Airway mucus

Bacterial and viral inoculants deposited onto airway mucus are normally inactivated by immunoglobins and macrophages while being physically... 

Disruption of these defense mechanisms can lead to bacterial colonization or viral infection. Mucus temperature is important in controlling respiratory infections because decreasing below central body core temperature not only impairs ciliary movement,hut also enhances viral replication,- greatly increasing the likelihood of respiratory infection. Drying of airway mucus also increases the possibility of respiratory infection by reducing mucus thickness and impairing mucociliary clearance, i- i--... 

Holma, B. (1989). Effects of inhaled acids on airway mucus and its consequences for health. Environ. Health Perspect. 79, 109-113. 

Yeadon, M., Price, R. and Payne, A.N. (1994). A method for measurement of upper airway mucus secretion in guinea-pigs in vivo. Am. J. Resp. Crit. Care Med. 149, A329. 

Samet JM, Cheng P-W (1994) The role of the airway mucus in pulmonary toxicology. Environ Health Perspect 102 89-103. 

The Hi Receptor and its Ligands. The H receptor mediates effects, through an increase in cyclic adenosine monophosphate (cAMP). such as gastric acid secretion relaxation of airway smooth muscle and of pulmonary vessels increased lower airway mucus secretion esophageal contraclion inhibition of basophil, but not mas cell histamine release inhibition of neutrophil activation and induction or suppressor T cells. There is no evidence that the H- receptor causes significant modulation of lung function in the healthy human subject or in the asthmatic. 

Figure 9.6 Diagram showing the infrastructure of an airway cilium. CM, central microtubules NX, nexin link RS, radial spoke SH, spoke head CP, projections of the central microtubules, (redrawn from Sanderson, M.J. (1997) Mechanisms controlling airway ciliary activity. In Rogers, D.F. andLethem, M.I. (eds.) Airway Mucus Basic Mechanisms and Clinical Perspectives. Birkhauser Verlag, Basel).

Rogers, D.F. and Lethem, M.I. (eds.) (1997) Airway Mucus Basic Mechanisms and Clinical Perspectives. Birkhauser Verlag, Basel. 

Lundgren, J.D., Davey, R.T.J., Lunc ren, B., Mullol, J., Marom, Z., Logun, C., Baraniuk, J., Kaliner, M.A. and Shel-hamer, J.H. (1991). Eosinophil cationic protein stimulates and major basic protein inhibits airway mucus secretion. J. Allergy Clin Immunol. 87, 689-698. 

The rate of removal of mucus from the airways is determined by such factors as mucus viscosity, the amount of mucus produced, and the degree of ciliary activity. These processes may be influenced by a variety of diseases, including asthma, cystic fibrosis, and chronic bronchitis [82,83], In patients suffering from cystic fibrosis or chronic bronchitis, mucus hypersecretion is evident and mucociliary function is impaired. The failure to clear mucus from the airways leads to airway obstruction and to chronic colonization of the airways with bacterial organisms (which leads to lung infections and airway inflammation and damage). In asthmatic subjects, airway mucus is more viscous and ciliary transport mechanisms are inhibited [82,83]. In these diseases, the therapeutic objective is to improve mucus clearance from the airways. For example, aerosols of water or saline (especially hypertonic saline) promote clearance of mucus by... 

Zahm JM, Galabert C, Chaffin A, Chazalette JP, Grosskopf C, Puchelle E. Improvement of cystic fibrosis airway mucus transportability by recombinant human DNase is related to changes in phospholipid profile. AM J Respir Crit Care Med 1998, 157, 1779-1784. 

Th2-type cytokines such as IL-4, IL-5, and IL-13 orchestrate a cascade of events during development of an allergic inflammatory response. This is demonstrated both clinically and in preclinical animal models (404, 405). IL-4 plays a critical role in the early commitment of ThO cells to Th2 cells and regulates IgE secretion by B-cells. It also induces V-CAM expression on endothelial cells, promotes eosinophilic inflammation, and increases airway mucus production. 

Three of the cell types in the epithelium have secretory functions. These cells are the mucous (goblet) cells, serous cells, and Clara cells. These cells contribute to the secretion of airway mucus, a complex mixture of water, glycoproteins, immunoglobulins, lipids, and salts. The secretion of mucus is a defense function that contributes to the removal of foreign objects from lung airways via the mucociliary transport process, as described in later sections of this chapter. Excess mucus secretion can be detrimental, however, since it can obstruct the movement of air through the airways and is a component of certain pulmonary diseases such as asthma, emphysema, chronic bronchitis, and cystic fibrosis. A hypertrophy of secretory cells in the epithelial layer of the airways is often characteristic of these diseases. 

Cohn L, RJ Homer, A Marinov J Rankin, K Bottomly. 1997. Induction of airway mucus production by T helper 2 (Th2) cells a critical role for interleukin 4 in ceU recruitment but not mucus production. J Exp Med 186 1737. 

The effective elimination of airway mucus and other debris is one of the most important factor that permits successful use of chronic and acute ventilation support (noninvasive and invasive) for patients with either ventilatory or oxygenation impairment. In ventilatory dependent patients, the goals of intervention are to maintain lung compliance and normal alveolar ventilation at all times and to maximize cough flows for adequate bronchopulmonary secretion clearance (6). 

Airway mucus elimination can be impaired by factors external to the lungs and airways. When mucociliary clearing fails and coughing is indispensable for bronehial elearanee, the effectiveness in eliminating secretions is determined by the amount of flow generated in the expulsive phase. These factors depend on the linear veloeity of gas flow, the diameter of the segment, and dynamic compression, and they are manifested basically in the peak cough flow (PCF) (26). 

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