Muscle torque relative to cross-sectional area and the functional muscle-bone unit in children and adolescents with chronic disease.

Measures of muscle mass or size are often used as surrogates of forces acting on bone. However, chronic diseases may be associated with abnormal muscle force relative to muscle size. The muscle-bone unit was examined in 64 children and adolescents with new-onset Crohn's disease (CD), 54 with chronic kidney disease (CKD), 51 treated with glucocorticoids for nephrotic syndrome (NS), and 264 healthy controls.

Stage 1 treatment of pediatric overweight and obesity: a pilot and feasibility randomized controlled trial.

Background: Staged clinical treatment of pediatric obesity is recommended, but untested. Understanding the lowest intensity stage's effectiveness is necessary for future research.

Methods: This was a randomized controlled trial of children ages 4 to <9 years.

Glucocorticoid effects on changes in bone mineral density and cortical structure in childhood nephrotic syndrome.

The impact of glucocorticoids (GC) on skeletal development has not been established. The objective of this study was to examine changes in volumetric bone mineral density (vBMD) and cortical structure over 1 year in childhood nephrotic syndrome (NS) and to identify associations with concurrent GC exposure and growth. Fifty-six NS participants, aged 5 to 21 years, were enrolled a median of 4.

Changes in bone structure and the muscle-bone unit in children with chronic kidney disease.

The impact of pediatric chronic kidney disease (CKD) on acquisition of volumetric bone mineral density (BMD) and cortical dimensions is lacking. To address this issue, we obtained tibia quantitative computed tomography scans from 103 patients aged 5-21 years with CKD (26 on dialysis) at baseline and 12 months later. Gender, ethnicity, tibia length, and/or age-specific Z-scores were generated for trabecular and cortical BMD, cortical area, periosteal and endosteal circumference, and muscle area based on over 700 reference subjects.

Assessment of dual-energy X-ray absorptiometry measures of bone health in pediatric chronic kidney disease.

Background: Dual-energy X-ray absorptiometry (DXA) techniques are limited in childhood chronic kidney disease (CKD) by the confounding effect of short stature and opposing parathyroid hormone effects on trabecular and cortical bone. Peripheral quantitative computed tomography (pQCT) is not subject to these limitations.

Methods: Lumbar spine (LS) and whole-body (WB) DXA and tibia pQCT scans were obtained in 88 stage 4-5 CKD and >650 healthy participants, ages 5-21 years.

Bone density and cortical structure after pediatric renal transplantation.

The impact of renal transplantation on trabecular and cortical bone mineral density (BMD) and cortical structure is unknown. We obtained quantitative computed tomography scans of the tibia in pediatric renal transplant recipients at transplantation and 3, 6, and 12 months; 58 recipients completed at least two visits. We used more than 700 reference participants to generate Z-scores for trabecular BMD, cortical BMD, section modulus (a summary measure of cortical dimensions and strength), and muscle and fat area.

Vitamin D deficiency is common in children and adolescents with chronic kidney disease.

Here we determined if vitamin D deficiency is more common in children with chronic kidney disease compared to healthy children. In addition, we sought to identify disease-specific risk factors for this deficiency, as well as its metabolic consequences. We found that nearly half of 182 patients (ages 5 to 21) with kidney disease (stages 2 to 5) and a third of age-matched 276 healthy children were 25-hydroxyvitamin D deficient (<20 ng/ml).

Volumetric bone mineral density and bone structure in childhood chronic kidney disease.

Chronic kidney disease (CKD) is associated with increased fracture risk and skeletal deformities. The impact of CKD on volumetric bone mineral density (vBMD) and cortical dimensions during growth is unknown. Tibia quantitative computed tomographic scans were obtained in 156 children with CKD [69 stages 2 to 3, 51 stages 4 to 5, and 36 stage 5D (dialysis)] and 831 healthy participants aged 5 to 21 years.

Mechanical loads and cortical bone geometry in healthy children and young adults.

