High density lipoproteins properties

Increases in serum lipids and glucose appear to be transient and of little clinical importance. /J- Blockers increase serum triglyceride levels and decrease high-density lipoprotein cholesterol levels slightly. /1-Blockers with -blocking properties (carvedilol and labetalol) do not affect serum lipid concentrations. 

Main Physical Properties op Human Sebum High-Density Lipoproteins... 

Raloxifene (Evista) is a new SERM approved for use in the treatment and prevention of osteoporosis because it has estrogenic activity in bone. Raloxifene is an estrogen antagonist in both breast and endometrial tissues. The estrogenhke properties of raloxifene result in the maintenance of a favorable serum Upid profile (decreased low-density lipoprotein levels with no change in either high-density lipoproteins or triglycerides). Raloxifene is 95% bound to plasma proteins. Absorption of raloxifene is impaired by cholestyramine. 

The role of the antioxidant properties of vitamins C, E, and p-carotene in the prevention of cardiovascular disease has been the focus of several recent studies. Antioxidants reduce the oxidation of low-density lipoproteins, which may play a role in the prevention of atherosclerosis. However, an inverse relationship between the intake or plasma levels of these vitamins and the incidence of coronary heart disease has been found in only a few epidemiological studies. One study showed that antioxidants lowered the level of high-density lipoprotein 2 and interfered with the effects of lipid-altering therapies given at the same time. While many groups recommend a varied diet rich in fruits and vegetables for the prevention of coronary artery disease, empirical data do not exist to recommend antioxidant supplementation for the prevention of coronary disease. 

Table 1 Metrological properties of methods used by the Choles- CV coefficient of variation, HDLC high-density lipoprotein cho-terol Reference Method Laboratory Network (CKMLN). 2 KM lesterol, SD standard deviation, LDLC low-density lipoprotein Secondary reference method, DCM designated comparison meth- cholesterol, NA not available od, IDMS isotope dilution mass spectroscopy, AK Abell-Kendall,...

Lipoproteins are globular, micelle-like particles consisting of a hydrophobic core of triacylglycerols and cholesterol esters surrounded by an amphipathic coat of protein, phospholipid and cholesterol. The apolipoproteins (apoproteins) on the surface of the lipoproteins help to solubilize the lipids and target the lipoproteins to the correct tissues. There are five different types of lipoprotein, classified according to their functional and physical properties chylomicrons, very low density lipoproteins (VLDLs), intermediate density lipoproteins (IDLs), low density lipoproteins (LDLs), and high density lipoproteins (HDLs). The major function of lipoproteins is to transport triacylglycerols, cholesterol and phospholipids around the body. 

J6. Jackson, R. L., Morrisett, J. D., Pownall, H. J., and Gotto, A. M., Jr., Human high density lipoprotein, apoliprotein glutamine II. The immunochemical and lipid-binding properties of apolipoprotein glutamine II derivatives. J. Biol. Chem. 248, 5218-5224 (1973). 

High density lipoprotein (HDL) and other lipoprotein can bind endotoxin, thereby attenuating the immunologic response, a property thought to be related to the phospholipid content (Feingold et al., 1995 Harris et al., 1990 Levine et al., 1993 Wu et al., 2004). 

Blood plasma contains a number of soluble lipoproteins, which are classified, according to their densities, into four major types. These lipid-protein complexes function as a lipid transport system. Isolated lipids are insoluble in blood, but they are rendered soluble, and therefore transportable, by combination with specific proteins, the so-called lipoproteins. There are four basic types in human blood (1) chylomicrons, (2) very low density lipoproteins (VLDL), (3) low-density lipoproteins (LDL). and (4) high-density lipoproteins (HDL). Their properties are summarized in Table 6.2. 

These lipids are insoluble in water and are classified on the basis of their ultracentrifugal properties into chylomicrons, very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) in order of ascending density. Table 2.4 gives the classification and roles of lipoproteins. 

Lipoproteins are assembled in two organs, the small intestine and the liver. The lipoproteins assembled in the intestine contain the lipids assimilated from the diet. These lipoproteins, called chylomicrons, leave the enterocyte and enter the bloodstream via the Lymphatic system. The lipoproteins assembled in the liver contain lipids originating from the bloodstream and from de novo synthesis in the liver. The term de novo simply means "newly made from simple components" as opposed to "acquired from the diet" or "recycled from preexisting complex components." These lipoproteins, called very-low-dcnslty lipoproteins (VLDLs), are secreted from the liver into the bloodstream. The liver also synthesizes and secretes other Lipoproteins called high-density Lipoproteins (HDLs), which interact with the chylomicrons and VLDLs in the bloodstream and promote their maturation and function. The data in Table 6-4 show that chylomicrons contain a small proportion of protein, whereas HDLs have a relatively high protein content. Of greater interest is the identity and function of the proteins that constitute these particles. These proteins confer specific properties to lipoprotein particles, as detailed later in this chapter. 

The nitroxide (33) closely resembles cholesterol in its physical and biological properties, and has been used as a spin-labelled analogue of cholesterol to investigate cholesterol-protein interactions in human high-density lipoprotein.146 The fluorescent cholesterol analogue A-(7-nitrobenz-2-oxa-l,3-diazole)-22-amino-23, 24-dinorchol-5-en-3p-ol (34) has been used as a substrate for lecithin cholesterol... 

Maziere JC, Santus R, Morliere P, et al. Cellular uptake and photosensitizing properties of anticancer porphyrins in cell membranes and low and high density lipoproteins. J Photochem Photobiol B 1990 6 61 68. 

Kruski, A.W. Scanu, A.M. (1975). Properties of rooster serum high density lipoproteins. Biochim. Biop/iys. Acta, 409,26-38. 

Eugene A. Podrez Anti-oxidant properties of high-density lipoprotein and atherosclerosis. Clin. Exp. Pharmacol. Physiol. 2010 37(7) 71925. 

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