Cortical bone geometry in asthmatic children

Intrauterine inflammation exacerbates maladaptive remodeling of the immature myocardium after preterm birth in lambs

BACKGROUND

Antenatal conditions that are linked with preterm birth, such as intrauterine inflammation, can influence fetal cardiac development thereby rendering the heart more vulnerable to the effects of prematurity. We aimed to investigate the effect of intrauterine inflammation, consequent to lipopolysaccharide exposure, on postnatal cardiac growth and maturation in preterm lambs.

METHODS

Preterm lambs (~129 days gestational age) exposed antenatally to lipopolysaccharide or saline were managed according to contemporary neonatal care and studied at postnatal day 7. Age-matched fetal controls were studied at ~136 days gestational age. Cardiac tissue was sampled for molecular analyses and assessment of cardiac structure and cardiomyocyte maturation.

RESULTS

Lambs delivered preterm showed distinct ventricular differences in cardiomyocyte growth and maturation trajectories as well as remodeling of the left ventricular myocardium compared to fetal controls. Antenatal exposure to lipopolysaccharide resulted in further collagen deposition in the left ventricle and a greater presence of immune cells in the preterm heart.

CONCLUSIONS

Adverse impacts of preterm birth on cardiac structure and cardiomyocyte growth kinetics within the first week of postnatal life are exacerbated by intrauterine inflammation. The maladaptive remodeling of the cardiac structure and perturbed cardiomyocyte growth likely contribute to the increased vulnerability to cardiac dysfunction following preterm birth.

IMPACT

Preterm birth induces maladaptive cardiac remodeling and adversely impacts cardiomyocyte growth kinetics within the first week of life in sheep. These effects of prematurity on the heart are exacerbated when preterm birth is preceded by exposure to intrauterine inflammation, a common antecedent of preterm birth. Inflammatory injury to the fetal heart coupled with preterm birth consequently alters neonatal cardiac growth and maturation and thus, may potentially influence long-term cardiac function and health.

Associations of self-reported allergic diseases and musculoskeletal problems in children: A US population-based study

BACKGROUND

Previous studies have found increased rates of musculoskeletal problems in adults with allergic disease, but whether this association holds true for children is unknown.

OBJECTIVE

To investigate the association of bone, joint, and muscle problems in children with a history of allergic disease.

METHODS

Data were obtained from the 2007 Child and Adolescent Health Measurement Initiative. Univariable and multivariable logistic regression models accounting for the sampling design were used to evaluate associations of bone, joint, and muscle problems with allergic diseases, such as asthma, hay fever, food allergies, and eczema. Associations were summarized with odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

The survey included 91,642 individuals aged 0 to 17 years. Multivariable modeling found statistically significant associations between the number of allergic diseases and bone, joint, and muscle problems (1 allergic disease: adjusted OR, 1.28; 95% CI, 1.04-1.56; P = .02; 2 allergic diseases: adjusted OR, 2.55; 95% CI, 1.92-3.39; P < .001; 3 allergic diseases: adjusted OR, 2.70; 95% CI, 1.88-3.86; P < .001; and 4 allergic diseases: adjusted OR, 4.35; 95% CI, 2.46-7.69; P < .001). Severe eczema (but not mild eczema) was associated with bone, joint, and muscle problems (adjusted OR, 2.81; 95% CI, 1.64-4.81; P < .001) and with bone problems (adjusted OR, 6.08; 95% CI, 1.94-19.12; P = .002).

CONCLUSION

Self-reported allergic diseases in children were associated with bone, joint, and muscle problems, and associations strengthened with allergic disease severity and number of allergic diseases. Severe eczema may be associated with bone problems in children. Bone, joint, and muscle problems must be considered in children with severe allergic disease, and prospective studies are necessary to define this association.

Trabecular and cortical bone deficits are present in children and adolescents with cystic fibrosis

Osteopenia and increased fracture rates are well-recognized in adults with CF, but neither the specific contributions of cortical and trabecular bone deficits to bone fragility nor their presence in youth with CF are well-characterized. This study sought to characterize cortical and trabecular volumetric bone mineral density (vBMD), geometry, and biomechanical competence in children with CF and determine their relationship to growth, body composition, and disease severity. Peripheral quantitative computerized tomography (pQCT) measures of total, cortical, and trabecular vBMD, cortical, muscle, and fat cross-sectional areas (CSA), periosteal and endosteal circumferences, and the polar unweighted section modulus (Zp) of the tibia were converted to age- and tibial length-adjusted Z-scores in 97 CF and 199 healthy children (aged 8-21y). Effects of body composition and pulmonary function (forced expiratory volume in 1s, FEV1) upon pQCT outcomes were determined using linear regression. Children with CF (FEV1%-predicted: 84.4+19.7) had lower weight-, height-, BMI-, and whole body lean mass (LBM)-Z and tibial length. Females with CF had lower (p<0.01) total and trabecular vBMD; cortical, muscle, and fat CSA; Zp and periosteal circumference than females in the healthy reference group. These bone differences persisted after adjustment for BMI-Z and to a great extent following adjustment for muscle CSA. Males with CF had lower (p<0.01) cortical, muscle, and fat CSA and their trabecular vBMD deficit approached significance (p=0.069). Deficits were attenuated by adjustment for BMI-Z and to a greater extent adjustment for muscle CSA-Z. The relationship between FEV1%-predicted and pQCT outcomes persisted only in males following adjustment for age and BMI-Z. The CF cohort had lower tibial muscle CSA than expected for their LBM. In this relatively healthy, young CF cohort, deficits in trabecular and multiple cortical bone parameters were present. In females, deficits were greater at older ages and were not fully explained by alterations in body composition. In males worsening pulmonary function was associated with greater deficits that was not explained by increasing age or compromised nutritional status. The occurrence of these differences in CF youth highlights the importance of instituting measures to optimize peak bone mass early in the course of CF.

