Mucus secretion

On a vitamin A-deficient diet, mucus-secreting tissues become keratinized. This condition tends to occur in the trachea, the skin, the saUvary glands, the cornea, and the testes. When this occurs in the cornea, it can be followed by blindness. Vitamin A deficiency is the principal cause of blindness in the very young. This problem is particularly acute in the third world (8). 

Frequently, the EAR is followed by a late phase response 4-6 h later and it is caused by the pulmonary sequestration of eosinophils, neutrophils, mast cells, and T-lymphocytes. This leukocyte recruitment depends on mast cell-derived mediators such as TNFa and various chemokines, as well as on the expression of adhesion molecules on leukocytes (e.g. VLA-4, CD11/18) and vascular endothelial cells (e.g. VCAM-1, ICAM-1, E-selectin). Products of these leukocytes have several functions First, they cause the second phase of bron-choconstriction, mucus secretion, and airway swelling second, they cause tissue destruction third, they launch and entertain the chronic inflammation. 

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. 

In the central airways (the trachea, bronchi, and bronchioles greater than 2 to 4 mm in internal diameter), inflammatory cells and mediators stimulate mucus-secreting gland hyperplasia... 

Pulmonary disease is characterized by thick mucus secretions, impaired mucus clearance, chronic airway infection and colonization, obstruction, and an exaggerated neutrophil-dominated inflammatory response. 

Ulcer formation is the net result of a lack of homeostasis between factors within the gastrointestinal tract responsible for the breakdown of food (e.g., gastric acid and pepsin) and factors that promote epithelial defense and repair (e.g., bicarbonate, mucus secretion, and prostaglandins). 

Elder flowers are considered neutral, bitter, drying and cooling. They are also slightly sweet. This is part of what empowers elder to cool a fever, heal infection and help dry mucus secretions. Thus elder is suitable for damp conditions such as excess mucus and fluid congestion. Thorton s 19-century Family Herbal declared that elder helps to "promote all the fluid secretions."... 

Precellular solute ionization dictates membrane permeability dependence on mucosal pH. Therefore, lumenal or cellular events that affect mucosal microclimate pH may alter the membrane transport of ionizable solutes. The mucosal microclimate pH is defined by a region in the neighborhood of the mucosal membrane in which pH is lower than in the lumenal fluid. This is the result of proton secretion by the enterocytes, for which outward diffusion is slowed by intestinal mucus. (In fact, mucosal secretion of any ion coupled with mucus-restricted diffusion will provide an ionic microclimate.) Important differences in solute transport between experimental systems may be due to differences in intestinal ions and mucus secretion. It might be anticipated that microclimate pH effects would be less pronounced in epithelial cell culture (devoid of goblet cells) transport studies than in whole intestinal tissue. 

Secretion of the large intestine. The large intestine produces an alkaline mucus secretion, the function of which is to protect the mucosa from mechanical or chemical injury. Mucus provides lubrication to facilitate the movement of the contents of the lumen. Bicarbonate ion neutralizes the irritating acids produced by local bacterial fermentation colonic secretion increases in... 

Fig. 11.4. Model for cholinergic signalling in the intestinal mucosa, providing a possible rationale for AChE secretion by parasitic nematodes. ACh released from enteric cholinergic motor neurons stimulates chloride secretion, mucus secretion and Paneth cell exocytosis through muscarinic receptors. Secretory responses may be modulated by mast cell mediators, either directly or via the induction of neural reflex programmes. The role of muscarinic receptor-positive cells in the lamina propria of rats infected with N. brasiliensis is undetermined, as are potential mechanisms of trans-epithelial transport of the enzymes. Adapted from Cooke (1984).

Specian, R.D. and Neutra, M.R. (1980) Mechanism of rapid mucus secretion in goblet cells stimulated by acetylcholine. Journal of Cell Biology 85, 626-640. 

It is the quality rather than the quantity of the goblet cell response that is important in resistance to nematode infection, as even strains that are susceptible to I. muris (harbouring chronic infections) have a dramatic increase in the number of goblet cells and amount of mucus secreted during infection. Indeed, detailed analysis of the biochemical nature of... 

Although it appears that severe IL-4-regulated enteropathy is not required for immune expulsion of T. spiralis, it is still possible that Th2 cytokines can act in a direct fashion to create an environment unfavourable for intestinal parasites. It remains to be shown directly whether these effects are sufficient to expel parasites. Indeed, there is considerable evidence to support a variety of pathophysiological effects of IL-4 and/or TNF on the gut. These effects may be mediated by factors including cytokines and mast-cell products (e.g. leukotrienes and 5-hydroxytryptamine). 7. spiralis infections result in increased fluid and mucus secretion into the lumen as well as increased intestinal propulsive activity and more rapid intestinal transit (Castro et al, 1979 Russell, 1986 Vermillion and Collins, 1988 Vermillion et al., 1991 Weisbrodt et al, 1994 Barbara et al, 1997). The increased contractility of radial and longitudinal muscle is greater in high-... 

Increased numbers of goblet cells (GCs) and qualitative changes in mucus secretions are coincident with infection with a number of nematode parasites and it has been proposed that mucin proteins mediate this response by enveloping the parasites and/or interrupting attachment (Nawa et al., 1994). However, the role of GCs and mucus in the generation of a protective response versus its role in resolving intestinal inflammation following infection with GI nematode parasites remains unresolved. 

Behrens, I., Stenberg, P., Arturs-son, P., Kissel, T., Transport of lipophilic drug molecules in a new mucus-secreting cell culture model based on HT29-MTX cells, Pharm. 

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