Baseline and post-bronchodilator interrupter resistance and spirometry in asthmatic children

In children unable to perform reliable spirometry, the interrupter resistance (R(int) ) technique for assessing respiratory resistance is easy to perform. However, few data are available on the possibility to use R(int) as a surrogate for spirometry. We aimed at comparing R(int) and spirometry at baseline and after bronchodilator administration in a large population of asthmatic children. We collected retrospectively R(int) and spirometry results measured in 695 children [median age 7.8 (range 4.8-13.9) years] referred to our lab for routine assessment of asthma disease. Correlations between R(int) and spirometry were studied using data expressed as z-scores. Receiver operator characteristic curves for the baseline R(int) value (z-score) and the bronchodilator effect (percentage predicted value and z-score) were generated to assess diagnostic performance. At baseline, the relationship between raw values of R(int) and FEV(1) was not linear. Despite a highly significant inverse correlation between R(int) and all of the spirometry indices (FEV(1) , FVC, FEV(1) /FVC, FEF(25-75%) ; P < 0.0001), R(int) could detect baseline obstruction (FEV(1) z-score ≤ -2) with only 42% sensitivity and 95% specificity. Post-bronchodilator changes in R(int) and FEV(1) were inversely correlated (rhô = -0.50, P < 0.0001), and R(int) (≥35% predicted value decrease) detected FEV(1) reversibility (>12% baseline increase) with 70% sensitivity and 69% specificity (AUC = 0.79). R(int) measurements fitted a one-compartment model that explained the relationship between flows and airway resistance. We found that R(int) had poor sensitivity to detect baseline obstruction, but fairly good sensitivity and specificity to detect reversibility. However, in order to implement asthma guidelines for children unable to produce reliable spirometry, bronchodilator response measured by R(int) should be systematically studied and further assessed in conjunction with clinical outcomes.

[Malnutrition in children with chronic bronchitis]

OBJECTIVE

To study nutritional status in children with chronic bronchitis (CB) in relation with lung function.

METHODS

In this cohort of study, 46 patients aged 6.0 to 17.5 years (mean: 11.9 years) with chronic bronchitis were recruited. None had cystic fibrosis. Body weight, height, skinfold thicknesses, percentage of ideal body weight-for-height (percentage of IBW), body mass index (BMI), BMI Z-score, fat mass and fat-free mass were used to evaluate nutritional status. Arterial blood gases, vital capacity (VC), forced expiratory volume in one s (FEV1), functional residual capacity (FRC) and maximum inspiratory (Pi(max)) and expiratory (Pe(max)) pressures at the mouth were used to evaluate respiratory function.

RESULTS

Thirteen children (28%) had malnutrition defined as percentage of IBW lower than 90%, with a predominant fat mass depletion. VC (65+/-13% versus 79+/-15%; p=0.006) and FEV1 (59+/-16% versus 69+/-14%; p=0.03) were significantly lower in children with malnutrition than in children without malnutrition, but no significant differences were observed with regard to the FEV1/VC ratio and blood gases. Pi(max) (56+/-11% versus 88+/-37%, p=0,02) and Pe(max) (46+/-12% versus 58+/-19%, p=0,3) were also lower in children with malnutrition as compared to than without malnutrition.

CONCLUSION

Malnutrition can be observed in children with CB and is associated with significant lower lung function parameters. This could be explained by decrease in respiratory muscle strength.

Lung and thorax development during adolescence: relationship with pubertal status

The aim of the present study was to define reference values for lung volumes and the lung transfer factor for carbon monoxide (TL,CO) for an adolescent population using thoracic volume index (TVI) and an index of pubertal stage in order to account for the variation in growth pattern between adolescents. TVI, pubertal stage by Tanner scale (PST), time since menarche, functional residual capacity measured using the helium-dilution technique, vital capacity, total lung capacity and TL,CO measured using a steady-state method were determined in 51 males (aged 13-20 yrs; PST T3-T5) and 52 females (aged 13-18 yrs; PST T2-T4; all but three had already undergone menarche). In male adolescents, height, weight, TVI, lung volumes and TL,CO increased with age. This was not the case in female adolescents. In males, the TVI was the independent variable that best correlated with pulmonary volumes. In females, height was the independent variable that best correlated with pulmonary volumes. In both sexes, the variable that best correlated with TL,CO was PST, associated with height in males. This cross-sectional study provides prediction equations for lung volumes and the lung transfer factor for carbon monoxide taking into account thoracic volume index and pubertal stage. It shows that, in adolescent males, lung and thoracic development occurs during and until the end of puberty. Conversely, in adolescent females, lung development is almost finished following menarche.

