Search PubMed⌕ Search

Biomedical subjects

C Delacourt

Publications and source records attributed to C Delacourt.

At least 37 records · Page 2Linked to original sources
PubMed2001

Relationship between bronchial responsiveness and clinical evolution in infants who wheeze: a four-year prospective study.

Recurrent illness involving wheezing during the first years of life is transient in most children. The role of bronchial hyperresponsiveness as a factor influencing the persistence of wheezing from infancy to school age remains unknown. In a prospective study we investigated whether infants who wheezed and subsequently developed persistent asthma differed from infants who wheezed and later became asymptomatic either in the initial degree of bronchial hyperresponsiveness or in the persistence of bronchial hyperresponsiveness with age. One hundred and twenty-nine infants with three or more wheezing episodes before 2 yr of age were followed during 4 yr with a clinical evaluation and a methacholine challenge performed every 6 mo until the child was 4 yr old and once per year thereafter. The clinical score significantly improved with time in most children. The proportion of children with persistent wheezing after 2 and 4 yr of follow-up was only 31% and 20%, respectively. Persistent wheezers had significantly lower VmaxFRC values at initial evaluation and higher SRaw values at the end of follow-up than infants who became asymptomatic. We used transcutaneous oxygen tension (PtcO(2)) to measure the response to methacholine. No significant difference in PD(15) PtcO(2) between groups with subsequently different clinical progression was observed at initial evaluation. Bronchial hyperresponsiveness persisted 4 yr later in all children but children with persistent wheezing showed significantly lower PD(15) PtcO(2) values than children who became asymptomatic, as early as 30 mo of age. However, an acceptable early PD(15) PtcO(2) cut-off point predictive for subsequent clinical progression could not be identified. The level of bronchial hyperresponsiveness in infants who wheezed was not predictive of the persistence of asthma 4 yr later.

Asthma↗
PubMed2001

Comparison of the forced oscillation technique and the interrupter technique for assessing airway obstruction and its reversibility in children.

The forced oscillation technique (FOT) and interrupter technique are particularly attractive for pediatric use as they require only passive cooperation from the patient. We compared the sensitivity and specificity of these methods for detecting airway obstruction and its reversibility in 118 children (3-16 yr) with asthma or chronic nocturnal cough. FOT (R(0) and R(16)) and interruption (Rint) parameters were measured at baseline and after bronchodilator inhalation (n = 94). Rint was significantly lower than R(0), especially in children with high baseline values. Baseline parameters were normalized for height and weight [R(SD)]. In children able to perform forced expiratory maneuvers (n = 93), the best discrimination between those with baseline FEV(1) < 80% or > or = 80% of predicted values was obtained with R(0)(SD). At a specificity of 80%, R(0)(SD) yielded 66% sensitivity, whereas Rint(SD) yielded only 33% sensitivity. Similarly, postbronchodilator changes in R(0)(SD) [DeltaR(0)(SD)] yielded the best discrimination between children with and without significant reversibility in FEV(1). At a specificity of 80%, DeltaR(0)(SD) yielded 67% sensitivity and DeltaRint(SD) yielded 58% sensitivity. In children unable to perform forced expiratory maneuvers (n = 25), FOT, contrary to the interrupter technique, clearly identified a subgroup of young children with high resistance values at baseline, which returned to normal after bronchodilation. We conclude that, in asthmatic children over 3 yr old, FOT measurements provide a more reliable evaluation of bronchial obstruction and its reversibility compared with the interrupter technique, especially in young children with high baseline values.

Adolescent↗
PubMed2001

[Physiopathology of the cough].

Cough is initiated from organs innervated by the vagus nerve. The larynx and the lower airways are the main sites involved in cough initiation. Cough is mainly triggered by mechanical stimuli, especially at the laryngeal level, and also by inflammatory stimuli and chemical irritants. Two receptor types are involved in the cough reflex: the irritant receptors (IR) and the C fibers. IR are directly involved in cough initiation whereas stimulated C fibers act essentially through tachykinin release, which in turn activates IR. Cough in asthma was initially thought to be related to the bronchospasm reflex, but seems in fact mainly due to airway inflammation.

Bronchial Spasm↗
PubMed2001

Diagnostic techniques in paediatric tuberculosis.

