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Biomedical subjects

B L Specker

Publications and source records attributed to B L Specker.

At least 19 recordsLinked to original sources
PubMed2006

Volumetric bone mineral density and bone size in sleep-deprived individuals.

INTRODUCTION: Chronic sleep deprivation, which is associated with several age-related pathologies and altered endocrine function, may adversely affect bone. Our a priori hypothesis was that bone mineral density was lower in sleep-deprived (<6.5 h/night) vs. sleep-adequate (>6.5-10 h/night) individuals. METHODS: Cross-sectional analysis of sleep and bone data on 1,146 individuals (652 women) was performed. Measurements were obtained at the distal radius by pQCT, and the spine and hip by DXA. Bone differences between sleep-deprived and sleep-adequate groups were compared after stratifying by sex and controlling for covariates. RESULTS: Overall, 19% of the population was sleep deprived. Sleep-deprived women had lower cortical volumetric BMD (1,208+/-4 vs. 1,219+/-2 mg/cm(3), P=0.03) than sleep-adequate women. Sleep-deprived men had lower pSSI, an estimate of torsional bending strength, than sleep-adequate men (358+/-10 vs. 382+/-5 mm(3), P=0.04), due to a slightly smaller periosteal circumference (43.9+/-0.4 vs. 44.8+/-0.2 mm, P=0.07) and cortical area (103+/-2 vs. 106+/-1+/-mm(2), P=0.06). CONCLUSION: Sleep deprivation is associated with some, but not all, bone outcomes. These findings may have important public health significance given the increasing prevalence of sleep deprivation.

Absorptiometry, Photon↗
PubMed2005

Bioavailability of vitamin D from fortified process cheese and effects on vitamin D status in the elderly.

We conducted 2 studies to determine the effect of vitamin D-fortified cheese on vitamin D status and the bioavailability of vitamin D in cheese. The first study was designed to determine the effect of 2 mo of daily consumption of vitamin D3-fortified (600 IU/d) process cheese on serum 25-hydroxyvitamin D (25-OHD), parathyroid hormone (PTH), and osteocalcin (OC) concentrations among 100 older (> or =60 yr) men and women. Participants were randomized to receive vitamin D-fortified cheese, nonfortified cheese, or no cheese. Serum levels of 25-OHD, PTH, and OC were measured at the beginning and end of the study. There were no differences in 25-OHD, PTH, or OC after 2 mo of fortified cheese intake. The vitamin D-fortified cheese group had a greater decrease in 25-OHD than other groups, due to higher baseline 25-OHD. A second study was conducted to determine whether the bioavailability of vitamin D2 in cheese (delivering 5880 IU of vitamin D2/56.7-g serving) and water (delivering 32,750 IU/250 mL) is similar and whether absorption differs between younger and older adults. The second study was a crossover trial involving 2 groups of 4 participants each (younger and older group) that received single acute feedings of either vitamin D2-fortified cheese or water. Serial blood measurements were taken over 24 h following the acute feeding. Peak serum vitamin D and area under the curve were similar between younger (23 to 50 yr) and older (72 to 84 yr) adults, and vitamin D2 was absorbed more efficiently from cheese than from water. These studies demonstrated that vitamin D in fortified process cheese is bioavailable, and that young and older adults have similar absorption. Among older individuals, consuming 600 IU of vitamin D3 daily from cheese for 2 mo was insufficient to increase serum 25-OHD during limited sunlight exposure.

Absorption↗
PubMed2001

No differences in growth or body composition from age 12 to 24 months between toddlers consuming 2% milk and toddlers consuming whole milk.

