Dyslipidemias

Question 1

What is the makeup of lipoproteins?

Answer 1

Lipid core
Phospholipid monolayer
Structural apolipoproteins

Question 2

What are the different apo-lipoproteins?

Answer 2

Apo B-100: VLDLs, IDLs, LDLs bind the LDL receptor

Apo B-48: Chylomicrons structrual role only

Apo A-I: HDL
Activates LCAT

Question 3

Where are the different Lipoproteins made?

Answer 3

Chylomicrons-Enterocytes
VLDLs Liver
IDLs In circulation from VLDL
LDLs In circulation from IDL
HDLs Liver/Intestine 80/20

Question 4

What is the role of the liver in cholesterol Metabolism?

Answer 4

Site of biosynthesis
Liver HMG-CoA Reductase most effected by statins
Major route for cholesterol elimination
Major distribution point for cholesterol

Question 5

What are the key enzymes of lipid metabolism?

Answer 5

HMG-CoA Reductase
Lipoprotein Lipase
Hepatic Lipase
CETP(Cholesterol ester transfer protein)
LCAT(Lecithin cholesterol acyl transferase)

Question 6

What is the action of HMG-CoA Reductase?

Answer 6

Reduces HMG-CoA Conversion to mevalonic acid in the RLS of Cholesterol biosynthesis

Question 7

What is the action of Lipoprotein Lipase?

Answer 7

Hydrolyzes TG core Of Chylomicrons, VLDL, and IDL

• induced by insulin
• located in capillary walls

Question 8

What is the action of Hepatic Lipase?

Answer 8

Hydrolyzes TAGs in IDL to facilitate conversion to LDL

Question 9

What is the action of CETP?

Answer 9

Transfers Cholesteryl esters from HDL to other lipoproteins in exchange for TG phospholipids and cholesterol
-Present on HDL

Question 10

What is the action of LCAT?

Answer 10

Transfers fatty acids from Lecithin to Cholesterol to form Chol. Esters in HDL. Keeps Chol concentration low in the phospholipid monolayer
-Present on HDL

Question 11

What are the Apo-B containing Lipoproteins?

Answer 11

LDL
IDL
VLDL
Chylomicrons

Question 12

What is Lipoprotiiene a?

Answer 12

Attached to B-100 and creates a pro-thrombotic state.
Structural similarity to plasminogen
Carried Oxidized phospholipids resulting in an increased inflammatory and atherogenic and thrombotic risk.

Question 13

What is the function of HDL cholesterol?

Answer 13

Made in the liver
apo A1
Removes free cholesterol from extrahepatic tissue
Esterification of C to CE
Transports TG, C/CE back to the liver for excretion
-direct
-indirect

Question 14

What are the pathways for HDL Transporting TG, C/CE back to the liver for excretion

• direct
• indirect

Answer 14

Dir: C, TAGs and especially CE directly to the liver via endocytosis
Indirect: Transfer some CE to LDL via CETP which is then taken up by the liver LDL receptor

Question 15

What is the role of the liver in reverse cholesterol transport?

Answer 15

Conv. Cholesterol to bile acids
Bile acids aid in digestion and are excreted in feces
Some reabsorbed in the ileum

Question 16

What are some other actions of HDL?

Answer 16

Antioxidant, Antiinflammatiory, Profibrinolytic

Question 17

What is the purpose of Chylomicrons?

Answer 17

Deliver Dietary TAG FAs to tissues by LPL

Question 18

What is the purpose of Chylomicron Remnants?

Answer 18

Deliver remaining chylomicron lipids to the liver via endocytosis

Question 19

What is the purpose of VLDLs?

Answer 19

Deliver TAG FAs from the liver the extra hepatic tissues

Question 20

What is the purpose of IDLs?

Answer 20

Deliver TAG FAs to Extra hepatic tissues AND BACK TO THE LIVER via HL

Question 21

What is the purpose of LDLs?

Answer 21

Deliver C and CE to tissues including the liver via ENDOCYTOSIS.

Question 22

What is the purpose of HDLs?

Answer 22

Reverse cholesterol transport from Extra hepatic tissues to the liver vi endocytosis or indirectly by transferring CE to LDL via CETP

Question 23

Who will statins work for?

Answer 23

Intermediate to very high cholesterol and even very late life patients

Question 24

How are lipoproteins measured?

Answer 24

Lipoprotein analysis after 12-14 hrs fasting

TC and HDL can be measured fasting or non fasting