Accurate diagnosis of tuberculosis (TB) in children is crucial to provide effective treatment and to identify the undiagnosed adult who probably infected the child. The diagnosis of tuberculosis in children is often based only on epidemiologic, clinical, and radiographic findings. Fibre-optic bronchoscopy may also be helpful but the recovery of tuberculous bacilli, which establishes the diagnosis, is difficult in children. Rapid diagnostic tests such as direct amplification and serological tests have been developed to improve early diagnosis. Their sensitivity is higher than that of conventional mycobacterial culture in most paediatric studies.

Adolescent↗
PubMed2000

Use of the forced oscillation technique to assess airway obstruction and reversibility in children.

The forced oscillation technique (FOT) is particularly attractive in a pediatric setting as it requires only passive cooperation from the child. We assessed the sensitivity and specificity of this method for detecting airway obstruction and its reversibility in 313 children (3 to 16 yr of age) with asthma or chronic nocturnal cough. Baseline and post-bronchodilator (n = 251) resistance were measured (R(0)) with the FOT. Baseline R(0) was normalized for height and weight [R(0)(SD)]. In children able to perform forced expiratory maneuvers (n = 181), R(0)(SD) was independently correlated with FEV(1) (p < 0.02) and maximal expiratory flow at 50% (MEF(50)) (p < 0.004). The optimal R(0)(SD) cutoff value given by receiver operating characteristic (ROC) curves to discriminate between children with baseline FEV(1) < 80% or >/= 80% of predicted values yielded 84% sensitivity and 73% specificity. Post-bronchodilator changes in R(0)(SD) [DeltaR(0)(SD)] were mostly correlated to changes in MEF(50). The optimal DeltaR(0)(SD) cutoff value to discriminate between children with the presence or absence of significant reversibility in FEV(1) yielded 69% sensitivity and 78% specificity. In children unable to perform forced expiratory maneuvers (n = 132), this DeltaR(0)(SD) cutoff clearly identified a subgroup of young children with high R(0) values at baseline, that returned to normal after bronchodilation. We conclude that FOT measurements allow reliable evaluation of bronchial obstruction and its reversibility in asthmatic children over 3 yr old.

Administration, Inhalation↗
PubMed1999

[Evaluation of the ability of asthmatic children to use a breath-actuated pressurized inhaler].

BACKGROUND: Poor inhaler technique in asthmatics is well documented. The objective of this study was to evaluate the influence of reading the instruction leaflet and the consultant's explanations on the use of the new breath-actuated inhaler (Autohaler 3M). METHODS: In this study were participating 379 asthmatic children and adolescents, aged from four to 17 years (mean age: 10; 64% boys), recruited by 80 pediatricians. The use of the Autohaler device was considered to be correct if the shaking, lip position, deep inhalation and apnea were all properly performed. RESULTS: The Autohaler was used correctly by 42% of the subjects simply after reading the instruction leaflet (phase I), and by 75% of the subjects who, having failed phase I, received the consultant's explanations (phase II). At the end of phases I and II, the device was correctly used by 84% of the subjects. In multivariate analysis, those under the age of nine years and those with no prior use of inhaler systems accounted for a significant amount of the incorrect use of the Autohaler during phase I. In phase II, only the fact of being less than nine years old was significantly related to incorrect use. CONCLUSION: More than four-fifths of the asthmatic children and adolescents properly used the Autohaler after merely reading the instructions and after receiving additional explanation from the consultant. The marked improvement obtained after medical explanations underlines the essential educative role of the physician when prescribing. Young children require specific training and particularly careful attention.

Adolescent↗
PubMed1999

[Extrinsic allergic alveolitis].

Extrinsic allergic alveolitis (EEA) is a lung disease mediated by immunologic mechanisms and induced by repeated exposure to organic dusts. EAA in children are mostly observed around 10 years of age. Subacute clinical presentation is the most frequent. Diagnosis is based on simultaneous presence of most of the following arguments: exposure to a known risk factor, spontaneous improvement after cessation of the exposure, identification of specific precipitins, demonstrative aspects on X-ray and tomodensitometry, and CD8+ lymphocytosis in bronchoalveolar lavage. Lung biopsy and specific provocation test are rarely necessary for diagnosis. Treatment is based on total eviction from inhaled antigen and on oral corticosteroids in acute and subacute forms.

Adrenal Cortex Hormones↗
PubMed1999

[Corticoids and allergy].

