Free radicals in exhaled breath condensate in cystic fibrosis and healthy subjects

Many markers of airway inflammation and oxidative stress can be measured non-invasively in exhaled breath condensate (EBC). However, no attempt has been made to directly detect free radicals using electron paramagnetic resonance (EPR) spectroscopy. Condensate was collected in 14 children with cystic fibrosis (CF) and seven healthy subjects. Free radicals were trapped by 5,5-dimethyl-1-pyrroline-N-oxide. EPR spectra were recorded using a Bruker EMX^® spectrometer. Secondly, to study the source of oxygen centered radical formation, catalase or hydrogen peroxide was added to the condensate. Radicals were detected in 18 out of 21 condensate samples. Analysis of spectra indicated that both oxygen and carbon centered radicals were trapped. Within-subject reproducibility was good in all but one subject. Quantitatively, there was a trend towards higher maximal peak heights of both oxygen and carbon centered radicals in the children with CF. Catalase completely suppressed the signals in condensate. Addition of hydrogen peroxide resulted in increased radical signal intensity. Detection of free radicals in EBC of children with CF and healthy subjects is feasible using EPR spectroscopy.     

Free radicals in exhaled breath condensate in cystic fibrosis and healthy subjects

Many markers of airway inflammation and oxidative stress can be measured non-invasively in exhaled breath condensate (EBC). However, no attempt has been made to directly detect free radicals using electron paramagnetic resonance (EPR) spectroscopy. Condensate was collected in 14 children with cystic fibrosis (CF) and seven healthy subjects. Free radicals were trapped by 5,5-dimethyl-1-pyrroline-N-oxide. EPR spectra were recorded using a Bruker EMX^® spectrometer. Secondly, to study the source of oxygen centered radical formation, catalase or hydrogen peroxide was added to the condensate. Radicals were detected in 18 out of 21 condensate samples. Analysis of spectra indicated that both oxygen and carbon centered radicals were trapped. Within-subject reproducibility was good in all but one subject. Quantitatively, there was a trend towards higher maximal peak heights of both oxygen and carbon centered radicals in the children with CF. Catalase completely suppressed the signals in condensate. Addition of hydrogen peroxide resulted in increased radical signal intensity. Detection of free radicals in EBC of children with CF and healthy subjects is feasible using EPR spectroscopy.     

Deep breaths, methacholine, and airway narrowing in healthy and mild asthmatic subjects.

Deep breaths taken before inhalation of methacholine attenuate the decrease in forced expiratory volume in 1 s and forced vital capacity in healthy but not in asthmatic subjects. We investigated whether this difference also exists by using measurements not preceded by full inflation, i.e., airway conductance, functional residual capacity, as well as flow and residual volume from partial forced expiration. We found that five deep breaths preceding a single dose of methacholine 1) transiently attenuated the decrements in forced expiratory volume in 1 s and forced vital capacity in healthy (n = 8) but not in mild asthmatic (n = 10) subjects and 2) increased the areas under the curve of changes in parameters not preceded by a full inflation over 40 min, during which further deep breaths were prohibited, without significant difference between healthy (n = 6) and mild asthmatic (n = 16) subjects. In conclusion, a series of deep breaths preceding methacholine inhalation significantly enhances bronchoconstrictor response similarly in mild asthmatic and healthy subjects but facilitates bronchodilatation on further full inflation in the latter.     

Adrenergic airway vascular smooth muscle responsiveness in healthy and asthmatic subjects.

