Screening for genetic variants in BDNF that contribute to childhood obesity.

UNLABELLED: What is already known about this subject BDNF is involved in the regulation of food intake and body weight. BDNF deficient animal models are obese. Chromosomal abnormalities cause obesity in humans. What this study adds Evaluation of point mutations in BDNF. Identification of BDNF mutations in obese children. Point mutations in BDNF are not a common cause of childhood obesity. INTRODUCTION: There is ample evidence that BDNF has a role in the regulation of food intake and body weight. Study of various mouse models gave a clear indication that BDNF deficiency leads to the development of obesity. Functional loss of one copy of the BDNF gene, due to chromosomal rearrangements or microdeletions, can cause an obesity phenotype in humans. Therefore, we wanted to investigate whether point mutations in the gene also result in a comparable phenotype. METHODS: We screened 554 severely overweight and obese children and adolescents and 565 lean adults for mutations in the coding region of BDNF. Mutation screening was performed by high-resolution melting curve analysis and direct sequencing. RESULTS: Screening of obese patients led to the identification of two synonymous variations (V37V and H65H) and two non-synonymous coding mutations (T2I and V46M) in the BDNF gene. When we subsequently screened our control population, we found T2I with comparable frequency and confirmed that this is a rare and non-pathogenic variant. In addition, we found another non-synonymous mutation (N187S) in the control population. CONCLUSIONS: In silico analysis of the V46M variant did not support a clear disease-causing effect and no family data were available in order to determine whether the mutation segregates with obesity. However, we cannot rule out a possible pathogenic effect for this variant. In general, we tend to conclude that mutations in the coding region of BDNF are uncommon in obese patients and are therefore not likely to play an essential role in the pathogenesis of childhood obesity.

Mutation screen of the SIM1 gene in pediatric patients with early-onset obesity.

BACKGROUND: The transcription factor SIM1 (Single-minded 1) is involved in the control of food intake and in the pathogenesis of obesity. In mice, Sim1 is involved in the development of the paraventricular nucleus, and Sim1 deficiency leads to severe obesity and hyperphagia. In humans, chromosomal abnormalities in the SIM1 gene region have been reported in obese individuals. Furthermore, recent data also suggest that loss-of-function point mutations in SIM1 are responsible for SIM1 haplo-insufficiency that is involved in causing human obesity. In this study, we therefore wanted to expand the evidence regarding the involvement of SIM1 mutations in the pathogenesis of severe early-onset obesity. METHODS: We screened 561 severely overweight and obese children and adolescents and 453 lean adults for mutations in the coding region of the SIM1 gene. Mutation screening in all patients and lean individuals was performed by high-resolution melting curve analysis combined with direct sequencing. To evaluate the effect of the mutations on SIM1 transcriptional activity, luciferase reporter assays were performed. RESULTS: Mutation analysis identified four novel nonsynonymous coding variants in SIM1 in four unrelated obese individuals: p.L242V, p.T481K, p.A517V and p.D590E. Five synonymous variants, p.P57P, p.F93F, p.I183I, p.V208V and p.T653T, were also identified. Screening of the lean control population revealed the occurrence of four other rare SIM1 variants: p.G408R, p.R471P, p.S492P and p.S622F. For variants p.T481K and p.A517V, which were found in obese individuals, a decrease in SIM1 transcriptional activity was observed, whereas the transcriptional activity of all variants found in lean individuals resembled wild type. CONCLUSIONS: In this study, we have demonstrated the presence of rare SIM1 variants in both an obese pediatric population and a population of lean adult controls. Further, we have shown that functional in vitro analysis of SIM1 variants may help in distinguishing benign variants of no pathogenic significance from variants which contribute to the obesity phenotype.

Metabolic disregulation in obese adolescents with sleep-disordered breathing before and after weight loss.