OBJECTIVE: To determine whether consumption of 2% milk during the second year of life leads to reduced growth or lower percentage body fat compared with consumption of whole milk. SUBJECTS: Subjects were healthy toddlers who participated in a larger trial examining the effects of the timing of introduction of solid foods on growth. DESIGN: Three-day diet diaries, anthropometric measurements, and body composition determined by dual-energy x-ray absorptiometry were assessed at 12, 18, and 24 months of age. At age 12 months, the toddlers were similar in length, weight, percentage body fat, and total energy intake. From 12 to 24 months of age, milk consumption consisted of whole milk exclusively in one group (n = 23) and 2% milk exclusively in another group (n = 28). STATISTICAL ANALYSES: Differences between the 2 groups in anthropometric measurements, changes in anthropometric measurements, and dietary intakes were determined by Student t tests. Mean differences were considered significant at the P = .05 level. Data are presented as mean +/- standard deviation. RESULTS: Despite lower intakes of total fat and saturated fat in the 2% milk group, there were no differences in height, weight, and percentage body fat. Total energy intake was not reduced in the 2% milk group. APPLICATIONS: Reductions in total fat and saturated fat intake in toddlers can be achieved through the use of 2% milk without compromising growth.

Absorptiometry, Photon↗
PubMed2001

Effect of timing of introduction of complementary foods on iron and zinc status of formula fed infants at 12, 24, and 36 months of age.

OBJECTIVE: The timing of introduction of complementary food to an infant's diet is variable throughout the world. Our objective was to determine whether early introduction of complementary foods affects iron and zinc status of formulated infants at 12, 24, and 36 months of age. DESIGN: A randomized, prospective trial was conducted. Infants were randomly assigned to receive either a) early introduction (at 3 to 4 months of age) of commercially prepared or parent's choice of complementary foods; or b) late introduction (at 6 months of age) of commercially prepared complementary foods or parent's choice of complementary foods. In addition to complementary foods, infants were fed commercial infant formula as recommended by their pediatrician. Hemoglobin, mean corpuscular volume, and serum ferritin and zinc concentrations were determined at 12, 24, and 36 months of age. Three-day diet diaries were completed at 3, 6, 12, 18, 24, 30, and 36 months of age. SUBJECTS/SETTING: One hundred seventy-five infants younger than 3 months were recruited by mailings to parents in the Cincinnati area. Of these, 172 were enrolled, 90 in the early-introduction group and 82 in the late-introduction group. One hundred thirty-three infants (n = 67 in the early, n = 66 in the late group) completed the study. STATISTICAL ANALYSES PERFORMED: Student t test and regression analyses were used to determine whether there were group differences and whether there was a relationship between serum parameters and dietary intake. RESULTS: Infants fed complementary foods early had significantly greater iron intakes until 6 months of age; however, there were no differences in the iron status parameters (ferritin, hemoglobin, and mean corpuscular volume) at 12, 24, or 36 months of age. The early introduction group consumed slightly less zinc than the late introduction group at 5 months (4.4 vs 4.8 mg/day, P < .01) and 6 months (4.4 vs 4.7 mg/day, P < .01). At all other times there were no differences between the early and late group in zinc intakes. The serum zinc concentration was not associated with dietary zinc. Both groups had normal serum zinc concentrations at 12, 24, and 36 months and there were no differences between groups. APPLICATIONS/CONCLUSIONS: The iron and zinc status of infants in this study was not influenced by the timing or type of complementary foods introduced. However, the infants were formula fed and the mean iron and zinc intakes that were equal or greater than the Recommended Dietary Allowances for the first 6 months of age.

Age Factors↗
PubMed2001

Comparison of bone parameters by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography in Hutterite vs. non-Hutterite women aged 35-60 years.

