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Biomedical subjects

D A Bailey

Publications and source records attributed to D A Bailey.

52 records · Page 3Linked to original sources
PubMedDate not supplied

Timing and magnitude of peak height velocity and peak tissue velocities for early, average, and late maturing boys and girls.

Height, weight, and tissue accrual were determined in 60 male and 53 female adolescents measured annually over six years using standard anthropometry and dual-energy X-ray absorptiometry (DXA). Annual velocities were derived, and the ages and magnitudes of peak height and peak tissue velocities were determined using a cubic spline fit to individual data. Individuals were rank ordered on the basis of sex and age at peak height velocity (PHV) and then divided into quartiles: early (lowest quartile), average (middle two quartiles), and late (highest quartile) maturers. Sex- and maturity-related comparisons in ages and magnitudes of peak height and peak tissue velocities were made. Males reached peak velocities significantly later than females for all tissues and had significantly greater magnitudes at peak. The age at PHV was negatively correlated with the magnitude of PHV in both sexes. At a similar maturity point (age at PHV) there were no differences in weight or fat mass among maturity groups in both sexes. Late maturing males, however, accrued more bone mineral and lean mass and were taller at the age of PHV compared to early maturers. Thus, maturational status (early, average, or late maturity) as indicated by age at PHV is inversely related to the magnitude of PHV in both sexes. At a similar maturational point there are no differences between early and late maturers for weight and fat mass in boys and girls.

Adolescent↗
PubMedDate not supplied

A longitudinal analysis of sex differences in bone mineral accrual in healthy 8-19-year-old boys and girls.

BACKGROUND: Although early in life there is little discernible difference in bone mass between boys and girls, at puberty sex differences are observed. It is uncertain if these differences represent differences in bone mass or just differences in anthropometric dimensions. AIM: The study aimed to identify whether sex independently affects bone mineral content (BMC) accrual in growing boys and girls. Three sites are investigated: total body (TB), femoral neck (FN) and lumbar spine (LS). SUBJECTS AND METHODS: 85 boys and 67 girls were assessed annually for seven consecutive years. BMC was assessed by dual energy X-ray absorptiometry (DXA). Biological age was defined as years from age at peak height velocity (PHV). Data were analysed using a hierarchical (random effects) modelling approach. RESULTS: When biological age, body size and body composition were controlled, boys had statistically significantly higher TB and FN BMC at all maturity levels (p < 0.05). No independent sex differences were found at the LS (p > 0.05). CONCLUSION: Although a statistical significant sex effect is observed, it is less than the error of the measurement, and thus sex difference are debatable. In general, sex difference are explained by anthropometric difference.

Absorptiometry, Photon↗
PubMedDate not supplied

Longitudinal comparison of aerobic power in active and inactive boys aged 7.0 to 17.0 years.

Height and maximal aerobic power (VO2 max) were analysed longitudinally in 14 active and 11 inactive boys from the Saskatchewan Longitudinal Growth Study. VO2 max values were obtained from a treadmill run repeated each year. The Preece-Baines Model I was fitted to height and VO2 max values over the duration of the study. No significant differences were found for height attained between the two groups. VO2 max comparisons revealed no significant differences before the take-off point for the adolescent growth spurt. Significant differences occurred in the VO2 max attained by the age of peak adolescent velocity in VO2 max, the increase from take-off to peak and in the adult value, with active boys having higher values. It is concluded that activity before adolescence causes no significant increase in VO2 max, but that adolescence is the critical period during which consistently higher rates of increase in the VO2 max of active boys result in a significantly greater adult value.

Adolescent↗
PubMedDate not supplied

The application of new height-prediction equations (Tanner-Whitehouse mark 2) to a sample of Canadian boys.

The adult statures of a sample of 71 Canadian boys from the Saskatchewan Longitudinal Growth Study were predicted using the original TW Mark 1 and the new TW Mark 2 prediction equations. The subjects had a mean chronological age of 11.59 years (SD = 0.30), a mean RUS bone age of 11.62 'years' (SD = 1.18), a mean height of 145.0 cm (SD = 6.98) and a mean measured adult height of 177.2 cm (SD = 6.65). The Mark 2 equations improved the predictions over Mark 1 by an average of 0.2-0.6 cm and slightly reduced the range of errors. No improvement in the prediction of boys above the 75th centile of British standards was noted but 60-70% of boys below the 25th centile predicted better with the Mark 2 equations. This pattern may well be repeated in more extreme subjects. About 80% of individuals who predicted badly with the Mark 1 equations, i.e. with errors equal to or greater than 5 cm, improved their predictions when Mark 2 equations were used.

Body Height↗
PubMedDate not supplied

Developing better critical paths in healthcare: combining 'best practice' and the quantitative approach.

Critical paths are tools to manage healthcare delivery and ensure favorable patient outcomes. Unfortunately, many of these paths are not evaluated or revised after their initial development. One potential problem faced by nursing managers is that critical paths may lose relevance in a rapidly changing healthcare environment. The authors suggest one strategy to strengthen existing critical paths in a way that is responsive to these changes.

Aged↗
PubMedDate not supplied

Critical evaluation of frame size determination in the 1983 Metropolitan Life weight for height tables.

According to Metropolitan Life, the criteria used in placing individuals into frame size classes on the basis of elbow breadth should result in a 25-50-25% (small-medium-large) distribution. This assumption was evaluated using a large sample of Canadians (n = 19,305). Results indicated that the hypothesized distribution was not achieved in either males or females; few subjects were classified as large frame. The small percentage of subjects classified as large frame resulted in a skewing of the weight categorizations in males, but not in females.

Adolescent↗
PubMedDate not supplied

The effect of water fluoridation on the bone mineral density of young women.

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.

Adult↗