OBJECTIVE: Sleep-disordered breathing (SDB) is prevalent in obesity. Weight loss is one of the most effective treatment options. The aim was to assess the association of SDB and metabolic disruption before and after weight loss. DESIGN AND METHODS: Obese adolescents were included when entering an in-patient weight loss program. Fasting blood analysis was performed at baseline and after 4-6 months. Sleep screening was done at baseline and at follow-up in case of baseline SDB. RESULTS: 224 obese adolescents were included. Median age was 15.5 years (10.1-18.0) and mean BMI z-score was 2.74 ± 0.42. About 30% had SDB at baseline (N = 68). High-density lipoprotein (HDL)-cholesterol was associated with mean nocturnal oxygen saturation () (partial r = 0.21; P = 0.002). Aspartate aminotransferase (ASAT) and alanine aminotransferase were related with oxygen desaturation index (partial r = -0.15; P = 0.03 and partial r = -0.15; P = 0.02), but this became insignificant after correction for sex. After weight loss, 24% had residual SDB. Linear regression showed an association between ASAT and (partial r = -0.34; P = 0.002). There were no significant correlations between improvements in laboratory measurements and sleep parameters. HDL-cholesterol improved in relation with the decrease in BMI z-score. CONCLUSION: SDB at baseline was associated with higher levels of liver enzymes and lower HDL-cholesterol concentration. Improvements in sleep parameters were not associated with improvements in laboratory measurements.

Sleep-disordered breathing and proteinuria in overweight and obese children and adolescents.

OBJECTIVES: To assess whether sleep-disordered breathing (SDB) in overweight children and adolescents has an additional effect on the spectrum of urinary albumin to protein loss, as markers of early kidney dysfunction. METHODS: Prospective study in a clinical sample of overweight children and adolescents. Each subject underwent anthropometry, blood sampling, oral glucose tolerance test and polysomnography. From a 24-hour urine collection, albumin excretion rate and total urinary protein to creatinine ratio (UPCR) were calculated. RESULTS: 94 nondiabetic subjects were included (mean age = 11.0 +/- 2.5, 42 boys). Average BMI z-score was 2.25 +/- 0.47 (26 overweight subjects and 68 obese subjects). There was no difference in albumin excretion rate or UPCR between subjects with and without SDB. None of the SDB parameters correlated with the transformed albumin excretion rate or UPCR. Albumin excretion rate significantly correlated with fasting insulin and C-peptide and with post-challenge glucose, insulin and C-peptide levels, while UPCR correlated with fasting and post-challenge C-peptide levels. Multiple regression indicated that post-challenge glucose levels were the most important predictors of albumin excretion rate. CONCLUSION: Insulin resistance, and not SDB, was associated with increased levels of albuminuria, indicating early renal dysfunction, in this clinical sample of overweight children and adolescents.

Sleep-disordered breathing and systemic inflammation in overweight children and adolescents.

OBJECTIVE: To assess if the severity of sleep-disordered breathing (SDB) and mainly intermittent hypoxia is associated with increased peripheral leukocytes in overweight children and adolescents, controlling for adiposity and obesity-related metabolic abnormalities. METHODS: Consecutive subjects were recruited at a pediatric obesity clinic. All subjects underwent polysomnography and a fasting blood sample. RESULTS: In total, 95 subjects were included ( =11.1+/-2.6, 43 boys, body mass index, =2.3+/-0.5, 29 subjects were overweight and 66 obese). Total white blood cell count increased significantly by worsening of intermittent hypoxia. Total white blood cell count was correlated with the maximal degree of desaturation, independent of puberty, HOMA and HDL-cholesterol. Neutrophil levels were associated with the degree of desaturation, while controlling for puberty and HOMA. CONCLUSION: This study supports the hypothesis of an independent interaction between intermittent hypoxia and nocturnal desaturation during sleep, and increased white blood cell and neutrophil levels in overweight and obese children and adolescents. This finding may contribute to the mechanisms linking SDB with increased cardiovascular morbidity.

Is wheezing associated with decreased sleep quality in Sri Lankan children? A questionnaire study.