A previous report of elevated dual-energy X-ray absorptiometry (DXA) bone mineral density (BMD) Z scores suggests that Hutterite females might be significantly less likely to develop osteoporosis compared with other U.S. females. In the present study, we sought to determine if high Hutterite DXA BMD Z scores were elevated because of larger bone size. Hutterites reside in isolated, self-sufficient colonies with an emphasis on agricultural production, and girls enter a strenuous task rotation at age 15 years. We obtained cross-sectional bone measurements of the 66% distal tibia using peripheral quantitative computed tomography (pQCT) to compare bone size and geometry on 97 Hutterite and 30 non-Hutterite women, aged 35-60 years. Total body (TB) and lumbar bone mineral content (BMC), BMD, and bone area measurements by DXA were available on a subset of the study population. We identified no differences between groups in pQCT total bone area, cortical bone area, or cortical bone density. Larger bone area by DXA was apparent in Hutterites compared with non-Hutterites at the TB (least square means: 2038 +/- 8 cm2 vs. 1953 +/- 19 cm2, p < 0.05) and lumbar (least square means: 58 +/- 0.5 cm2 vs. 57 +/- 2 cm2, p < 0.01) sites. TB BMC adjusted for TB bone area was marginally higher in Hutterites compared with non-Hutterites (least square means: 2341 +/- 15 g vs. 2281 +/- 30 g, p = 0.08). Hutterites had marginally higher TB BMD Z scores when controlling for weight and age (least square means: 1.3 +/- 0.1 vs. 0.8 +/- 0.2, p = 0.07). Hutterites had higher lumbar BMC adjusted for lumbar bone area and weight (least square means: 65 +/- 1 g vs. 58 +/- 2 g, p < 0.01) and higher weight-and age-adjusted lumbar BMD Z scores (least square means: 1.1 +/- 0.1 vs. 0.1 +/- 0.4, p = 0.01). Our data indicate that a true advantage in trabecular bone density probably exists among Hutterite women aged 35-60 years. Hutterite women might be protected against age-related fractures because of their larger bone size and higher bone density at normally susceptible trabecular sites.

Absorptiometry, Photon↗
PubMed2001

Total body bone mineral content and tibial cortical bone measures in preschool children.

This study was undertaken to identify factors that influence total body bone area (TBBA), total body bone mineral content (TBBMC), and tibial cortical bone measures in 239 children aged 3-5 years. We obtained information on demographic and anthropometric characteristics and measurements of diet, physical activity, and strength. In multiple regression analysis, TBBA correlated with height (p < 0.001), weight (p < 0.001), percent body fat (p < 0.001), and calcium intake (p = 0.02). TBBMC correlated with TBBA (p < 0.001), age (p = 0.001), and weight (p = 0.02) and inversely correlated with height (p < 0.001) and percent body fat (p < 0.001). Children born preterm had lower TBBMC compared with children born at term (p = 0.02). Both periosteal and endosteal circumferences were correlated with weight (both,p < 0.001) and inversely correlated with age (p = 0.006 and p = 0.003, respectively) and percent body fat (p = 0.002 and p = 0.005 respectively). Endosteal circumference was greater and cortical bone area was lower in children born preterm compared with those born at term (both, p = 0.04). Findings of higher TBBA and lower TBBMC in children with high percent body fat indicate undermineralization of bone and suggest that obesity in preschool children may have detrimental effects on total body bone mass accretion. A smaller tibial periosteal circumference and thus cross-sectional area in children with the same weight but higher percent body fat also would lead to a biomechanical disadvantage in these children. Findings of low TBBMC and cortical bone area among children born preterm need to be confirmed in other populations. We speculate that differences in these measurements between children born preterm and at term may be caused by differences in activity.

Age Factors↗
PubMed2000

Total-body bone mineral content in non-corticosteroid-treated postpubertal females with juvenile rheumatoid arthritis: frequency of osteopenia and contributing factors.

