| lipoprotein | <biochemistry> An important class of serum proteins in which a spherical hydrophobic core of triglycerides or cholesterol esters surrounded by an amphipathic monolayer of phospholipids, cholesterol and apolipoproteins. Classified according to density: chylomicrons, large low density particles, very low density, low density and high density species. Important in lipid transport, especially cholesterol transport in the blood stream. Abnormalities in lipoprotein metabolism have been implicated in certain heart diseases. (13 Nov 1997) |
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| lipoprotein(a) | A family of lipoprotein particles varying in density and size depending on the protein-lipid ratio and the protein composition. These particles consist of apolipoprotein b-100 covalently linked to apolipoprotein-a by one or two disulfide bonds. There is a correlation between high plasma levels of this lipoprotein and increased risk for atherosclerotic cardiovascular disease. (12 Dec 1998) |
| lipoprotein(a) hyperlipoproteinaemia | Elevated levels of lipoprotein(a) in the serum; associated with an increased risk of coronary disease. (05 Mar 2000) |
| lipoprotein-associated coagulation inhibitor | Formerly known as anticonvertin; a protein that inhibits the extrinsic pathway of coagulation by binding to the tissue factor III-factor VII-Calcium-factor Xa complex. (05 Mar 2000) |
| lipoprotein electrophoresis | Electrophoretic separation of plasma lipoproteins. (05 Mar 2000) |
| lipoprotein lipase | <enzyme> An enzyme of the hydrolase class that catalyses the reaction of triacylglycerol and water to yield diacylglycerol and a fatty acid anion. The enzyme hydrolyzes triacylglycerols in chylomicrons, very-low-density lipoproteins, low-density lipoproteins, and diacylglycerols. It occurs on capillary endothelial surfaces, especially in mammary, muscle, and adipose tissue. Genetic deficiency of the enzyme causes familial hyperlipoproteinaemia type I. Chemical name: Triacylglycero-protein acylhydrolase Registry number: EC 3.1.1.34 (12 Dec 1998) |
| lipoprotein lipase deficiency, familial | A rare familial condition characterised by massive chylomicronaemia and decreased levels of other lipoproteins. It is due to deficiency of lipoprotein lipase, an alkaline triglyceride hydrolase which catalyses an important step in the extrahepatic removal of triglyceride-rich lipoproteins from the blood. (12 Dec 1998) |
| lipoprotein Lp(a) | A lipoprotein composed of an LDL particle combined with an additional protein, Lp(a) specific protein; elevated levels have been identified as a risk factor for coronary artery disease. (05 Mar 2000) |
| lipoprotein polymorphism | Heritable variations in low density beta-lipoproteins; the variant lipoproteins exhibit different antigenic and chemical properties when compared with normal lipoproteins. (05 Mar 2000) |
| lipoprotein-x | An abnormal lipoprotein which is present in large amounts in individuals suffering from obstructive liver diseases. It exists as a bilayer vesicle of equimolar phospholipids and unesterified cholesterol containing small amounts of plasma proteins (mainly albumin) in its internal aqueous compartment together with some apolipoproteins adsorbed on its surface. Separates with ldl by ultracentrifugation. (12 Dec 1998) |
| bone density | Bone density is the amount of bone tissue in a certain volume of bone. It can be measured using a special X-ray called a quantitative computed tomogram. (12 Dec 1998) |
| bulk density | Weight per unit of volume, usually specified in pounds per cubic foot. (05 Dec 1998) |
| buoyant density | The density that allows a substance to float in some standard fluid. (05 Mar 2000) |
| vapor density | The mass per unit volume of a vapor; since the vapor density changes with temperature and pressure, it is commonly expressed as a specific gravity, i.e., the weight of the vapor divided by the weight of an equal volume of a reference gas (e.g., oxygen or hydrogen) at the same temperature and pressure. (05 Mar 2000) |
| centrifugation, density gradient | Separation of particles according to density by employing a gradient of varying densities. at equilibrium each particle settles in the gradient at a point equal to its density. (12 Dec 1998) |