Mucosal surfaces

Diarrhea is a common problem that is usually self-limiting and of short duration. Increased accumulations of small intestinal and colonic contents are known to be responsible for producing diarrhea. The former may be caused by increased intestinal secretion which may be enterotoxin-induced, eg, cholera and E. col] or hormone and dmg-induced, eg, caffeine, prostaglandins, and laxatives decreased intestinal absorption because of decreased mucosal surface area, mucosal disease, eg, tropical spme, or osmotic deficiency, eg, disaccharidase or lactase deficiency and rapid transit of contents. An increased accumulation of colonic content may be linked to increased colonic secretion owing to hydroxy fatty acid or bile acids, and exudation, eg, inflammatory bowel disease or amebiasis decreased colonic absorption caused by decreased surface area, mucosal disease, and osmotic factors and rapid transit, eg, irritable bowel syndrome. 

The use of a bioadhesive, polymeric dosage form for sustained dehvery raises questions about swallowing or aspirating the device. The surface area is small, and patient comfort should be addressed by designing a small (less than 2 cm ), thin (less than 0.1 mm (4 mil) thick) device that conforms to the mucosal surface. The buccal route may prove useful for peptide or protein dehvery because of the absence of protease activity in the sahva. However, the epithelium is relatively tight, based on its electrophysiological properties. An average conductance in the dog is 1 mS/cm (57) as compared to conductances of about 27 and 10 mS/cm in the small intestine and nasal mucosa, respectively (58,59) these may be classified as leaky epitheha. 

Finer particles ( < 3 pm), termed respirable particles, pass beyond the ex-trathoracic airways and enter the tracheobronchial tree. Impaction plays a significant role near the tracheal jet, but sedimentation predominates as the effects of rapid conduit expansion dampen in the distal trachea and beyond. Sedimentation occurs when gravitational forces exerted on a particle equal drag forces, i.e., when particle velocity falls to u . As mean inspiratory air-stream velocity gradually declines along the tracheobronchial tree, particle momentum diminishes and 0.5-3 pm MMAD particles settle out of the airflow and onto mucosal surfaces. 

Microbes responsible for skin infection often arise from the normal skin flora which includes Staph, aureus. In addition Strep, pyogenes, Ps. aeruginosa and anaerobic bacteria are other recognized pathogens. Vimses also affect the skin and mucosal surfaces, either as a result of generalized infection or localized disease as in the case of herpes simplex. The latter is amenable to antiviral therapy in selected patients, although for the majority of patients, vims infections of the skin are self-limiting. 

Sterilization is an essential stage in the processing of aity product destined for parenteral administration, or for contact with broken skin, mucosal surfaces or internal organs, where the threat of infection exists, hi addition, the sterilization of microbiological materials, soiled dressings and other contaminated items is necessary to minimize the health hazard associated with these articles. 

Genital herpes simplex virus. Infants born to mothers with active disease at birth should be monitored for signs and symptoms of disease. Surveillance culture of mucosal surfaces is optional.38... 

May be applied to both keratinized epithelial and mucosal surfaces. 

Since HSV is only found in humans, infection may only be transmitted from infectious secretions onto mucosal surfaces (i.e., cervix or urethra) or abraded skin. It has also been noted that the virus may survive for a limited amount of time on environmental surfaces. 

HIV infection occurs through three primary modes of transmission sexual, parenteral, and perinatal. The most common method for transmission is receptive anal and vaginal intercourse, with the probability of transmission up to 3% per sexual contact for the former, and up to 0.2% per sexual contact for the latter. The probability of transmission increases when the index partner has a high level of viral replication (which occurs at the very beginning of infection or late in disease), or when the uninfected partner has ulcerative disease, compromised mucosal surfaces, or (in the case of men) has not been circumcised. 

K0/w as measured in the rat intestine [15,16], As with other examples that are available, as K0/w increases, the rate of absorption increases. One very extensive study [17-19] has examined in depth the physicochemical factors governing nonelectrolyte permeability for several hundred compounds. This study employed an in vitro preparation of rabbit gallbladder, an organ whose mucosal surface is lined by epithelial cells. The... 

Figure 2 (Left) Microscopic magnification (X46,500) of mucosal surface (S) associated with intestinal microvilli (V). (Right) Schematic of the microvilli illustrating the cytoskele-ton elements including junctional complexes. (From Ref. 76.)... 

H Daniel, G Rehner. Effect of metabolizable sugar on the mucosal surface pH of rat intestine. J Nutr 116 768-777, 1986. 

Mucus is produced by the mucus neck cells and by the surface epithelial cells of the stomach wall. A thick layer of mucus adheres to the wall of the stomach, forming the gastric mucosal barrier. The function of this barrier is to protect the gastric mucosa from injury — specifically, from the corrosive actions of HCl and pepsin. Together with bicarbonate ion released into the lumen of the stomach, mucus neutralizes the acid and maintains the mucosal surface at a nearly neutral pH. 

Cartwright [124] reported that miconazole was slightly absorbed from epithelial and mucosal surface. The drug is well absorbed from the gastrointestinal tract, but caused nausea and vomiting in some patients. The drug may be given intravenously but was associated phlebitis. Up to 90% of the active compound was bound to plasma protein. Distribution into other body compartments was poor. Metabolism was primarily in the liver, and only metabolites were excreted in the urine. At therapeutic levels, they were relatively nontoxic both locally and systematically, but occasionally produced disturbances on the central nervous system. 

The biosphere includes ecological niches where microbes peacefully co-exist with their eukaryotic host in the human this includes the concept of the micro-biome [14], which is defined as the totality of microbial organisms that co-habit with human beings. On the other hand, microbial colonization of human mucosal surfaces or prosthetic devices, often results in the development of biofilms, with significant deleterious effects on human health [15]. These are some of the challenges in infectious diseases that reflect the need to maximally utilize genomic sequence information and related sciences to better control microbial disease in human populations, and to develop anti-microbial agents with a better therapeutic index. 

At pH 4 most bacteria are killed within 30 min, and at physiological luminal pH, 99% of bacteria are killed within 5 min [14], Certain bacteria, like lactobacilli, are more acid-resistant, and some microbes survive the hostile gastric environment by colonizing luminal niches at the mucosal surface, protected by gastric bicarbonate secretion. This is the case for Helicobacter pylori, related spiral-... 

Fig. 1. Typical presentation of pseudomembranous colitis. At endoscopy (left), the mucosal surface of the colon appears hyper-emic and almost completely covered by a yellow-green exudate. The mucosa itself is somewhat eroded. Microscopically (right), the pseudomembrane is composed of inflammatory cells, necrotic epithelium, and mucus in which the overgrowth of microorganisms usually takes place. 

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