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Nasal Function
The eosinophil, found commonly in tissue in asthma, allergic rhinitis, and nasal polyposis, is generally believed to be cleared from tissue by a combination of apoptosis and subsequent phagocytosis. Uller and coworkers used histochemical and ultrastructural techniques to examine human nasal polyp tissue and peripheral blood eosinophils for apoptosis, secondary necrosis, and cytolysis. They found that apoptotic eosinophils are exceedingly rare in human nasal polyp tissue. Although macrophages were seen commonly in tissue, histochemical techniques and transmission electron microscopy did not suggest engulfment of eosinophils. They found evidence that eosinophils migrate between epithelial cells into the airway lumen and that proinflammatory disintegration through cytolysis occurs as a primary event. The authors concluded that local turnover of tissue eosinophils in diseased airways occurs through pathways other than apoptosis, including paraepithelial migration and cytolysis.
Hypoxia is known to inhibit the activity and expression of ion-transport proteins of cultured alveolar epithelial cells. To determine whether in vivo hypoxia inhibits lung ion transport, Mairbaurl and coworkers measured transepithelial nasal potentials before and during a stay at high altitude (4,559 m). In normoxia, total nasal potential was about 20% higher in 12 control subjects than in 10 mountaineers with a history of high-altitude pulmonary edema; the groups did not differ in nasal potentials that could be inhibited by amiloride. At high altitude, total nasal potential increased by 250% in both groups; nasal potential sensitive to amiloride decreased by about 80% solely in the control subjects, and the portion of nasal potential sensitive to chloride ion almost doubled. Because nasal dryness is common at high altitude, the effect of controlled humidity of 50% was also studied during normobaric hypoxia: no change was observed in total nasal potential or in the fractions sensitive to amiloride or chloride. The authors conclude that an increase in chloride secretion compensating for drying of the nasal mucosa is responsible for the transepithelial nasal potential at high altitude, and that changes in nasal potentials at high altitude reflect a specific response of the nasal mucosa and do not reflect the alveolar epithelium.
Bronchoprotection induced by deep inspiration protects against the development of airway obstruction induced by spasmogens. To determine whether bronchoprotection induced by deep inspiration is not active against allergic reactions, Pyrgos and coworkers
studied 10 subjects with allergic rhinitis. Methacholine induced a 37% decrease in FEV1; when five deep inspirations preceded the methacholine, the decrease in FEV1 was 15%. Inhalation of allergen in the absence of deep inspiration induced a decrease in FEV1 of 25%; when deep inspirations preceded the allergen, the decrease in FEV1 was 29%. The authors conclude that the bronchoprotective action of deep inspirations is absent against allergic reactions.
Citations 1-3 of 3 total displayed.
Occurrence of Apoptosis, Secondary Necrosis, and Cytolysis in Eosinophilic Nasal Polyps
- Lena Uller, Morgan Andersson, Lennart Greiff, Carl G. A. Persson, and Jonas S. Erjefält
Am. J. Respir. Crit. Care Med. 170: 742 -747. First published online as doi:10.1164/rccm.200402-240OC
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Absence of Deep Inspiration–induced Bronchoprotection against Inhaled Allergen
- George Pyrgos, Trisevgeni Kapsali, Solbert Permutt, and Alkis Togias
Am. J. Respir. Crit. Care Med. 167: 1660-1663.
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Nasal Epithelium Potential Difference at High Altitude (4,559 m): Evidence for Secretion
- Heimo Mairbäurl, Jörn Weymann, Andreas Möhrlein, Erik R. Swenson, Marco Maggiorini, J. Simon R. Gibbs, and Peter Bärtsch
Am. J. Respir. Crit. Care Med. 167: 862 -867. First published online as doi:10.1164/rccm.200208-864OC
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