Chronic stridor caused by laryngomalacia in children: work of breathing and effects of noninvasive ventilatory assistance

Breathing pattern, gas exchange, and respiratory effort were assessed in five awake children with chronic stridor caused by laryngomalacia during spontaneous breathing (SB) and noninvasive mechanical ventilation (NIMV). During SB, the youngest children were able to maintain normal gas exchange at the expense of an increased work of breathing as assessed by calculated diaphragmatic pressure-time product (PTPdi), whereas the opposite was observed in the older children. NIMV increased tidal volume, from 8.77 +/- 2.04 ml/kg during SB to 11.67 +/- 2.52 ml/kg during NIMV, p = 0.04, and decreased respiratory rate, from 24.4 +/- 5.6 breaths/ min during SB to 16.6 +/- 0.9 breaths/min during NIMV, p = 0.04. NIMV unloaded the respiratory muscles as reflected by the significant reduction in PTPdi, from a mean value of 541.0 +/- 196.6 cm H(2)O x s x min(-1) during SB to 214.8 +/- 116.0 cm H(2)O x s x min(-1) during NIMV, p = 0.04. Therefore, NIMV successfully relieves the additional load imposed on the respiratory muscles. Long-term home NIMV was provided to a total of 12 children with laryngomalacia (including these five) and was associated with clinical improvement in sleep and growth.

Abnormal central complex is a marker of severity in the presence of partial ciliary defect

BACKGROUND

Ciliary ultrastructural defects with total lack of dynein arms (DA) cause abnormal mucociliary function leading to the chronic infections observed in primary ciliary dyskinesia. The role of partial ciliary ultrastructural defects, especially those involving the central complex, and their relationship with respiratory symptoms have been less thoroughly investigated.

OBJECTIVE

In a pediatric population with partial ciliary defects, we determined the relationship(s) between ultrastructural findings, ciliary motility, and clinical and functional features, and evaluated the outcome of this population.

DESIGN

We analyzed the clinical presentation and pulmonary function of 43 children with chronic bronchitis and partial ultrastructural defects (from 15% to 90%) of their respiratory cilia demonstrated on bronchial biopsies. The study population was divided into 3 groups according to ciliary ultrastructure: the main ultrastructural defect concerned the central complex in 23 patients (CC group), peripheral microtubules in 8 patients (PMT group), and DA in 12 patients (DA group).

RESULTS

The percentage of ciliary defects was lower in the PMT group than in the CC and DA groups. Patients in the PMT group had less severe disease with frequent normal ciliary motility. Patients in the CC group had initially a higher incidence of respiratory tract infections, extensive bronchiectasis frequently requiring surgery, and arguments in favor of a congenital origin (high proportion of sibling form). Partial absence of DA, although of congenital origin, was associated with a good prognosis. In all groups, follow-up showed that the functional prognosis remained good with appropriate treatment.

CONCLUSIONS

In children with chronic respiratory infections, presence of situs inversus, sibling form, obstructive pulmonary syndrome, or bronchiectasis required ultrastructural analysis, regardless of ciliary motility. Detection of CC abnormalities is a marker of severity and required intensive therapy and close follow-up.

Pulmonary sarcoidosis in children: a follow-up study

Progression of pulmonary sarcoidosis in children remains poorly documented. The aim of this work was to gather follow-up information on pulmonary outcomes in children with sarcoidosis and to obtain data of relevance to a discussion of the optimal length and regimen of glucocorticoid therapy. In the present study, the authors experience of pulmonary sarcoidosis in 21 children referred to the paediatric pulmonary department over a 10-yr period is reported with a documented follow-up of at least 4 yr. Evaluation of the disease during the follow-up included analysis of clinical manifestations, chest radiographs, pulmonary function tests with measurements of the vital capacity (VC), dynamic lung compliance (CL,dyn), lung transfer for CO (TL,CO), and arterial blood gases, as well as bronchoalveolar lavage (BAL) with determination of total and differential cell counts. After initial evaluation the decision was a careful observation of four children without therapy. Corticosteroid treatment was initiated in 17 children. Analysis of results indicated that after 6-12 months of treatment most clinical manifestations of the disease and chest radiograph abnormalities disappeared, and beneficial effects on VC and TL,CO were apparent. After 18 months of steroids no benefit on pulmonary function tests could be noticed, with mainly persistence of alterations of CL,dyn. Results of BAL studies documented the presence of an alveolitis with increased lymphocyte populations throughout the follow-up. Relapses were observed in four children during tapering of prednisone; they were not reported after discontinuation of steroid therapy. Taken together data obtained in the presented population can lead to the following suggestions for the management of pulmonary sarcoidosis in children. BAL should be performed at the initial evaluation to document alveolitis; however, nothing seems to be gained from repeating this investigation during follow-up in the absence of specific reasons. Once the decision to initiate glucocorticoid therapy is made, 18 months may be a reasonable treatment duration. Discontinuation of therapy can be decided even if the pulmonary function tests remain abnormal, but the child should then be carefully monitored for a relapse.

