Gastrointestinal tract microflora

Both pirlimycin and its sulfoxide metabolite were partially converted to ribonucleotide adducts by gastrointestinal tract microflora and excreted in feces. Such adducts have been well documented as products of antibiotic inactivation by bacteria for a variety of substances including lincomycin and clindamycin (117-119). 

Different factors inclnding nntrients, bile salts, pH, and microflora present in the gastrointestinal tract dnring the digestion process can affect the bioaccessibility of a compound (Table 3.2.1). The compoimd of interest is generally consiuned together with other nutrients present in the meal and, once the compound and these nutrients are released from the food matrix during the same period, they may interact in the intestinal liunen. 

In most species, chloramphenicol is rapidly and almost completely absorbed from the gastrointestinal tract. This route of administration provides antibiotic levels in blood comparable witli or higher than die intramuscular or the subcutaneous routes. The only known exception is in ruminants in which the drug is destroyed by the rumen microflora. 

The enzymes responsible for reduction may be located in both the microsomal fraction and the soluble cell fraction. Reductases in the microflora present in the gastrointestinal tract may also... 

Before reaching the systemic circulation, polyphenols orally administered will transit by the gastrointestinal tract (GIT) where they will be submitted to different biological and physiological parameters, which will participate to their bioavailability, such as the pH, the digestive enzymes, or the microflora. 

The gastrointestinal (GI) microflora plays an important role in the health status of people and animals. The GI tract represents a much larger contact area with the environment, compared to the 2 m2 skin surface of our body (van Dijk 1997). The mucosal surface of the small intestine is increased by forming folds, intestinal villi, and the formation of microvilli in the enterocyte resorptive luminal membrane. The resulting surface of GI system is calculated to be 150-200m2, therefore it provides enough space for the interactions related to digestion and for the adhesion to the mucosal wall. 

Microflora Microorganisms such as bacteria that normally inhabit the gastrointestinal tract. 

The microflora of the gastrointestinal tract, which develop shortly after birth, are found in the lumen, associated with remnants of food, on the mucosal surface, and in the cry pts- These microorganisms, including prokaryotic and eukaryotic species, lend not to use oxygen in their energy metabolism since they exist in an environment that is essentially anaerobic. Over of the bacterial cells are... 

The primary fate of dietary fibers is digestion and catabolism by the gut microflora to short-chain fatty acids and carbon dioxide. The major products of this microbial metabolism — acetic, propionic, and butyric acid — are important sources of energy for ruminants (sheep, cows). Dietary fiber is retained in a chamber of their gastrointestinal tracts, called the rumen, where it is converted to short-chain fatty acids by the gut microflora. The fatty acids produced may supply 35-75% of the energy requirement of the ruminant. 

The gut microflora consist of microorganisms, mainly bacteria, of the gastrointestinal tract. The small intestine of the adult human is about 4.0 m long. The large intestine, or colon, is about one-third this length (1.5 m). The colon receives 1.5-2.0 liters of water per day, most of which is absorbed. Only 150-200 ml of water is lost in the feces. The colon also absorbs sodium and chloride originating from the diet and from secretions of the small intestine. The lumenal surface of the large intestine secretes mucus, as does the small intestine. However, the mucosa of the colon contains crypts but lacks viUi. 

Extensive data are available on the prebiotic efficacy of oligosaccharides from in vitro models representing the human colon and from human clinical trials. Whether results from these studies can be extended to animals needs to be determined. The physiology and microflora of the gastrointestinal tract will vary from animal to animal and in most cases there may be limited or no knowledge of the microecology. 

Bile salts are extensively metabolized to secondary bile acids by intestinal microflora in the gut. Approximately 94% of the bile salts are reabsorbed at special mucosal receptor sites in the distal ileum and reused by the liver by the process of enterohe-patic circulation. In enterohepatic circulation, compounds secreted in bile are reabsorbed in the gastrointestinal tract and returned to the liver. On reaching the liver in the portal blood, almost all of the bile salts are taken up across the sinusoidal membranes of hepatocytes (predominantly in periportal... 

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