Plasma fatty acids

Fatty acids occur mainly as esters in natural fats and oils but do occur in the unesterified form as free fatty acids, a transport form found in the plasma. Fatty acids that occur in natural fats are usually straight-chain derivatives containing an even number of carbon atoms. The chain may be saturated (containing no double bonds) or unsaturated (containing one or more double bonds). 

Babin, F., Lemonnier, F., Goguelin, A., AlagiUe, D. and Lemonnier, A. (1988). Plasma fatty acid composition and lipid peroxide levels in children with paucity of interlobular bile ducts. Annu. Rev. Metab. 32, 220-230. 

Thiazolidinediones are known to increase insulin sensitivity by stimulating peroxisome proliferator-activated receptor gamma (PPAR-y). Stimulation of PPAR-y results in a number of intracellular and extracellular changes, including an increased number of insulin receptors, increased insulin receptor sensitivity, decreased plasma fatty acid levels, and an increase in a host of intracellular signaling proteins that enhance glucose uptake. 

Figure 3.23 A sequence of processes explaining the role of glucokinase in the liver and fi-cells in regulation of the blood glucose concentration. The increase in the plasma insulin increases glucose uptake by muscle and decreases fatty acid mobilisation from adipose tissue which lowers the plasma fatty acid level which also increases glucose uptake (Chapter 12).

In this book it is suggested that one possible cause of death in prolonged starvation is severe hypoglycaemia. This may be due to a lack of amino acid precursors since almost all the body protein has been broken down. Alternatively, the fat store in the body has been totally depleted, so that the plasma fatty acid level will be close to zero. Consequently, there will be no fatty acid oxidation in the liver and therefore little or no ATP generation to support gluconeogenesis. Post-mortem studies on individuals who have died of starvation show that the fat stores are totally depleted. This topic is discussed further in Chapter 16. 

Condition Approx, plasma fatty acid concentration (mmol/L)... 

It appears from the data in this table that a level of 2 mmol/L plasma fatty acid is about the highest that can be achieved in any condition so far studied. A similar message comes from studies on exercise in domestic animals. Florses that were ridden over 50 miles at an average speed of 8 mph had a plasma fatty acid concentration of 1.4 mmol/L. Dogs that had been run on a treadmill for 4 hours had a plasma concentration of 2.1 mmol/L. 

In pregnancy, there is a sharp increase in the plasma fatty acid level after about 12 hours of fasting, much sooner than in the non-pregnant woman. This may be important in maintaining the plasma glucose level not only for the mother but also the foetus. This maintenance is achieved via the glucose fatty acid cycle (Chapter 16). 

Figure 7.14 Regulation of rate of fatty acid oxidation in tissues. Arrows indicate direction of change (i) Changes in the concentrations of various hormones control the activity of hormone-sensitive lipase in adipose tissue (see Figure 7.10). (ii) Changes in the blood level of fatty acid govern the uptake and oxidation of fatty acid, (iii) The activity of the enzyme CPT-I is controlled by changes in the intracellular level of malonyl-CoA, the formation of which is controlled by the hormones insulin and glucagon. Insulin increases malonyl-CoA concentration, glucagon decrease it. Three factors are important TAG-lipase, plasma fatty acid concentration and the intracellular malonyl-CoA concentration.

Fatty acids are released from adipose tissue into the bloodstream, from where they can be taken up and used by aerobic tissues, with the exception of brain and the intestine. In addition, an increase in the plasma fatty acid concentration is one factor that increases the rate of fatty acid oxidation by tissues. Flence, an increase in the mobilisation of fatty acid from adipose tissue is an immediate signal for tissues such as muscle, heart and kidney cortex to increase... 

The plasma fatty acid levels are increased in both but especially in kwashiorkor. 

Hydrolysis of triacylglycerol and release of the resultant fatty acids from adipose tissue is increased and accounts, in part, for loss of body weight. Despite this, the plasma fatty acid level is not always increased, which suggests... 

Toxicology. Propionic acid is an irritant to skin, eyes, and mucous membranes. Propionic acid is a normal intermediary metabolite during the oxidation of fatty acids. It occurs ubiquitously in the gastrointestinal tract as an end product of microbial digestion of carbohydrates. It represents up to 4% of the normal total plasma fatty acids. ... 

Plasma fatty acids. Oil, administered to chicken at doses of 10% and 20% of the diet, produced an increase in the percentages of lauric and myristic acids in free fatty... 

Mohamed, A. I., A. S. Hussein, S. J. Bhathena, and Y. S. Hafez. The effect of dietary menhaden, olive, and coconut oil fed with three levels of vitamin E on plasma and liver lipids and plasma fatty acid composition in rats. J Nutr Biochem 2002 13(7) 435-441. Kawano, K., S. Qin S, C. Vieu, X. Collet, and X. C. Jiang. Role of hepatic lipase and scavenger receptor BI in clearing phospholipid/free cholesterol-rich lipoproteins in PLTP-deficient... 

Krajcovicova-Kudlackova, M., Simoncic, R., Bederova, A., and Klva-nova, J. (1997) Plasma fatty acid profile and alternative nutrition. Ann Nutr Metab 41 365-370. 

Aldamiz-Echevarria L, Pocheville I, Sanjurjo P, Elorz J, Prieto JA, Rodriguez-Soriano J. Abnormalities in plasma fatty acid composition in human immunodeficiency virus-infected children treated with protease inhibitors. Acta Paediatr 2005 94(6) 672-7. 