[Clinical and respiratory function follow-up of 39 infants treated with neonatal respiratory extracorporeal assistance]

The aim of this prospective study was to evaluate the consequences of neonatal treatment with a venovenous extracorporeal respiratory assistance.

POPULATION AND METHODS

Thirty nine neonates (28 boys) with acute respiratory failure were included. Extracorporeal respiratory assistance consisted of an apnoeic oxygenation with low frequency positive pressure ventilation and extracorporeal membrane CO2 removal through a venous single canula perfusion circuit. The causes of respiratory distress were: 15 meconium aspiration syndrome, 12 respiratory distress syndrome, six hyaline membrane disease, three sepsis, two diaphragmatic hernia, and one post-surgery Mendelson syndrome. The mean duration of mechanical ventilation was 18 days, including 5 days of extracorporeal respiratory assistance. The prospective follow-up included physical examination, chest radiographs, scintigraphy and pulmonary function tests. These tests studied the following parameters: functional residual capacity by helium dilution technique, lung resistance and dynamic lung compliance by the esophageal balloon technique and blood gases with arterialized blood samples.

RESULTS

The mean duration of the follow-up was 21.3 months (6 months to 5 years). Results showed in the first year 33% of children with chronic obstructive pulmonary disease and chest (X-ray abnormalities, such as bronchopulmonary dysplasia in 23% of children. Data of pulmonary function test at the end of the first year: lung resistance and functional residual capacity were within limits of predicted values for height, and dynamic lung compliance was slightly decreased; according to the analysis of the functional profile: 31% without abnormality, 41% of obstructive syndrome and 26% with restrictive pattern. Blood gases were normal in 37 children. At the end of the second year, we noticed normal functional residual capacity, an increase of lung resistance while lung compliance was normalized; functional profile was quite different: with a decrease of the number of patients without abnormality (22%) and increase of those with obstructive syndrome (56%).

CONCLUSION

The percentage of abnormalities is high but these are moderate in most cases, especially if we compare with the initial seriousness of the pulmonary pathology. We suggest a regular follow-up to study the respective incidence of pulmonary disease and/or extracorporeal respiratory assistance over these abnormalities.

Chest physiotherapy in cystic fibrosis: improved tolerance with nasal pressure support ventilation

OBJECTIVE

Chest physiotherapy (CPT) is an integral part of the treatment of patients with cystic fibrosis (CF). CPT imposes additional respiratory work that may carry a risk of respiratory muscle fatigue. Inspiratory pressure support ventilation (PSV) is a new mode of ventilatory assistance designed to maintain a constant preset positive airway pressure during spontaneous inspiration with the goal of decreasing the patient's inspiratory work. The aim of our study was 1) to evaluate respiratory muscle fatigue and oxygen desaturation during CPT and 2) to determine whether noninvasive PSV can relieve these potential adverse effects of CPT.

METHODS

Sixteen CF patients in stable condition with a mean age of 13 +/- 4 years participated to the study. For CPT, we used the forced expiratory technique (FET), which consisted of one or more slow active expirations starting near the total lung capacity (TLC) and ending near the residual volume. After each expiration, the child was asked to perform a slow, nonmaximal, diaphragmatic inspiration. After one to four forced breathing cycles, the child was asked to cough and to expectorate. A typical 20-minute CPT session consisted of 10 to 15 FET maneuvers separated by rest periods of 10 to 20 breathing cycles each. During the study, each patient received two CPT sessions in random order on two different days, at the same time of day, with the same physiotherapist. During one of these two sessions, PSV was provided throughout the session (PSV session) via a nasal mask using the pressure support generator ARM25 designed for acute patients (TAEMA, Antony, France). The control session was performed with no nasal mask or PSV. Both CPT sessions were performed without supplemental oxygen. Lung function and maximal inspiratory pressures (PImax) and expiratory pressures (PEmax) were recorded before and after each CPT session.

