D. A. Bailey

A six-year longitudinal study of the relationship of physical activity to bone mineral accrual in growing children : The University of Saskatchewan Bone Mineral Accrual Study

To investigate the influence of physical activity on bone mineral accrual during the adolescent years, we analyzed 6 years of data from 53 girls and 60 boys. Physical activity, dietary intakes, and anthropometry were measured every 6 months and dual‐energy X‐ray absorptiometry scans of the total body (TB), lumbar spine (LS), and proximal femur (Hologic 2000, array mode) were collected annually. Distance and velocity curves for height and bone mineral content (BMC) were fitted for each child at several skeletal sites using a cubic spline procedure, from which ages at peak height velocity (PHV) and peak BMC velocity (PBMCV) were identified. A mean age‐ and gender‐specific standardized activity (Z) score was calculated for each subject based on multiple yearly activity assessments collected up until age of PHV. This score was used to identify active (top quartile), average (middle 2 quartiles), or inactive (bottom quartile) groups. Two‐way analysis of covariance, with height and weight at PHV controlled for, demonstrated significant physical activity and gender main effects (but no interaction) for PBMCV, for BMC accrued for 2 years around peak velocity, and for BMC at 1 year post‐PBMCV for the TB and femoral neck and for physical activity but not gender at the LS (all p < 0.05). Controlling for maturational and size differences between groups, we noted a 9% and 17% greater TB BMC for active boys and girls, respectively, over their inactive peers 1 year after the age of PBMCV. We also estimated that, on average, 26% of adult TB bone mineral was accrued during the 2 years around PBMCV.

Peak bone mineral accrual and age at menarche in adolescent girls: A 6-year longitudinal study

BACKGROUND AND OBJECTIVES The greatest increase in bone mineral content occurs during adolescence. The amount of bone accrued may significantly affect bone mineral status in later life. We carried out a longitudinal investigation of the magnitude and timing of peak bone mineral content velocity (PBMCV) in relation to peak height velocity (PHV) and the age at menarche in a group of adolescent girls over a 6-year period. METHODS The 53 girls in this study are a subset of the 115 girls (initially 8 to 16 years) in a 6-year longitudinal study of bone mineral accretion. The ages at PBMCV and PHV were determined by using a cubic spline curve fitting procedure. Determinations were based on height (n = 12) and bone (n = 6) measurements over 6 years. RESULTS The timing of PBMCV and menarche were coincident, preceded approximately 1 year earlier by PHV. Correlation showed a negative relationship between age at menarche and both peak bone mineral accrual (r = -0.42, P < .002) and PHV (r = -0.45, P < .001). CONCLUSIONS This longitudinal study demonstrated the close association between age at PBMCV and age at menarche and confirmed the relationship between greater PBMCV and PHV in earlier, as compared with later, maturing girls.

Analysis of Proximal Femur DXA Scans in Growing Children: Comparisons of Different Protocols for Cross- Sectional 8-Month and 7-Year Longitudinal Data

Dual‐energy X‐ray absorptiometry (DXA) is a widely used method for measuring bone mineral in the growing skeleton. Because scan analysis in children offers a number of challenges, we compared DXA results using six analysis methods at the total proximal femur (PF) and five methods at the femoral neck (FN). In total we assessed 50 scans (25 boys, 25 girls) from two separate studies for cross‐sectional differences in bone area, bone mineral content (BMC), and areal bone mineral density (aBMD) and for percentage change over the short term (8 months) and long term (7 years). At the proximal femur for the short‐term longitudinal analysis, there was an approximate 3.5% greater change in bone area and BMC when the global region of interest (ROI) was allowed to increase in size between years as compared with when the global ROI was held constant. Trend analysis showed a significant (p < 0.05) difference between scan analysis methods for bone area and BMC across 7 years. At the femoral neck, cross‐sectional analysis using a narrower (from default) ROI, without change in location, resulted in a 12.9 and 12.6% smaller bone area and BMC, respectively (both p < 0.001). Changes in FN area and BMC over 8 months were significantly greater (2.3%, p < 0.05) using a narrower FN rather than the default ROI. Similarly, the 7‐year longitudinal data revealed that differences between scan analysis methods were greatest when the narrower FN ROI was maintained across all years (p < 0.001). For aBMD there were no significant differences in group means between analysis methods at either the PF or FN. Our findings show the need to standardize the analysis of proximal femur DXA scans in growing children.

