Triglycerides dietary

Chylomicrons Transport dietary triglyceride and cholesterol fiom intestine to tissues apoB-48 apoOn apoE Secreted by epithelial cells Activates lipoprotein lipase Lfptake by liver... 

Chylomicrons are assembled from dietary triglyceride (containing predominantly the longer-chain fatty adds) and cholesterol esters by intestinal epithelial cells. The core lipid is surrounded by phospholipids similar to those found in cell membranes, which increase the solubility of chylomicrons in lymph and blood. ApoB-48 is attached and required for release from the epithelial cells into the lymphatics. 

In 1987, scientists at Hoffmann-La Roche described their discovery of hpstatin (5), a secondary metabolite isolated from Strptomyces toxytricini, and demonstrated that it is a potent inhibitor of pancreatic lipase.Simple hydrogenation of 5 formed terahydrolipstatin (1,USAN, orlistat) which possesses comparable biological activity but is more stable than 5. Orlistat (1, Xenical ) works through pancreatic lipase inhibition. Pancreatic lipase is the key enzyme of dietary triglyceride absorption, exerting its activity... 

Dietary triglycerides are hydrolyzed in the small intestine by pancreatic lipase. This enzyme action is associated with a cofactor, colipase, also a pancreatic protein, molecular weight (MW) 12,000, which helps to anchor lipase to the fat droplets. Without colipase, lipase is rapidly denatured. Colipase is apparently secreted by the pancreas as a zymogen and is activated to its active form in the small intestine by trypsin. Pancreatic lipase appears in the circulation in large amounts during acute pancreatitis. 

Emulsification/absorption of dietary lipid in the intestine. Bile acids are stored in the gallbladder and released into the duodenum when cholecys-tokinin is released. In the small intestine, bile acids help to solubilise monoglycerides and fatty acids which are formed as the result of the digestion of dietary triglyceride, thereby enhancing the absorption of lipids and the fat-soluble vitamins A, D, E and K. 

Dietary triglycerides and esterified cholesterol and phospholipids are broken down in the intestine Uiivugh, respectively, pancreatic lipase, cholesterol ester hydrolase, and phospholipase A2, to form free fatty acids, unesterified cholesterol and lysophospholipids (phospholipids with only one fatty acid group), which are absorbed. 

Dietary triglycerides (TGs) are packaged into chylomicrons in the enterocyte and delivered to the circulatory system via the thoracic duct. Normally the lacteals and thoracic duct contain a clear, yellowish fluid. After a fabcontaining meal, however, they are filled with an opaque white liquid that contains chylomicrons laden with TGs. Arise in the plasma concentration of chylomicrons can be detected after a meal of fat or oil by assays for particulate matter or for one constituent of the chylomicrons, the TGs, The rise in chylomicron concentration usually is followed by a fall to very low basal concentrations. However, defects in the mechanisms that facilitate this decline are revealed when the levels of particulate matter or of plasma TGs remain elevated. These defects, which can present a serious health risk, are illustrated by data from patients suffering from hypertriglyceridemia. (The prefix "hyper" means higher than normal "hypo" means lower than normal.)... 

Dietary triglycerides, 226, 319-320, 366-367 Digestion, see also AbsorpOon Digestive hormones Digestive molecules Digestive system carbohydrates, 10(3-116 control, 58,88 Cephalic phase, 66-68 chemical phase, 69 innerv ation, 58,66-69 dietary bbers. 143 lipids, 93-103... 

Chylomicrons are synthesized in the intestine and transport dietary triglycerides and cholesterol. While circulating, the core triglycerides in these particles are hydrolyzed by lipoprotein lipase, which results in the production of a cholesterol-enriched remnant particle. When synthesized and initially released by the intestine, chylomicrons contain essentially no apoE, but as they circulate and are processed to remnants, the particles acquire apoE from other lipoprotein classes. This results in a shift of the distribution of apoE in plasma to the triglyceride-rich remnants in the absorptive state (Blum, 1982). 

Chylomicrons, large triglyceride-rich particles containing apolipoprotein B-48, B-lOO, and E, are formed from dietary fat solubilized by bile salts in intestinal mucosal cells (Fig. 21-2). Chylomicrons normally are not present in the plasma after a fast of 12 to 14 hours and are catabolized by lipoprotein lipase (LPL), which is activated by apolipoprotein C-II, in the vascular endothelium and hepatic lipase to form chylomicron remnants. The remnants that contain apolipoprotein E (see Fig. 21-2) are taken up by the remnant receptor, which may be an LDL-receptor-related protein, in the liver. Free cholesterol is liberated intracellularly after attachment to the remnant receptor. Chylomicrons also function to deliver dietary triglyceride to skeletal muscle and adipose tissue. During the catabolism of nascent chylomicrons to remnants, triglyceride is converted to free fatty acids and apolipoproteins A-I, A-II, A-IV (free in plasma), C-I, C-II, and... 

Sanderson, L. M., de Groot, P. J., Hooiveld, G. J., Koppen, A., Kalkhoven, E., Muller, M., and Kersten, S. (2008). Effect of synthetic dietary triglycerides a novel research paradigm for nutrigenomics. PLoS OAE3, el681. 

L. Blackberg, O. Hemell, G. Bengtsson, and T. Olivecrona. Colipase enhances hydrolysis of dietary triglycerides in the absence of bile salts. J. Clin. Invest. 64 1303 (1979). 

Four main classes of Upoproteins are present in normal human plasma (for reviews, see refs. 1-3). The largest of these, the chylomicrons (diameter 800-5000 A, density < 0.95 g/ml they remain at the origin during electrophoresis. Fig. 1), contain predominantly dietary triglycerides and a spectrum of apoUpoproteins (Fig. 2). Chylomicrons are manufactured in the intestines from dietary Upids, secreted into the lymph, and subsequently enter the blood circulation. Since chylomicrons are too large to cross the vascular endothelium, they are degraded in plasma by the enzyme Upoprotein lipase which is present on the surface of endotheUal cells that... 

Major physiological function Transports dietary triglyceride (Tg) from intestines to extrahepatic tissues (e.g., muscle, adipose tissue) Tg-depleted remnants deliver dietary cholesterol and some Tg to the liver Transports hepatic Tg to extrahepatic tissues converted into LDL Transports plasma cholesterol to liver and to extrahepatic tissues Takes up cholesterol from extrahepatic tissues and delivers it to liver, steroid-producing tissues, and other lipoproteins... 

Chylomicrons, which have a density of less than 0.95 g/mL, carry dietary triglycerides from the intestine to other tissues. The remaining lipoproteins are classified by their densities. 

Plasma lipoproteins are complex lipids that transport other lipids through the bloodstream. Chylomicrons carry dietary triglycerides from the intestine to other tissues. Very low density lipoproteins carry triglycerides synthesized in the liver to other tissues for storage. Low-density lipoproteins carry cholesterol to peripheral tissues and help regulate blood cholesterol levels. High-density lipoproteins transport cholesterol from peripheral tissues to the liver. 

Chylomicrons are plasma lipoproteins (aggregates of protein and triglycerides) that carry dietary triglycerides from the intestine to all tissues via the bloodstream. 

Chylomictons B . A-l. C-ll. E Largest lipoprotein. Synthesized by gut after a meal.Not present in normal lasting plasma. Main carrier of dietary triglyceride... 

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