RESULTS

Mean lung function parameters were comparable before the PSV and the control sessions. Baseline pulse oximetry (SpO2) was significantly correlated with the baseline vital capacity (% predicted) and forced expiratory volume in 1 second (FEV1) (% predicted). PSV was associated with an increase in tidal volume (Vt) from 0.42 +/- 0.01 liters to 1.0 +/- 0.02 liters. Respiratory rate was significantly lower during PSV. SpO2 between the FET maneuvers was significantly higher during PSV as compared with the control session. SpO2 decreases after FET were significantly larger during the control session (nadir: 91.8 +/- 0. 7%) than during the PSV session (93.8 +/- 0.6%). Maximal pressures decreased during the control session (from 71.9 +/- 6.1 to 60.9 +/- 5.3 cmH2O, and from 85.3 +/- 7.9 to 77.5 +/- 4.8 cmH2O, for PImax and PEmax, respectively) and increased during the PSV session (from 71.6 +/- 8.6 to 83.9 +/- 8.7 cmH2O, and from 80.4 +/- 7.8 to 88.0 +/- 7.4 cmH2O, for PImax and PEmax, respectively). The decrease in PEmax was significantly correlated with the severity of bronchial obstruction as evaluated based on baseline FEV1 (% predicted). Forced expiratory flows did not change after either CPT session. The amount of sputum expectorated was similar for the two CPT sessions (5.3 +/- 5.3 g vs 4.6 +/- 4.8 g after the control and PSV session, respectively; NS). Fifteen patients felt less tired after the PSV session. Ten patients reported that expectoration was easier with PSV, whereas 4 did not note any difference; 2 patients did not expectorate. Nine patients expressed a marked and 5 a small preference for PSV, and 2 patients had no preference. The physiotherapists found it easier to perform CPT with PSV in 14 patients and did not perceive any difference in 2 patients.

DISCUSSION

Our study in CF children shows that respiratory muscle performance, as evaluated based on various parameters, decreased after CPT and that significant falls in oxygen saturation occurred after the FET maneuvers despite the quiet breathing periods between each FET cycle. These unwanted effects of CPT were

Longitudinal clinical and functional pulmonary follow-up after megatherapy, fractionated total body irradiation, and autologous bone marrow transplantation for metastatic neuroblastoma

BACKGROUND

A prospective follow-up was undertaken to document longitudinal changes in lung function in children with neuroblastoma treated with the Lyon-Marseille-Curie-East of France Group protocol, consisting of high-dose chemotherapy schedules in combination with total body irradiation (TBI) and autologous bone marrow transplantation (ABMT), to determine the extent and timing of any changes seen and to describe late clinical and functional pulmonary sequelae.

PROCEDURES

Eighteen children (1.5-6.9 years of age at TBI) performed pulmonary function tests (PFTs). These included measurement of functional residual capacity (FRC) to assess lung growth and dynamic lung compliance (CLdyn) and lung transfer factor for CO (TLCO) for evaluation of distal bronchi and/or interstitial abnormalities.

RESULTS

The clinical follow-up showed that bronchopulmonary symptoms occurred in 12 children. Three of them were clinically severely incapacitated. Serial PFTs showed an initial decrease of all mean values 6 months after TBI, with improvement in mean values of FRC and TLCO at 1 year. Thereafter, a significant decrease of mean FRC and CLdyn was observed from 2 years to 4 years after TBI with preservation of TLCO, suggesting restrictive ventilatory defects rather than pulmonary fibrosis. Individual analysis showed PFT defects in 100% of children 4 years after TBI. There was a higher incidence of lung pathology after two blocks of high-dose chemotherapy than after one block (100% versus 40%) and more severe sequelae. However these children had residual disease present after induction associated with lower baseline PFT.

CONCLUSIONS

PFT defects were found in all children 4 years after TBI-ABMT, but they remained within acceptable limits except in very young children.

Impaired ability of Cftr knockout mice to control lung infection with Pseudomonas aeruginosa

The present study was aimed at investigating the innate susceptibility of C57BL/6-Cftrunc/Cftrunc knockout [B6-Cftr (-/-)] mice to pulmonary infection with Pseudomonas aeruginosa. Our results indicate that 58.4% of B6-Cftr (-/-) mice died within 6 d following lung infection with 10(5) P. aeruginosa entrapped in agar beads, whereas only 12.1% of B6-Cftr (+/+) mice died over the same period of time. Moreover, the number of bacteria recovered from the lungs of B6-Cftr (-/-) mice 3 and 6 d after infection was significantly higher than that observed in their littermate controls. No correlation was found between the weight or age of the animals and the number of viable bacteria recovered from the lungs of mice. Histopathological examination of lung sections from P. aeruginosa-infected mice revealed that the infection results in a severe bronchopneumonia. Both B6-Cftr (-/-) knockout mice and their littermate controls developed similar lung pathology during the course of infection. Overall, results reported in the present study suggest that a defect at the Cftr locus leads to an exacerbation of P. aeruginosa lung infection resulting in a dramatically increased mortality rate and higher bacterial load.