OBJECTIVE: To determine the extent of low total-body bone mineral content (BMC) in non-corticosteroid-treated white postpubertal females with juvenile rheumatoid arthritis (JRA) compared with healthy age- and race-matched female controls, and to identify variables that significantly contribute to total-body BMC. METHODS: Thirty-six females with definite JRA who had never received corticosteroids and 51 healthy female controls were evaluated. All subjects had had their first menstrual period at least 2 years prior to enrollment. Total-body BMC, lumbar spine bone mineral density, and body composition were determined by dual x-ray absorptiometry. Total-body BMC Z-scores were calculated for JRA patients using data from controls. JRA patients were dichotomized into those with "normal" bone mass (total-body BMC at or above the mean or no more than 1 SD below the mean) and those with "low" bone mass (total-body BMC more than 1 SD below the mean). Comparisons of anthropometric measurements, laboratory measurements of bone metabolism, disease activity, dietary intake, and physical activity were performed. Stepwise logistic regression was utilized to determine the presence or absence of low total-body BMC and to identify associated contributing factors. RESULTS: Total-body BMC was 4.5% lower in JRA patients than in controls (mean +/- SD 2,050 +/- 379 gm versus 2,143 +/- 308 gm; P = 0.21). Twenty-five of 36 patients (69.4%) had "normal" and 11 of 36 (30.6%) had "low" total-body BMC. Comparison of JRA patients with "normal" versus those with "low" total-body BMC revealed significant differences in disease characteristics, anthropometric and physical development characteristics, laboratory measures of bone mineralization, and dietary intake. The final regression model contained only lean mass (P = 0.01), which accounted for 76.3% of the variance in total-body BMC. The odds ratio for lean mass was 0.4451 (95% confidence interval 0.2374-0.8348). CONCLUSION: In this study, approximately 30% of the subjects in a sample of postpubertal female patients with mild-to-moderate, non-corticosteroid-treated JRA had low bone mass. The predictor variable that significantly contributed to total-body BMC was lean mass, which demonstrated a protective effect of 0.56 risk reduction for low total-body BMC.

Adolescent↗
PubMed2000

The relationship of childhood adiposity to parent body mass index and eating behavior.

OBJECTIVE: To better understand risk factors for the development of obesity in early childhood, we examined the association between children's adiposity and their parents' eating behavior and body mass index (BMI). RESEARCH METHODS AND PROCEDURES: Parents of 85 white children 36 months of age (49 boys and 36 girls) completed the Three-Factor Eating Questionnaire measuring three dimensions of parent eating behavior: disinhibited eating, cognitive restraint of eating, and susceptibility to hunger. Parent BMI (kg/m2) was calculated using self-reported height and weight. The children's percentage body fat was assessed by dual energy X-ray absorptiometry analysis. RESULTS: Twenty-six percent of parents were obese (BMI > or = 30 kg/m2). Both maternal and paternal BMI were associated with higher scores for disinhibition (r = 0.69 and r = 0.68, p < 0.001), and maternal BMI was also associated with higher scores for hunger (r = 0.51, p < 0.001). There were no significant relationships between children's percentage body fat and parent eating scores, and the correlation between children's percentage body fat and parent BMI was significant only between mothers and daughters (r = 0.35, p = 0.04). Obese parents were no more likely to have a child who was fatter (upper quintile of percentage body fat for gender). DISCUSSION: Among 36 month-old white children, parent eating behavior was related to parent BMI, but not to children's adiposity. There was only a weak relationship between parent BMI and child adiposity. Despite the aggregation of adiposity within families due to shared genes and environments, children may not express differences in susceptibility to obesity by 3 years of age.

Absorptiometry, Photon↗
PubMed2000

Role of calcium in bone health during childhood.

A discussion of observational and longitudinal studies examining the effect of early-life calcium intake on bone health is provided. A critical analysis of pediatric calcium supplementation trials is conducted by determining annualized percent changes in bone mineral density (BMD). The focus of the analysis is to identify consistent findings at specific bone sites, determine whether effects differed by the age of children studied, and establish the relationship between bone changes and baseline calcium intake. We found that increases in BMD owing to higher calcium intake among children appear to occur primarily in cortical bone sites, are most apparent among populations with low baseline calcium intakes, and do not seem to persist beyond the calcium supplementation period. Older (e.g., pubertal) children appear to have greater annual increases in lumbar BMD than younger (e.g., prepubertal) children. The annual percent increase in midradius BMD appears to be greater at higher intakes among the older children, but such a relationship is less apparent among the younger children.

Absorptiometry, Photon↗
PubMed2000

High bone mass in a female Hutterite population.

