Cytokine concentrations in exhaled breath condensates in systemic sclerosis

BACKGROUND

Pulmonary fibrosis in systemic sclerosis (SSc) involves inflammatory processes in the lower respiratory tract. Analysis of exhaled breath condensate (EBC) is a non-invasive method for studying inflammatory mediators, such as cytokines, which are of interest from both physiological and therapeutic perspectives. The aim of this study was to assess and compare cytokine concentrations in the EBC of SSc patients and controls.

MATERIAL AND METHODS

EBC was collected from 19 SSc patients and 19 controls. We used a multiplex assay test kit to assay interleukin (IL)-2, -4, -6, -10, tumour necrosis factor-alpha, and interferon-gamma in samples concentrated by lyophilization.

RESULTS

Cytokine concentrations in EBC were higher in SSc patients than in controls. The stepwise analyses showed that IL-4 was the biomarker which contributed most to the discrimination between controls and patients (Wilk's Lambda = 0.55, p < 0.001). We observed significant negative correlations of EBC cytokines with total lung capacity and diffusion capacity of the lung for carbon monoxide.

CONCLUSIONS

These findings suggest that EBC sampling permits the non-invasive study of inflammation in SSc patients, and may be correlated with the severity of interstitial lung disease.

Evidence for linkage of a new region (11p14) to eczema and allergic diseases

Asthma, allergic rhinitis (AR) and atopic dermatitis also called eczema are allergic co-morbidites, which are likely to depend on pleiotropic genetic effects as well as on specific genetic factors. After a previous genome-wide linkage screen conducted for asthma and AR in a sample of 295 French EGEA families ascertained through asthmatic subjects, the aim here was to search for genetic factors involved in eczema and more particularly the ones shared by the three allergic diseases using the same EGEA data. In this sake, eczema and phenotypes of "allergic disease" accounting for the joint information on the presence/absence of the three diseases were examined by linkage analyses using the maximum likelihood binomial method. A fine mapping was carried out in regions detected for potential linkage, followed by association studies using the family-based association test (FBAT). Evidence for linkage to 11p14 region was shown for "allergic disease" and eczema. Linkage was also indicated between eczema and 5q13 and between "allergic disease" and both 5p15 and 17q21 regions. Fine mapping supported the evidence of linkage to 11p14 and FBAT analyses showed the association between "allergic disease" and a marker located at the linkage peak on 11p14. Further investigations in this region will allow identifying genetic factor(s) which could have pleiotropic effect in the three allergic diseases.

Effect of short recovery intensities on the performance during two Wingate tests

PURPOSE

To assess the effects of the intensity of short recoveries on performance by a Wingate test and on the deoxyhemoglobin variations.

METHODS

Twelve male subjects performed a graded test and three sessions of repeated all-out tests with different recovery natures. The repeated all-out tests included two sprints: a 15-s Wingate test followed by a 30-s Wingate test. The recovery between the two was 15 s in duration and was either passive, active at 20% of maximal aerobic power, or active at 40% of maximal aerobic power. Changes in deoxyhemoglobin were measured using by the near-infrared spectroscopy technique.

RESULTS

Mean power (517 +/- 26 W) and peak power (1085 +/- 153 W) of the 30-s Wingate test performed after passive recovery were significantly higher (P < 0.05) than mean power and peak power performed after active recovery at 20% (484 +/- 30 and 973 +/- 112 W, respectively) and 40% of maximal aerobic power (492 +/- 35 and 928 +/- 116 W, respectively). Deoxyhemoglobin variations were significantly higher (P < 0.05) during the passive recovery (12.8 +/- 5.3 microM) than during the active recovery conditions at 20% (4.3 +/- 2.6 microM) and 40% of maximal aerobic power (3.9 +/- 2.6 microM).

CONCLUSION

These results demonstrate that when two Wingate tests are performed almost successively but with a short recovery between the two, passive recovery is more appropriate than active recovery to restore the performance level.