International longitudinal pediatric reference standards for bone mineral content

To render a diagnosis pediatricians rely upon reference standards for bone mineral density or bone mineral content, which are based on cross-sectional data from a relatively small sample of children. These standards are unable to adequately represent growth in a diverse pediatric population. Thus, the goal of this study was to develop sex and site-specific standards for BMC using longitudinal data collected from four international sites in Canada and the United States. Data from four studies were combined; Saskatchewan Paediatric Bone Mineral Accrual Study (n=251), UBC Healthy Bones Study (n=382); Penn State Young Womens Health Study (n=112) and Stanfords Bone Mineral Accretion study (n=423). Males and females (8 to 25 years) were measured for whole body (WB), total proximal femur (PF), femoral neck (FN) and lumbar spine (LS) BMC (g). Data were analyzed using random effects models. Bland-Altman was used to investigate agreement between predicted and actual data. Age, height, weight and ethnicity independently predicted BMC accrual across sites (P<0.05). Compared to White males, Asian males had 31.8 (6.8) g less WB BMC accrual; Hispanic 75.4 (28.2) g less BMC accrual; Blacks 82.8 (26.3) g more BMC accrual with confounders of age, height and weight controlled. We report similar findings for the PF and FN. Models for females for all sites were similar with age, height and weight as independent significant predictors of BMC accrual (P<0.05). We provide a tool to calculate a childs BMC Z-score, accounting for age, size, sex and ethnicity. In conclusion, when interpreting BMC in pediatrics we recommend standards that are sex, age, size and ethnic specific.

Change in lean body mass Is a major determinant of change in areal bone mineral density of the proximal femur: A 12-year observational study

Our objective was to assess the contribution of lean body mass (LBM) and fat body mass (FBM) to areal bone mineral density (aBMD) in women during the years surrounding menopause. We used a 12-year observational design. Participants included 75 Caucasian women who were premenopausal, 53 of whom were available for follow-up. There were two measurement periods: baseline and 12-year follow-up. At both measurement periods, bone mineral content and aBMD of the proximal femur, posterior-anterior lumbar spine, and total body was assessed using dual-energy X-ray absorptiometry (DXA). LBM and FBM were derived from the total-body scans. General health, including current menopausal status, hormone replace therapy use, medication use, and physical activity, was assessed by questionnaires. At the end of the study, 44% of the women were postmenopausal. After controlling for baseline aBMD, current menopausal status, and current hormone replacement therapy, we found that change in LBM was independently associated with change in aBMD of the proximal femur (P = 0.001). The cross-sectional analyses also indicated that LBM was a significant determinant of aBMD of all three DXA-scanned sites at both baseline and follow-up. These novel longitudinal data highlight the important contribution of LBM to the maintenance of proximal femur bone mass at a key time in women’s life span, the years surrounding menopause.

Effect of water fluoridation on the bone mineral density of young women (The)

INTRODUCTION Osteogenic effects of therapeutic fluoride have been reported; however, the impact of exposure to low level water fluoridation on bone density is not clear. We investigated the effect of long-term exposure to fluoridated water from growth to young adulthood on bone mineral density (BMD). METHODS BMD was measured in 24 healthy women from Regina (fluoride 0.1 mg/L) and 33 from Saskatoon (fluoride 1.0 mg/L), with no differences between groups for height, weight, lifestyle or dietary factors. RESULTS Saskatoon women had significantly higher mean BMD at total anterior-posterior lumbar spine (APS) and estimated volumetric 1.3 (VLS), with no difference at total body (TB) or proximal femur (PF). CONCLUSION Exposure to water fluoridation during the growing years may have a positive impact on axial spine bone density in young women.

Longitudinal bone mineral changes in the femoral neck in growing children: dimensional considerations

Not only the title, but the plan and a good deal of the incidental symbolism of the poem were suggested by Miss Jessie L. Westons book on the Grail legend: From Ritual to Romance (Macmillan). Indeed, so deeply am I indebted, Miss Westons book will elucidate the difficulties of the poem much better than my notes can do; and I recommend it (apart from the great interest of the book itself) to any who think such elucidation of the poem worth the trouble. To another work of anthropology I am indebted in general, one which has influenced our generation profoundly; I mean The Golden Bough; I have used especially the two volumes Adonis, Attis, Osiris. Anyone who is acquainted with these works will immediately recognize in the poem certain references to vegetation ceremonies.

Bone Mineral Density: A mother - daughter - grandmother comparison

Not only the title, but the plan and a good deal of the incidental symbolism of the poem were suggested by Miss Jessie L. Westons book on the Grail legend: From Ritual to Romance (Macmillan). Indeed, so deeply am I indebted, Miss Westons book will elucidate the difficulties of the poem much better than my notes can do; and I recommend it (apart from the great interest of the book itself) to any who think such elucidation of the poem worth the trouble. To another work of anthropology I am indebted in general, one which has influenced our generation profoundly; I mean The Golden Bough; I have used especially the two volumes Adonis, Attis, Osiris. Anyone who is acquainted with these works will immediately recognize in the poem certain references to vegetation ceremonies.

Dietary intakes of children in the first year of the University of Saskatchewan pediatric bone density study: Relationship to bone measurements

Not only the title, but the plan and a good deal of the incidental symbolism of the poem were suggested by Miss Jessie L. Westons book on the Grail legend: From Ritual to Romance (Macmillan). Indeed, so deeply am I indebted, Miss Westons book will elucidate the difficulties of the poem much better than my notes can do; and I recommend it (apart from the great interest of the book itself) to any who think such elucidation of the poem worth the trouble. To another work of anthropology I am indebted in general, one which has influenced our generation profoundly; I mean The Golden Bough; I have used especially the two volumes Adonis, Attis, Osiris. Anyone who is acquainted with these works will immediately recognize in the poem certain references to vegetation ceremonies.