Consequently, a more objective way to measure the habitual intake of milk fat would be the fatty acid composition of adipose tissue. However, this is not routinely performed in larger cohort studies, due to cost and that the procedure is invasive and less tolerated by study participants. Analysis of plasma fatty acid composition is thus a more feasible option for examination to determine dairy intake in the study population. While some groups have separated plasma into its constituent phospholipids and cholesterol esters to analyze serum 15 0 and 17 0 as markers of dairy intake (Smedman et al., 1999), Baylin et al. (2005) found that plasma that was not separated into its constituent cholesteryl ester, phospholipids, and triacylglycerols was still able to reflect habitual dairy intakes comparably to adipose tissue. Thus, whole plasma is an acceptable alternative to fractionated plasma in the absence of adipose tissue for analysis to reflect habitual dairy intakes and may be a cost effective option for consideration when conducting future intervention studies to assess the affect of dairy products on health outcomes. 

Ma, J., Folsom, A. R., Shahar, E., and Eckfeldt, J. H. (1995). Plasma fatty acid composition as an indicator of habitual dietary fat intake in middle-aged adults. The Atherosclerosis Risk in Communities (ARIC) Study Investigators. Am. J. Clin. Nutr. 62,564-571. 

Chan, J.K., McDonald, B.E., Gerrad, J.M., Bruce, V.M., Weaver, B.J., and Holub, B.J. 1993. Effect of dietary alpha-linolenic acid and its ratio to linoleic acid on platelet and plasma fatty acids and thrombogenesis. Lipids 28, 811-817. 

Gann, P.H., Hennekens, C.H., and Sacks, F.M. 1994. Prospective study of plasma fatty acids and risk of prostate cancer. J. Natl. Cancer Inst. 86, 281-286. 

Rl. Ramirez, M., Gallardo, E. M., Souto, A. S., Weissheimer, C., and Gil, A., Plasma fatty-acid composition and antioxidant capacity in low birth-weight infants fed formula enriched with... 

Lopaschuk, G. D., Collins-Nakai, R., Olley, P. M., Montague, T. J., McNeil, G., Gayle, M., Penkoske, P., and Finegan, B. A. 1994. Plasma fatty acid levels in infants and adults after myocardial ischemia. Am Heart J 128 61-67. 

G9. Glomset, J. A., The mechanism of the plasma cholesterol esterification reaction Plasma fatty acid transferase. Biochim. Biophys. Acta 65, 128-135 (1962). 

Because insulin normally inhibits lipolysis, a diabetic has an extensive lipolytic activity in the adipose tissue. As is seen in Table 21.4, plasma fatty acid concentrations become remarkably high. /3-Oxidation activity in the liver increases because of a low insulin/glucagon ratio, acetyl-CoA carboxylase is relatively inactive and acyl-CoA-camitine acyltransferase is derepressed. /3-Oxidation produces acetyl-CoA which in turn generates ketone bodies. Ketosis is perhaps the most prominent feature of diabetes mellitus. Table 21.5 compares ketone body production and utilization in fasting and in diabetic individuals. It may be seen that, whereas in the fasting state ketone body production is roughly equal to excretion plus utilization, in diabetes this is not so. Ketone bodies therefore accumulate in diabetic blood. 

Palmquist, D.L., Conrad. H.R. 1971. Origin of plasma fatty acids in lactating cows fed high grain or high fat diets. J. Dairy Sci. 54, 1025-1033. 

Pullen, D.L., Palmquist, D.L., Emery, R.S. 1989. Effect of days of lactation and methionine hydroxy analog on incorporation of plasma fatty acids into plasma triglycerides.. / Dairy Sci. 72, 49-58. 

Muscle glycogen Plasma glucose Plasma fatty acids... 

Hickson, R.C., Rennie, M.J., Conlee, R.K., Winder, W.W. 4 Holloszy, J.O. (1977) Effects of increased plasma fatty acids on glycogen utilization and endurance. Appl. 

Acetate is simultaneously produced and used (oxidized) by the gut, possibly accounting for up to 50% of the gut s energy requirement in ruminants. Propionate and butyrate produced in the rumen and/or hind gut fermentations (nonruminant herbivores) are extensively metabolized by the visceral tissues, so that only insignificant amounts reach the portal circulation. Plasma fatty acids, rather than acetate, are the major energy source for skeletal muscle energy in ruminants and other mammals (53). 

Conflicting results have been reported about the absorption of EPA and DHA either as an ethyl ester (EE) or in a triglyceride (TG) formula. Based on a randomized double-blind study on the effects of EE and TG on plasma fatty acids, platelet function and haemostasis, it has been concluded that TG and EE fish oils are well incorporated... 

Rasmussen, L.B., Kiens, B., Pedersen, B.K., and Richter, E.A. 1994. Effect of diet and plasma fatty acid composition on immune status in elderly men. Am. J. Clin. Nutr. 59, 572-577. 

The ability of albumin to bind eosin has been examined (G26) by observing the spectral shift from 516 to 536 nm which occurs when albumin solution is added to eosin (final concentration 6 X 10 M) in phosphate buffer (0.05 M) at pH 7.1. A technique was devised for the estimation of albumin in 0.02-0.20 ml oxalated plasma. The results found were lower than those obtained by carrying out la technique classique, and the explanation given is that the plasma fatty acids present cause a reduction in eosin binding to plasma albumin. The extent to the difference in values obtained... 

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