Perfluorooctyl bromide (perflubron) stimulates mucin secretion in the ferret trachea

Perfluorodecalin lavage of a longstanding lung atelectasis in a child with spinal muscle atrophy

OBJECTIVE

Persistent lung atelectasis is difficult to treat and perfluorochemical (PFC) liquid may be an option for bronchioalveolar lavage (BAL).

CASE REPORT

A 4-year-old girl with spinal muscle atrophy was admitted in respiratory failure. On admission, the X-ray confirmed the persistence of total right-sided lung atelectasis, which had been present for 14 months. She was endotracheally intubated and ventilated from the day of admission. BAL with normal saline was performed twice without improvement. Following failed extubation and being dependent on continuous respiratory support, a trial of BAL using PFC liquid (Perfluorodecalin HP) was carried out. The PFC was delivered through the endotracheal tube on three consecutive days. A loading dose of 3 ml/kg was administered, followed by a varying dose in order to more effectively lavage the lungs. She tolerated the procedure well the first 2 days, although there were no clinical signs of improvement in the atelectasis. Intentionally, higher inflation pressures were applied after PFC instillation on day 3. Chest X-ray then showed hazy infiltrates on her left lung and she required more ventilatory support. However, lung infiltrates cleared over the next 3 days. A tracheotomy was done 6 days after the last PFC instillation. She had a slow recovery and was successfully decanulated. Clinical improvement of lung function was seen including less need of BiPAP and oxygen. A chest CT scan showed then functional lung tissue appearing in the previous total atelectatic right lung.

CONCLUSION

Lavage with PFC can safely be performed with a therapeutic effect in a child with unilateral total lung atelectasis.

Quantitation of major protein constituents of murine intestinal fluid

The gastrointestinal tract is a hostile biological environment, yet not all ingested materials are destroyed. The minute differences that determine whether a substance persists or is digested, liberated, adsorbed, excreted, or taken up are still poorly understood. Most attempts to investigate the events occurring during an orogastrointestinal passage rely on simplified in vitro systems where an analyte is exposed to artificial intestinal fluids. To closely mimic the events in the gastrointestinal tract, the exact intestinal fluid composition and the in vivo concentration of its constituents must be known. The widely used lavage procedures, however, dilute the intestinal fluids to an extent that precludes recalculation to the original concentrations. Thus, we developed procedures with which undiluted murine intestinal fluid can be harvested; determined the in vivo concentrations of the digestive enzymes trypsin, chymotrypsin, and elastase and the adsorbents mucin and immunoglobulin A in small intestinal fluid of fasted and unfasted female Balb/c mice; and identified chymotrypsin and immunoglobulin A as valid endogenous dilution markers for the recalculation of aqueous lavages. With these technologies and information at hand, more reliable investigations on the fate of allergens, pathogens, food, and anthropogenic xenobiotics in the gastrointestinal tract will be possible.

Liquid ventilation: an adjunct for respiratory management

Although significant advances in respiratory care have reduced mortality of patients with respiratory failure, morbidity persists, often resulting from iatrogenic mechanisms. Mechanical ventilation with gas has been shown to initiate as well as exacerbate underlying lung injury, resulting in progressive structural damage and release of inflammatory mediators within the lung. Alternative means to support pulmonary gas exchange while preserving lung structure and function are therefore required. Perfluorochemical (PFC) liquids are currently used clinically in a number of ways, such as intravascular PFC emulsions for volume expansion/oxygen carrying/angiography and intracavitary neat PFC liquid for image contrast enhancement or vitreous fluid replacement. As a novel approach to replace gas as the respiratory medium, liquid assisted ventilation (LAV) with PFC liquids has been investigated as an alternative respiratory modality for over 30 years. Currently, there are several theoretical and practical applications of LAV in the immature or mature lung at risk for acute respiratory distress and injury associated with mechanical ventilation.

Hyperosmolar solutions stimulate mucus secretion in the ferret trachea

STUDY OBJECTIVES

Inhalation of hypertonic saline or mannitol solutions acutely increases mucociliary clearance. Because increased clearance is often coupled with increased mucus secretion, we hypothesized that hyperosmolar agents would stimulate mucus secretion.

SETTING AND SUBJECTS

The isolated tracheae of healthy young adult ferrets were studied in a basic research laboratory.