The purpose of the present study was to determine the responsiveness of airway vascular smooth muscle (AVSM) as assessed by airway mucosal blood flow (Qaw) to inhaled methoxamine (alpha(1)-agonist; 0.6-2.3 mg) and albuterol (beta(2)-agonist; 0.2-1.2 mg) in healthy [n = 11; forced expiratory volume in 1 s, 92 +/- 4 (SE) % of predicted] and asthmatic (n = 11, mean forced expiratory volume in 1 s, 81 +/- 5%) adults. Mean baseline values for Qaw were 43.8 +/- 0.7 and 54.3 +/- 0.8 microl. min(-1). ml(-1) of anatomic dead space in healthy and asthmatic subjects, respectively (P < 0.05). After methoxamine inhalation, the maximal mean change in Qaw was -13.5 +/- 1.0 microl. min(-1). ml(-1) in asthmatic and -7.1 +/- 2.1 microl. min(-1). ml(-1) in healthy subjects (P < 0.05). After albuterol, the mean maximal change in Qaw was 3.0 +/- 0.8 microl. min(-1). ml(-1) in asthmatic and 14.0 +/- 1.1 microl. min(-1). ml(-1) in healthy subjects (P < 0.05). These results demonstrate that the contractile response of AVSM to alpha(1)-adrenoceptor activation is enhanced and the dilator response of AVSM to beta(2)-adrenoceptor activation is blunted in asthmatic subjects.     

Lymphocyte beta-adrenergic refractoriness induced by theophylline or metaproterenol in healthy and asthmatic subjects

Beta-adrenergic refractoriness was assessed in human lymphocytes following in vivo administration of the beta-adrenergic agonist, metaproterenol, the phosphodiesterase inhibitor, theophylline, or both concomitantly, to normal and asthmatic subjects. In normal subjects both beta-adrenergic receptor number and isoproterenol stimulated cAMP response decreases during therapy with metaproterenol (59±3; 51±16% of control, respectively), theophylline (76±6; 78±16), or concommitant metaproterenol and theophylline (47±4; 69±13). The asthmatic subjects were of two types; one type responding to metaproterenol or theophylline therapy by down regulation of receptor number to zero or near zero values, and a second group of asthmatics insensitive to down regulation of receptor number. The results suggest that the induction of the refractory state is different between asthmatics and non-asthmatics, and that there may be a role for cAMP in the development of beta-adrenergic refractoriness, in vivo.     

Respiratory and abdominal muscle responses to expiratory threshold loading in cystic fibrosis.

We hypothesized that the hyperinflation and pulmonary dysfunction of cystic fibrosis (CF) would distort feedback and therefore alter the abdominal muscle response to graded expiratory threshold loads (ETLs). We compared the respiratory and abdominal muscle responses with graded ETLs of seven CF patients with severe lung dysfunction with those of matched healthy control subjects in the supine and 60 degrees head-up positions. Breathing frequency, tidal volume, and ventilatory timing were determined from inspiratory flow recordings. Abdominal electromyograms (EMGs) were detected with surface electrodes placed unilaterally over the external and internal oblique and the rectus abdominis muscles. Thresholds, times of onset, and durations of phasic abdominal activity were determined from raw EMGs; peak amplitudes were determined from integrated EMGs. Graded ETLs were imposed by submerging a tube from the expiratory port of the breathing valve into a column of water at depths of 0-25 cmH2O. We found that breathing frequency, tidal volume, and expired minute ventilation were higher in CF patients than in control subjects during low ETLs; a change in body position did not alter these ventilatory responses in the CF patients but did in the control subjects. All CF patients, but none of the control subjects, had tonic abdominal activity while supine. CF patients recruited abdominal muscles at lower loads, earlier in the respiratory cycle, and to a higher recruitment level in both positions than the control subjects, but burst duration of phasic activity was not different between groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Respiratory sound analysis in healthy and pathological subjects: A wavelet approach

In this paper we describe the application of a wavelet analysis-based method, to characterize the frequency power distribution of the unsteady respiratory sound signals in order to better discriminate the healthy state of a given subject. To evaluate the methodology, both normal tracheal sounds as well as adventitious respiratory sounds were investigated. In particular, our analysis shows the possibility to extract useful statistical information on the energy content and its mean frequency distribution giving us a quantitative characteristic hallmark of the respiratory pattern. The presence of sound anomalies can be pointed out through some specific patterns of the wavelet mean power spectra and thus the localization of the related quartiles which can be used as simple and efficient diagnostic indices. In this study the method has been applied in healthy subjects and patients with different respiratory diseases. Results show that different power spectra patterns characterize health from disease. Some preliminary results indicate also that pathological patterns can change as result of therapeutical interventions like mechanical ventilation.     

Airway distensibility in healthy and asthmatic subjects: effect of lung volume history.

