and biochemical composition of articular cartilage from growing boars was examined. Growth of the radius and tibia was characterized by radiography at eight equal time points from 110 to 330 d of age. Although ad libitum-fed boars had larger bones in most cases, calculation of weight corrected differences suggested that restriction of energy resulted in lover weight gain but that reduced energy intake slightly increased the rate of bone growth of the restrict-fed boars. Although elevation of vitamin and mineral levels resulted in a few scattered differences in bone size, no consistent trends were evident. Neither restriction of energy intake nor elevation of vitamins and minerals had any consistent effect on the reduction of histological lesion severity. Age, expressed as days on test, produced no definite trends toward increasing or decreasing frequency of histological lesions. The frequency and severity of gross lesions were unaffected by altered energy or vitamin-mineral levels, however, a sevenfold age-related increase in frequency of gross lesions was observed over time. Uronic acid content of the articular cartilage from the femur was greater for the restrict-fed boars, however, uronic acid content of cartilage from the humerus and radius tended to be greater for the ad libitum fed boars. Elevation of vitamins and minerals had no effect on uronic acid content of articular cartilage from the femur, humerus or radius. Uronic acid content of articular cartilage decreased consistently with age throughout the trial period. Galactose and hydroxyproline levels in cartilage samples from the femur, humerus and radius were generally unaffected by the imposed dietary treatments. Galactose levels were unaffected by age. Hydroxyproline content of cartilage from the radius and humerus increased with age, whereas, cartilage from the femur remained unchanged throughout the experimental period. No changes in percentage fat-free dry weight of articular cartilage samples from the femur, humerus, or radius due to treatment or age were evident. Articular cartilage from the radius had a higher percentage of fat-free dry weight than either the humerus or femur. Articular cartilage from the radius also contained less uronic acid than the femur or humerus. Galactose content of the radius was less than that of the humerus, however, galactose levels of the femur and radius did not differ. Hydroxyproline levels were similar among all areas sampled. In summary, skeletal growth rate was slightly greater for restrict-fed boars after weight correction, however, elevation of vitamins and minerals had no overall impact on any parameters measured. Age had a more pronounced, though inconsistent influence on lesion frequency, severity, and biochemical composition of the articular cartilage than the imposed dietary treatments. / Master of Science

The purpose of this study was (1) to compare the lower body strength, power, and the bone mineral density (BMD) of the proximal femur in a group of trained postmenopausal women who have been in low intensity exercise program for a long time with age-matched sedentary controls, and (2) to evaluate the magnitude of the correlation between muscle function and site-specific BMD in these postmenopausal women. Healthy postmenopausal women (n = 17) between the age of 60 and 80 were divided into two groups: 9 exercisers (mean ± SE, 74.8 ± 3.2 years) who had been in an exercise training program for at least 5 years and 8 control (mean ± SE, 71.6 ± 3.4 years) who had not been in any exercise program for at least 5 years. The exercise group performed three one hour sessions a week of aerobic and resistance training for an average of 9.9 years. The exercise training consisted of 30 minutes walking and one or two sets of twelve to fifteen repetitions focused on large muscle groups. The BMD of the proximal femoral region was assessed using dual-energy x-ray absorptiometry (DEXA). By using a Cybex Leg Press machine, 1-repetition maximum (1-RM) tests were performed for lower body strength and power of lower body were obtained by a seated chair rise. Statistical analysis demonstrated no statistical differences between the left and right region of the femur BMD for either group, with the averaged BMD being 0.858 g/cm2 for the controls and 0.853 g/cm2 for the exercisers. The trochanter BMD for the exercisers were 7 % (left) and 6 % (right) higher than the controls although these values were not statistically significant. The 1RM leg press strength ranged from 29.5 to 47.6 kg (mean ± SE, 40.21 ± 2.62 kg) in controls and from 31.8 to 61.2 kg (mean ± SE, 45.93 ± 3.72 kg) in exercisers. Although the exerciser group lifted 14.2 % more weight than the control group, the difference was not statistically significant. The results of power test ranged from 14.59 to 31.21 kg • m/sec (mean ± SE, 22.94 ± 5.67 kg • m/sec) in controls and from 13.63 to 38.60 (mean ± SE, 28.88 ± 6.81 kg • m/sec). The power did not differ significantly between the two groups. However, it is noted that between group differences approached significance at p < 0.07. Correlations between body composition and femoral neck BMD were also determined. Neither weight, nor BMI was significantly correlated with femoral neck BMD in the exercise and control group. Lower body strength and power did not correlate with the BMD of the femoral neck, Ward's triangle, or trochanter in either group. Although the BMD of the proximal femoral region did not differ between two groups the higher mean age (+ 3.2 years) of the exercise group suggested that a low intensity exercise training program can increase power and strength and maintain BMD in postmenopausal women. However, the low intensity of resistance training program utilized by the exercise group was no more effective in maintaining BMD than an active lifestyle. / School of Physical Education

The mechanical behavior of any bone depends upon structural and material properties. Therefore, whole bone, cross-sectional geometric and bone mineral data need to be integrated in studies of bone growth and aging. This dissertation examines femoral growth and aging in the prehistoric Grasshopper Pueblo population of Arizona (A.D. 1275 to 1400). The techniques include osteometrics, computed tomography and photon absorptiometry. Human osteological collections obtained from archaeological sites are useful for studies of bone physiology and mechanics. Even though the subjects are no longer living, non-invasive techniques must often be used because the skeletal collections are data bases for many researchers. This apparently limiting attribute of the sample used in the present study forced the application of computed tomography for analysis of cross-sectional geometry. As the availability of computed tomography to research increases, it will become the method of choice because digital images are well-suited to automated analysis and CT can also provide density data. Variability related to side, age and sex is explored. Additionally, (1) structural properties increase much more than material properties in growth, (2) the morphology of the proximal femoral diaphysis depends more upon the angle of antetorsion than the cervicodiaphyseal angle, (3) there is evidence suggestive of structural compensation for loss of bone mineral in aging, (4) osteoporosis is found not to protect the femoral compartment of the knee joint from osteoarthrosis, (5) the onset of bone loss in females seems to have been early by modern standards, although the rates of loss were similar, and (6) differential bone loss within the femur due to the amount of bone present at maturity and not different rates of loss.