[Isocapnic hyperventilation test adjusted to child's resting ventilation rate]

In order to validate an Isocapnic Voluntary Hyperventilation (IVH) test applicable to daily practice and to adapt the stimulus to height, 9 healthy and 15 asthmatic children performed a Resting Ventilation Rate (RVR)-corrected IVH. They performed a three-minute IVH with room temperature dry air achieving twice (IVH2) and three times (IVH3) their RVR. Mean Maximal Expiratory Flow (MEF) in the middle half of Forced Vital Capacity (FVC) (MEF25-75%) and mean MEF at 25% of FVC (MEF25%) are decreased in the asthmatic group 10 minutes IVH3 (p = 0.02 and < 0.002) compared to healthy group. Mean FEV1 of both group are not different. Comparing Forced Expiratory Flows variation after IVH to baseline intrasubject coefficient of variation, sensitivity of the test is 80% and specificity 100% when variations of MEF25-75% and MEF25% together with FEV1 variations are considered. This suggests an easy way to adapt an hyperventilation stimulus to size and emphasizes the utility of taking account of MEF25-75% and MEF25% in detecting non specific bronchial hyperreactivity in asthmatic children.

Role of tumor necrosis factor alpha in innate resistance to mouse pulmonary infection with Pseudomonas aeruginosa

In the present study, we have investigated the mechanisms underlying mouse resistance to endobronchial infection with Pseudomonas aeruginosa enmeshed in agar beads. This was done by monitoring macrophage activation-associated gene expression in lung and alveolar cells harvested from resistant (BALB/c) and susceptible (DBA/2, C57BL/6, and A/J) strains of mice over the course of infection with P. aeruginosa. Interleukin-1 alpha, interleukin-1 beta, macrophage inflammatory protein-1 alpha, JE, and tumor necrosis factor alpha (TNF-alpha) mRNA expression levels were up-regulated in all strains of mice during the early phase of the infection. The level of TNF-alpha mRNA expression was increased to a greater extent in resistant BALB/c mice than in susceptible DBA/2, C57BL/6, and A/J strains of mice. This observation paralleled a higher secretion of TNF-alpha into the alveolar space of BALB/c mice at 3 and 6 h postinfection. The concentration of TNF-alpha released in alveoli returned to basal levels within 24 h of infection in mice of all strains, even though the TNF-alpha mRNA expression remained high until 3 days after infection. In vivo treatments with either anti-murine TNF-alpha monoclonal antibodies or with aminoguanidine significantly increased the number of P. aeruginosa bacteria detected in the lungs of resistant mice at 3 days postinfection. Overall, these findings indicate that both TNF-alpha and nitric oxide exert a protective role in response to pulmonary infection with P. aeruginosa.

Expandable prosthesis in right postpneumonectomy syndrome in childhood and adolescence

Right pneumonectomy can lead to severe respiratory impairment due to stenosis of the left main bronchus. This syndrome is usually treated by inserting a fixed-volume prosthesis but, in children, expandable prostheses have the advantage of being adaptable to growth and permit progressive recentering of the mediastinum. We report 3 such cases, with the results of pulmonary function tests. The patients were aged 11, 17, and 22 years at the time of implantation and had undergone pneumonectomy during childhood for either bronchiectasis or complete pulmonary sequestration. All 3 patients are doing well, with a follow-up of 1 to 3 1/2 years. Pulmonary function tests have shown a substantial improvement in the obstructive syndrome in 2 patients whereas, in the third patient, in whom the contralateral lung was not perfectly healthy, the functional improvement was only moderate.

[Value of accelerated hyposensitization with mixed allergens in severe childhood asthma]

The value (in terms of decreased numbers of attacks and of hospitalizations for attacks, decreased need for asthma medications, and improved tolerance to allergens) of rush immunotherapy to a mixture of allergens was studied in children with multiple sensitizations and severe asthma (as evaluated on the number of attacks, number of hospitalizations, and dependence on corticosteroids) already receiving optimal medical therapy. Because syndromic reactions are common, rush immunotherapy should be performed in the hospital and premedication with corticosteroids may be warranted in the most severe cases.

Pulmonary functional outcome at one year of age in infants treated with natural porcine surfactant at birth

This prospective study was designed to assess pulmonary function (functional residual capacity, FRC; dynamic lung compliance, CLdyn; and total pulmonary resistance, RL) at 1 year of corrected age in infants with neonatal respiratory distress syndrome treated with natural porcine surfactant (Curosurf) (n = 13), as compared to nontreated control infants (n = 9). Values from 21 healthy infants of similar age served as reference. We found similar pulmonary dysfunction (decreased CLdyn, elevated RL) in both patient groups. These results suggest that surfactant replacement therapy does not affect pulmonary function at 1 year of age in infants who survive respiratory distress syndrome.

