Lipoproteins high density

Cholesterol is biosynthesized in the liver trans ported throughout the body to be used in a va riety of ways and returned to the liver where it serves as the biosynthetic precursor to other steroids But cholesterol is a lipid and isn t soluble in water How can it move through the blood if it doesn t dis solve in if The answer is that it doesn t dissolve but IS instead carried through the blood and tissues as part of a lipoprotein (lipid + protein = lipoprotein) The proteins that carry cholesterol from the liver are called low density lipoproteins or LDLs those that return it to the liver are the high-density lipoproteins or HDLs If too much cholesterol is being transported by LDL or too little by HDL the extra cholesterol builds up on the walls of the arteries caus mg atherosclerosis A thorough physical examination nowadays measures not only total cholesterol con centration but also the distribution between LDL and HDL cholesterol An elevated level of LDL cholesterol IS a risk factor for heart disease LDL cholesterol is bad cholesterol HDLs on the other hand remove excess cholesterol and are protective HDL cholesterol IS good cholesterol... 

Heterogeneous reaction (Section 6 1) A reaction involving two or more substances present in different phases Hydro genation of alkenes is a heterogeneous reaction that takes place on the surface of an insoluble metal catalyst Heterolytic cleavage (Section 4 16) Dissociation of a two electron covalent bond in such a way that both electrons are retained by one of the initially bonded atoms Hexose (Section 25 4) A carbohydrate with six carbon atoms High density lipoprotein (HDL) (Section 26 11) A protein that carries cholesterol from the tissues to the liver where it is metabolized HDL is often called good cholesterol Histones (Section 28 9) Proteins that are associated with DNA in nucleosomes... 

High-density lipoprotein (HDL) (Section 26.11) Aprotein that carries cholesterol from the tissues to the liver where it is metabolized. HDL is often called good cholesterol. ... 

High density lipoprotein (HDL) (a-lipoprotein) Triacylglycerols, phospholipids, cholesterol 75... 

High-density lipoproteins (HDL) have much longer life spans in the body (5 to 6 days) than other lipoproteins. Newly formed HDL contains virtually no cholesterol ester. However, over time, cholesterol esters are accumulated through the action of lecithin cholesterol acyltransferase (LCAT), a 59-kD glycoprotein associated with HDLs. Another associated protein, cholesterol ester transfer protein, transfers some of these esters to VLDL and LDL. Alternatively, HDLs function to return cholesterol and cholesterol esters to the liver. This latter process apparently explains the correlation between high HDL levels and reduced risk of cardiovascular disease. (High LDL levels, on the other hand, are correlated with an increased risk of coronary artery and cardiovascular disease.)... 

Heterogeneous Non-uniform composition, 4 catalysis, 305-306 equilibrium, 329-331 High-density lipoprotein, 603 High-spin complex A complex that, for a particular metal cation, has the largest number of unpaired electrons, 419 Hindenburg, 111... 

Endothelial-anchored enzyme in liver primarily responsible for hydrolysis of triglycerides and phospholipids in Intermediate Density Lipoproteins (IDL) and High Density Lipoproteins (HDL). 

Szapary PO, Rader DJ (2004) The triglyceride-high-density lipoprotein axis an important target of therapy Am Heart J 148 211-221... 

Abbtvviations apoC-lll, apolipoprotein C-lll apoA-l, apolipoprotein A-l apoA-ll, apolipoprotein A-ll CRP, C-reactive protein VLDL, very low density lipoprotein TG, triglycerides LDL-C, low density lipoprotein cholesterol HDL-C, high density lipoprotein cholesterol. 

Systemic treatment of 13-cis retinoic acid frequently leads to cheilitis and eye irritations (e.g., unspecific cornea inflammation). Also other symptoms such as headache, pruritus, alopecia, pains of joints and bone, and exostosis formation have been reported. Notably, an increase of very low density lipoproteins and triglycerides accompanied by a decrease of the high density lipoproteins has been reported in 10-20% of treated patients. Transiently, liver function markers can increase during oral retinoid therapy. Etretinate causes the side effects of 13-cis retinoid acid at lower doses. In addition to this, generalized edema and centrilobulary toxic liver cell necrosis have been observed. 

Heparin Sulfate Proteoglycans Hepatic Lipase Hepatitis Hepatitis C Heptahelical Domain Heptahelical Receptors HERG-channels Heterologous Desensitization Heterologous Expression System Heterotrimeric G-Proteins Hidden Markov Model High-density Lipoprotein (HDL)... 

F9 embryonal carcinoma cells have a simple set of growth supplements which are required for growth in serum-free medium insulin, transferrin, and fibronectin (Rizzino and Sato, 1978). Fibronectin is a component of the extracellular matrix and facilitates the attachment of the cells to the culture dish. In addition, high density lipoprotein (HDL) has been observed to promote the growth of F9 cells serum-free. 

Part of a minor fraction known as very high density lipoproteins (VHDL). 

Figure 25-3. Metabolic fate of chylomicrons. (A, apolipoprotein A B-48, apolipoprotein B-48 , apolipoprotein C E, apolipoprotein E HDL, high-density lipoprotein TG, triacylgiycerol C, cholesterol and cholesteryl ester P, phospholipid HL, hepatic lipase LRP, LDL receptor-reiated protein.) Only the predominant lipids are shown.

Figure 25-5. Metabolism of high-density lipoprotein (HDL) in reverse cholesteroi transport. (LCAT, lecithinxholesterol acyltransferase C, cholesterol CE, cholesteryl ester PL, phospholipid A-l, apolipoprotein A-l SR-Bl, scavenger receptor B1 ABC-1, ATP binding cassette transporter 1.) Prep-HDL, HDLj, HDL3—see Table 25-1. Surplus surface constituents from the action of lipoprotein lipase on chylomicrons and VLDL are another source of preP-HDL. Hepatic lipase activity is increased by androgens and decreased by estrogens, which may account for higher concentrations of plasma HDLj in women.

Four major groups of lipoproteins are recognized Chylomicrons transport lipids resulting from digestion and absorption. Very low density lipoproteins (VLDL) transport triacylglycerol from the liver. Low-density lipoproteins (LDL) deliver cholesterol to the tissues, and high-density lipoproteins (HDL) remove cholesterol from the tissues in the process known as reverse cholesterol transport. 

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