The gastrointestinal system

Increased paracellular permeability such as that induced by the majority of nonselective NSAIDs favors the entry of pathogens, allergens, and bacterial translocation, giving rise to enteropathy and septic shock. Simple tests performed in animals by measurement of permeability to macromolecules in basal and simulated conditions may provide relevant information. Similarly, drugs may directly affect both functional and nociceptive sensitivity of the gut and subsequently inhibit enzyme secretion and many upstream inhibitory reflexes, and initiate abdominal pain in response to normal mechanical stimuli. 

Finally, safety pharmacology, particularly for drugs administered orally, also must evaluate the effect of drugs on other important functions of the gut with specific attention to paracellular permeability, enzyme secretion, immune status of the mucosa, and sensitivity. 

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In addition, the alkaloid colchicine (from Colchicum autumnale) blocks tubulin polymerization by binding to heterodimeric (3-tubulin between amino acids 239 and 254. Since it inhibits the MT-dependent migration of granulocytes into areas of inflammation and their MT-dependent release of proinflammatory agents, it is used to treat attacks of gout. Its antimitotic effect in the gastrointestinal system induces diarrhoea. Nocodazole competes for the binding site of colchicine and has similar effects on heterodimeric (3-tubulin. 

Q Constipation related to the effects of the narcotics on the gastrointestinal system... 

Goldenseal Hydrastis canadens s Antiseptic for skin (topical), astringent for mucous membranes (mouthwash), wash for inflamed eyes, sinus infections, peptic ulcers, colitis, gastritis Large doses may cause dry or irritated mucous membranes and injury to the gastrointestinal system may reduce the beneficial bacteria in the intestines. Siould not be taken for more than 3-7 days. 

Chapter 48 Drugs That Affect the Gastrointestinal System... 

Unit VIII lias been expanded to cover drugs that affect both the gastrointestinal and urinary systems. The unit consists of three chapters uretics, urinary anti-infectives and miscellaneous urinary drugp, and drag s that affect the gastrointestinal system. 

Meiss, R.A. (1989). Mechanics of gastrointestinal smooth muscle. In Handbook of Physiology, Section VI. The Gastrointestinal System, Volume 1, Part 1 (Wood, J.D. ed.), pp. 273-329, American, Physiological Society, Bethesda, MD. 

A further interesting phenotype identified in SDF-1/CXCR4 knockout mice is a deficiency in blood vessel development, initially observed in the gastrointestinal system (Tachibana et al. 1998). Consistent with such observations, CXCR4 receptors have been shown to be expressed by hemangioblasts, the earliest common precursor to hematopoietic and endothelial stem cells, found in yolk sac... 

ROBERFROID M B (1996) Functional effects of food components and the gastrointestinal system chicory fructooligosaccharides. Nutr Rev. 54 S38-42. 

Explain why barium sulfate is used in X-ray 2. Explain why using a base such as baking soda diagnosis of the gastrointestinal system. is effective in cleaning up a spill of an acid,... 

Nausea and vomiting are due to complex interactions of the gastrointestinal system, the vestibular system, and various portions of the brain. Nausea and vomiting have a variety of causes that can be simple or complex. Preventing and treating... 

Zweibaum A, M Laburthe, E Grasset, D Louvard. (1991). Use of cultured cell lines in studies of intestinal cell differentiation and function. In M Field, CA Frizzell, eds. Handbook of Physiology, Section 6, The Gastrointestinal System, Vol. IV, Intestinal Absorption and Secretion. Bethesda, MD Am Physiol Society, pp 223-255. 

Gastrointestinal Effects. There were no histopathological effects on the stomach, small intestines, or large intestines with inhalation or oral exposure to hexachloroethane at any concentration tested (15-5,900 ppm for the inhalation route and 1-750 mg/kg/day for the oral route) and with acute, intermediate, or chronic exposure durations (Gorzinski et al. 1985 NTP 1977, 1989 Weeks et al. 1979). The risk that humans will experience adverse effects on the gastrointestinal system as the result of exposure to hexachloroethane in the environment seems to be relatively low. 

In a study reported by the National Cancer Institute (NCI 1980), rats exposed to 16-1,694 mg/kg/day and mice exposed to 25-2,642 mg/kg/day phenol in drinking water exhibited no indication of histopathological effects on the gastrointestinal system after 13 weeks of exposure. No histological abnormalities of the gastrointestinal tract were observed in rats or mice exposed to 2,500 or 5,000 mg/L phenol in drinking water for 103 weeks (mg/kg/day doses 322 or 645 for male rats 360 or 721 for female rats 590 or 1,180 for male mice 602 or 1,204 for female mice) (NCI 1980). 

The gastrointestinal system of zebrafish presents clear differences from the human system. The zebrafish does not possess a stomach, the intestine is continuous with the pharynx through a short esophagus, and no sphincters are present [61]. However, zebrafish have most of the cell types observed in the small intestine -absorptive, endocrine, goblet, and interstitial cells of Cajal, although Paneth cells are absent. Gut contractions are under the control of the enteric nervous systems, which respond to different pharmaceuticals in similar way as the mammalian counterpart. For example, zebrafish embryos can be used as predictor of emetic response to pharmaceuticals, one of the most commonly reported clinical adverse effects to be considered in the development of new dmgs [61]. 

Meijer DKF, In Handbook of Physiology. The Gastrointestinal System, Vol HI (Eds Schulz J, Forte G, Rauner BB), pp. 717-758. Oxford University Press, New York, 1989. 

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