Exhaled breath condensate: methodological recommendations and unresolved questions

Collection of exhaled breath condensate (EBC) is a noninvasive method for obtaining samples from the lungs. EBC contains large number of mediators including adenosine, ammonia, hydrogen peroxide, isoprostanes, leukotrienes, nitrogen oxides, peptides and cytokines. Concentrations of these mediators are influenced by lung diseases and modulated by therapeutic interventions. Similarly EBC pH also changes in respiratory diseases. The aim of the American Thoracic Society/European Respiratory Society Task Force on EBC was to identify the important methodological issues surrounding EBC collection and assay, to provide recommendations for the measurements and to highlight areas where further research is required. Based on the currently available evidence and the consensus of the expert panel for EBC collection, the following general recommendations were put together for oral sample collection: collect during tidal breathing using a noseclip and a saliva trap; define cooling temperature and collection time (10 min is generally sufficient to obtain 1-2 mL of sample and well tolerated by patients); use inert material for condenser; do not use resistor and do not use filter between the subject and the condenser. These are only general recommendations and certain circumstances may dictate variation from them. Important areas for future research involve: ascertaining mechanisms and site of exhaled breath condensate particle formation; determination of dilution markers; improving reproducibility; employment of EBC in longitudinal studies; and determining the utility of exhaled breath condensate measures for the management of individual patients. These studies are required before recommending this technique for use in clinical practice.

Assessment of exhaled nitric oxide kinetics in healthy infants

Exhaled nitric oxide (Fe(NO)) measurements provide a noninvasive approach to the evaluation of airway inflammation. Flow-independent NO exchange parameters [airway NO transfer factor (D(NO)) and airway wall NO concentration (Cw(NO))] can be estimated from Fe(NO) measurements at low flows and may elucidate mechanisms of disturbances in NO exchange. We measured Fe(NO) in sedated infants by using an adaptation of a raised lung volume rapid thoracic compression technique that creates forced expiration through a mass-flow controller that lasts 5-10 s, at a constant preset flow. We measured Fe(NO) at expired flows of 50, 25, and 15 ml/s in five healthy infants (7-31 mo). Median Fe(NO) increased [24, 40, and 60 parts per billion (ppb)] with decreasing expiratory flows (50, 25, and 15 ml/s). Group median (range) for D(NO) and Cw(NO) were 12.7 (3.2-37) x 10(-3) nl. s(-1). ppb(-1) and 108.9 (49-385) ppb, respectively, similar to values reported in healthy adults. Exhaled NO is flow dependent; flow-independent parameters of exhaled NO kinetics can be assessed in infants and are similar to values described in adults.

Nitric oxide accumulation in the nonventilated nasal cavity

BACKGROUND

Nasal nitric oxide is present in high concentrations in the upper airway relative to the lower respiratory tract.

OBJECTIVE

To explore the rate of nitric oxide accumulation in the nonventilated nasal cavity.

METHODS

In 9 healthy subjects previously trained to close the soft palate, steady-state plateau nitric oxide levels were recorded while air was aspirated through the nasal airway in series at a constant flow rate. Nitric oxide was then allowed to accumulate in the nasal cavity by occluding both nares and keeping the velum closed. After varying occlusion times, peak nitric oxide levels and a second plateau were ascertained.

RESULTS

While the subjects aspirated air at a constant flow, there was a slow rise to a first nitric oxide plateau. On opening to the analyzer after the accumulation period, the peak nitric oxide level was several times higher than the initial plateau (range, 2810-19008 ppb) and then slowly returned to previous plateau levels. There was no significant difference between initial and second plateau nitric oxide levels for any period. The accumulated nitric oxide peak increased in direct proportion to the accumulation time (P<.001).

CONCLUSIONS

Nitric oxide concentrations accumulate in the nonventilated nasal cavity in proportion to the time of nonventilation. Peak nasal nitric oxide values after accumulation are similar to published sinus nitric oxide measurements obtained by direct puncture. These results suggest an important alternative source of nitric oxide in humans.

Methotrexate in steroid-dependent asthma: long-term results

Treatment of 21 steroid-dependent asthmatic patients with methotrexate (MTX) 15 mg/week was prospectively evaluated for a mean of 14.7 (SD 3.7) months. Before MTX, therapy consisted of a mean prednisone dose of 16.6 (SD 9.2) mg, in addition to inhaled beclomethasone/budesonide (mean daily dose 1157 (SD 330) micrograms) and bronchodilators. Thirteen patients were weaned from all regular systemic steroid therapy, a 50% or more reduction was achieved in four patients, and a less than 50% reduction in four patients. Abnormal liver function tests were noted in six of the 21 patients; this resolved despite continuation of MTX in five. In one patient, MTX was stopped because of symptoms as well as a fivefold rise in serum transaminases, and a speedy resolution was noted. Gastrointestinal side-effects were reported in six patients but were resolved in five with intramuscular MTX. There were no hematologic or pulmonary complications. We conclude that MTX appears to be both safe and efficacious as a steroid-sparing agent in most steroid-dependent asthmatic patients when taken over a long period.

Effect of substance P on rat gastrointestinal transit

The in vivo effect of substance P and related peptide analogs on gastrointestinal transit in unanesthetized rats was studied. Fasted male rats were given intragastrically 0.5 ml of a powdered charcoal (BaSo4.H2O) meal and were concomitantly injected intraperitoneally with 8 micrograms/kg of substance P or a related peptide. In control rats, the percentage of small intestine traversed by the meal 15 min after feeding was 44.9 +/- 1.4 (N = 12). Substance P, [pGlu6]SP, [pGlu6, gPhe8, mGly9]SP and [pGlu5, N-MePhe8, N-MeGly9]SP significantly accelerated intestinal transit: 59.5 +/- 3.1% (N = 7); 66.0 +/- 3.8% (N = 14), 66.8 +/- 2.4% (N = 25), and 58.4 +/- 4.4% (N = 4), respectively. Concomitant injection of [pGlu6]SP and BOC-Phe-Phe-Gly-NHOH, an inhibitor of enzyme degradation at a dose of 800 micrograms/kg lowered by 10-fold the dose of [pGlu6]SP needed to induce the same degree of intestinal transit acceleration. These results indicate that in rats, substance P and related peptides accelerate gastrointestinal transit.

Corynebacterium xerosis endocarditis

Bacterial endocarditis due to Corynebacterium xerosis developed in a previously healthy person. Diphtheroid infection is a rare cause of endocarditis and, when present, it usually affects immunocompromised hosts or prosthetic valves. There are few reports of diphtheroid endocarditis on intact valves, and, to our knowledge, this is the first case in which the offending organism was identified as C xerosis. We call attention to the virulence of C xerosis in a person with no previous valvular disease.