Genetic resistance/susceptibility to mycobacteria: phenotypic expression in bone marrow derived macrophage lines

Congenic strains of mice susceptible (B10A.Bcgs) or resistant (B10A.Bcgr) to BCG were established. Here we describe the model system which has been established to analyze the functional activities of macrophages in the two strains. We have immortalized bone marrow macrophages from B10A.Bcgs and B10A.Bcgr congenic strains of mice and derived cloned macrophage lines designated B10S and B10R, respectively. B10R and B10S cell lines exhibited surface markers and morphology typical of macrophages. B10S and B10R were similar in their phagocytic activity, in their level of c-fms, in their transforming growth factor beta (TGF beta) mRNAs expression, and in their expression of tumoricidal activity in response to interferon-gamma (IFN gamma) plus lipopolysaccharides (LPS). However, B10R macrophages expressed a higher level of la mRNA when activated with IFN gamma compared with B10S macrophages. Analysis of the bacteriostatic activity of the two cell lines revealed that B10R macrophages were much more active in inhibiting Mycobacterium smegmatis replication than B10S. To measure the intracellular destruction of bacilli, a bactericidal assay based on hybridization with an oligonucleotide probe specific for mycobacterial ribosomal RNA was designed. The results demonstrated that B10R macrophages were endowed with enhanced constitutive bactericidal activity as compared with B10S. In conclusion we have obtained macrophage lines from bone marrow of B10A.Bcgs and B10A.Bcgr mice that express to a similar extent functional and phenotypic characteristics of macrophages. However, we demonstrate that relative to B10S macrophages, the B10R macrophages have higher expression of la mRNA and that they are constitutively more active in expressing mycobactericidal activity.

Pulmonary function in infancy and in childhood following mechanical ventilation in the neonatal period

Pulmonary function was evaluated in both infancy and childhood in the same 19 prematurely born infants, who required mechanical ventilation (MV) during the neonatal period. Results of our patients were compared with those of control subjects. Upon first evaluation, we found that lung resistance (RL) was significantly elevated (24.85 +/- 6.06 vs. 17.77 +/- 2.39 cmH2O/L/s; P less than 0.01). The mean value of dynamic lung compliance (CLdyn) was low, but the difference compared to controls did not reach significance. From infancy to childhood, elevated RL persisted (9.33 +/- 2.51 vs. 6.52 +/- 1.52 cm H2O/L/s; P less than 0.01), and the decrease of CLdyn became significant (46.86 +/- 12.84 vs. 59.34 +/- 15.68 mL/cmH2O; P less than 0.05). In addition, maximum flow at functional residual capacity was significantly decreased (0.824 +/- 0.284 vs. 1.215 +/- 0.358 L/s; P less than 0.01); whereas pulmonary diffusing capacity for carbon monoxide was similar in the patients (7.62 +/- 2.16 mL/min/mm Hg) and in the controls (8.38 +/- 1.6). Pulmonary dysfunction following premature birth, respiratory distress, and prolonged MV may not resolve from infancy to childhood.

Lung transfer for carbon monoxide during the first three years of life

Lung transfer for CO (TLCO) was measured in 35 healthy infants. A steady state, non-invasive method using a technique of alveolar sampling was employed [3]. During the first three years of life, TLCO expressed as mmol.min-1.kPa-1 increased linearly with height (cm): y = 0.036x - 1.15 (r = 0.91); with body weight (kg): y = 0.18x - 0.005 (r = 0.85); with body surface area (m2): y = 3.48x - 0.375 (r = 0.88); and with logn of age (months): y = 0.406x + 0.184 (r = 0.88). FRC was also measured in 29 of these infants by the helium dilution technique. FRC expressed in ml increased linearly with logn of age: y = 62.24x + 62.4 (r = 0.86) and was correlated with TLCO: y = 0.05x + 0.084 (r = 0.8). TLCO and FRC were correlated with the number of alveoli [7, 9]. Thus, in the first three years of life, lung volume and lung gas transfer seem to progressively adapt in order to satisfy energetic needs during growth.

Inspiratory force reserve of the respiratory muscles in children with chronic obstructive pulmonary disease

The purpose of this study was to evaluate inspiratory muscle force reserve in children with chronic obstructive pulmonary disease (COPD). In 15 hyperinflated (FRC/TLC, 65 +/- 0.7%) children, maximal mouth inspiratory static pressure (PImax) at FRC, mouth occlusion pressure (P0.1), tidal volume (VT), inspiratory time (TI), and total duration of the respiratory cycle (Ttot) were all measured. It was found that PImax at FRC was reduced compared with predicted values. However, after lung volume correction, PImax was in the normal range, and P0.1 was higher, TI was shorter, and Ti/Ttot was lower than predicted. The estimated mean inspiratory pressure for breathing at rest (PI) was significantly higher than predicted and was related to total pulmonary resistance (r = 0.74, p less than 0.001). The fraction of PImax developed by the respiratory muscles for breathing at rest (PI/PImax) significantly increased. The higher the PI/PImax ratio, the more the TI/Ttot ratio decreased (r = -0.64, p = 0.01). At rest, our subjects had to develop a mean inspiratory power (W) of as much as 48% (range, 30 to 76%) of the critical W above which fatigue occurs. Thus, even minimal increases in breathing load might expose children with COPD to respiratory muscle fatigue and to respiratory failure.