AIM: To investigate the association between wheezing and impaired sleep in Sri Lankan children, aged 6-12 years; and, to report the prevalence of asthma-related symptoms in these subjects. METHODS: The International Study of Asthma and Allergies in Childhood questionnaire and a separate sleep questionnaire were completed. RESULTS: Of 800 originally distributed questionnaires, 652 were analyzed. Wheezing was present in 89 children (14%). Within this group, 66% reported wheezing in the last 12 months. Wheezing children had a significantly higher presence of snoring, restless sleep, nocturnal awakenings and daytime tiredness. Wheezing was found to be independently associated with restless sleep (odds ratio (OR) = 2.4). There was no association between wheezing and difficulties falling asleep, nocturnal awakenings, apneas, and daytime sleepiness and tiredness. After adjusting for possible confounders, the following significant associations were present: snoring and apneas (OR = 1.6), chronic rhinitis and apneas (OR = 1.6), snoring and restless sleep (OR = 3.2), chronic rhinitis and restless sleep (OR = 2.1), and hayfever and daytime tiredness (OR = 4.3). Wheezing was related to an increased risk of snoring (OR = 2.8) and subjects with chronic rhinitis had also an increased risk of snoring (OR = 1.7), adjusting for possible confounders. CONCLUSION: The sleep of wheezing children was impaired compared with their non-wheezing peers, resulting in an increased prevalence of daytime tiredness. Upper airway symptoms, such as chronic rhinitis or hayfever, should be carefully considered in these children, as they might be responsible for these sleep problems.

Sleep-disordered breathing and the metabolic syndrome in overweight and obese children and adolescents.

OBJECTIVE: To assess whether sleep-disordered breathing (SDB) is a risk factor of the metabolic syndrome (MS) in children and adolescents who are overweight and to examine whether the severity of SDB was independently associated with glucose intolerance, insulin resistance, and/or dyslipidemia. STUDY DESIGN: Consecutive subjects who were overweight or obese underwent polysomnography, fasting blood sample, and oral glucose tolerance test (for calculation of area under the curve [AUC]). SDB was defined as a respiratory disturbance index > or = 2. MS was present when > or = 3 of these factors were present: waist circumference > or = 90th percentile; fasting glucose level > or = 110 mg/dL; triglyceride level > or = 110 mg/dL; high-density lipoprotein cholesterol level < or = 40 mg/dL; blood pressure > or = 90th percentile. RESULTS: A total of 104 subjects were included in the study (44% boys; 58% prepubertal; mean age, 11.1 +/- 2.6 years; 69% obese). Mean SaO2 (odds ratio, 0.54) and SaO2nadir (odds ratio, 0.89) were independent, significant predictors of the presence of MS. Multiple regression showed significant associations between SaO2nadir and high-density lipoprotein cholesterol level, mean SaO2 and both AUC glucose and triglyceride levels, and between the percentage of total sleep time with SaO2 > or = 95% and cholesterol level, while controlling for adiposity and sex, puberty, or both. CONCLUSION: This study supports the hypothesis of an interaction between SDB and metabolic abnormalities, independent of estimates of body fat distribution, in children and adolescents who are overweight and obese.

Reference values for sleep-related respiratory variables in asymptomatic European children and adolescents.

AIM: Only a limited number of studies, designed to establish normal values for sleep-related respiratory variables in children, have been reported, and all are non-European. The aim of this study was to expand the knowledge on normative data in children. METHODS: Subjects ranging from 6 to 16 years were recruited and underwent full polysomnography. Only subjects without sleep disordered breathing or other sleep problems as assessed by clinical history were included. RESULTS: Sixty subjects were studied ( = 11.7 +/- 2.6 years; 28 boys; = 118.8 +/- 30.6%). was 0.85 +/- 1.06 (range: 0.0-5.5). was 0.06 +/- 0.16 (range: 0.0-0.9); 11 patients had a total of 31 obstructive apneas. Only five obstructive hypopneas were detected with = 0.08 +/- 0.17 (range: 0.0-0.9). was 1.98 +/- 1.39 (range: 0.1-7.2). was 97.0 +/- 0.6% (range: 96.0-98.0); was 91.8 +/- 2.7% (range: 82.0-96.0); <% of total sleep time with SaO2 >or= 95%> was 98.7 +/- 2.1% (range: 90.8-100.0); was 0.8 +/- 0.9 (range: 0.0-4.9) and was 6.1 +/- 1.8 (range: 2.7-10.9). Snoring was detected in 15 patients (4 overweight subjects), with no difference in patient characteristics and sleep-related respiratory variables between snorers and non-snorers. Subjects in the overweight group (n = 22) had a lower SaO2nadir (90.8 +/- 2.7 vs. 92.4 +/- 2.6; P = 0.01) and a higher ODI (1.3 +/- 1.3 vs. 0.4 +/- 0.4; P = 0.0002) than their normal weight peers. CONCLUSION: Our data are in agreement with other non-European studies, designed to establish normal values in children.

