Intestines, structure

A12. Ament, M. E., and Rubin, C. E., Relation of giardiasis to abnormal intestinal structure and function in gastrointestinal immunodeficiency syndromes. Gastroenterology 62, 216-226 (1972). 

Table 3.1. Potential changes in intestinal structure and function induced by parasitic infections. (Data from Wakelin, 1986,)...

Noninsulin-dependent diabetes mellitus (NIDDM) is an increasingly common disease, and involves an increase in the capacity of the intestine to absorb monosaccharides. This has been linked to a combination of intestinal structural change with a specific increase in the expression of the monosaccharide transporters SGLTl, GLUT5, and GLUT2 [87]. 

ApoA-I 130 11 29 Liver, intestine Structural in HDL LCAT cofactor ligand of ABCAl receptor reverse cholesterol transport... 

ApoB-48 Fluctuates according to dietary fat intake 2 -241 Intestine Structural protein of chylomicrons... 

Yates MR, Morgan DE, Baron TH (1998) Palliation of malignant gastric and small intestinal structures with self-expandable metal stents. Endoscopy 30 266 272 Yim HB, Jacobson BC, SaJtzman JR (2001) Clinical outcome of the use of enteral stents for palliation of patients with malignant upper GI obstruction. Gastrointest Endosc 53 329-332... 

BILE ACIDS AND SMALL INTESTINAL STRUCTURE AND FUNCTION... 

Saponins. Although the hypocholesterolemic activity of saponins has been known since the 1950s, thek low potency and difficult purification sparked Htde interest in natural saponins as hypolipidemic agents. Synthetic steroids (292, 293) that are structurally related to saponins have been shown to lower plasma cholesterol in a variety of different species (252). Steroid (292) is designated CP-88,818 [99759-19-0]. The hypocholesterolemic agent CP-148,623 [150332-35-7] (293) is not absorbed into the systemic ckculation and does not inhibit enzymes involved in cholesterol synthesis, release, or uptake. Rather, (293) specifically inhibits cholesterol absorption into the intestinal mucosa (253). As of late 1996, CP-148,623 is in clinical trials as an agent that lowers blood concentrations of cholesterol (254). 

Nonrepetitive but well-defined structures of this type form many important features of enzyme active sites. In some cases, a particular arrangement of coil structure providing a specific type of functional site recurs in several functionally related proteins. The peptide loop that binds iron-sulfur clusters in both ferredoxin and high potential iron protein is one example. Another is the central loop portion of the E—F hand structure that binds a calcium ion in several calcium-binding proteins, including calmodulin, carp parvalbumin, troponin C, and the intestinal calcium-binding protein. This loop, shown in Figure 6.26, connects two short a-helices. The calcium ion nestles into the pocket formed by this structure. 

Actual and predicted structures of three domains of intestinal fatty acid binding protein... 

The practical development of plant sterol drugs as cholesterol-lowering agents will depend both on structural features of the sterols themselves and on the form of the administered agent. For example, the unsaturated sterol sitosterol is poorly absorbed in the human intestine, whereas sitostanol, the saturated analog, is almost totally unabsorbable. In addition, there is evidence that plant sterols administered in a soluble, micellar form (see page 261 for a description of micelles) are more effective in blocking cholesterol absorption than plant sterols administered in a solid, crystalline form. 

HDL and VLDL are assembled primarily in the endoplasmic reticulum of the liver (with smaller amounts produced in the intestine), whereas chylomicrons form in the intestine. LDL is not synthesized directly, but is made from VLDL. LDL appears to be the major circulatory complex for cholesterol and cholesterol esters. The primary task of chylomicrons is to transport triacylglycerols. Despite all this, it is extremely important to note that each of these lipoprotein classes contains some of each type of lipid. The relative amounts of HDL and LDL are important in the disposition of cholesterol in the body and in the development of arterial plaques (Figure 25.36). The structures of the various... 

Calcium-binding proteins, 6, 564, 572, 596 intestinal, 6, 576 structure, 6, 573 Calcium carbonate calcium deposition as, 6, 597 Calcium complexes acetylacetone, 2, 372 amides, 2,164 amino acids, 3, 33 arsine oxides, 3, 9 biology, 6, 549 bipyridyl, 3, 13 crown ethers, 3, 39 dimethylphthalate, 3, 16 enzyme stabilization, 6, 549 hydrates, 3, 7 ionophores, 3, 66 malonic acid, 2, 444 peptides, 3, 33 phosphines, 3, 9 phthalocyanines, 2,863 porphyrins, 2, 820 proteins, 2, 770 pyridine oxide, 3,9 Schiff bases, 3, 29 urea, 3, 9... 

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