Influence of three nasal continuous positive airway pressure devices on breathing pattern in preterm infants

The pattern of breathing was studied in 13 premature newborns treated by variable-flow Nasal Continuous Positive Airway Pressure (NCPAP), conventional NCPAP, and nasal cannulae. Compared to constant-flow NCPAP and nasal cannulae, the variable-flow NCPAP increases tidal volume and improves thoraco-abdominal synchrony, suggesting that variable-flow NCPAP provides more effective ventilatory support than conventional NCPAP or nasal cannulae.

[Effect of thoracic bracing on lung function in children with neuromuscular disease]

Respiratory muscle weakness associated with scoliosis in neuromuscular disease leads to respiratory impairment. Children with scoliosis are usually treated with spinal bracing to delay the progress of disease. We studied the impact of spinal bracing on lung function in these children.

METHODS

Retrospective study of patient data from January 1997 to January 2003. Spirometry and measurement of lung volume involved 32 observations, corresponding to 17 children with neuromuscular disease, including 14 with spinal muscular atrophy. Data for children with and without a brace were studied.

RESULTS

A total of 72% of the children had severe scoliosis (Cobb score>30 degrees ); 40% wore a Garchois brace. Children without a brace showed a mean vital capacity of 65% of predicted value, with a restrictive syndrome in 44% of observations. Children with a brace showed significantly reduced vital capacity (-4.6%; P<0.001) and forced expiratory volume in 1 s (-4.6%; P=0.002). The reduced vital capacity was lower in children with the Garchois brace: -1% (P=0.02). Severity of scoliosis and measured volumes were not related.

CONCLUSION

Spinal bracing in children with neuromusclar disease leads to significant respiratory impairment. Assessment of pulmonary function is necessary when a brace is indicated. The Garchois brace might lead to less impairment of respiratory function.

Prediction of one-hour running performance using constant duration tests

Critical velocity (CV) represents, theoretically, the highest velocity that can be sustained without fatigue. The aim of this study was to compare CV computed from 5 mathematical models in order to determine which CV estimate is better correlated with 1-hour performance and which model provides the most accurate prediction of performance. Twelve trained middle- and long-distance male runners (29 +/- 5 years) performed 3 randomly ordered constant duration tests (6, 9, and 12 minutes), a maximal running velocity test for the estimation of CV, and a 1-hour track test (actual performance). Two linear, 2 nonlinear, and 1 exponential mathematical models were used to estimate CV and to predict the highest velocity that could be sustained during 1 hour (predicted performance). Although all CV estimates were correlated with performance (0.80 < r < 0.93, p < 0.01), it appeared that CV estimated from the exponential model was more closely associated with performance than all other models (r = 0.93; p < 0.01). Analysis of the bias +/- 95% interval of confidence between actual and predicted performance revealed that none of the models provided an accurate prediction of the 1-hour performance velocity. In conclusion, the estimation of CV allows us to rank middle- and long-distance runners with regard to their ability to perform well in long-distance running. However, no models provide an accurate prediction of performance that could be used as a reference for coaches or athletes.

Longitudinal changes in hyperinflation parameters and exercise capacity after giant bullous emphysema surgery

OBJECTIVE

Although resection of giant bullae for the purpose of improving the function of underlying compressed lung is an accepted form of surgery for emphysema, there is only limited information regarding long-term improvement in dynamic hyperinflation and exercise tolerance. Our major goal was to investigate the effects of lung resection for giant bullae on pulmonary function, dynamic hyperinflation, and exercise capacity in patients with chronic obstructive pulmonary disease characterized by emphysema.

METHODS

Pulmonary function and exercise testing were assessed prospectively before and 3, 6, 12, 24, and 48 months after surgery in 12 patients who had chronic obstructive pulmonary disease with emphysema who underwent lung resection of giant bullae.

RESULTS

Forced expiratory volume, diffusing capacity for carbon monoxide, arterial partial pressure of oxygen, and exercise capacity were significantly increased after resection of surgical bullae. Dynamic hyperinflation, as assessed by reduction in inspiratory capacity and dyspnea Borg scale, were significantly decreased during exercise. Improvement in baseline and exercise functional capacity slightly decreased over time, remaining, however, far above the value before surgery.

CONCLUSION

Altogether, these findings suggest that surgery for resection of giant bullae is an effective procedure for improving airflow, limiting gas exchange, and limiting exercise dynamic hyperinflation over time.