The change in energy absorbed post removal of metalwork in a simulated paediatric long bone fracture

PURPOSE

The surgical treatment of paediatric fractures is increasing. Open reduction and internal fixation (ORIF) with plates and screws is long established, whilst the use of elastic stable intramedullary nailing (ESIN) has become increasingly popular. This study quantifies, in terms of the energy required to produce a fracture, the biomechanical sequelae of both techniques post removal of metalwork, to provide clinicians with evidence to guide post-operative advice.

METHODS

An immature bovine model was adopted to ascertain whether these techniques exposed the bone to a greater re-fracture risk following removal of the device. Bones were prepared to reflect ORIF or ESIN techniques, or prepared intact for the acquisition of control data. Each bone was tested to failure at 90 °/s, with the absorbed energy then being calculated to determine the relative difference between each technique and versus control data. Data describing peak shear stress and torque were recorded.

RESULTS

Absorbed energy was reduced by 47 % in the ORIF group compared to both the control (p = 0.011) and ESIN (p = 0.018) groups. The peak shear stress and torque were also significantly different. All ORIF bones failed through drill holes, suggesting stress localisation around the defects.

CONCLUSION

This study suggests that there is a significantly higher re-fracture risk following the removal of ORIF plates when compared to both ESIN and the control environment. Whilst this may reflect the intuitive view of many clinicians, this study provides a quantitative value of the reduction in strength and should help clinicians to appropriately caution patients and parents prior to surgery.

Musculoskeletal phenotype through the life course: the role of nutrition

This review considers the definition of a healthy bone phenotype through the life course and the modulating effects of muscle function and nutrition. In particular, it will emphasise that optimal bone strength (and how that is regulated) is more important than simple measures of bone mass. The forces imposed on bone by muscle loading are the primary determinants of musculoskeletal health. Any factor that changes muscle loading on the bone, or the response of bone to loading results in alterations of bone strength. Advances in technology have enhanced the understanding of a healthy bone phenotype in different skeletal compartments. Multiple components of muscle strength can also be quantified. The critical evaluation of emerging technologies for assessment of bone and muscle phenotype is vital. Populations with low and moderate/high daily Ca intakes and/or different vitamin D status illustrate the importance of nutrition in determining musculoskeletal phenotype. Changes in mass and architecture maintain strength despite low Ca intake or vitamin D status. There is a complex interaction between body fat and bone which, in addition to protein intake, is emerging as a key area of research. Muscle and bone should be considered as an integrative unit; the role of body fat requires definition. There remains a lack of longitudinal evidence to understand how nutrition and lifestyle define musculoskeletal health. In conclusion, a life-course approach is required to understand the definition of healthy skeletal phenotype in different populations and at different stages of life.

A reference database for the Stratec XCT-2000 peripheral quantitative computed tomography (pQCT) scanner in healthy children and young adults aged 6-19 years

SUMMARY

We have produced paediatric reference data for forearm sites using the Stratec XCT-2000 peripheral quantitative computed tomography scanner. These data are intended for clinical and research use and will assist in the interpretation of bone mineral density and bone geometric parameters at the distal and mid-shaft radius in children and young adults aged between 6-19 years.

INTRODUCTION

Peripheral quantitative computed tomography (pQCT) provides measurements of bone mineral content (BMC), density (BMD) and bone geometry. There is a lack of reference data available for the interpretation of pQCT measurements in children and young adults. The aim of this study was to provide reference data at the distal and mid-shaft radius.

METHODS

pQCT was used to measure the 4% and 50% sites of the non-dominant radius in a cohort of healthy white Caucasian children and young adults aged between 5 and 25 years. The lambda, mu, sigma (LMS) technique was used to produce gender-specific reference centile curves and LMS tables for calculating individual standard deviations scores.

RESULTS

The study population consisted of 629 participants (380 males). Reference centile curves were produced; total and trabecular BMD for age (distal radius) and for age and height, bone area (distal and mid-shaft radius), cortical area, cortical thickness, BMC, axial moment of inertia, stress-strain index and muscle area (mid-shaft radius).

CONCLUSIONS

We present gender-specific databases for the assessment of the distal and mid-shaft radius by pQCT. These data can be used as control data for research studies and allow the clinical interpretation of pQCT measurements in children and young adults by age and height.

Peripheral quantitative computed tomography in children and adolescents: the 2007 ISCD Pediatric Official Positions

Peripheral quantitative computed tomography (pQCT) has mainly been used as a research tool in children. To evaluate the clinical utility of pQCT and formulate recommendations for its use in children, the International Society of Clinical Densitometry (ISCD) convened a task force to review the literature and propose areas of consensus and future research. The types of pQCT technology available, the clinical application of pQCT for bone health assessment in children, the important elements to be included in a pQCT report, and quality control monitoring techniques were evaluated. The review revealed a lack of standardization of pQCT techniques, and a paucity of data regarding differences between pQCT manufacturers, models and software versions and their impact in pediatric assessment. Measurement sites varied across studies. Adequate reference data, a critical element for interpretation of pQCT results, were entirely lacking, although some comparative data on healthy children were available. The elements of the pQCT clinical report and quality control procedures are similar to those recommended for dual-energy X-ray absorptiometry. Future research is needed to establish evidence-based criteria for the selection of the measurement site, scan acquisition and analysis parameters, and outcome measures. Reference data that sufficiently characterize the normal range of variability in the population also need to be established.