Small and Large Intestine

Gastrointestinal x-ray imaging is the imaging of the small and large intestines and the colon. The contrast between the various tissues found in the abdomen is poor. As a consequence, a contrast agent is introduced into the digestive tract which absorbs more x-rays than do the tissues in the abdomen. 

Diarrhea was observed in rats exposed for 5 days, 6 hours/day to both lethal and sublethal doses of P-endosulfan ( 250 mg/kg/day for males and i6 mg/kg/day for females) (Hoechst 1989b). Autopsy of animals from this study revealed that the mesenteric blood vessels of one of the surviving females exposed to 16 mg/kg/day were distended with blood, and that the small intestines of animals dying as a result of exposure were filled with a reddish fluid (500 mg/kg/day for males and 31.25 for mg/kg/day females). In contrast, no treatment-related effects were revealed by routine gross and histopathological examination of gastrointestinal tissues (stomach, small and large intestines, and pancreas) from rats exposed to doses of 27 mg/kg/day (females) and 81 mg/kg/day (males) for 30 days, 6 hours/day,... 

Mineral Oil Hydraulic Fluids. Subserosal hemorrhaging was observed in the small and large intestine and the omentum of a child who accidentally ingested a lethal amount of automobile transmission fluid (Perrot and Palmer 1992). 

Fig. 1 Diagrammatic sketch of the gastrointestinal tract (and subdivisions of the small and large intestines) along with associated organs. (Modified from Ref. 4.)...

RB Sund, F Lauterbach. 1-Naphthol metabolism and metabolite transport in the small and large intestine. Pharmacol Toxicol 60 262-268, 1987. 

Barnard, A.J., Warwick, G.J. and Gold, C.I. (1993) Localisation of TGFa isoforms in the normal murine small and large intestine. Gastroenterology 105, 67-73. 

J. Taipalensuu, C. Otter, B. Leidvik, and P. Artursson. CYP3A4, CYP3A5, and MDR1 in human small and large intestinal cell lines suitable for drug transport studies,/. Pharm. Sci. 2001,... 

The paracellular pathway, between the epithelial cells, is both size- (MW, volume) and charge-dependent [60, 109, 110]. In general, compounds that are limited to paracellular transport are not efficiently absorbed due to the small available absorptive area and the restriction by tight junctions. The molecular weight cut-off seems to be around 400 g mol-1 and 300 g mol-1 for the small and large intestine respectively, and 300 g mol-1 for the Caco-2 cell monolayers [60], which shows the more colonic nature of the Caco-2 monolayer model. Compounds with a... 

The jejunal perfusion approach generates data which may be used to predict absorption/bioavailability and to establish in vivo-in vitro correlation (IVIVC) even for extended release (ER) products. If a dmg is transported mainly by passive diffusion and has a jejunal Peff higher than metoprolol (1.5 x 10-4 cm s 1 = high-permeability compound), it can be expected to be completely absorbed throughout the small and large intestine [5, 46]. 

Bjarnason I, Hayllar J, Macherson AJ, Russell AS Side effects of nonsteroidal anti-inflammatory drugs on the small and large intestine in humans. Gastroenterology 1993,104 1832-1847. 

Trauma, major surgery, bums or haemorrhagic shock can result in damage to the small and large intestine. Damage to the colon in particular can increase the translocation of bacteria into the peritoneal cavity leading to sepsis ( see below and Chapter 18). 

Persons with familial adenomatous polyposis are at 105,106 increased risk for adenomas and cancers of the small and large intestines. In the small intestine, these lesions occur mainly around the Ampulla of Vater, where their distribution parallels mucosal exposure to bile. 

Ulcerative or inflammatory lesions may affect the physiology of the small and large intestine. Ulcer formation entails a circumscribed loss of tissue from the surface of an organ, which results from necrosis following cell destruction by chemicals and the like, or by restriction of the blood supply. Ulcers are among the most common and important lesions. Those that do not penetrate the muscularis mucosa are called erosions. Ulcerative conditions in humans must be differentiated from malignant ulcers, which are associated with neoplasia. Among... 

Gastrointestinal tract. Serotonin released from myenteric neurons or enterochromaffin cells acts on 5-HT3 and 5-HT4 receptors to enhance bowel motility and enteral fluid secretion Cisapride is a proldnetic agent that promotes propulsive motor activity in the stomach and in small and large intestines. It is used in motility disorders. Its mechanism of action is unclear, but stimulation of 5HT4 receptors may be important... 

Pharmacokinetics Minimal absorption from the G1 tract. Acts in small and large intestines. Results usually occur 1-2 days after first dose, but may take 3-5 days. 

The antidiarrheal activity of codeine results from two actions. First, there is a decrease in the propulsive contractile activity of the small and large intestines, which delays the forward movement of the contents of the intestines. Second, codeine causes an increase in the absorption of water from the intestinal contents. These gastrointestinal effects are mediated by specific opioid receptors in the gut (as we will see in... 

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