Physiologic correlates of dyspnea in patients with morbid obesity

OBJECTIVE

Mechanisms of dyspnea in obesity remain unclear. This study was undertaken to determine the relationships between dyspnea and pulmonary function including inspiratory muscle endurance (IME) in morbidly obese patients before bariatric surgery.

RESEARCH METHODS AND PROCEDURES

Fifty-five patients with a mean+/-s.d. body mass index (BMI) of 49.4+/-7.0 kg/m(2) were included. Dyspnea was evaluated by the Baseline Dyspnea Index (BDI; 0-12, 0=maximal dyspnea). Pulmonary function tests included a plethysmography, maximal inspiratory pressure (PImax) and IME was assessed by the incremental threshold loading test, determining the maximal pressure sustained for 2 min (Plim(2)) and Plim(2)/PImax ratio. Patients were classified according to their BMI in two groups: BMI < or =49 (n=27) and >49 kg/m(2) (n=28).

RESULTS

Breathlessness was higher in the BMI >49 kg/m(2) group compared to the BMI < or =49 kg/m(2) group (BDI score at 6.9+/-2.2 in the BMI >49 kg/m(2) group vs 8.9+/-2.5 in the BMI < or =49 kg/m(2) group, P<0.01). Patients with BMI >49 kg/m(2) had significantly higher PaCO(2) level and significantly lower vital capacity, inspiratory capacity and PImax values compared with the BMI < or =49 kg/m(2) group. Correlations between BDI and lung function were moderate: forced expiratory volume in 1 s (FEV(1))% pred: Rho=0.27; P=0.05; vital capacity % pred: Rho=0.40; P=0.004; and Plim(2)/PImax: Rho=0.40; P=0.003. Higher correlations with dyspnea were found in the BMI < or =49 kg/m(2) group: FEV(1)% pred: Rho=0.38; P=0.05; and Plim(2)/PImax: Rho=0.49; P=0.01.

DISCUSSION

Inspiratory muscle performance is moderately reduced in morbid obesity. Dyspnea in these patients remains moderately related to lung function and inspiratory muscle performance. However, inspiratory muscles performance correlates more significantly with dyspnea in patients with a BMI < or =49 kg/m(2).

Nutritional status at 2 years in former infants with bronchopulmonary dysplasia influences nutrition and pulmonary outcomes during childhood

Improved survival rates for extreme prematurity have been accompanied by an increase in the incidence of bronchopulmonary dysplasia (BPD). The objective of this study was to assess factors associated with long-term nutritional and pulmonary function outcomes. The study was a cross-sectional study of 52 children who had been born prematurely, had experienced BPD, and were 4-8 y old at the time of the study. Undernutrition was defined as a Z score for weight-for-height of <-2 SD. Body composition and lung function were evaluated. Resting energy expenditure (REE) was measured using indirect calorimetry. Stepwise logistic regression was used to test for factors associated with undernutrition and pulmonary function. Eighteen children (35%) with BPD, predominantly girls, were undernourished. Undernutrition occurred within the first months of life and was associated with high REE. Multivariate analysis showed that factors significantly associated with undernutrition were female sex and undernutrition at age 2 y. Thirty-one children (60%) had abnormal lung function tests. Multivariate analysis showed that undernutrition at age 2 y was the only factor associated with the risk of developing distension of the airways. Nutritional status at age 2 y in children who had BPD in infancy influences nutritional and pulmonary outcomes in childhood.