Lung function of children treated for malignant extrapulmonary tumors

Lung function was studied in 29 children suffering from extrapulmonary tumors of varying etiology (Wilm's tumor, n = 7; bone malignancy, n = 17; nasopharyngeal epithelioma, n = 5). Lung volume: vital capacity (VC) and functional residual capacity (FRC), lung mechanics: lung resistance (RL), dynamic lung compliance (CLdyn) and static lung compliance (CLstat) and lung transfer factor for CO (TLCO), and blood gases were determined at different stages of therapy: at t0, before any aggressive treatment for respiratory function; at t1, after the initiation of polychemotherapy with or without local tumoral treatment (surgery or local irradiation); at t2, less than 6 months after onset of thoracopulmonary irradiation (whole lung irradiation at 20 grays) (group I), or local thoracopulmonary irradiation at high exposure greater than 40 grays (group II); at t3 after more than 6 months following irradiation with chemotherapy maintained; at t4, after cessation of all treatment (mean: 25 months +/- 14 after cessation of treatment). At t0, lung function data in children without pulmonary metastases did not deviate from predicted values. At t1, group I showed a significant decrease in CLdyn, which could be due to chemotherapy and for 5 children to consequences of abdominal surgery. In group II, only two children had a low CLdyn and also a significant decrease in VC (possibly due to the site of the tumor). After irradiation (at t2), FRC, TLCO and CLdyn were significantly lower than the predicted values and lower than at t1 in both groups (p greater than 0.01). At t3, functional parameters did not show any change compared to t2. At t4, FRC and TLCO were within normal limits in both groups but CLdyn, CLstat and the CLdyn/FRC ratio remained significantly decreased. It is suggested that these functional abnormalities are due to inadequate alveolar growth.

Regulation and SOS induction of division inhibition in Escherichia coli K12

When Escherichia coli is subjected to treatments that damage DNA or perturb DNA replication considerable cell filamentation occurs. It has been postulated that this phenomenon is associated with the presence of a division inhibitor induced coordinately with the SOS functions. The role of this induction would be to delay septation during DNA repair to prevent the formation of DNAless cells. In this communication, we present evidence for such a division inhibitor based on the properties of a division mutant which is hyperactive in the septation delay. Cells of this mutant filament extensively after a nutritional shift-up, have drastically reduced colony-forming abilities on a rich medium but not on a minimal medium following treatment with ultraviolet radiation and, are deficient in the lysogenization of phage lambda; phenotypes which are characteristic of but expressed to a much lower extent in another type of division mutant called Ion. Cells harboring the division mutation plus either one of the lexA mutant alleles, spr-51 or tsl-1, are filamentous suggesting that they are permanently derepressed for division inhibition. These results are in agreement with models that assign the regulation of cell division to a division inhibitor which is regulated by the lexA repressor protein.

Effects of naloxone on the control of breathing in children with chronic obstructive pulmonary disease

The effect of naloxone on occlusion pressure (P0.1), the pattern of breathing and the expiratory flows during spontaneous ventilation was studied in 16 children with chronic obstructive pulmonary disease under control conditions, after isotonic saline injection and 5 (N5) and 25 (N25) min after i.v. injection of naloxone (2 micrograms X kg-1). At N5, no change was observed in tidal volume normalized for body weight (VTBW), inspiratory time (TI), respiratory frequency (f), mean inspiratory flow (VTBW/TI) and the ratio of TI and total duration of the respiratory cycle (TI/TT). P0.1 decreased significantly (p less than 0.001) at N5 and returned to control values at N25. The decrease in P0.1 without any change in the breathing pattern suggests that naloxone has an effect on respiratory mechanics. Indeed, at N5, the expiratory flows generated at 25% of VT, measured on the flow-volume curves during spontaneous ventilation, increased significantly when compared to control values. Moreover, the decrease of P0.1 after naloxone was found to be correlated to the reduction of dynamic lung compliance (CLdyn) (p less than 0.02). It is speculated that peripheral airway obstruction, as reflected by the decrease in CLdyn, might be a triggering factor for the release of endorphins. The bronchodilation observed after naloxone could then be due to naloxone's antagonistic effect on endorphin-induced bronchoconstriction.