MEASUREMENTS AND RESULTS

We demonstrated that there was a dose-dependent increase in mucin secretion by enzyme-linked lectin assay after incubation with 1.69 g/dL (597 mOsm/L), 3.69 g/dL (1,192 mOsm/L), 5.69 g/dL (1,823 mOsm/L), and 10.69 g/dL (3,612 mOsm/L) of saline solution over Krebs-Henseleit solution control (288 mOsm/L) [p < 0.01 for 1.69 g/dL of saline solution and p < 0.0001 for others]. Mannitol solution, 15 g/dL (1,040 mOsm/L), also significantly increased mucin secretion (n = 4, p < 0.005). There was a 47% and 54% increase in secretion of the serous cell product lysozyme after exposure to 3.69 g/dL (1,192 mOsm/L) and 10.69 g/dL (3,612 mOsm/L) saline solutions, respectively (n = 5, p < 0.05). Secretion was only stimulated when the hyperosmolar exposure was on the luminal side of the epithelium. Mucin secretion was induced within minutes of 3.69 g/dL of saline solution exposure, and this increased mucin secretion quickly peaked. The ratio of mucin to lysozyme secretion was approximately 2. This ratio appeared to be independent of the osmotic concentration of the stimulus and therefore of secretory rate.

CONCLUSIONS

Mucus secretion is markedly stimulated in response to hyperosmolarity. This may be a protective response. These results also suggest that the therapeutic use of hyperosmolar aerosols should be evaluated with care when used for patients with mucus hypersecretion and impaired mucus clearance.

Airway surface liquid recovered by lavage with perfluorocarbon liquid in cats

BACKGROUND

Airway surface liquid (ASL) is difficult to sample. Lavage with an immiscible perfluorocarbon (PFC) liquid to recover ASL was evaluated in cats.

MATERIALS AND METHODS

Six wild-type cats underwent bronchoscopic lavage with a PFC (perfluorohexane), with the bronchoscope wedged in the feline equivalent of the right lower lobe. Two cats (control animals) were lavaged with a saline vehicle only. Four procedures were performed on each animal at 2-3-week intervals. Ionic composition of ASL was determined by flame photometry.

RESULTS

Cats lavaged with PFC showed significantly more acute respiratory distress than those lavaged with saline (respiratory rate following procedure: PFC, 47 +/- 5 min-1 vs. saline, 27 +/- 2 min-1, P < 0.05; O2 saturation: PFC 80 +/- 1% vs. saline, 91 +/- 1%, P < 0.01). The PFC group also had clinical evidence of chronic respiratory compromise (mean respiratory rate before next anaesthetic; PFC, 37 +/- 2 min-1 vs. saline, 20 +/- 3 min-1, P < 0.01). The PFC-lavaged lungs demonstrated persistent radiographic changes and histological evidence of small airways obstruction with distal alveolar damage. Six PFC lavages yielded ASL samples (> 100 microL) which were sufficient for analysis. Mean (+/- SEM) ionic concentrations in these samples were Na+ 157.4 +/- 14.5 mmol L-1, Cl- 150.5 +/- 16.8 mmol L-1 and K+ 10.1 +/- 1.7 mmol L-1.

CONCLUSIONS

Perfluorocarbon lavage can be used to collect unmodified ASL from the distal lung. However, repeated lavage with perfluorohexane was associated with significant pathological changes in this study.

Regulation of secretion from mucous and serous cells in the excised ferret trachea

Mucus hypersecretion is an important characteristic of many airway diseases. Mucin is the major component of mucus, and is secreted from surface goblet cells of the airway epithelium and mucous cells of submucosal glands. Lysozyme is an enzyme secreted by serous cells of airway submucosal glands. We hypothesized that secretagogues acting through different pathways would have different effects on tracheal mucin and lysozyme secretion. We used a sandwich enzyme-linked lectin assay (ELLA) to measure mucin-like glycoprotein secretion and a spectrophotometric method to measure lysozyme secretion from isolated ferret tracheal segments. We evaluated the secretory response to four secretagogues; prostaglandin F(2alpha) (PGF(2alpha)), adenosine triphosphate (ATP), methacholine (MCh), and human neutrophil elastase (HNE). Each agent stimulated mucin and lysozyme secretion. The relative potency was PGF(2alpha)< or =ATP<MCh<HNE for mucin and ATP< or =PGF(2alpha)<MCh<HNE for lysozyme secretion. We showed that there is an anatomic gradient for constitutive and stimulated mucin and lysozyme secretion with the distal tracheal segments secreting more mucin and lysozyme per gram of tissue than the proximal segments. This robust model system can be used to evaluate the regulation of airway mucous and serous cell secretion and to assess the effect of agents that might alter the secretory response. We confirm that on an equimolar basis, HNE is one of the most potent mucus secretagogues.