Oral mucosa components

FIG. 1. Schematic diagram showing the principal components of oral mucosa (from Ref. 8). 

Oral mucosae are covered with mucus which serves as a link between the adhesive and the membrane. Mucus is a glycoprotein consisting of a large peptide backbone with pendant oligosaccharide side chains. The side chains terminate in sialic or sulfonic acids, L-fucose, sulfated galactose, or A -acetylglucosamine. The glycoprotein component imparts the viscous or gel-like (non-Newtonian) nature due to its capacity... 

Once an agent is topically applied in the oral cavity, the free drug can act at the primary site (i.e., bacteria in the plaque), or it can be partitioned to compartments where the drug binds nonspecifically. These drug reservoirs include the enamel, dentin, and/or cementum of the tooth, the oral mucosa, the organic and inorganic components of plaque, and salivary proteins. 

Siebert also discovered that when ingesting Salvia divinorum, its active components are absorbed primarily through contact with the oral mucosa. 

The oral mucosa contains both hydrophilic and hydrophobic components and a combination of both keratinized and nonkeratinized epithelia. Passive diffusion is the most common route... 

Various experimental techniques have demonstrated that cell membranes have a large lipid component, and most drugs cross such membranes by simple passive diffusion. In order to cross these lipid membranes, a drug should be in the lipid-soluble or un-ionized form and also be in solution. The various physicochemical characteristics of the drug are, therefore, of paramount importance as far as drug penetration across the oral mucosa is concerned. 

Ganem-Quintanar, A. Falson-Rieg, F. Buri, P. Contribution of lipid components to the permeability barrier of oral mucosa. Eur. J. Pharm. Biopharm. 1997, 44 (2), 107-120. 

Mouthwashes, toothpastes and other preparations are introduced into the oral cavity for local prophylactic and therapeutic reasons. It is not known to what extent components of these formulations are absorbed and give rise to systemic effects. The absorption of drugs through the oral mucosa, however, provides a route for systemic administration which avoids exposure to the gastrointestinal system. Dmgs absorbed in this way bypass the liver and have direct access to the systemic circulation. The sublingual, buccal and gingival... 

Reutilization of Nuclear Components. The question whether the constituents of nucleic acids may be salvaged and used again is not a simple one, and some lines of evidence do point to this possibility. Direct evidence in oral mucosa and epidermis of the rat for DNA reutilization has been presented by Outright and Bauer (CIS). This is in direct contrast to the study of Baden quoted above. In addition, studies utilizing radioactive iron injected intradermally in humans indicated reutilization of iron by epidermal cells since the half-life of the injected iron was found to be 67 days (02, 03). This is far greater than the usually... 

Mucilage, the component of coltsfoot responsible for its soothing effect on the throat and oral mucosa, is not absorbed it produces a local effect only (Tyler, 1994). 

The rapid loss of radioisotope following a single oral dose suggests that the intestine is the major component in the regulation of Mn absorption. Our finding of a very low efficiency of mucosa to serosa transfer of Mn is consistent with the studies of Thompson and Valberg (29,30). They demonstrated that approximately 25% of the Mn taken up in the mucosal cells is transferred to the carcass. 

GIP is synthesized and released by K cells located in the duodenal and jejunal mucosa. Plasma GIP is increased by oral administration of glucose, triacylglycerols, or intraduo-denai infusions of solutions containing a mixture of amino acids none of these, however, increases GIP concentrations when given intravenously. Protein ingestion does not significantly increase GIP. For food components to stimulate GIP release, they must be absorbed by the intestinal mucosa. 

Compared with some of the other mycotoxins such as aflatoxin, the trichothecenes do not appear to require metabolic activation to exert their biological activity.50 After direct dermal application or oral ingestion, the trichothecene mycotoxins can cause rapid irritation to the skin or intestinal mucosa. In cell-free systems or single cells in culture, these mycotoxins cause a rapid inhibition of protein synthesis and polyribosomal disaggregation.35 47 50 Thus, we can postulate that the trichothecene mycotoxins have molecular capability of direct reaction with cellular components. Despite this direct effect, it is possible to measure the toxicokinetics and the metabolism of the trichothecene mycotoxins. 

In Wright s 27 patients, 5 had recurrent ulceration of the oral and nasal mucosa, which stopped when practolol therapy was discontinued. Although there is no argument that this is part of the oculomucocutaneous syndrome, it is not a major component. 

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