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Biomedical subjects

R Wellens

Publications and source records attributed to R Wellens.

10 recordsLinked to original sources
PubMed1994

Body composition in white adults by dual-energy x-ray absorptiometry, densitometry, and total body water.

Percent body fat (%BF) and fat-free mass (FFM) were determined in 151 adults from the Fels Longitudinal Study by total body scans with a Lunar DPX (DXA), by underwater weighing and residual lung volume with a two-compartment model using body density (Dens), and total body water (TBW) using deuterium dilution. For the DPX, the medium scan mode ensures precision up to 100 kg body wt and for a ratio of weight to stature < or = 0.7214. Because of these specifications, 15% (n = 23) of the original sample of 151 were excluded. Results for 78 women and 50 men are presented. %BFTBW was significantly (P < 0.05) less than %BFDens in women (mean difference 2.7 +/- 4.2%) and %BFDXA in men (mean difference 2.2 +/- 4.3%). No other significant intermethod differences were observed for %BF and FFM estimates. Pairwise regressions showed the lowest SEEs for %BFDens regressed vs %BFDXA (2.3% for men, 3.2% for women) and for FFMDens vs FFMDXA (2.2 kg for men, 1.9 kg for women). For each sex, reliability analyses and limits of agreement for body composition estimates showed less agreement between TBW and either Dens and DXA than between Dens and DXA.

Absorptiometry, Photon↗
PubMed1994

Bone mineral content and dietary calcium intake in children prescribed a low-lactose diet.

Bone density is related to body size and other factors including dietary calcium intake. The purpose of this study was to determine the effect of a low-lactose, low-calcium diet on the bone mineral content (BMC) of prepubertal children with documented lactose intolerance. Radial BMC was determined by single-photon absorptiometry. Dietary intake was assessed by 24-h recall and two 3-day food records, and weight and height were measured. The group of lactose-intolerant children was compared with a group of healthy children of similar age, gender, race, and size and to the prediction equations based on body size from Chan's Utah children. Nineteen children, ages 9.6 +/- 1.9 years, participated in the study. They were relatively short compared with standards (height Z score, -0.30 +/- 0.83). BMC was 0.428 +/- 0.081 g/cm in the study group versus 0.440 +/- 0.116 g/cm in the comparison group (n = 19; p > 0.05). Both the study group and the size-selected comparison group had lower BMC than the Utah children. The diet of the study group was low in calcium: 84% of the Recommended Dietary Allowance in children < 11 years old and 32% in children > 11. Calcium intake was associated (p = 0.03) with BMC in the study group after adjusting for body size. The low-lactose diet resulted in a low calcium intake, and BMC was associated with calcium intake in prepubertal children with lactose intolerance. Evaluation of dietary calcium intake should be considered in this group of patients, with follow-up dietary counseling, calcium supplementation (diet or medication), and bone density assessment when clinically indicated.

Body Height↗
PubMedDate not supplied

Skeletal maturity and body size of teenage Belgian track and field athletes.

Attained skeletal maturity (TW2 RUS method), skeletal maturity relative to chronological age, and body size of national-level Belgian track and field athletes 15 to 18 years of age were considered. Among the 47 male athletes, 29 (62%) were skeletally mature, while 15 (52%) of the 29 female athletes were skeletally mature. There appeared to be a predominance of skeletally mature individuals among male sprinters and jumpers, while a majority of female sprinters were not skeletally mature. Both skeletally mature and immature individuals were rather evenly represented in the other track and field categories, with the exception of female throwers, who were skeletally mature. Mean statures and weights of skeletally mature and immature 16-, 17-and 18-year-old male athletes did not differ significantly, though the skeletally mature tended to be heavier. In contrast, the skeletally mature female athletes, on the average, were taller and heavier than the skeletally immature, although the differences among the small groups were not statistically significant.

Adolescent↗
PubMedDate not supplied

Age at menarche in Flemish girls: current status and secular change in the 20th century.

The age at menarche in a national sample of 4894 Flemish schoolgirls was surveyed in 1979-1980. The probit estimate of the mean age at menarche was 13.20 +/- 0.02 years (SD = 1.25 years). This estimate falls well within the range of reported ages at menarche for girls in northwestern Europe, but is slightly later than those for French-speaking girls in Belgium and in France. Status quo secular data for the 20th century indicate a decline in estimated mean ages at menarche of Flemish girls from about 14.3 years before World War II to 13.6 and 13.2 years, respectively, among girls born just before and during the war. Subsequently, mean ages at menarche of Flemish girls are fairly stable between 13.0 and 13.2 years. These secular changes are of the same magnitude as those observed in other European countries.

Adolescent↗
PubMedDate not supplied

The timing of sexual maturation in a group of US white youths.

The purpose of this study was to present US reference data for chronological ages at which stages of sexual maturation were observed in white youths. Recent serial data from 78 males and 67 females were analyzed to obtain descriptive statistics for the ages at onset of these stages and the mean ages at which the stages are observed. These reference data should assist the identification of white US youths who are maturing at rapid or slow rates and the interpretation of growth data.

Adolescent↗