Inflammation is constantly observed in allergic reactions. Corticosteroids are most effective in preventing the late phase of allergic reaction. The action of glucocorticosteroids is mediated through glucocorticoid receptors present in the cellular cytoplasm. When activated, glucocorticoid receptors form a dimer and bind to DNA after migration into the nucleus. Interaction to DNA induces changes in the transcription rate, leading to either gene induction or gene repression. Glucocorticoid receptors are also able to interact with transcriptional factors such as AP-1 (activator protein-1) of NF-kappa B (nuclear factor-kappa B). Through these actions glucocorticosteroids are susceptible to modify functions of cells involved in the allergic inflammatory response. They are in particular able to inhibit most of the pro-inflammatory functions of the eosinophils.

Asthma↗
PubMed1998

[What is new in pediatric pneumology?].

Have been selected for this review: 1) the recent and impressive development of high-resolution and spiral CT scan in pediatric thoracic imaging; 2) the emerging of new and promising therapies for asthma (long acting inhaled beta 2-agonists, leukotriene antagonists, anti-IgE monoclonal antibodies); 3) the multifactorial origin of asthma in childhood; 4) the development of thoracoscopic surgery, a minimal-invasive approach beneficial in numerous circumstances.

Child↗
PubMed1998

Repeatability of lung function tests during methacholine challenge in wheezy infants.

BACKGROUND: The repeatability of lung function tests and methacholine inhalation tests was evaluated in recurrently wheezy infants over a one month period using the rapid thoracic compression technique. METHODS: Eighty-one wheezy, symptom free infants had pairs of methacholine challenge tests performed one month apart. Maximal flow at functional residual capacity (VmaxFRC) and transcutaneous oxygen tension (Ptco2) were measured at baseline and after methacholine inhalation. Provocative doses of methacholine causing a 15% fall in Ptco2 (PD15 Ptco2) or a 30% fall in VmaxFRC (PD30 VmaxFRC) were determined. RESULTS: Large changes in VmaxFRC were measured from T1 to T2 with a mean difference between measurements (T2-T1) of 7 (113) ml/s and a 95% range for a single determination for VmaxFRC of 160 ml/s. The mean (SD) difference between pairs of PD30 VmaxFRC measurements was 0.33 (1.89) doubling doses with a 95% range for a single determination of 2.7 doubling doses. Repeatability of PD15Ptco2 was similar. A change of 3.7 doubling doses of methacholine measured on successive occasions represents a significant change. CONCLUSIONS: Baseline VmaxFRC values are highly variable in wheezy, symptom free infants. Using either VmaxFRC or Ptco2 as the outcome measure for methacholine challenges provided similar repeatability. A change of more than 3.7 doubling doses of methacholine is required for clinical significance.

Asthma↗
PubMed1998

Protective effect of endotoxin instillation on subsequent bacteria-induced acute lung injury in rats.

The phagocytic capability afforded by neutrophil influx into the lungs is essential to ward off invading bacteria. The objective of this study was to evaluate the effect of prior neutrophil recruitment induced by alveolar instillation of endotoxin (LPS, 200 micrograms/kg) 16 h before a pulmonary infection caused by instillation of live Pseudomonas aeruginosa ([PYO]: 1.5 x 10(8) colony-forming units [cfu]/kg) in rats. A first series of experiments showed that lipopolysaccharide (LPS) instillation induced recruitment of alveolar neutrophils that were capable, ex vivo, of elastase exocytosis, reactive oxygen species secretion, and PYO killing. In a second set of experiments, LPS followed by PYO was compared with PYO alone (n = 11 surviving rats in each group). Parameters were studied 24 h after the bacterial challenge. As compared with PYO alone, pretreatment with LPS followed by PYO was associated with decreased mortality (0% versus 54%, p < 0.05), decreased protein leakage into bronchoalveolar lavage (BAL) fluid (1.8 +/- 0.4 versus 13.5 +/- 2.2 mg/ml, p < 0.001), and improved bacterial clearance from BAL (4.0 +/- 1.4 x 10(2) versus 1.2 +/- 0.5 x 10(4) cfu/ml, p < 0.05) and from pulmonary parenchyma (8.5 +/- 6.4 x 10(5) versus 1.9 +/- 0.8 x 10(7) cfu/ml, p < 0.05). We conclude that prior alveolar endotoxin instillation induces local recruitment of functionally active neutrophils, and that this is associated with resistance to subsequent experimental pneumonia.

Animals↗