Muscle and bone form a functional unit. While muscle size is a useful surrogate of mechanical load on bone, the independent contributions to bone strength of muscle force, muscle size, gravitational load (body weight), and physical activity have not been assessed. Three hundred twenty-one healthy participants (32% black, 47% male), aged 5-35 years were assessed.

Association of chronic kidney disease with muscle deficits in children.

The effect of chronic kidney disease (CKD) on muscle mass in children, independent of poor growth and delayed maturation, is not well understood. We sought to characterize whole body and regional lean mass (LM) and fat mass (FM) in children and adolescents with CKD and to identify correlates of LM deficits in CKD. We estimated LM and FM from dual energy x-ray absorptiometry scans in 143 children with CKD and 958 controls at two pediatric centers.

Vitamin D deficiency and parathyroid hormone levels following renal transplantation in children.

The objectives were to determine the prevalence of vitamin D deficiency [25(OH)D < 10 ng/ml] in pediatric renal transplant (RTx) recipients, compared with controls and identify correlates of changes in 25(OH)D and intact parathyroid hormone (iPTH) levels following transplantation. Serum 25(OH)D, 1,25(OH)(2)D, and iPTH were measured once in 275 healthy controls and at transplantation, and 3 and 12 months posttransplantation in 58 RTx recipients. Multivariate logistic regression models determined the odds ratio (OR) of vitamin D deficiency in RTx recipients vs.

Effects of sex, race, and puberty on cortical bone and the functional muscle bone unit in children, adolescents, and young adults.

Context: Sex and race differences in bone development are associated with differences in growth, maturation, and body composition.

Objective: The aim of the study was to determine the independent effects of sex, race, and puberty on cortical bone development and muscle-bone relations in children and young adults.

Design And Participants: We conducted a cross-sectional study of 665 healthy participants (310 male, 306 black) ages 5-35 yr.

Bone volumetric density, geometry, and strength in female and male collegiate runners.

Purpose: To explore differences in tibial bone geometry, volumetric density, and estimates of bone strength in runners and healthy controls.

Methods: Male (n = 21) and female (n = 38) runners (49.1 +/- 13.

Divergent effects of glucocorticoids on cortical and trabecular compartment BMD in childhood nephrotic syndrome.

Glucocorticoid (GC) effects on skeletal development have not been established. The objective of this pQCT study was to assess volumetric BMD (vBMD) and cortical dimensions in childhood steroid-sensitive nephrotic syndrome (SSNS), a disorder with minimal independent deleterious skeletal effects. Tibia pQCT was used to assess trabecular and cortical vBMD, cortical dimensions, and muscle area in 55 SSNS (age, 5-19 yr) and >650 control participants.

Bone structure and volumetric BMD in overweight children: a longitudinal study.

The effect of excess body fat on bone strength accrual is not well understood. Therefore, we assessed bone measures in healthy weight (HW) and overweight (OW) children. Children (9-11 yr) were classified as HW (n = 302) or OW (n = 143) based on body mass index.

Lessons learned from school-based skeletal loading intervention trials: putting research into practice.

In recent years, there have been a number of school-based physical activity intervention trials aimed at optimizing bone development. Various approaches have been taken including interventions ranging from 3 to 50 min in length performed 2-5 times per week incorporated within the school day (typically in physical education) or as an after-school program. Overall, these studies showed that school-based skeletal loading interventions are efficacious, safe, and feasible.

Inflammation, insulin, and endothelial function in overweight children and adolescents: the role of exercise.

Objectives: To assess subclinical inflammation, fasting insulin, and endothelial function before and after exercise in overweight children and adolescents.

Study Design: Twenty-five children (body mass index [BMI] >85th percentile) were assessed for brachial artery flow-mediated dilation (FMD), nitroglycerin-induced dilation, C-reactive protein (CRP), lipids, glucose, insulin, oral glucose tolerance, body composition, aerobic fitness (peak oxygen uptake [VO 2 peak]), and blood pressure. Twenty of these persons were equally and randomly assigned to either 8 weeks of stationary cycling or to a non-exercising control group.