Phospholipid esters

The lipid layer, which consists of cholesterol esters, phospholipids, and triglycerides, prevents and regulates aqueous evaporation from the tear film. 

Loading of guests within the SCKs (for potential delivery) is modeled after lipoproteins, which are composites of cholesterol, cholesteryl ester, phospholipids, and protein forming biological structures of core-shell morphology... 

Triacylglycerols Cholesterol and cholesterol esters Phospholipids Proteins ... 

Most of the mention of cholesterol in the popular press positions this molecule as a threat to human health. Many foods are proudly labeled cholesterol-free. People are properly warned to pay attention to their plasma cholesterol level, particnlarly that carried in the low-density lipoproteins, LDLs, commonly known, with pretty good reason, as bad cholesterol. LDLs are lipoprotein particles containing a large protein known as B-100 associated with cholesterol, cholesteryl esters, phospholipids, and some triglycerides. 

Unesterified cholesterol Cholesterol esters Phospholipids Glycerides... 

An adult ingests about 60 to 150 g of lipids per day, of which more than n nety percent is normally triacylglycerol (formerly called triglyceride). Uhe remainder of the dietary lipids consists primarily of cholesterol, cholesteryl esters, phospholipids, and unesterified ("free") fatty acids. "The digestion of dietary lipids is summarized in Figure 15.2. 

Fate of the remaining chylomicron components After most of tt triacylglycerol has been removed, the chylomicron remnan (which contain cholesteryl esters, phospholipids, apolipoprotein and some triacylglycerol) bind to receptors on the liver (seej 228) and are then endocytosed. The remnants are the hydrolyzed to their component parts. Cholesterol and the nitrogf nous bases of phopholipids (for example, choline) can be req cled by the body. [Note If removal of chylomicron remnants by th liver is defective, they accumulate in the plasma. This is seen i type III hyperlipoproteinemia (also called familial dysbetalipopro teinemia, see p. 229). 

Digestion of dietary lipids Dietary lipids DIGESTION OF DIETARY LIPIDS (p. 171) Dietary lipids consist primarily of triacylglycerol, with some cholesterol, cholesteryl esters, phospholipids, and free (nonesterified) fatty acids. 

Data on the proportions of different fatty acids in plasma lipid esters (cholesteryl esters, phospholipids, free fatty acids, or triacylglycerol), erythrocyte membranes, or adipose tissue may provide a more objective and accurate path to evaluating dietary fatty acid composition (Arab, 2003 Baylin and Campos, 2006). The fatty acid composition in blood and body tissues reflects the fatty acid composition of the diet at different time points after ingestion. Short and medium-term changes in the composition of dietary fatty acid intake are reflected in plasma lipids and erythrocyte membranes, weeks and months after intake, respectively. The incorporation of fatty acids in adipose tissue reflects long-term changes in the diet (years) (Baylin and Campos, 2006 Katan et al., 1997 Ma et al., 1995 Zock et al, 1997). 

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. 

Lipids include fatty acids (aliphatic carboxylic acids), fatty acid esters, phospholipids, and glycolipids. Plants containing lipids with anticancer properties include the following ... 

T2. Tall, A. R, Abreu, E., and Shuman, J., Separation of a plasma phospholipid transfer protein from cholesterol ester/phospholipid exchange protein. J. Biol. Chem. 258, 2174-2180 (1983). 

In the work of Loomeijer and work on similar lines carried out in the author s laboratory no evidence was found for the presence in important amounts of the common fatty esters, phospholipids, or steroids in purified preparations of elastin in these circumstances there seems to be little reason to classify elastin with the lipoproteins. The uptake of lipophilic dyes, which has been mentioned by several authors as indicating a lipoprotein character, can as well be explained by the presence of massive nonpolar radicals in the fluorescent prosthetic group, as described by Loomeijer, or to interactions with lipophilic sections of the peptide chain due to the large concentrations of nonpolar amino acids such as valine, the leucines, and phenylalanine. 

The major components of lipoproteins are triacylglycerols, cholesterol, cholesterol esters, phospholipids, and proteins. Purified proteins (apoproteins) are designated A, B, C, and E. 

Major lipids Exogenous triglycerides Endogenous triglycerides Endogenous triglycerides, cholesteryl esters. Cholesteryl. esters Phospholipids Cholesteryl esters, Phospholipidj... 

Generalized structure of a lipoprotein molecule showing the distribution of polar components in an outer shell composed of free cholesterol, phospholipids, and amphipathic proteins and in an inner core composed of neutral triacylglycerols and cholesteryl esters. Phospholipids are oriented with polar head groups toward the aqueous environment and hydrophobic tails toward the neutral core, analogous to their positioning in the outer leaflet of the typical cell membrane. 

Cholesterol and triglycerides, as the major plasma hpids, are essential substrates for cell membrane formation and hormone synthesis and provide a source of free fatty acids. Hyperlipidemia is defined as an elevation of one or more of cholesterol, cholesterol esters, phospholipids, or triglycerides. Lipids, being water immiscible, are not present in free form in the plasma but rather circulate as hpoproteins. Hyperlipoproteinemia describes an increased concentration of the lipoprotein macromolecules that transport lipids in the plasma. The density of plasma lipoproteins is determined by their relative content of protein and lipid. Density, composition, size, and electrophoretic mobility divide lipoproteins into four classes (Table 21-1). 