Anatomic dead space (VD) is known to increase with end-inspiratory lung volume (EILV), and the gradient of the relationship has been proposed as an index of airway distensibility (DeltaVD). The aims of this study were to apply a rapid method for measuring DeltaVD and to determine whether it was affected by lung volume history. VD of 16 healthy and 16 mildly asthmatic subjects was measured at a number of known EILVs by using a tidal breathing, CO(2)-washout method. The effect of lung volume history was assessed by using three tidal breathing regimens: 1) three discrete EILVs (low/medium/high; LMH); 2) progressively decreasing EILVs from total lung capacity (TLC; TLC-RV); and 3) progressively increasing EILVs from residual volume (RV; RV-TLC). DeltaVD was lower in the asthmatic group for the LMH (25.3 +/- 2.24 vs. 21.2 +/- 1.66 ml/l, means +/- SE) and TLC-RV (24. 3 +/- 1.69 vs. 18.7 +/- 1.16 ml/l) regimens. There was a trend for a lower DeltaVD in the asthmatic group for the RV-TLC regimen (23.3 +/- 2.19 vs. 18.8 +/- 1.68 ml/l). There was no difference in DeltaVD between groups. In conclusion, mild asthmatic subjects have stiffer airways than normal subjects, and this is not obviously affected by lung volume history.     

Bolus transit patterns in healthy subjects: a study using simultaneous impedance monitoring, videoesophagram, and esophageal manometry

Impedance monitoring (Imp) measures bolus transit. Combining Imp with manometry (EM) allows the effect of contractile patterns on transit to be assessed. The objective of this study is to identify bolus transit patterns in normal subjects, correlate Imp findings with the gold standard barium esophagram (Ba), and compare bolus transit with concomitant EM findings. Simultaneous Ba-Imp-EM was performed for 2 min in 15 normal volunteers (women, 11; age, 43 yr). Combined impedance-pressure sites were 5, 10, 15, 20 cm above the lower esophageal sphincter (LES). Boluses (10 ml) of 45% barium mixed with 0.9% NaCl were swallowed at > or = 20-s intervals (5-6 swallows/subject). Imp and Ba showed three bolus transit patterns, and the two methods were in agreement on the pattern type in 97% (83/86) of swallows. Normal bolus transit was found in 73% (61/83), and each had normal peristalsis and contraction amplitude. Stasis in the proximal esophagus occurred in 7 of 83 swallows despite normal manometric parameters in 4 of 7 swallows. Retrograde escape of a residue of incompletely cleared bolus from just above the LES to the site 5 cm above occurred in 14 of 83 swallows. Retrograde escape was triggered by the next swallow, occurred despite normal manometric parameters, and did not occur if the swallow interval was >30 s. In 55% (47/86) of swallows, air accumulated in the distal esophagus and persisted there for a mean of 3.6 s until cleared into the stomach. We conclude that impedance monitoring is a valid transit test and describe bolus transit patterns in normal subjects for comparison with patients with esophageal motility disorders.     

Infection,inflammation and exercise in cystic fibrosis

Regular exercise is positively associated with health. It has also been suggested to exert anti-inflammatory effects. In healthy subjects, a single exercise session results in immune cell activation, which is characterized by production of immune modulatory peptides (e.g. IL-6, IL-8), a leukocytosis and enhanced immune cell functions. Upon cessation of exercise, immune activation is followed by a tolerizing phase, characterized by a reduced responsiveness of immune cells. Regular exercise of moderate intensity and duration has been shown to exert anti-inflammatory effects and is associated with a reduced disease incidence and viral infection susceptibility. Specific exercise programs may therefore be used to modify the course of chronic inflammatory and infectious diseases such as cystic fibrosis (CF).Patients with CF suffer from severe and chronic pulmonary infections and inflammation, leading to obstructive and restrictive pulmonary disease, exercise intolerance and muscle cachexia. Inflammation is characterized by a hyper-inflammatory phenotype. Patients are encouraged to engage in exercise programs to maintain physical fitness, quality of life, pulmonary function and health.In this review, we present an overview of available literature describing the association between regular exercise, inflammation and infection susceptibility and discuss the implications of these observations for prevention and treatment of inflammation and infection susceptibility in patients with CF.     

