Kathleen De Waele

Comparative bone status assessment by dual energy X-ray absorptiometry, peripheral quantitative computed tomography and quantitative ultrasound in adolescents and young adults with cystic fibrosis

PURPOSE Quantitative ultrasound bone sonometry (QUS) might be a promising screening method for cystic fibrosis (CF)-related bone disease, given its absence of radiation exposure, portability of the equipment and low cost.The value of axial transmission forearm QUS in detecting osteopenia in CF was therefore studied. METHODS We investigated the application of QUS in the evaluation of bone status in a group of 64 adolescents (>12 years) and young adults (<40 years) with CF in a comparison with a dual X-ray absorptiometry (DXA) of the whole body and peripheral quantitative computed tomography (pQCT) of the radius at 4% and 66% sites. RESULTS Mean (SD) Z-scores of speed of sound (SOS), whole body bone mineral content (BMC), radial trabecular bone mineral density (BMD), and radial cortical BMD were respectively -0.31 (0.78), -0.09 (1.28), 0.10 (1.16) and -0.62 (2.88). The pQCT determined bone geometry values (cortical bone area and cortical thickness) were more depressed than the BMD data. QUS had a sensitivity and specificity of respectively 0% and 96% for diagnosing osteopenia (based on a whole body BMC Z-score<-2). CONCLUSIONS QUS cannot replace DXA, but can screen out patients with normal bone mass. Further and larger studies are needed to examine if QUS may reflect other aspects than bone mass, or if it is possible to improve its sensitivity by supplementing the SOS results with clinical risk factors.

Cognitive, emotional and psychosocial functioning of girls treated with pharmacological puberty blockage for idiopathic central precocious puberty

Central precocious puberty (CPP) develops due to premature activation of the hypothalamic-pituitary-gonadal (HPG) axis, resulting in early pubertal changes and rapid bone maturation. CPP is associated with lower adult height and increased risk for development of psychological problems. Standard treatment of CPP is based on postponement of pubertal development by blockade of the HPG axis with gonadotropin releasing hormone analogs (GnRHa) leading to abolition of gonadal sex hormones synthesis. Whereas the hormonal and auxological effects of GnRHa are well-researched, there is a lack of knowledge whether GnRHa treatment influences psychological functioning of treated children, despite the fact that prevention of psychological problems is used as one of the main reasons for treatment initiation. In the present study we seek to address this issue by exploring differences in cognitive function, behavior, emotional reactivity, and psychosocial problems between GnRHa treated CPP girls and age-matched controls. Fifteen girls with idiopathic CPP; median age 10.4 years, treated with slow-release GnRHa (triptorelin acetate—Decapeptyl SR® 11.25) and 15 age-matched controls, were assessed with a comprehensive test battery consisting of paper and pencil tests, computerized tasks, behavioral paradigms, heart rate variability, and questionnaires filled in by the childrens parents. Both groups showed very similar scores with regard to cognitive performance, behavioral and psychosocial problems. Compared to controls, treated girls displayed significantly higher emotional reactivity (p = 0.016; Cohens d = 1.04) on one of the two emotional reactivity task conditions. Unexpectedly, the CPP group showed significantly lower resting heart rates than the controls (p = 0.004; Cohens d = 1.03); lower heart rate was associated with longer treatment duration (r = −0.582, p = 0.037). The results suggest that GnRHa treated CPP girls do not differ in their cognitive or psychosocial functioning from age matched controls. However, they might process emotional stimuli differently. The unexpected finding of lower heart rate that was associated with longer duration of the treatment should be further explored by methods appropriate for assessment of cardiac health.

Profiling of conserved non-coding elements upstream of SHOX and functional characterisation of the SHOX cis -regulatory landscape

Genetic defects such as copy number variations (CNVs) in non-coding regions containing conserved non-coding elements (CNEs) outside the transcription unit of their target gene, can underlie genetic disease. An example of this is the short stature homeobox (SHOX) gene, regulated by seven CNEs located downstream and upstream of SHOX, with proven enhancer capacity in chicken limbs. CNVs of the downstream CNEs have been reported in many idiopathic short stature (ISS) cases, however, only recently have a few CNVs of the upstream enhancers been identified. Here, we set out to provide insight into: (i) the cis-regulatory role of these upstream CNEs in human cells, (ii) the prevalence of upstream CNVs in ISS, and (iii) the chromatin architecture of the SHOX cis-regulatory landscape in chicken and human cells. Firstly, luciferase assays in human U2OS cells, and 4C-seq both in chicken limb buds and human U2OS cells, demonstrated cis-regulatory enhancer capacities of the upstream CNEs. Secondly, CNVs of these upstream CNEs were found in three of 501 ISS patients. Finally, our 4C-seq interaction map of the SHOX region reveals a cis-regulatory domain spanning more than 1 Mb and harbouring putative new cis-regulatory elements.