Spirometry in 3-5-year-old children with asthma

Spirometry with incentive games was applied to 207 2-5-year-old preschool children (PSC) with asthma in order to refine the quality-control criteria proposed by Aurora et al. (Am J Respir Crit Care Med 2004;169:1152-159). The data set in our study was much larger compared to that in Aurora et al. (Am J Respir Crit Care Med 2004;169:1152-159), where 42 children with cystic fibrosis and 37 healthy control were studied. At least two acceptable maneuvers were obtained in 178 (86%) children. Data were focused on 3-5-year-old children (n = 171). The proportion of children achieving a larger number of thresholds for each quality-control criterion (backward-extrapolated volume (Vbe), Vbe in percent of forced vital capacity (FVC, Vbe/FVC), time-to-peak expiratory flow (time-to-PEF), and difference (Delta) between the two FVCs (DeltaFVC), forced expiratory volume in 1 sec (DeltaFEV(1)), and forced expiratory volume in 0.5 sec (DeltaFEV(0.5)) from the two "best" curves) was calculated, and cumulative plots were obtained. The optimal threshold was determined for all ages by derivative function of rate of success-threshold curves, close to the inflexion point. The following thresholds were defined for acceptability: Vbe <or=75 ml and <or=10% of FVC, time-to-PEF <120 msec, and repeatability: DeltaFEV(1) and DeltaFEV(0.5) <or=110 ml and <or=10% of best effort, and DeltaFVC <or=100 ml and <or=12.5%. These were obtained in 85%, 93%, 94%, 90%, and 89% of children, respectively. For practical reasons, we suggest choosing the same threshold for all repeatability criteria, i.e., DeltaFVC, DeltaFEV(1), and DeltaFEV(0.5) <or=110 ml and <or=10%. In conclusion, a majority of PSC with asthma can perform at least two acceptable maneuvers. Acceptability and repeatability criteria defined in a larger data set can be applied to preschool children. Spirometry could therefore be used to assess respiratory function in preschool children with asthma.

Tests de marche : une avancée dans l'évaluation fonctionnelle cardiorespiratoire

Exercise testing provides information on physical capacity during exercise in addition to spirometric measures of lung function or assessment on treadmills or ergonomic cycle. The "gold standard" assessment of exercise tolerance is measured in the laboratory using treadmills or ergonomic cycle but the necessary equipment is expensive and may not be readily accessible; such tests require people used to work with children. Walking tests are field tests providing a valid and easily accessible method of measuring function-limited exercise tolerance in patients with respiratory or cardiac chronic diseases. These walking tests are non-threatening, inexpensive, easy to perform and to understand for children. Walking tests performed in daily practice are the following: "time-based" tests (2-, 6- or 12-min walking test), 3-min step test (on a step) and the shuttle walking test. It may be a useful measure to assess therapeutic intervention and provide information on the prognosis. They are simple and safe methods to evaluate quality of life in these patients.

[Methacholine challenge in young children: measurement of resistance by interruption]

The aims of this study were 1. To evaluate the measurement of resistance by interruption (Rint) of bronchoconstriction induced by inhalation of methacholine and 2. To determine a threshold of increase of resistance in young children to differentiate responders from non-responders. Forty-six children (mean age 5 [4.3-6.1] years) referred for methacholine challenge were tested by measurement of Rint and transcutaneous oxygen tension. A fall of 20% or more in oxygen tension from the baseline was used to define the responders. The children studied had a baseline Rint significantly higher than normal (0.84 [0.68-1.01] vs. 0.76 [0.60-0.90] kPa L(-1)s; p < 0.03). Forty-one children were responders and had an increase in Rint significantly different from the non-responders (p < 0/04). An increase in Rint of 35% distinguished responders from non-responders in young children with chronic cough. Interrupter resistance increases significantly during bronchial provocation in responding young children and may be used to measure the degree of bronchoconstriction.

Genome screen in the French EGEA study: detection of linked regions shared or not shared by allergic rhinitis and asthma

In the sample of 295 French EGEA families with at least one asthmatic subject, a genome screen was conducted to identify potential linkage regions specific either to allergic rhinitis (AR) or to asthma as well as those shared by the two diseases. Two binary rhinitis phenotypes based on (1) diagnosis (ARbin1) and (2) symptoms (ARbin2) and a categorical ordered trait (ARcat) were considered. Asthma phenotype was based on answers to a standardized questionnaire plus the presence of bronchial hyper-responsiveness. Linkage analyses were conducted using the maximum likelihood binomial (MLB) method. These analyses provided potential evidence for linkage to three regions in the whole sample: 1p31 for the phenotype defined by ARbin2 plus asthma (P=0.00016), 2q32 for ARbin2 (P=0.00016) and 3p24-p14 for ARcat (P=0.001). Two other regions were detected in the subset of 185 families with at most one asthmatic sib: 9p22 and 9q22-q34 for ARbin1 (P=0.001 and 0.0007, respectively). No region showed evidence for linkage to asthma without being also linked to AR. While 1p31 may contain a genetic determinant common to asthma and AR, 2q32, 3p24-p14, 9p22 and 9q22-q34 are more likely to harbor genetic factors specific to AR.

