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Dive into the research topics where W. C. J. Hop is active.

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Featured researches published by W. C. J. Hop.


Thorax | 2005

Exhaled nitric oxide predicts asthma relapse in children with clinical asthma remission

M W Pijnenburg; Ward Hofhuis; W. C. J. Hop; J. C. de Jongste

Background: Nitric oxide in exhaled air (FENO) is a marker of eosinophilic airway inflammation. A study was undertaken to determine whether FENO predicts asthma relapse in asymptomatic asthmatic children in whom inhaled corticosteroids are discontinued. Methods: Forty children (21 boys) of mean age 12.2 years on a median dose of 400 μg budesonide or equivalent (range 100–400) were included. FENO was measured before and 2, 4, 12, and 24 weeks after withdrawal of steroids. A relapse was defined as more than one exacerbation per month, or need for β agonist treatment on 4 days per week for at least 2 weeks, or diurnal peak flow variability of >20%. FENO measurements were performed online with an expiratory flow of 50 ml/s. Results: Nine patients relapsed. Two and 4 weeks after withdrawal of steroids geometric mean FENO in children who were about to relapse was higher than in those who did not relapse: 35.3 ppb v 15.7 ppb at 2 weeks (ratio 2.3; 95% CI 1.2 to 4.1; pu200a=u200a0.01) and 40.8 ppb v 15.9 ppb at 4 weeks (ratio 2.6; 95% CI 1.3 to 5.1). An FENO value of 49 ppb at 4 weeks after discontinuation of steroids had the best combination of sensitivity (71%) and specificity (93%) for asthma relapse. Conclusion: FENO 2 and 4 weeks after discontinuation of steroids in asymptomatic asthmatic children may be an objective predictor of asthma relapse.


Thorax | 2005

Progression of lung disease on computed tomography and pulmonary function tests in children and adults with cystic fibrosis

P A de Jong; A Lindblad; L Rubin; W. C. J. Hop; J. C. de Jongste; M Brink; H.A.W.M. Tiddens

Background: A study was undertaken to compare the ability of computed tomographic (CT) scores and pulmonary function tests to detect changes in lung disease in children and adults with cystic fibrosis (CF). Methods: CT scans and pulmonary function tests were retrospectively studied in a cohort of patients with CF aged 5–52 years for whom two or three CT scans at 3 year intervals were available, together with pulmonary function test results. All CT scans were scored by two observers. Pulmonary function results were expressed as percentage predicted and Z scores. Results: Of 119 patients studied, two CT scans were available in 92 patients and three in 24. CT (composite and component) scores and lung function both deteriorated significantly (p<0.02). Peripheral bronchiectasis worsened by 1.7% per year in children (p<0.0001) and by 1.5% per year in adults (p<0.0001). Bronchiectasis worsened in 68 of 92 patients while forced expiratory volume in 1 second (FEV1) worsened in 54 of 92 patients; bronchiectasis also deteriorated in 27 patients with stable or improving FEV1. The CT score (and its components) and pulmonary function tests showed similar rates of deterioration in adults and children (p>0.09). Conclusion: The peripheral bronchiectasis CT score deteriorates faster and more frequently than lung function parameters in children and adults with CF, which indicates that pulmonary function tests and CT scans measure different aspects of CF lung disease. Our data support previous findings that the peripheral bronchiectasis CT score has an added value to pulmonary function tests in monitoring CF lung disease.


The Journal of Allergy and Clinical Immunology | 2008

The acquisition of tolerance toward cow's milk through probiotic supplementation: a randomized, controlled trial.

J Hol; Eduard H.G. van Leer; Beatrix Elink Schuurman; Lilian F. de Ruiter; Janneke N. Samsom; W. C. J. Hop; Herman J. Neijens; Johan C. de Jongste; Edward E. S. Nieuwenhuis

