The Gut Microbial Flora

Ingested plant metabolites, drugs and other compounds are processed both by the animal and by the microbial flora of the gut. The composition and activities of the gut microflora vary greatly from one animal species to another and have been very extensively reviewed. In true ruminants (sheep, cattle and deer) and in functional ruminants, such as camels and llamas, a mixed population of bacteria, 

Blaauboer, W. C. Mennes and H. M. Wortelboer, in Developments and Ethical Considerations in Toxicology, ed. M.I. Weitzner, The Royal Society of Chemistry, Cambridge, 1993, p. 60. 

Mitsuoka, in Medical and Dental Aspects of Anaerobes, ed. B. I. Duerden, W.G. Wade, J. S. Brazier, A. Eley, B. Wren and M. J. Hudson, Science Reviews, Northwood, 1995, p. 87. 

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The production of reduced products like methane and ammonia by the gut microbial flora has important environmental consequences, as such compounds contribute to the chemical and biological oxygen demand. The detection of dissolved oxygen in the gut of piglets led to tests to show whether methane and other reduced products could be oxidized in the pig gut. The production of C-labelledCOj from C-labelledmethane has been demonstrated however, it is calculated that at most only a very small proportion of methane produced is likely to be oxidized using O 2 as electron acceptor. Methane may also be oxidized anaerobically, but only an extremely small amount of methane is likely to... 

The structurally close congener am-picillin (no 4-hydroxy group) has a similar activity spectrum. However, because it is poorly absorbed (<50%) and therefore causes more extensive damage to the gut microbial flora (side effect diarrhea), it should be given only by injection. 

Disturbance of the gut microbial flora often leads to decreased availability of vitamin K. with enhancement of the anticoagulant effects of coumarins. The answer is (C). (Can you name the drags in the other drug interactions listed )... 

Kleesen B, Hartmann L, Blaut M. Oligofructose and long-chain inulin influence on the gut microbial ecology of rats associated with a human faecal flora. Br J Nutr. 2001 86 291-300. 

Metabolic reactions in the liver and the small intestine are well documented [24]. However, only sparse information is available on drug metabolism in the eolon. Drug metabolism in the colon can be brought about by the host enzymes in the epithelial cells or by the microbial enzymes in the gut flora. Metabolie aetivities in the wall of the colon can be attributed to the eytochrome P450, esterases, amidases, and various transferases [25]. Reductive drug metabolism does not appear to be important at this site. 

A major factor in the development of mucosal immunity in the infant is exposure to the microbial flora colonizing the gut (Brandtzaeg, 1996). Unlike pathogens which induce strong activation of immune defense... 

Nestle Nutrition Services. (1999). Normal microbial flora of the gut and the immune system. In "Probiotics, Other Nutritional Factors, and Intestinal Microflora." (Lars A. Hanson and Robert H. Yolken, eds.), pp. 217-228. Lippincott-Raven, Philadelphia. 

Cholic (III) and chenodesoxycholic (VII) acids (Fig. 5), two of the common primary bile acids, undergo further chemical alterations by the action of microbial flora in the gut to give rise to several secondary bile acids (also possessing 24 carbon atoms), such as desoxycholic (VIII), hyodesoxy-cholic (IX), and lithocholic (X) acids (Fig. 5). 

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