Clustering patterns of LOD scores for asthma-related phenotypes revealed by a genome-wide screen in 295 French EGEA families

A genome-wide scan for asthma phenotypes was conducted in the whole sample of 295 EGEA families selected through at least one asthmatic subject. In addition to asthma, seven phenotypes involved in the main asthma physiopathological pathways were considered: SPT (positive skin prick test response to at least one of 11 allergens), SPTQ score being the number of positive skin test responses to 11 allergens, Phadiatop (positive specific IgE response to a mixture of allergens), total IgE levels, eosinophils, bronchial responsiveness (BR) to methacholine challenge and %predicted FEV(1). Four regions showed evidence for linkage (P</=0.001): 6q14 for %FEV(1), 12p13 for IgE, 17q22-q24 for SPT and 21q21 for both SPTQ and %FEV(1). Nine other regions indicated smaller linkage signals (0.001<P</=0.005). While most of these regions have been reported by previous asthma and lung function screens, 6q14 appears to be a new region potentially linked to %FEV(1). To determine which of these various asthma phenotypes are more likely to share common genetic determinants, a principal component analysis was applied to the genome-wide LOD scores. This analysis revealed clustering of LODs for asthma, SPT and Phadiatop on one axis and clustering of LODs for %FEV(1), BR and SPTQ on the other, while LODs for IgE and eosinophils appeared to be independent from all other LODs. These results provide new insights into the potential sharing of genetic determinants by asthma-related phenotypes.

Dynamic behavior of respiratory system during nasal continuous positive airway pressure in spontaneously breathing premature newborn infants

The end-expiratory lung-volume level of premature newborn infants is maintained above passive resting volume during active breathing, through the combination of reduced time constant and high respiratory rate. To determine whether nasal continuous positive airway pressure (NCPAP) alters this characteristic dynamic breathing pattern, we studied the effects of various NCPAP levels on the dynamic elevation of end-expiratory lung volume level (DeltaEELV) in spontaneously breathing premature newborn infants, using respiratory inductive plethysmography (RIP). Eleven premature newborn infants with moderate respiratory failure were included. NCPAP levels were set in a random order to 0, 2, 4, and 6 cm H2O. Tidal volume (Vt), rib-cage contribution to Vt (%RC), phase angle between abdominal and thoracic motions (theta), respiratory rate (RR), and inspiratory and expiratory times (Ti and Te) were continuously recorded by RIP. The slope of the linear part of the expiratory flow-volume relation was extrapolated up to zero flow level to evaluate the dynamic elevation of the functional residual capacity (FRC) (DeltaEELV). The time-constant of the respiratory system (tauRS) was calculated as the slope of the linear part of the expiratory flow-volume loop. At NCPAP = 6 cm H2O, DeltaEELV reached 0.6 +/- 0.2 times the Vt at NCPAP = 0 cm H2O. An increase in NCPAP level resulted in a significant decrease in DeltaEELV (P < 0.01). A decrease in DeltaEELV during NCPAP was associated with a significant increase in Te from 0.62 +/- 0.13 sec at NCPAP = 0 cm H2O to 0.80 +/- 0.07 sec at NCPAP = 6 cm H2O (P < 0.05), and a decrease in tauRS from 0.4 +/- 0.1 sec at NCPAP = 0 cm H2O to 0.24 +/- 0.04 sec at NCPAP = 6 cm H2O (P < 0.01). These results indicate that the characteristic spontaneous breathing pattern causing a dynamic elevation of FRC is abolished by NCPAP. We speculate that the dynamic volume-preserving mechanisms resulting from expiratory flow braking are no longer required during NCPAP, as the constant pressure may passively elevate FRC.