We examined a Hutterite population (n = 243) to determine if their agriculturally diverse, self-sufficient communal lifestyle promotes optimal bone mass attainment because of adequate calcium intake and high physical activity levels during growth and young adulthood. We measured total body (TB) and lumbar bone mineral content (BMC) and bone mineral density (BMD) in 39 school-age (younger) females and 204 working (older) females. Forty-five percent of older females and 79% of younger females currently consumed > or = 3 servings (svg) of dairy per day. Older females had lumbar (0.6 +/- 1.3) and TB (1.1 +/- 1.1) BMD Z scores greater than 0 (both, p < 0.001). The lumbar BMD Z score of younger females was not different from 0 (-0.1 +/- 1.0; p = 0.5). Both lumbar (r = 0.46; p < 0.001) and TB (r = 0.20; p = 0.02) BMD Z scores increased with increasing age. In multiple regression analyses for older females, lumbar bone area (p < 0.001), weight (p < 0.001), current hours on feet per day (p = 0.01), colony workload (p < 0.01), and estrogen status (p = 0.06) predicted lumbar BMC. TB bone area (p < 0.001), current hours on feet per day (p < 0.001), and colony workload (p < 0.01) predicted TB BMC. For younger females, lumbar bone area (p < 0.001), weight (p < 0.01), years in present colony (p = 0.02), and menses (p < 0.001) predicted lumbar BMC. TB bone area (p < 0.001), height (p < 0.01), years in present colony (p = 0.03), and menses (p < 0.01) predicted TB BMC. The effect of colony workload could not be separated from other factors different by colony. A heritability estimate of 0.66 was calculated for lumbar BMD using mother and daughter Z scores. Adequate calcium intake during growth, high physical activity early in life, and genetic factors may be contributing to above normal BMD levels in adult female Hutterites.

Adolescent↗
PubMed2000

pQCT measurement of bone parameters in young children: validation of technique.

Dual-energy X-ray absorptiometry (DXA) measures areal bone mineral density (BMD) and is affected by bone size. Peripheral quantitative computed tomography (pQCT) measures volumetric density and should not be affected by bone size. We hypothesized that pQCT could be used to measure geometric parameters in the tibia and that bone size, not density, would correlate with weight and height in 3 and 4 yr olds. Phantom measurements indicate that accurate results for cortical volumetric bone mineral density can be obtained at cortical thickness > 2 mm with voxel/speed sizes of 0.40/20 mm/s. Correlations between pQCT measured geometric bone parameters and phantom calculations were observed (all r > 0.96). Baseline data from an ongoing trial of 101 preschool children (53 male) were used to correlate bone parameters and anthropometrics. Total cross-sectional area, cortical area, and cortical thickness correlated with weight (r = 0.54, p < 0.001; r = 0.52, p < 0. 001; r = 0.30, p = 0.002) and height (r = 0.41, p < 0.001; r = 0.55, p < 0.001; r = 0.41, p < 0.001). Because of the small cortical thickness at this age (mean = 1.2 mm) cortical density was not analyzed. In a regression model including height and weight, weight was the only predictor of total cross-sectional area (p < 0.001); cortical thickness was predicted by height (p = 0.006). Both height (p = 0.005) and weight (p = 0.05) predicted the cortical area. In summary, pQCT accurately measures total cross-sectional area, cortical area, and cortical thickness in children age 3-4 yr.

Absorptiometry, Photon↗
PubMed1999

Effects of calcium supplementation on calcium homeostasis and bone turnover in lactating women.

Lactation is a time of calcium flux, because women secrete approximately 210 mg calcium/day in breast milk, and they experience a transient bone loss. The objectives of this study were to determine the effect of calcium supplementation on adaptive responses in calcium homeostasis during lactation and after weaning. Two cohorts of women participated in a 6-month randomized calcium supplementation trial. Lactation cohort women (97 lactating, 99 nonlactating) were studied during the first 6 months post partum, and weaning cohort women (95 lactating, 92 nonlactating) were studied during the second 6 months post partum. Lactating women in the weaning cohort weaned approximately 1.5 months after enrollment. PTH was 18-30% lower in lactating than in nonlactating women (P < 0.01). Serum 1,25-dihydroxyvitamin D was 11-16% higher in lactating than in nonlactating women and remained elevated for approximately 1.5 months after weaning (P = 0.06). Calcium supplementation decreased serum PTH and 1,25-dihydroxyvitamin D in lactating and nonlactating women similarly. At 6 months, the calciuric response to calcium supplementation was less in lactating (compared with nonlactating) women (P = 0.06). Biomarkers of bone turnover were higher in lactating than in nonlactating women during lactation and after weaning but were not effected by calcium supplementation. Calcium supplementation has little effect on lactation-induced changes in the calcium economy.