First night effect for polysomnographic data in children and adolescents with suspected sleep disordered breathing.

AIMS: To assess the presence of a first night effect (FNE) in children and adolescents and to examine if a single night polysomnography (PSG) is sufficient for diagnosing obstructive sleep apnoea syndrome (OSAS). METHODS: Prospective case study of 70 patients (group 1: 2-6 years, n = 22; group 2: 7-12 years, n = 32; group 3: 13-17 years, n = 16) referred for OSAS. Diagnostic criteria for OSAS: one or more of the following: (1) obstructive apnoea index (OAI) > or =1; (2) obstructive apnoea hypopnoea index (oAHI) > or =2; (3) SaO2 < or =89% in association with obstruction. RESULTS: In all age groups, but mainly in the oldest children, REMS increased during the second night, mainly at the expense of stage 2 sleep. The first night PSG correctly identified OSAS in 86%, 91%, and 100% of the children for groups 1, 2, and 3 respectively. This represents 9% false negatives for OSAS when only the first night PSG was used. All cases missed had mild OSAS, except for one with oAHI >5 on night 2. There were also seven patients with OSAS on night 1 but with a normal PSG on night 2: all had oAHI <5. CONCLUSION: There is a FNE in children and adolescents. A single night PSG is sufficient for diagnosing OSAS, but in cases with a suggestive history and examination and with a negative first night, a second night study might be advisable.

Critical evaluation of prognostic factors in childhood asthma.

Current knowledge of the natural history of asthma is improving through the establishment of a more precise definition of asthma linked with information from a number of large-scale longitudinal studies. Risk factors for the development of childhood asthma are now more clearly understood. They include gender, atopic status, genetic and familial factors, respiratory infections, and outdoor and indoor pollution (1). In the present review two types of asthma and their prognosis will be discussed: (1) Asthma in preschool children and its risk factors for evolution towards persistent childhood asthma. (2) Asthma in older children and its risk factors for evolution towards adult asthma.

Effect of salbutamol on lung function parameters of healthy children.

UNLABELLED: In the present study, the effect of 200 microg salbutamol compared to placebo was evaluated on lung function parameters of 37 healthy children aged 7-14 years. Salbutamol or placebo were administered, using a single blind study design, and spirometry was performed before and after 10 min of inhalation. At the time of the study, all children were symptom-free and had not suffered from any respiratory infection during the previous 4 weeks. The administration of salbutamol resulted in a significant increase of mean forced expiratory volume in 1 s (111%-115%, P<0.05), maximal expiratory flow at 50% of forced vital capacity (101%-110%, P<0.05) and maximal expiratory flow at 25 % of forced vital capacity (96%-115%, P<0.05). The administration of placebo resulted in no significant change in lung function parameters. CONCLUSION: The administration of 200 microg salbutamol results in the occurrence of a small but significant bronchodilation in healthy, non-asthmatic children.

Influence of upper airway shunt on total respiratory impedance in infants.

When input impedance is determined by means of the forced oscillation technique, part of the oscillatory flow measured at the mouth is lost in the motion of the upper airway wall acting as a shunt. This is avoided by applying the oscillations around the subject's head (head generator) rather than at the mouth (conventional technique). In seven wheezing infants, we compared both techniques to estimate the importance of the upper airway wall shunt impedance (Zuaw) for the interpretation of the conventional technique results. Computation of Zuaw required, in addition, estimation of nasal impedance values, which were drawn from previous measurements (K. N. Desager, M. Willemen, H. P. Van Bever, W. De Backer, and P. A. Vermeire. Pediatr. Pulmonol. 11: 1-7, 1991). Upper airway resistance and reactance at 12 Hz ranged from 40 to 120 and from 0 to -150 hPa. l(-1). s, respectively. Varying nasal impedance within the range observed in infants did not result in major changes in the estimates of Zuaw or lung impedance (ZL), the impedance of the respiratory system in parallel with Zuaw. The conventional technique underestimated ZL, depending on the value of Zuaw. The head generator technique slightly overestimated ZL, probably because the pressure gradient across the upper airway was not completely suppressed. Because of the need to enclose the head in a box (which is not required with the conventional technique), the head generator technique is difficult to perform in infants.