BACKGROUNDnCows milk allergy (CMA) is the most frequently diagnosed food allergy in infancy. In general, patients have a good prognosis because the majority acquire tolerance within the first years. Interventions have been proposed to accelerate tolerance and reduce morbidity. Probiotic supplementation could be effective through modulation of the immune system.nnnOBJECTIVEnWe sought to determine whether supplementation with a combination of probiotics (Lactobacillus casei CRL431 and Bifidobacterium lactis Bb-12) accelerates tolerance to cows milk (CM) in infants with CMA.nnnMETHODSnWe performed a double-blind, randomized, placebo-controlled trial in 119 infants with CMA. Infants received CRL431 and Bb-12 supplemented to their standard treatment of extensively hydrolyzed formula for 12 months. Primary outcome was clinical tolerance to CM at 6 and 12 months of treatment. Furthermore, we analyzed T- and B-lymphocyte subsets (CD3(+), CD3(+)CD4(+), CD3(+)CD8(+), and CD20(+)) in peripheral blood at randomization and at 12 months with flow cytometry and examined the presence of viable probiotic strains in fecal samples.nnnRESULTSnThe cumulative percentage of tolerance to CM at 6 and 12 months was similar in both groups: 56 (77%) in the probiotics group versus 54 (81%) in the placebo group. Infants in the placebo group had higher percentages of CD3(+) and CD3(+)CD4(+) lymphocytes compared with those seen in probiotic-treated infants. Probiotic intake was confirmed because probiotics were isolated from feces more often in treated infants than in the placebo group.nnnCONCLUSIONnSupplementation of CRL431 and Bb-12 to extensively hydrolyzed formula does not accelerate CM tolerance in infants with CMA.


Pediatric Nephrology | 2010

Reference values for serum creatinine in children younger than 1 year of age

Dirk P. Boer; Yolanda B. de Rijke; W. C. J. Hop; Karlien Cransberg; Eiske M. Dorresteijn

Reliable reference values of enzymatically assayed serum creatinine categorized in small age intervals are lacking in young children. The aim of this study was to determine reference values for serum creatinine during the first year of life and study the influence of gender, weight and height on these values. Serum creatinine determinations between 2003 and 2008 were retrieved from the hospital database. Strict exclusion criteria ensured the selection of patients without kidney damage. Correlation analysis was performed to evaluate the relation between height, weight and serum creatinine; the Mann–Whitney test was used to evaluate the relation between gender and serum creatinine. A broken stick model was designed to predict normal serum creatinine values. Mean serum creatinine values were found to decrease rapidly from 55xa0μmol/L on day 1 to 22xa0μmol/L in the second month of life; they then stabilized at 20 μmol/L until the seventh month, followed by a slight increase. No significant relation was found between serum creatinine and gender, weight and height. We present here reference values of serum creatinine in infants not at risk of decreased renal function. The absence of a relationship with gender, weight and height confirms that height-based equations to estimate glomerular filtration rate are less useful in patients of this age group.


Clinical & Experimental Allergy | 2005

High fractional concentration of nitric oxide in exhaled air despite steroid treatment in asthmatic children

M W Pijnenburg; E. M. Bakker; S. Lever; W. C. J. Hop; J. C. de Jongste

Background The fractional concentration of nitric oxide in exhaled air (FENO) is elevated in atopic asthma and typically responds to treatment with inhaled corticosteroids (ICS). However, some patients have persistently high FENO levels despite treatment.


European Respiratory Journal | 1998

Hydrogen peroxide in exhaled air of healthy children: reference values

Quirijn Jöbsis; H. C. Raatgeep; S. L. Schellekens; W. C. J. Hop; P. W. M. Hermans; J. C. de Jongste

An increased content of hydrogen peroxide (H2O2), a marker of inflammation, has been described in the condensate of exhaled air from adults and children with inflammatory lung disorders, including asthma. However, the normal range of [H2O2] in the exhaled air condensate from healthy children has not been established. Therefore, the aim of this study was to determine the reference range of exhaled [H2O2] in healthy school-aged children. Ninety-three healthy nonsmoking children (48 female and 45 male, mean age 10 yrs, range 8-13 yrs), with a negative history for allergy, eczema or respiratory disease and with a normal lung function, participated. Exhaled air condensate was examined fluorimetrically for the presence of H2O2. In addition, the reproducibility of [H2O2] within subjects and between days and the stability of [H2O2] during storage at -20 degrees C were assessed. The median [H2O2] in the exhaled air condensate of all children was 0.13 microM, with a 2.5-97.5% reference range of <0.01-0.48 microM. No significant difference existed between males and females. There was no correlation between exhaled [H2O2] and age or lung function. Repeated [H2O2] measurements on 2 consecutive days showed satisfactory within-subject reproducibility and [H2O2] in stored samples remained stable for at least 1 month at -20 degrees C. In conclusion, this study provides reference data for exhaled hydrogen peroxide in a large group of healthy children. The observed levels were lower than those reported previously for healthy adults and were independent of age, sex and lung function.


Clinical Pharmacology & Therapeutics | 2001

Pharmacokinetics and metabolism of intravenous midazolam in preterm infants.

S.N. de Wildt; Gregory L. Kearns; W. C. J. Hop; Daryl J. Murry; Susan M. Abdel-Rahman; J. N. van den Anker

Midazolam, a benzodiazepine, is finding expanded use in neonatal intensive care units. We studied the pharmacokinetics and metabolism of midazolam after a single intravenous dose in preterm infants.