AIMS. To determine the cardio-metabolic risk profile and incidence of low bone mineral density in African and Indian postmenopausal women attending the IALCH menopause clinic and to determine whether there is a correlation between cardio-metabolic parameters and low bone mineral density. METHODS. A retrospective, descriptive study involving all Indian and African postmenopausal women, above the age of 40, referred to the menopause outpatient clinic at IALCH from 01 July 2009 to 31 December 2010 was conducted. Data was collected from the medi-com database using a structured questionnaire. Cardio-metabolic data was analysed as continuous variables and summarized using means and standard deviations. Bone mineral density was treated as a quantitative variable and correlation analysis was used to assess relationships between the variables. This was done for each race group separately. The Students T-test was used to compare cardio-metabolic variables between the two ethnic groups. SPSS version 18.0 was used to analyse data. RESULTS. The records of 106 women were analysed (51 African and 55 Indian). In African and Indian women, the prevalence of hypertension was 54.9% vs 65.5%, the prevalence of diabetes was 31.4% vs 56.4%, the prevalence of dyslipidaemia was 17.6% vs 32.7% and the prevalence of ischaemic heart disease was 5.9% vs 14.9% respectively. The prevalence of low bone mineral density was higher in Indian women (40%) compared to African women (23.5%). The mean body mass index (BMI) of African women was significantly higher than Indian women, (33 vs 29). There were no significant differences between African and Indian postmenopausal women regarding their lipid profile, fasting glucose, fasting insulin and thyroid profile. The mean bone mineral density (BMD) in the hip and spine was lower in Indian women compared to African women, however the prevalence of osteopaenia and osteoporosis, as defined by T-scores, was not statistically significant. Statistically significant positive correlations were observed between an increasing BMI and BMD (p<0.001) and increases in weight and BMD (p<0.001). A statistically significant correlation were observed between serum LDL-cholesterol values and BMD (p=0.03), where serum LDL-cholesterol values were inversely proportional to BMD. There were no significant correlations between BMD and the remaining cardio-metabolic variables (ie blood pressure; waist-hip ratio; clinical stigma of dyslipidaemia; clinical stigma of insulin resistance; cholesterol; HDL; triglycerides; fasting glucose; fasting insulin and thyroid function). CONCLUSIONS. There is a high prevalence of cardiovascular risks and low BMD amongst the local menopausal population, irrespective of ethnicity. African and Indian postmenopausal women had a high prevalence of hypertension (60%), diabetes (44%), dyslipidaemia (25%) and obesity (54%). In African women, the incidence of low BMD was 35% in the hip, 53% in the neck of femur and 55% in the lumbar spine. In Indian women, the incidence of low BMD was 55% in the hip, 67% in the neck of femur and 69% in the lumbar spine. BMI and weight showed a positive correlation with bone mineral density. Regarding the cardio-metabolic variables, an increasing LDL value was negatively correlated with bone mineral density. It thus is apparent that a screening lipid profile during the peri-menopausal years, coupled with early and appropriate lifestyle management regarding body mass index/ weight may limit the burden of morbidity in later life. / Thesis (M.Med.)-University of KwaZulu-Natal, Durban, 2013.

Graduation date: 1993

One indication of increasing fragility of bone is the accumulation of microscopic cracks, or microdamage, within the bone matrix. Microdamage accumulates in bone of the elderly, when changes in bone material properties and matrix architecture coupled with a decrease in bone repair mechanisms compromise bone integrity. To preserve bone mass and reduce fracture risk, therapeutics such as alendronate are prescribed which increase bone volume fraction by decreasing the rate of bone turnover. However, concerns over adverse effects of prolonged turnover suppression have been reinforced by findings of increased microdamage density with alendronate use. Microdamage formation is not always pathologic, but extensive accumulation of damage can be an indicator of reduced bone quality. The work in this thesis explores the hypothesis that microdamage in bone of lower quality will form more easily and progress more extensively than in bone of higher quality. Microdamage initiation stresses and strains were obtained for trabecular bone from older females, older males, and younger females to determine whether thresholds for damage initiation were lower in older females. Results suggest that the stress threshold for damage initiation in older females may indeed be lower compared with younger females, and that normalized strain thresholds for severe damage formation in older males may be decreased compared with older females. Damage propagation was evaluated as a function of age and sex to determine whether damage in older women progressed more extensively than in younger women or men. Results suggest that bone from older individuals had decreased resistance to crack propagation evidenced by an increased number of severely damaged trabeculae which expanded in area under cyclic loading; however no sex differences were uncovered. Finally, the stress/strain thresholds for damage initiation were investigated in alendronate-treated bone, and results indicate that a decreased stress threshold was needed to initiate damage formation of a linear and severe morphology after one year of treatment. After three years of treatment, however, micromechanical properties recovered, perhaps due to increased matrix mineralization which increased tissue level stiffness.