Does treatment of asthmatic children with inhaled corticosteroids affect their adult height?

In this retrospective study, adult height was assessed in young adult asthmatics who were treated with inhaled corticosteroids (ICs) during childhood (n = 42; 26 boys) and compared to those obtained in asthmatic patients who were never treated with ICs during childhood (n = 43; 23 boys). Standing height of all subjects and their parents was measured. Height data were analyzed using actual length and target height in centimeters, standard deviation scores (SDS), and difference between adult height of the patients and their target height (adult height minus target height). Mean adult height was the same in subjects who took ICs during childhood as compared to those who had never received ICs (boys: 179.3cm+/-6.8 vs. 180.4 cm+/-5.6; girls: 165.8 cm+/-7.5 vs. 167.7 cm+/-7.2). SDS of adult height was also not different between the two groups: in subjects who did not take ICs it was 0.89+/-1.00, while in those who took ICs it was 0.66+/-1.10 (P = 0.31). SDS of target height was also not different between the two groups: in subjects not taking ICs it was 0.95+/-0.86, while in those who took ICs it was 0.28+/-0.76 (P = 0.30). However, subjects who took ICs during childhood showed a statistically significant lower value of adult height minus target height than those who never took ICs (whole group: -0.003+/-5.9 vs. 2.54 +/-4.8, P = 0.03 ; boys: 0.004+/-5.8 vs. 3.09+/-4.5, P = 0.04 ; girls: -0.075+/-6.3 vs. 1.91+/-5.2, P = 0.31). Patients on ICs during childhood who had ever been hospitalized for asthma showed a lower value for adult height minus target height than those who took ICs but were never hospitalized (-3.08+/-7.8 vs. 1.06+/-4.8, P = 0.046). A logistic regression analysis predicting growth impairment showed that the best-fitting model was one that used only ICs as a dependent variable (crude odds ratio, 3.3; 95% CI, 1.3-8.4). Patients who were treated with ICs in combination with intranasal corticosteroids (treatment for rhinitis) tended to have a lower value of adult height minus target height than the other children, but the difference was not statistically significant (P = 0.07). We conclude that although adult height was the same in young adults who were treated with ICs during childhood compared to those who were not treated with ICs during childhood, there was a statistically significant difference between the two groups for adult height minus target height, suggesting mild growth retardation in patients who took ICs during childhood. These findings may be explained by the use of ICs, but it seems more likely that a difference in asthma severity between both groups was responsible for it.

Study of the bronchodilating effect of three doses of nebulized oxitropium bromide in asthmatic preschool children using the forced oscillation technique.

UNLABELLED: The aim of this study was to evaluate the bronchodilating capacity of nebulized oxitropium bromide (OB) in preschool asthmatic children and to determine an appropriate dose for usage in this age group. The trial enrolled 20 patients with moderate to severe stable asthma aged between 3.2 and 6.2 years (mean 4.7). Applying a placebo controlled, double-blind design, the effect of placebo was compared with three different doses of OB (375, 750 and 1500 micrograms) and with 400 micrograms fenoterol. The three different doses of OB resulted in a highly significant bronchodilation within 15 min after administration. The observed bronchodilation was comparable between the three doses during the first 2 h. However, after 4 h the lowest dose was significantly less powerful than the highest dose. Compared to the additional bronchodilation induced by fenoterol, no difference was found with the degree of bronchodilation of OB which occurred during the first 2 h. Furthermore, after 4 h only the lowest dose of OB was significantly less powerful than fenoterol assessed 10 min following a single 400 micrograms dose. CONCLUSION: Oxitropium bromide is a potent and long-acting bronchodilator in preschool children at a dose of 750 micrograms and 1500 micrograms. No side-effects were observed. The exact duration of action remains uncertain, but even 4 h after inhaling 750 or 1500 micrograms of OB no additive bronchodilation induced by fenoterol could be observed.

Two-point calibration procedure of the forced oscillation technique.

