CV I - Hyperlipidemia Flashcards
What percent of deaths in a year are due to CV disease?
40%
What is the magnitude of increased risk for increases in serum cholesterol?
4-fold, upper vs. lower 10%
What are the four classes of circulating lipoproteins?
- Chylomicrons (Largest, triglyceride rich)
- VLDL
- LDL
- HDL (smallest, triglyceride poor)
Which apoproteins do chylomicrons and VLDL have?
- apo B-48
- apo B-100
- apo C
- apo E
What apoproteins do LDL have?
- Apo B-100
Which apoproteins do HDL have?
- Apo A-I
- apo A-II
- Apo C
- apo E
What does HDL do?
Takes excess cholesterol from the peripheral and brings it to the liver for metabolism and elimination (reverse cholesterol transport).
It acts with scavenger receptor-BI on the liver
Where is cholesterol generated?
Liver
Where are chylomicrons generated? What happens to them?
Generated in the GI tract from digesting fat.
They interact with lipoprotien lipase to liberate free fatty acids into peripheral tissue. Apolipoprotein C-LL (apo C-II) present on the chylomicron surface for this purpose.
Chylomicron remnant is taken up by the liver by receptor mediated endocytosis.
Where do VLDLs come from and where are they going?
Come from liver, go to peripheral tissue where they deposit fatty acids before becoming ‘VLDL remnants (IDL)’ in the blood and getting converted to LDL in the blood via removal of some apolipoproteins and lipolysis of remaining triglyceride.
What is cholesterol synthesized from? What is it metabolized to?
Liver synthesizes cholesterol from acetyl CoA.
Liver metabolizes cholesterol to form bile acids, which are sent to the duodenum and reabsorbed back to the liver for reutilization.
Give the synthetic pathway for hepatic cholesterol, including the rate limiting step.
- Acetyl CoA
- HMG-CoA
- HMG-CoA reductase converts HMG-CoA to cholesterol (RLS)
True or false? In addition to being metabolized to bile salts. Cholesterol can be deposited straight into the bile?
True
What do VLDLs do?
They transport lipids from the liver to other tissues. The majority of serum triglycerides are found in VLDL.
Where is the majority of circulating cholesterol found in humans?
In LDL
LDL are the primary means of delivery of cholesterol to peripheral tissues
Cholesterol uptake is achieved via LDL receptor-mediated endocytosis (50% by liver; remainder by other tissues)
How do HDL particles mature?
- Acquiring lipids (primarily cholesterol) from VLDL and chlyomicrons during lipolysis
- Acquiring cholesterol from peripheral tissues
What is type IIa hyperlipoproteinemia?
High levels of cholesterol (LDL) with no change to triglyceride level.
Also known as familial hypercholesterolemia if there is a LDL receptor mutation. But it is multifactorial (genetic or other)
It has a high incidence
What is type IIb hyperlipoprotienemia?
High LDL and VLDL elevates cholesterol AND triglyceride levels.
AKA familial combined hyperlipoproteinemia.
Characterized by incresed VLDL secretion.
It has a high occurrence of cardiovascular disease risk.
Which two hyperlipoproteinemias are the most commonly targeted by therapeutics?
Type IIa and IIb
What is an atherosclerosis?
- Reduction in blood flow leading to increased risk for CV disease (heart attack, stroke, kidney failure etc.)
- Consequence of aging, as well as certain factors (genetic and other)
List the risks for getting atherosclerosis
- Hypertension
- Hyperlipidemia
- Smoking
- Hyperglycemia
- Obesity
- Infection
- Inflammation
Give the steps for athersclerosis formation
- Injury to endothelium allows LDL to get into intima. It is oxidized (oxLDL) which causes immune response
- Foam cell formation (macrophage cells migrate from blood through tear in endothelium and uptake oxLDL, which is scavenger receptor mediated).
- Cholesterol stored as cholesterol esters (which can be removed by efflux to HDL, which is ABCA1 transporter mediated)
- Lysing of foam cells releases cholesterol esters back and further propagates the inflammatory response)
- Formation of necrotic core, fibrosis and advancement of lesion formation
What lipoprotein concentrations are positively correlated with risk for atherosclerosis?
- Serum total cholesterol
- Serum LDL
- Serum LDL:HDL
Give six categories for the treatment of hyperlipidemia
- Therapeutic lifestyle changes (TLC)
- Statins
- Niacins
- Bile acid binding resins
- Cholesterol absorption inhibitors
- Fibrates