Adult↗
PubMed1999

Longitudinal study of calcium intake, physical activity, and bone mineral content in infants 6-18 months of age.

Although increased physical activity early in life is recommended for optimizing bone health, no controlled trials on the effect of activity on bone mass accretion during periods of rapid growth have been reported. The purpose of this study was to determine whether infants randomized to a 1 year gross motor activity program had a greater bone mass accretion than infants randomized to a fine motor activity program. The gross motor program included activities that focused on loading the skeleton and were performed for 15-20 minutes/day, 5 days/week by study personnel. Infants (n = 72) were enrolled at 6 months of age, and total body bone mineral content (BMC), 3-day diet records, and activity levels were obtained at 6, 9, 12, 15, and 18 months. BMC was associated with weight, length, and bone area at all ages and correlated with earlier calcium intakes. Calcium intake appeared to modify the effect of gross motor activity on bone mass accretion; infants in both groups had similar bone accretion at moderately high calcium intakes, but at low calcium intakes infants in the gross motor program had less bone accretion than infants in the fine motor program. Compliant infants in the gross motor group had lower BMC at 18 months compared with noncompliant infants. These results indicate that BMC in infants is related to calcium intake, and we speculate that participation in a gross motor program during rapid bone growth may lead to reduced bone accretion in the presence of a moderate to moderately low calcium intake.

Bone Density↗
PubMed1998

Bone mineral content in children with short bowel syndrome after discontinuation of parental nutrition.

To determine whether children with short bowel syndrome had evidence of metabolic bone disease, total body bone mineral content was measured by dual-energy x-ray absorptiometry in 18 patients and 36 age-, sex-, and race-matched control subjects. Children with short bowel syndrome had decreased bone mineral content compared with control subjects; however, it was not significant when adjusted for differences in weight and height. Whether these children will have normal bone accretion throughout puberty is not known.

25-Hydroxyvitamin D 2↗
PubMed1998

Trial on timing of introduction to solids and food type on infant growth.

OBJECTIVE: The optimal time and choice of solid foods to introduce to an infant's diet is unknown. The aim of this randomized trial was to determine whether early versus late introduction of solid foods and commercially prepared versus parent's choice of solid foods affects growth or body composition in the first year. METHODS: White infants (n = 165) were recruited before 3 months of age and were randomized to receive: 1) commercially prepared solid foods (commercial) from 3 to 12 months, 2) commercially prepared solid foods from 6 to 12 months, 3) parent's choice of solid foods (choice) from 3 to 12 months, or 4) parent's choice of solid foods from 6 to 12 months. Anthropometrics and body composition, using dual energy x-ray absorptiometry, were determined at 3, 6, and 12 months. Three-day diet diaries were completed at 3, 6, 9, and 12 months. RESULTS: There were no differences in growth or body composition between infants in early versus late introduction groups or commercial versus choice groups at any age. The total energy intake was not different among infants in the early compared with the late group at any age. Infants in the commercial group consumed less protein calories at 9 months (80 +/- 3 kcal/d vs 88 +/- 3 kcal/d) and 12 months 101 +/- 5 kcal/d vs 148 +/- 5 kcal/d), less fat calories at 12 months (263 +/- 10 kcal/d vs 343 +/- 10 kcal/d), and less total calories at 12 months (884 +/- 24 kcal/d vs 1022 +/- 25 kcal/d) compared with the choice group. CONCLUSION: The early introduction of solid foods to an infant's diet does not alter growth or body composition during the first year of life and results in a displacement of energy intake from formula. Infants consuming commercially prepared foods have a decreased caloric intake from protein and fat; however, despite this difference, there is no effect on growth or body composition.

Age Factors↗