The forced oscillation technique is usually calibrated by loading the measuring device with a known impedance. A correction function is calculated, relating the measured and reference impedances at each frequency. However, this one point calibration procedure does not account for transducer asymmetry. A procedure has previously been presented to circumvent this problem: in addition to one known reference impedance, the calibration was repeated with the system occluded (infinite impedance). The aim of the present study was to evaluate a variant of this procedure, in which instead of resorting to an extreme condition imposing high requirements on the flow measuring system, two reference loads of 4 and 50 hPal-1 s were measured, thus covering the range of impedances observed in children and infants (a two-point procedure). The calibration procedure was performed with these two impedances and evaluated with a third impedance of approximately 17 hPal-1 s. The results of three calibration procedures were compared: one-point, two-point and a previously reported calibration procedure. Impedances consisted of sintered glass and mesh wire screens mounted in glass or polyvinyl tubes. For low impedance values, in the range of 4 to 17 hPal-1 s, measured and predicted values were similar for the three calibration procedures at frequencies from 4-52 Hz, although with the one point calibration procedure there was some underestimation above 44 Hz. With the highest load, especially above 32 Hz, marked discrepancies between measured and predicted values were observed with the one-point calibration procedure and the previously reported calibration procedure. Under these circumstances the two-point procedure is preferred.

Functional residual capacity in healthy preschool children.

The purpose of this study was to evaluate the feasibility of routine functional residual capacity (FRC) measurements in healthy preschool children aged 2.7-6.4 yrs. Furthermore, accuracy and reproducibility were investigated and normal values were collected. A mass-produced closed-circuit helium dilution device (rolling seal) was used. Selection of the 113 healthy children (from the 571 measured) was based on an extensive personal and family history questionnaire and on clinical examination before measurements were performed. With three successive attempts it was possible to achieve at least two reproducible measurements in 73% of the children (repeatability coefficient 95.3 mL). The main problems were leakage at the corner of the mouth and irregular breathing pattern. The mean time to perform a measurement was 113 s. Mean FRC was significantly higher in boys than in girls: 778 versus 739 mL for a body length of 110 cm (p<0.05). FRC correlated with height (H) (r=0.69), weight (W) (r=0.56), age (A) (r=0.62) and all three combined (r=0.70): FRC = -534.89 + 1.84 x W (kg) + 10.07 x H (cm) + 2.51 x A (months). When a power or exponential function was used to describe FRC as a function of height, the results were not superior to the linear regression (r=0.69): FRC (mL) = -766.2 + 13.8 x H (cm) (r=0.69) or FRC (L) = 0.620 x H (m)(2.03) (r=0.69) or FRC (mL)= 99.5 x e(0.018xH (cm)) (r=0.69). Among these, we recommend the power function because it will better fit broader height ranges. Reliable functional residual capacity measurements can be routinely performed in preschool children with a mass-produced device. Reference values were collected for children 95-125 cm in height.

Aerosolized furosemide in wheezy infants: a negative report.

We investigated the effects of 10 mg aerosolized furosemide on clinical score in 28 acutely wheezing infants (Part A) and in a second group of 20 intermittently wheezing babies on airway resistance and functional residual capacity during a symptomfree period (Part B), using a double-blind, placebo-controlled design. In both parts of the study no therapeutic effects were observed during and following aerosol inhalation of 10 mg furosemide.

Comparison of the bronchodilating effect of oxitropium bromide and fenoterol in asthmatic children.

Using a randomized double blind study design, the bronchodilating effect of 200 micrograms inhaled oxitropium bromide (OB) was compared with 200 micrograms inhaled fenoterol (F) after an interval of 20 min, in 20 asthmatic children aged 12.7 years (range: 4.9-15.1 years), suffering from mild bronchoconstriction (mean forced expiratory volume during ls: 73.4%, range: 51%-85%). Both drugs induced a comparable degree of bronchodilatation and no significant differences were found between the OB group and the F group, suggesting equipotency for both drugs after a 20 min interval, at the 200 micrograms dose level. Furthermore, a significant improvement of lung function parameters was detected in both groups after subsequent administration of 400 micrograms F, indicating that inhalation of 200 micrograms of OB or F results in submaximal bronchodilation in asthmatic children suffering from mild bronchoconstriction.