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1.  Effects of topical budesonide on epithelial restitution in vivo in guinea pig trachea. 
Thorax  1995;50(7):785-792.
BACKGROUND--Continuous epithelial shedding and restitution processes may characterise the airways in diseases such as asthma. Epithelial restitution involves several humoral and cellular mechanisms that may potentially be affected by inhaled anti-asthma drugs. The present study examines the effect of a topical steroid on epithelial restitution in vivo in the guinea pig. METHODS--The airway epithelium was mechanically removed from well defined areas of guinea pig trachea without surgery and without damage to the basement membrane or bleeding. An anti-inflammatory dose of budesonide (1 mg) was administered repeatedly to the tracheal surface by local superfusion 24 hours before, at (0 hours), and 24 hours after the denudation. Migration of epithelial cells, formation of a plasma exudation-derived gel, and appearance of luminal leucocytes were recorded by scanning electron microscopy. Cell proliferation was visualised by bromodeoxyuridine immunohistochemistry and tissue neutrophils and eosinophils by enzyme histochemistry. RESULTS--Immediately after creation of the denuded zone ciliated and secretory cells on its border dedifferentiated, flattened out, and migrated speedily (mean (SE) 2.3 (0.3) micron/min) over the basement membrane. After 48 hours the entire denuded zone (800 microns wide) was covered by a tightly sealed epithelium; at this time increased proliferation was observed in new and old epithelium and subepithelial cells. Budesonide had no detectable effect on epithelial dedifferentiation, migration, sealing, or proliferation. Immediately after denudation and continuously during the migration phase plasma was extravasated creating a fibrinous gel rich in leucocytes, particularly neutrophils, over the denuded area. Budesonide had no effect on either the gel or the leucocyte density. CONCLUSIONS--These observations suggest that topical glucocorticoids may not interfere with a fast and efficient restitution of the epithelium in the airways.
PMCID: PMC474655  PMID: 7570417
2.  Effects of nicotine on the human nasal mucosa. 
Thorax  1993;48(6):651-655.
BACKGROUND--Topical application of nicotine and stimulation of tachykinin containing sensory nerves have been shown to produce mucosal exudation of plasma and derangement of the epithelial lining in guinea pig and rat airways. If this occurred in man these effects might contribute to the pathogenesis of airway disease. This study, performed in healthy volunteers without atopy, examined whether nicotine affects the plasma exudation response and the mucosal absorption permeability of the human nasal airway. METHODS--The acute effects of increasing topical doses of nicotine (0.08-2.0 mg) were examined (n = 8) on nasal symptoms (pain), mucosal exudation of plasma (albumin), mucosal secretion of mucin (fucose), and mucosal exudative responsiveness (histamine induced mucosal exudation of albumin). A separate placebo controlled study was carried out to determine whether frequent applications of the high dose of nicotine (2.0 mg given eight times daily for nine days) had any deleterious effects on the airway mucosa detectable as altered responses to histamine challenge. Both mucosal exudation of plasma (n = 12) and mucosal absorption of chromium-51 labelled EDTA (n = 8) were thus examined in nasal airways exposed to both nicotine and histamine. RESULTS--Nicotine caused nasal pain and produced dose dependent mucosal secretion of fucose but failed to produce any mucosal exudation of albumin. The exudative responsiveness to histamine was, indeed, decreased when the challenge was performed immediately after administration of acute doses of nicotine, whereas the responsiveness was unaffected when histamine challenges were carried out during prolonged treatment with nicotine. The nasal mucosal absorption of 51Cr-EDTA in the presence of histamine did not differ between subjects receiving either placebo or nicotine treatment for nine days. CONCLUSIONS--The results indicate that nicotine applied to the human airway mucosa produces pain and secretion of mucin, but inflammatory changes such as mucosal exudation of plasma and epithelial disruption may not be produced. Neurogenic inflammatory responses, which are so readily produced in guinea pig and rat airways, may not occur in human airways.
PMCID: PMC464599  PMID: 8346498
4.  Effects of histamine, ethanol, and a detergent on exudation and absorption across guinea pig airway mucosa in vivo. 
Thorax  1991;46(10):700-705.
This study examined effects of three substances that cause mucosal provocation (histamine, ethanol, and the detergent dioctylsodium sulphosuccinate (DOSS] on the flux of solutes across airway vascular mucosal barriers in anaesthetised guinea pigs. The inward flux was assessed as absorption of iodine-131 labelled albumin (MW 69,000) from the tracheobronchial surface into the circulation and the outward flux as the exudation of two intravenously administered plasma tracers--125I albumin (MW 69,000) and fluorescein isothiocyanate conjugated (FITC) dextran (MW 70,000)--into the airway. The absorption of technetium-99m labelled DTPA (MW 492) from the tracheobronchial airways was determined in separate experiments. Histamine (5.0 nmol) dissolved in 40 microliters saline and superfused on the tracheobronchial mucosal surface caused significant and similar entry of 125I albumin and FITC dextran into the airway lumen. This dose of histamine did not, however, alter the absorption of small (99mTc DTPA) or large (131I albumin) solutes across the airway mucosa. Ethanol (0.17 mumol), superfused in the same way, also caused significant exudation of the plasma tracers into the airway lumen. In addition, ethanol increased the absorption of 131I albumin without causing change in the disappearance rate of 99mTc DTPA. The detergent, DOSS (0.28 nmol), dissolved in ethanol (0.17 mumol), caused a pronounced increase in exudation and much increased absorption of small and large tracer solutes. Thus three patterns of change in airway mucosal barriers were found. The agents that are toxic to membranes, ethanol and DOSS, caused a bidirectional increase in permeability across the mucosa, whereas histamine caused only an outward exudative flux. The results obtained with histamine are similar to those seen previously with bradykinin, capsaicin, and allergen, suggesting that endogenous inflammatory mediators have a role in mucosal defence, producing entry of plasma exudates into the airway lumen without increasing the mucosal absorption of luminal material.
PMCID: PMC463386  PMID: 1721244
5.  Clearance of 99mTc DTPA from guinea pig nasal, tracheobronchial, and bronchoalveolar airways. 
Thorax  1990;45(11):841-845.
Technetium-99m labelled diethylenetriamine penta-acetate (99mTc-DTPA) was used to compare small solute absorption (clearance) from nasal, tracheobronchial, and bronchoalveolar airways in anaesthetised guinea pigs. 99mTc DTPA dissolved in saline was superfused through nasal and orolaryngeal catheters on to nasal and tracheobronchial airways; a small particle aerosol of nebulised 99mTc DTPA was delivered to the bronchoalveolar airways through a tracheostomy. Radioactivity over the appropriate region was then determined with a gamma camera. Mucociliary transport of 99mTc DTPA appeared not to contribute to the disappearance of 99mTc DTPA. Time-activity curves were obtained and half life values calculated by fitting a monoexponential equation to the experimental data. A progressive reduction in 99mTc DTPA was recorded from the nasal and tracheobronchial airways and from the bronchoalveolar airway, suggesting that absorption was occurring. The disappearance of 99mTc DTPA was fastest from the bronchoalveolar region, which also had the largest mucosal surface. The similar shape of the retention curves for the nasal and tracheobronchial regions suggests that the characteristics of nasal absorption of 99mTc DTPA could prove applicable to the tracheobronchial region. It is proposed that the present methods are suited for comparing the pharmacology of small solute absorption across nasal, tracheobronchial, and bronchoalveolar airway mucosa.
PMCID: PMC462780  PMID: 2256011

Results 1-5 (5)