Swelling mucus

The freshly discharged and swelled mucus is now free to flow and anneal with the extracellular mucus gel. Since the same tracer protein diffuses at least 150-fold faster in the extracellular matrix than in the intragranular mucin matrix (Perez-Vilar et al. 2005a Perez-Vilar, unpublished observations), which has an average pore size of 5-10 nm, the mucus network mesh size might be in the micron range (see Section 2.7). 

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. 

By definition, mucoadhesive hydrogels are a elass of polymeric biomaterials that exhibit the basic characteristic of an hydrogel to swell by absorbing water and interacting by means of adhesion with the mucus that covers epithelia. 

Not interact physicochemically with the active compound or create a hostile artificial environment that would lead to inactivation and degradation of the active compound Swell in the aqueous biological environment of the delivery-absorption site Interact with mucus or its components for adequate adhesion ... 

The dendrites on the receptor cells have swellings, the olfactory knobs. These knobs have smooth vesicles that may be open to the mucus covering the epithelium. From each knob extend 1 to 150 cilia, floating in the mucus. The precise number of cilia varies with the species. The rabbit, for example, has 10-12 cilia on each knob. The surrounding mucus consists of mucopolysaccharides, lipids, and phosphatides. The axons of the olfactory receptor cells extend through the cribriform plate and terminate in the olfactory bulb (Fig. 5.1). 

Mucoadhesive polymers can be divided into non-covalent binding and covalent binding polymers. On the one hand the mechanism of mucoadhesion is based on hydrogen bonds, ionic interactions and van der Waal forces for non-covalent binding polymers, and on the other hand, on covalent bonds between the mucus and certain residues of the polymer. Moreover, physical interactions such as interpenetration of the polymer into the mucus gel layer entangle the polymer chains, which is strongly influenced by the swelling behaviour of the... 

Chitosan and its derivatives are the most widely used cationic polymeric excipients. Chitosan consists of (31—>4 D-glucosamine units and is derived by the deacetylation of chitin from insects, crustaceans and fungi. It interacts ionically with the anionic substructures of sialic acid residues on the mucus layer. Chitosans are rapidly hydrated in a low pH environment like the gastric fluid and do not swell above pH levels of 6.5, exhibiting no more mucoadhesion. 

Most compounds of interest for nasal delivery have a molecular weight in excess of 1,000 Da and until recently were thought to cross the cells endocytically. However, a recent study in rats has shown the transport of fluoroscein isothiocyanate (FITC)-labeled dextran (M. Wt. = 3,000 Da) to be via the paracellular pathway, with only a proportion moving endocytically. Hardly any transport of FITC-labeled dextran with a molecular weight of 10,000 Da was observed unless a penetration enhancer was coadministered, but the penetration enhancer, sodium taurodihydrofusidate (STDHF), caused cell swelling and extrusion of mucus. 

Q3 A type 1 hypersensitivity reaction is responsible for the development of the allergy. The symptoms are due to the effects of mast cell degranulation with the release of histamine. Mast cells are located in the nasal passages and the nasal mucosa is sensitive to the effects of histamine released from these cells, leading to inflammation of the mucous membranes of the nose. The inflammation is associated with oedema and swelling, vasodilation and an increase in the secretion of mucus. The mucous membrane of other sections of the respiratory tract (accessory sinuses, nasopharynx, and upper and lower respiratory tract) will also be affected by the allergic reaction. 

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