Clinical Pharmacology & Therapeutics | 1995

Ceftazidime pharmacokinetics in preterm infants: Effects of renal function and gestational age

John N. van den Anker; Rik C Schoemaker; W. C. J. Hop; Bert J. van der Heijden; Allan Weber; P. J. J. Sauer; Herman J. Neijens; Ronald de Groot

The objectives of this study were (1) to determine the effects of gestational age on ceftazidime pharmacokinetics in the preterm infant, (2) to relate these effects to changes in glomerular filtration rate (GFR), and (3) to establish appropriate dosage recommendations for preterm infants on day 3 of life.


European Respiratory Journal | 2007

Long-term asthma treatment guided by airway hyperresponsiveness in children: a randomised controlled trial

Marianne Nuijsink; W. C. J. Hop; P. J. Sterk; E. J. Duiverman; J. C. de Jongste

Management plans for childhood asthma show limited success in optimising asthma control. The aim of the present study was to assess whether a treatment strategy guided by airway hyperresponsiveness (AHR) increased the number of symptom-free days and improved lung function in asthmatic children, compared with a symptom-driven reference strategy. In a multicentre, double-blind, parallel-group, randomised, 2-yr intervention trial, 210 children (aged 6–16u2005yrs) with moderate atopic asthma, selected on the basis of symptom scores and/or the presence of AHR, were studied. At 3-monthly visits, symptom scores, forced expiratory volume in one second (FEV1) and methacholine challenge results were obtained, and medication (five levels of fluticasone with or without salmeterol) adjusted according to algorithms based on symptom score (reference strategy, nu200a=u200a104) or AHR and symptom score (AHR strategy, nu200a=u200a102). After 2u2005yrs, no difference was found in the percentage of symptom-free days between treatment strategies. Pre-bronchodilator FEV1 was higher in the AHR strategy (2.3% predicted). This was entirely explained by a gradual worsening of FEV1 in a subgroup of 91 hyperresponsive children enrolled with low symptom scores (final difference between study arms was 6%). Asthma treatment guided by airway hyperresponsiveness showed no benefits in terms of number of symptom-free days, but produced a better outcome in terms of pre-bronchodilator forced expiratory volume in one second in allergic asthmatic children, especially those characterised by low symptom scores despite airway hyperresponsiveness.


Seminars in Pediatric Surgery | 2009

Percutaneous endoscopic gastrostomy (PEG) in children is not a minor procedure: risk factors for major complications

Dirk Vervloessem; Frank van Leersum; Dirk P. Boer; W. C. J. Hop; Johanna C. Escher; Gerard C. Madern; Lissy de Ridder; Klaas M. A. Bax

Percutaneous endoscopic gastrostomy (PEG) provides for enteral nutrition in children with feeding problems. PEG, however, is not without complications. The present study has a twofold aim: (1) comparing our incidence of major complications after PEG with the incidence in other centers, and (2) identifying risk factors for major complications. All patients receiving a PEG or laparoscopic-assisted PEG (lap PEG) in the period 1992-2008 were reviewed. Primary outcome was the occurrence of major complications, defined as the need for surgery, non-prophylactic antibiotics, or blood transfusion, and procedure-related death. Potential risk factors, eg, age under 1 year, mental retardation, scoliosis, constipation, hepatomegaly, upper abdominal surgery, ventriculoperitoneal shunt, peritoneal dialysis, esophageal stenosis, and coagulopathy, were analyzed. Of the 467 patients (448 PEG, 19 lap PEG), 12.6% developed major complications. The complication rate significantly decreased (P = 0.003) over the years. A significantly higher complication rate of 32% (P = 0.02) occurred in children with a ventriculoperitoneal shunt. None of the lap PEG procedures was associated with a major complication, but the difference was not significant, perhaps because of the small numbers in the latter group. The major complication rate after PEG in children is high. Preexisting ventriculoperitoneal shunt is a significant risk factor. Laparoscopically assisted PEG procedures seem to be associated with a lesser major complication rate.

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J. C. de Jongste

Erasmus University Rotterdam

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H.A.W.M. Tiddens

Erasmus University Medical Center

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R. de Groot

Radboud University Nijmegen

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Harm A.W.M. Tiddens

Erasmus University Rotterdam

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Quirijn Jöbsis

Maastricht University Medical Centre

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Ward Hofhuis

Boston Children's Hospital

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A. Kroesbergen

Erasmus University Rotterdam

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Johan C. de Jongste

Erasmus University Rotterdam

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M W Pijnenburg

Erasmus University Medical Center

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H. J. Neijens

Erasmus University Rotterdam

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