Polyunsaturated fatty acid effect

Karanian JW, Kim HY, and Salem N Jr. (1996). The structure-activity relationship of lipoxygenase products of long-chain polyunsaturated fatty acids effects on human piglet aggregation, lipids. 31 (Suppl), S305-308. 

Osmundsen H, Cervenka J. Bremer J. Arole for 2,4-enoyl-CoA reductase in mitochondrial fl-oxidalion of polyunsaturated fatty acids. Effects of treatment with clofibrate on oxidation of polyunsaturated acylcarnitines by isolated rat liver. Biochem J 1982 208 749-757. 

Grune, T., Kramer, K., Hoppe, PR, and Siems, W., Enrichment of eggs with n-3 polyunsaturated fatty acids effects of vitamin E supplementation. Lipids, 36, 833-838, 2001. 

Unfortunately, excess consumption of fatty foods has been correlated with serious human disease conditions. Effects on cardiovascular disease (95), cancer (96), and function of the immune system (97) have been shown. Numerous studies have been conducted to determine the effects of saturated, monounsaturated, and polyunsaturated fatty acids on semm cholesterol and more recently high density Hpoprotein (HDL) and low density Hpoprotein... 

Animal cells can modify arachidonic acid and other polyunsaturated fatty acids, in processes often involving cyclization and oxygenation, to produce so-called local hormones that (1) exert their effects at very low concentrations and (2) usually act near their sites of synthesis. These substances include the prostaglandins (PG) (Figure 25.27) as well as thromboxanes (Tx), leukotrienes, and other hydroxyeicosanoic acids. Thromboxanes, discovered in blood platelets (thrombocytes), are cyclic ethers (TxBg is actually a hemiacetal see Figure 25.27) with a hydroxyl group at C-15. 

The reason for the cholesterol-lowering effect of polyunsaturated fatty acids is still not fully understood. It is clear, however, that one of the mechanisms involved is the up-regulation of LDL receptors by poly-and monounsaturated as compared with saturated fatty acids, causing an increase in the catabolic rate of LDL, the main atherogenic lipoprotein. In addition, saturated fatty acids cause the formation of smaller VLDL particles that contain relatively more cholesterol, and they are utilized by extrahepatic tissues at a slower rate than are larger particles—tendencies that may be regarded as atherogenic. 

Mensink, R. P., Katan, M. B., Effect of a diet enriched with monounsaturated or polyunsaturated fatty acids on levels of low-density and high-density lipoprotein cholesterol in healthy women, N Engl J Med, 321, 436, 1989... 

Becker, N., Illingsworth, R., Alaupovic, P., Connor, W. E., Sundberg, E. E., Effects of saturated, monounsaturated, and w-6 polyunsaturated fatty acids on plasma lipids, lipoproteins and apoproteins in humans, Am J Clin Nutr, 37, 355, 1983... 

Chilliard Y, Ferlay A and Doreau M (2001), Effects of different types of forages, animal fat or marine oils in cow s diet on milk fat secretion and composition, especially conjugated linoleic acid (CLA) and polyunsaturated fatty acids , Livestock Production Science, 70, 31-48. 

Wamants N, van Oeckel M J and Boucque C V (1998), Effect of incorporation of dietary polyunsaturated fatty acids in pork back-fat on the quality of salami , Meat Sci, 49, 435 145. 

Palakurthi, S. S., Fluckiger, R., Aktas, H., Changolkar, A. K., Shahsafaei, A., Hameit, S., Kilic, E., and Halperin, J. A. (2000). Inhibition of translation initiation mediates the anticancer effect of the n-3 polyunsaturated fatty acid eicosapentaenoic acid. Cancer Res. 60, 2919-2925. 

FIGURE 3-7 Pathways for the interconversion of brain fatty acids. Palmitic acid (16 0) is the main end product of brain fatty acid synthesis. It may then be elongated, desaturated, and/or P-oxidized to form different long chain fatty acids. The monoenes (18 1 A7, 18 1 A9, 24 1 A15) are the main unsaturated fatty acids formed de novo by A9 desaturation and chain elongation. As shown, the very long chain fatty acids are a-oxidized to form a-hydroxy and odd numbered fatty acids. The polyunsaturated fatty acids are formed mainly from exogenous dietary fatty acids, such as linoleic (18 2, n-6) and a-linoleic (18 2, n-3) acids by chain elongation and desaturation at A5 and A6, as shown. A A4 desaturase has also been proposed, but its existence has been questioned. Instead, it has been shown that unsaturation at the A4 position is effected by retroconversion i.e. A6 unsaturation in the endoplasmic reticulum, followed by one cycle of P-oxidation (-C2) in peroxisomes [11], This is illustrated in the biosynthesis of DHA (22 6, n-3) above. In severe essential fatty acid deficiency, the abnormal polyenes, such as 20 3, n-9 are also synthesized de novo to substitute for the normal polyunsaturated acids. 

Dietary polyunsaturated fatty acids (PUFAs), especially the n-3 series that are found in marine fish oils, modulate a variety of normal and disease processes, and consequently affect human health. PUFAs are classified based on the position of double bonds in their lipid structure and include the n-3 and n-6 series. Dietary n-3 PUFAs include a-linolenic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) whereas the most common n-6 PUFAs are linoleic acid, y-linolenic acid, and arachidonic acid (AA). AA is the primary precursor of eicosanoids, which includes the prostaglandins, leukotrienes, and thromboxanes. Collectively, these AA-derived mediators can exert profound effects on immune and inflammatory processes. Mammals can neither synthesize n-3 and n-6 PUFAs nor convert one variety to the other as they do not possess the appropriate enzymes. PUFAs are required for membrane formation and function... 

Stulnig, T.M., Immunomodulation by polyunsaturated fatty acids Mechanisms and effects, Int Arch Allergy Immunol, 132, 310, 2003. 

Busnach, G. et al., Effect of n-3 polyunsaturated fatty acids on cyclosporine pharmacokinetics in kidney graft recipients A randomized placebo-controlled study, J Nephrol, 11, 87, 1998. 

Polyunsaturated fatty acids (PUFAs), 5 33t 10 830 17 663-666 health effects of, 17 665-666 Polyunsaturates, 10 814 Polyurea, colloidal suspensions, 7 275 Polyurea greases, 15 243 Polyurethane (PU). See also Polyurethanes (PUs)... 

Arachidonic acid (C20 4 n-6) is the precursor for the synthesis of prostaglandin molecules (Section 4.4.4), which have a wide range of biochemical effects on for example, the perception of pain, inflammation, blood clotting and smooth muscle contraction. Docosahexaenoic acid (DHA, C22 6) and eicosapentaenoic acid (EPA, C20 5) are both n-3 long-chain polyunsaturated fatty acids (PUFA) which have been shown to have significantly beneficial effects on intellectual development and inflammatory conditions such as asthma and cardiovascular disease. 

They act as local messengers in tissues and they provide communication between one cell type and another within a single tissue or an organ (i.e. they have a paracrine effect). They are synthesised from the polyunsaturated fatty acids that contain 20 carbons (e.g. arachidonate, eicosapentaenoic acids). These fatty acids are generated from the hydrolysis of membrane phospholipids by the activity of a phospholipase which releases the fatty acids from position 2 of the phospholipids. Their roles are described in detail below. 

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