Hypoxemia in attack free asthmatic children: relationship with lung volumes and lung mechanics

In 113 asthmatic children (mean age +/- SD = 11.0 +/- 2.8 years), the presence of hypoxemia was evaluated during an attack free period. Blood gases were measured in arterialized blood samples. 71% of the patients were hypoxemic. Hypoxemia was defined as partial pressure of O2 (PaO2) below 90% of the mean value for normal children. In a first step, the relationship between hypoxemia and frequency of asthma attacks was examined: frequency of attacks appeared to be a poor predictor of hypoxemia in an attack free period. In a second step, the relationship between hypoxemia and 9 pulmonary function test variables was examined. The static lung volumes considered were: functional residual capacity (FRC: helium dilution technique); thoracic gas volume (TGV: body plethysmography technique) and trapped gases (TG: difference between TGV and FRC). TG was expressed as a percentage of 1) measured FRC (TG/FRCmeas), 2) measured TGV (TG/TGVmeas), 3) predicted FRC (TG/FRCpred). Lung mechanics variables were determined by the oesophageal catheter technique: lung resistance (RL) and dynamic lung compliance (CLdyn). RL and CLdyn were expressed 1) in absolute terms, 2) as a percentage of the index of distension (ID: TGV/FRCpred). All variables are expressed as a percentage of predicted values except for TG/FRCmeas and TG/TGVmeas. Considering lung volumes, hypoxemia was found when TG was present. When lung mechanics were altered, hypoxemia was also present. The relationship between PaO2 and PFT variables was best expressed by the following equation: PaO2 (%) = 85.393 + 0.121 CLdyn/ID--0.151 TG/FRCpred--0.026 RL.(ABSTRACT TRUNCATED AT 250 WORDS)

Occlusion pressure and breathing pattern in children with chronic obstructive pulmonary disease

The control of breathing at rest was studied in 30 children (3 to 17 years old) with chronic obstructive pulmonary disease (COPD). Five of them were tested several times during the follow-up of the COPD. Breathing pattern was evaluated and mouth occlusion pressure (PO.1) was measured. Results in COPD children were compared to previously reported values in healthy controls. PO.1 was significantly increased. In 11 children breathing O2, PO.1 decreased but remained at higher levels than predicted. However, the decrease in PO.1 in COPD was not significantly greater than in healthy children. These results may be explained by the relative mild hypoxemia in those children. The increase in PO.1 was significantly correlated with the increase in lung resistance (p less than 0.02) and with the decrease in dynamic lung compliance (p less than 0.01). Most of the COPD children were normocapnic. However, modifications in the breathing pattern were observed. The inspiratory time (TI) was significantly shortened, the expiratory time was prolonged and the TI over the total duration of the respiratory cycle was lowered. The respiratory frequency was unchanged. The tidal volume, normalized for body weight (VTBW), was increased. The mean inspiratory flow (VTBW/TI) was significantly augmented, but not as much as PO.1: in consequence, the effective inspiratory impedance was higher than predicted. Thus, as adults, COPD children had a greater inspiratory neural drive. In contrast to normocapnic COPD adults, they had a modified respiratory timing.

[Functional respiratory disorders in children with left-to-right shunt]

The respiratory function of 19 children aged from 2 months to 9 years old with a cardiac lesion giving a left-to-right shunt was studied and analysed with respect to the hemodynamic disturbance. Respiratory function tests (RFTs) included measurement of functional residual capacity (FRC), the partial pressure in oxygen (Pa 02) on arterialised blood taken from the ear lobe, dynamic pulmonary compliance (CI dyn.) and total pulmonary resistance (RI). FRC and RI were not significantly modified. On the other hand, CI. dyn. was low (-31.2 +/- 22.9%, p less than 0,001) as were the CI. dyn. CFR ratio (-25.5 +/- 20.9%, p less than 0.001) and the Pa 02 (-7.6 +/- 12.7% p less than 0.02). There was a significant correlation between the reduction of CI. dyn. and mean pulmonary arterial pressure (PAP) and the increase in the pulmonary blood flow. In addition, a significant correlation was also found between the reduction in Pa 02 and the PAP and increase in pulmonary blood flow. These results show that cardiac lesions with left-to-right shunts give rise to diffuse changes in respiratory function and are discussed in the light of the abnormalities in pulmonary development previously described in pulmonary biopsy of patients with left-to-right shunts. The value of RFTs in the surveillance of patients with left-to-right shunts is underlined.

Decrease in the rate of protein synthesis by polysomes from cultured fibroblasts of patients and carriers with Duchenne muscular dystrophy

Polysomes extracted from cultured fibroblast cells isolated from patients with Duchenne muscular dystrophy (DMD), carriers of the disease, and normal controls were used for in vitro measurement of protein synthesis in a wheat germ extract system. It was observed that polysomes from patients and carriers (seven of each aged 17 years or older) exhibited a 3-fold and a 1.5-fold decrease in the rate of protein synthesis, respectively, as compared with controls. These results are discussed with a view to developing a sensitive and easily available assay for the detection of DMD carriers.