Lipoprotein Class Density Range (g/mL) Diameter (nm) Protein Triglyceride Free Ester Phospholipid... 

Proportional (Relative) Number of Cholesterol, Cholesteryl Ester, Phospholipid, and Protein Molecules in Four Major Classes of Plasma Lipoproteins. 

Lipids are a diverse group of biomolecules that dissolve in nonpolar solvents. They can be separated into the following classes fatty acids and their derivatives, triacylglycerols, wax esters, phospholipids, lipoproteins, sphingolipids, and the isoprenoids. 

Cholesterol is probably the best-known lipid because of the correlation between cholesterol levels in the blood and heart disease. Cholesterol is synthesized in the hver and is also found in almost all body tissues. Cholesterol is also found in many foods, but we do not require it in our diet because the body can synthesize all we need. A diet high in cholesterol can lead to high levels of cholesterol in the bloodstream, and the excess can accumulate on the walls of arteries, restricting the flow of blood. This disease of the circulatory system is known as atherosclerosis and is a primary cause of heart disease. Cholesterol travels through the bloodstream packaged in particles that also contain cholesterol esters, phospholipids, and proteins. The... 

The lipid classes of hazelnut oil include triacylglycerols (TAG) as nonpolar lipids (98.4%) and glucolipids (1.4%) and phosphoUpids (<0.2%) [phosphatidylcholine (PC) and phosphatidylinositol (PI)] as polar lipids [116]. The 18 lo)9 is dominant in the nonpolar lipid class (TAG), whereas 16 0, 18 0, and 18 2o)6 are most predominant in the polar Upid class in hazelnut oil. Recently, Alasalvar et al. [117] examined lipid class composition of Tombul hazelnut oil and found that it contained 98.8% of nonpolar and 1.2% of polar constituents. The main nonpolar lipid class in hazelnut oil is TAG, contributing nearly 100% to the total amount PC, phosphatidylethanolamine (PE), and PI are main polar Upids, contributing 56.4%, 30.8%, and 11.7% to the total polar lipids, respectively. Similar results were reported by Parcerisa et al. [105]. More recently, Miraliakbari and Shahidi [216] examined the lipid classes in tree nut oils that included TAG, sterols and sterol esters, phospholipids, and sphingoUpids. Hazelnut oil contained TAG, sterols, sterol esters, phosphatidylserine (PS), PC, PI, phosphatidic acid, and sphingoUpids. 

Triglycerides Practical routine methods for the determination of the main blood lipid classes, cholesterol and cholesterol esters, phospholipids, and triglycerides have been proposed. Triglycerides have been determined with lipoprotein lipase (EC 3.1.1.34) immobilized on CPG with a pore size of 200 nm. The assay buffer was 0.1 mol 1 TRIS buffer, pH 8.0, containing 0.5% Triton X-100. The linear response was 0.05-10 mmol 1 for tributyrin and 0.1—5 mmol 1 for triolein. 

Where R and R = H or a fetty acyl group and X = H (acylglycerols), phosphate ester (phospholipid) or glycosyl residue (galactolipid, sulpholipid). 

Fig. 2. Possible routes of glycerolipid deacylation. X = phosphate ester (phospholipids), glycoside (glycolipids), or hydrogen (acylglycerols). (For alternative nomenclature for reactions I-V, see Table I.)...

The third pathway involves metal catalysis. Metal catalysts appear to be necessary to initiate lipid peroxidation in cells since LDL oxidatively modified in the presence of cells has the same physico-chemical and biological properties as LDL oxidized by metals in the absence of cells. However, monocytes derived from macrophages can initiate both metal-induced and metal-independent oxidation processes. The polyunsaturated lipids (LH) in cholesteryl esters, phospholipids and triacylglycerols in LDL undergo oxidation by the same free radical chain mechanism as that established for food... 

Bovine milk fat is made up of 97-98 (wt% of total lipids) triacylglycerols accompanied by much smaller amounts of diacylglycerols (0.36%) and monoacylglyc-erols (0.03%), free cholesterol (0.31%), trace amounts of cholesteryl esters, phospholipids (0.60%), and minor amounts of free fatty acids. For reviews of the composition of bovine milk lipids, the reader is referred to Christie (4) and Jensen and Clarke (5). More than 400 fatty acids have been identified in milk fat, although it is generally accepted that 15 major and 12 minor fatty acids dominate the fatty acid spectrum. The major fatty acids found in milk are long chain (Cj. , myristic Ci6-o. palmitic Cjg., stearic Cjg.j, oleic) and the minor fatty acids are short chain... 

Total lipids, total cholesterol, cholesterol esters, phospholipids, triglycerides and FFA in serum and lipomatous and normal adipose tissue. All parameters were within the normal range The... 

R., Teicke, R., and Ullrich, B. Gas Chromatographic Studies of Serum Fatty Acids in Man. III. The Fatty Acids of Cholesterol Esters, Phospholipids, and Triglycerides, and the Unesterified Fatty Acids in Healthy and Arteriosclerotic Subjects Klin. Wochschr. 38 739-753 (1960) CA 54 25192g... 

Gas Chromatographic Analysis of Fatty Acids of Sertcn Cholesterol Esters, Phospholipids and Triglycerides of Hypothyroid Subjects Gerontol. 14(5) 417-423 (1966) CA 66 17654b... 

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