Lipoproteins II Flashcards
……. is filled in the blood with cholesteryl esters which are delivered back to the liver.
HDL
HDLs act as a “reservoir” of ……. and ……which are transferred to chylomicrons and VLDL.
Apo- E and Apo-C
This enzyme is synthesized in hepatocytes and released into the blood and forms cholesteryl esters
Lecithin-cholesterol-acyl transferase (LCAT or PCAT)
HDL3 is changed to the larger ……….after uptake of more cholesterol esters
HDL2
HDL2 interact via CETP (cholesteryl ester transfer protein) with VLDL
HDL2 binds to the scavenger receptor ……. and the cholesteryl esters in HDL are equilibrated with the intracellular cholesteryl esters.
SR-B1
The smaller HDL leaves the hepatic SR-B1 and can be filled in the …….again with cholesteryl esters.
Blood
LCAT needs activation by ……. and binds to HDL
Apo A-1
The transfer of a fatty acid from phosphatidylcholine (lecithin) from the HDL membrane to free cholesterol is catalyzed by …… in the blood.
LCAT
Free cholesterol is provided by the plasma membrane cholesterol ……… transporter
ABCA1
…… is a protein in the blood that can form a bridge between VLDL and HDL which allows the movement of cholesteryl esters (CE) from HDL into VLDL in exchange for TAGs
CETP
CE exchanged from HDL can reach the liver via ………. and aid with the reverse cholesterol transport
IDL or LDL
Hypoalphalipoproteinemia:
Low HDL and low Apo A-1 levels
Abetalipoproteinemia: a rare hereditary disease caused by an abnormal MTP (microsomal TAG transfer protein) results in ….
No or low LDL
Rare hereditary disease characterized by orange colored tonsils in children and accumulation of cholesteryl esters in liver or spleen due to extremely low HDL.
Tangier Disease (example of a Hypoalphalipoproteinemia)
The very low HDL levels in Tangier Disease result from the degradation of ……. and deficiency of the cholesterol transporter……
Apo A-1
ABCA1
All are characteristics of which disease?
- Strongly reduced release of VLDL and chylomicrons
- Blood TAG levels <19 mg/dL (normal 150)
- Total cholesterol <50 mg/dL (normal 200)
- Failure to thrive. Fat malabsorption
- TAG accumulation in liver and intestine
Abetalipoproteinemia: MTP deficiency
What are the normal levels of LDL, HDL, and VLDL in the blood?
LDL- 100-130
HDL- 40-70
VLDL- 20-30
…………refers to an abnormal lipoprotein pattern that is risk factor for cardiovascular disease (CVD):
- High total cholesterol > 200 mg/dL
- High LDL-C > 160 mg/dL
- High TAG > 200 mg/dL
- Low HDL-C < 40mg/dL
Dyslipidemia
Friedewald Equation: Lipid profile for screening for CVD risk factors
[LDL-C] = [total C] – ( [HDL-C] +[TAG: 5] )
Type I: Familial Hyperchylomicronemia
Rare disease characterized by a high serum TAG level (>750 mg/dL) caused by a high chylomicron level. Creamy layer on top of blood sample
Patients with Type I: Familial Hyperchylomicronemia present with:
Xanthomas, Hepatosplenomegaly, lipemia retinalis (vessels creamy white)
Type IIa: Familial Hypercholesterolemia
High LDL, normal VLDL and clear serum.
Total cholesterol 250-500 mg/dL
Tendon Xanthomas and Xanthelasma near eyelids
Cause of Type IIa: Familial Hypercholesterolemia is mainly a defect in ………..
LDL receptor or clearance of LDL (Apo-100)
Type IIb: Familial Combined Hyperlipidemia
High LDL, high VLDL and turbid serum
Total cholesterol: 250-500 mg/dL
TAG 250-750 mg/dL
– Overproduction of apo B100
– Overproduction of VLDL
– Defective clearance of LDL may be the cause of …………
Type IIb: Familial Combined Hyperlipidemia
Type III: Dysbetalipoproteinemia:
High remnant levels (chylomicron remnants and IDL) but also abnormal b-VLDL
- Total cholesterol 250-500 mg/dL
- TAG 250-500 mg/dL
Deficiency in Apo-E resulting in palmar xanthomas and tuber-eruptive xanthomas over the elbows and knees are characteristic of…..
Type III: Dysbetalipoproteinemia
Type IV: Familial Hyperprebetalipoproteinemia:
High VLDL
TAG 200-500 mg/dL
High VLDL levels in Type IV may be caused by
LPL deficiency or overproduction of VLDL
Type V: Familial Mixed Hypertriacylglyerolemia
High chylomicron levels
High VLDL levels.
What is the concept to treat hypercholesterolemia?
Reduction of hepatic cytosolic cholesterol with statin drugs (inhibit hepatic cholesterol synthesis) which increases of LDL-receptors and LDL-clearance.
What is another concept to treat hypertriacylglyerolemia?
Reduction of hepatic TAG synthesis which leads to lower levels of VLDL, LDL and elevates HDL level with niacin and fibrates
LDL pattern …… is considered a risk factor for CHD (coronary heart disease)
LDL pattern B
……….. is a risk for coronary heart disease because it may reduce the removal of blood clots which could trigger MI or stroke.
Lipoprotein A