Insulin sensitivity modulates the growth response during the first year of high-dose growth hormone treatment in short prepubertal children born small for gestational age

Aim: To study the relationship between insulin sensitivity and growth response in short children born small for gestational age (SGA) treated with growth hormone (GH). Methods: Randomized, open-label, 24-month intervention study in 40 short prepubertal SGA children [age (mean ± SD) 5.3 ± 1.5 years], who either remained untreated (n = 20) or were treated with GH (66 µg/kg/day; n = 20). Changes in fasting glucose, insulin, quantitative insulin sensitivity check index (QUICKI), IGF-1 and leptin after 1 and 2 years were studied. Results: Mean height SDS increased from –3.3 ± 0.7 to –2.3 ± 0.7 after 1 year, and to –1.9 ± 0.7 after 2 years of treatment. QUICKI decreased significantly (p = 0.008) in the first year of GH treatment and stabilized in the second year. Baseline QUICKI was positively associated (r = 0.40; p < 0.05) with the change in height SDS in the first year. Conclusion: Higher insulin sensitivity at the start of GH therapy is associated with greater first-year growth response to GH, and could be a promising parameter in selecting prepubertal short SGA children for GH treatment. However, this finding needs to be confirmed in larger studies.

Desmopressin Lyophilisate for the Treatment of Central Diabetes Insipidus: First Experience in Very Young Infants

Introduction: In neonates and small infants, early diagnosis of central diabetes insipidus (CDI) and treatment with desmopressin in low doses (avoiding severe hypo- or hypernatremia) are important to prevent associated high morbidity and mortality in this particular age group. Case Presentation: We described pharmacokinetic and pharmacodynamic results of the use of recently launched oral desmopressin lyophilisate (Minirin Melt®) in two infants with CDI, diagnosed at the age of 12 and 62 days, respectively. We observed that a starting dose of 60 μg of Minirin Melt® in the first case resulted in a pharmacokinetic profile largely exceeding the reference frame observed in children with nocturnal enuresis, while a dose of 15 μg in the second case resulted in acceptable concentrations. After initial dose adjustments, administration of sublingual lyophilisate resulted in rather stable serum sodium concentrations. Conclusions: Using Minirin Melt® in infants with CDI appears to be effective, easy to use and well tolerated.

QUANTITATIVE BONE ULTRASOUND AT THE DISTAL RADIUS IN ADULTS WITH CYSTIC FIBROSIS

It is of clinical importance to identify bone disease related to cystic fibrosis (CF) early in its course to allow therapeutic interventions that optimize bone health. To test the technical (precision) and clinical (percentage of abnormal results, correlation with clinical parameters) performance of a commercial quantitative ultrasound apparatus for radial measurements, speed of sound (SOS) was measured at the distal third of the left radius with the Omnisense 7000p apparatus (Sunlight Medical, Tel-Aviv, Israel) in a group of young adult CF patients with regular follow-up at the Brussels and Ghent University Hospital. Sixty-three (37 males) CF patients at a median (range) age of 23.5 y (18.1-39.9) were included. SOS, SOS z-score and SOS t-score were respectively 4017 ± 97 m/s, -0.31 ± 0.74 and -0.60 ± 0.78 in males and 4086 ± 97 m/s, -0.19 ± 0.75 and -0.51 ± 0.95 in females. Mean SOS t-score was significantly lower compared with the manufacturers reference data for males (p < 0.0001) and females (p = 0.01). SOS z- and t-scores correlated with weight z-score and body mass index z-score in females. No significant correlation was found between SOS and forced expiratory volume in 1 s (%). Neither diabetes mellitus nor liver disease was found to influence SOS. Radial quantitative ultrasound has a precision of 0.55%. The SOS is in the low normal range in 14% of CF patients and is influenced by weight in female patients, but not by the severity of the lung disease.

Transient exocrine pancreatic insufficiency as a possible complication of an enterovirus infection

Exocrine pancreatic insufficiency is an exceptional problem in children, mostly associated with diseases like cystic fibrosis, Shwachman-Diamond syndrome or chronic pancreatitis, as is the case in idiopathic fibrosing pancreatitis. Many viral infections are known to cause acute pancreatitis. Most of them, however, are transient with no remaining damage. The differential diagnosis of persisting diarrhoea after gastrointestinal infection does not routinely include a search for exocrine pancreatic insufficiency. Conclusion: This is the first description of a child with a transient but severe exocrine pancreatic insufficiency probably induced by an ordinary enterovirus infection

Evaluation of cardiopulmonary exercise testing, heart function, and quality of life in children after allogenic hematopoietic stem cell transplantation

Physical fitness is an important determinant of quality of life (QOL) after hematopoietic stem cell transplantation. Cardiac function can influence exercise performance. The aim of this study was to assess these factors and their interrelationship.