Role of nitric oxide in the airway response to exercise in healthy and asthmatic subjects.

A role of nitric oxide (NO) has been suggested in the airway response to exercise. However, it is unclear whether NO may act as a protective or a stimulatory factor. Therefore, we examined the role of NO in the airway response to exercise by using N-monomethyl-L-arginine (L-NMMA, an NO synthase inhibitor), L-arginine (the NO synthase substrate), or placebo as pretreatment to exercise challenge in 12 healthy nonsmoking, nonatopic subjects and 12 nonsmoking, atopic asthmatic patients in a double-blind, crossover study. Fifteen minutes after inhalation of L-NMMA (10 mg), L-arginine (375 mg), or placebo, standardized bicycle ergometry was performed for 6 min using dry air, while ventilation was kept constant. The forced expiratory volume in 1-s response was expressed as area under the time-response curve (AUC) over 30 min. In healthy subjects, there was no significant change in AUC between L-NMMA and placebo treatment [28.6 +/- 17.0 and 1.3 +/- 20.4 (SE) for placebo and L-NMMA, respectively, P = 0.2]. In the asthmatic group, L-NMMA and L-arginine induced significant changes in exhaled NO (P < 0.01) but had no significant effect on AUC compared with placebo (geometric mean +/- SE: -204.3 +/- 1.5, -186.9 +/- 1.4, and -318.1 +/- 1.2%. h for placebo, L-NMMA, and L-arginine, respectively, P > 0.2). However, there was a borderline significant difference in AUC between L-NMMA and L-arginine treatment (P = 0.052). We conclude that modulation of NO synthesis has no effect on the airway response to exercise in healthy subjects but that NO synthesis inhibition slightly attenuates exercise-induced bronchoconstriction compared with NO synthase substrate supplementation in asthma. These data suggest that the net effect of endogenous NO is not inhibitory during exercise-induced bronchoconstriction in asthma.     

Quantitative variation in cystic fibrosis-associated proteins in cystic fibrosis patients,carriers, and controls

Summary Serum samples from patients with cystic fibrosis (CF), obligate heterozygotes, and normal controls have been examined by isoelectric focusing (IEF). Our results suggest that cystic fibrosis protein (CFP) is a normal serum protein exhibiting quantitative variation primarily dependent on possession of the CF allele. It is concluded that detection of CFP by IEF is an inappropriate screening test for the CF gene due to lack of specificity.     

An outward-rectifying potassium channel in primary cultures of sweat glands from cystic fibrosis subjects

We have previously described a high conductance calcium-activated 'maxi K' channel in primary cultures of human eccrine sweat gland cells both from normal subjects and those with cystic fibrosis. In further studies we have now identified a potassium-selective channel of much lower conductance which shows outward-rectification and which is present in sweat glands isolated from cystic fibrosis subjects. In experiments with inside-out patches using symmetrical pipette and bath solutions containing 140 mM K+ the channel showed an outward slope conductance (at +50 mV) of approximately 26 pS and an inward conductance (at -50 mV) of approximately 11 pS. When K+ in the bath was replaced by Na+ the reversal potential shifts to reveal a permeability ratio PK/PNa approximately 40 Unlike the maxi-K+ channel, the outward-rectifying channel does not show sensitivity to Ca2+. Channels were found in cells cultured from the glands of four out of five cystic fibrosis subjects. In cells cultured from 30 subjects who did not have cystic fibrosis, an outward-rectifying potassium channel was seen in only one out of approximately 3000 patches.     

Chloride channels, Golgi pH and cystic fibrosis

Cystic fibrosis (CF) is associated with a defect in a cAMP-activated chloride channel in secretory epithelia, which leads to decreased fluid secretion. In addition, many mucus glycoproteins show decreased sialylation but increased sulphation. We have recently shown that the pH of intracellular organelles is elevated in CF cells, due to defective chloride conductance in the vesicle membranes. We postulate that this may affect the activity of sialyl-, fucosyl- and sulphotransferases, and thus explain the abnormal glycosylation. Defects in sialylation of glycolipids might also generate receptors for Pseudomonas, which infects the respiratory tract of CF patients.