Term
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Definition
Delivers de novo TAG to periphery
Contains apo B-100, ApoE and C
Picks up more ApoE and C later from HDL
Lipoprotein Lipase relases FA from VLDL |
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Term
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Definition
Half of VLDL remnants that have multiple copies of ApoE are taken up by liver
Smaller VLDL remnants with few ApoE copies become IDL -> LDL via hepatic triacylglycerol(HTGL) |
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Term
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Definition
Has most cholesterol
Deliver cholesterol to periphery and liver
Contains apoB-100. Receptor mediated endocytosis. 2/3 cholesterol taken up by liver.
Some LDL cleared by macrophages that have scavenger receptors and affinity for acetylated or oxidized LDL. |
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Term
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Definition
least TAGs and high choelsterol. Made by liver + intestine.
Delivers cholesterol to liver for elmination.
Important reservoir of apoproteins. |
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Term
| Hepatic Triacylglycerol Lipase |
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Definition
Found on endothelial cells in space of disse, attached to lumen via heparin sulfate
Hydrolysis of TAGs and phospholipids
IDL -> LDL and HDL2 -> HDL3 |
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Term
| Apoplipoproteins on plasma lipoproteins |
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Definition
Chylomicron: B-48
VLDL, IDL, LDL: B-100
HDL: no B |
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Term
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Definition
Formed with ApoB-48 and ApoA lipoproteins
ApoE and CII-Apolipoproteins are acquired later from HDL |
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Term
| Disposal of chylomicron remnants |
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Definition
Chylomicron remnants bind to heparin sulfate and then bind to lipoprotein receptors(Requires ApoE) on surface of hepatocyte
Complex is endocytosed in space of disse
Hydrolyzed by lysosomal enzymes |
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Term
| REgulation of Cholesterol and LDL receptors |
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Definition
Excess cholesterol -> ACAT -> Reduces choelsterol synthesis.
Reduces LDL receptor synthesis via SREBP |
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Term
| Free cholesterol acts on 3 proteins |
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Definition
Induces Acyl-CoA cholesterol acyl transferase (Makes cholesterol Ester)
Represses HMG-CoA reductase: cholesterol synthesis
Reduces synthesis of LDL receptors |
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Term
| Function and Fates of HDL |
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Definition
HDL transports cholesterol from extrahepatic tissues to liver for elimination
Nacent HDL: Liver and intestine: Contain ApoA-I,ApoA-II, and ApoC.
Intestinal only formed with ApoA-1 others picked up lateer.
HDL picks up apoplipoproteins from VLDL and chylomicrons.
Functions as mobile store for apoproteins ecept Apo-Bs(48,100) |
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Term
| Enzymes Determining HDL function |
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Definition
Lecithin-cholesterol acyl transferase(LCAT) binds to surface of HDL and activated by ApoA-I (facilitates transfer of FA from cholesterol-ester to Lecithin)
Cholesterol ester transer protein(CETP) transfers cholesterol ester from HDL to other lipoproteins. |
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Term
| Risk factors for atherosclerosis and CHD |
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Definition
LDL cholesterol correlates with CHD better than plasma cholesterol
High HDL is associated with reduction in risk |
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Term
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Definition
Cholesterol ester deposits occur first in macrophages than in extracellular space.
Oxidized LDL causes endothelial injury ->
macrophage migration and uptake of oxidized lipoprotein -> Foam cells. |
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Term
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Definition
Form of LDL in which glycoprotein(apolipoprotien(a) is disulfide bonded to ApoB-100 molecule of LDL.
Elevated Lp(a) levels: risk factor for atherosclerosis
Not affected by diet. Determined by gene expression in liver. |
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Term
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Definition
AR, Rare
Mutation in microsomal triglyceride transfer protein(MTP)
Effects absorption of dietary fats, cholesterol, and fat soluble vitamins(ADEK)
Liver, intestine cannot assemble normal TAG-rich ApoB containing lipoproteins.
VLDL, LDL, chylomicrons virtually absent. |
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Term
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Definition
ApoE transports lipoproteins, fat-soluble vitamins, and cholesterol
Enhances protelytic breakdown of peptide beta amyloid. |
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Term
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Definition
Assist in HDL formation
ApoA1 binds ABCA1 -> accumulation of cholesterol -> nascent pre-HDL
(loads cholesterol onto HDL)
Tangier disease: mutation in ABCA1: orange tonsils. HDL levels reduced. |
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Term
| Triglyceride lowering drugs |
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Definition
Fibric Acid derivatives
Clofibrate, Gemfibrosil, fenofibrate
Stimulates lipoprotein lipase
Interact with PPAra(peroxisome proliferator activated receptors)
Inhibits triglyceridie lipolysis in adipose, decreases FFA intake by liver, Decreases heapatic VLDL/TG synthesis |
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Term
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Definition
Water soluble B vitamin
converted to amide and incorporated into NAD
Triglyceride and cholesterol lowering. Decreases VLDL and LDL
Decreases TG lipase in adipose tissue.
Increases Lipoprotein lipase in adipose |
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Term
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Definition
Lecithin cholesterol acyl transferase
(lecithin = phosphatidyl choline)
Lecithin + cholesterol -> CE + lysolecithin
CHolestero acquired by HDL cannot be esterfied -> higher free cholesterol/CE ratio in all lipoproteins.
Complete: corneal clouding
Incomplete: Fish eye(opacity) |
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Term
| Type I hyperchylomicronemia |
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Definition
Hydrolysis of TAGs impaired
Most plasma cholesterol is in VLDL(LDL formation impaired)
Deficiency of LPL or Apo-CII(LPL activator) |
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Term
| Type II Hypercholesterolemia |
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Definition
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Term
| Type III: dysbetalipoproteinemia |
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Definition
ApoE that cannot bind hepatic ApoE receptors.
Chylomicron remnants and IDL-like VLDL remnants, accumulate in blood |
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Term
| Typie IV and Type IV hyperlipoprotenemia |
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Definition
Elevated VLDL and chylomicrons.
Obseity, DM, ALcholism.
Dietary treatment is effective |
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