Lipids

Question 1

Free fatty acids

Answer 1

chains of C w/ terminal carboxyl group

energy, bound to albumin for transport

Question 2

Triglycerides

Answer 2

3 fatty acids + glycerol

hydrophobic, neutral lipid

Question 3

Phospholipids

Answer 3

glycerol, 2 fatty acids + phospholipid head group
hydrophilic head, hydrophobic body
1 saturated fatty acid, 1 unsaturated fatty acid

Question 4

Cholesterol

Answer 4

unsaturated steroid alcohol

free cholesterol & cholesterol esters

Question 5

Free Cholesterol

Answer 5

hydrophilic at OH group on A ring; rest is hydrophobic

used for hormones, bile acids, 7-dehydrocholesterol (vit D uses this)

Question 6

Cholesterole esters

Answer 6

fatty acid joined to cholesterol at OH group on ring A

makes hydrophobic, neutral charge

Question 7

Lipoproteins

Answer 7

various classes

consist of protein, cholesterol esters, cholesterol, triglycerides, & phospholipids

Question 8

Chylomicrons

Answer 8

type of lipoprotein
carries exogenous triglycerides
SHOULD NOT BE PRESENT IN FASTING SPECIMENS
Apoprotein -48 send remnants to the liver

Question 9

Lipoprotein Lipase (LPL)

Answer 9

releases fatty acids from chylomicrons to be utilized for energy

Question 10

VLDL

Answer 10

carries endogenous triglycerides
liver triglycerides made from diet excess
loses triglycerides in circulation via LPL
apoproteins include B-100, E, C’s

Question 11

LDL

Answer 11

formed in circulation, carries cholesterol & cholesterol esters to cells
from VLDL degradation, apo B-100 stays on the complex
will deliver cholesterol to cells w/ apo B-100 receptors

Question 12

HDL

Answer 12

collects cholesterol from cells & returns it to the liver
anti-atherogenic lipoprotein ‘reverse cholesterol transport’
APOPROTEIN A-1!

Question 13

Lipid Metabolism

Answer 13

absorbed fatty acids & lipids are converted into chylomicrons which then enter the circulation
Lipoprotein Lipase (LPL) degradation of chylomicrons leads to chylomicron remnants as free fatty acids to be taken up by tissue cells which need apo C-II as co-factor for LPL
chylomicron remnants are take up by the liver through receptors
liver then makes VLDL & HDL- VLDL is transport for endogenous triglycerides

Question 14

Atherosclerosis

Answer 14

plague already formed!!!!!

blood vessels partly occluded

Question 15

Arteriosclerosis

Answer 15

the process by which fatty streaks develop into plauges due to oxidized LDL uptake by macrophages etc fostering the inflammatory process

Question 16

Hormones that affect cholesterol levels

Answer 16

thyroid, estrogens, insulin
^^ cholesterol levels = low levels of above hormones
overall low levels of cholesterol are better than high levels

Question 17

Hypercholesterolemia

Answer 17

increase in cholesterol
familia hypercholesterol
hetero- 300-600 mg/dL (statin drugs help)
homo- 800-1000 mg/dL (LDL pheresis)

Question 18

Hypertriglyceridemia

Answer 18

increased triglyercides

genetic, diabetes, hormone imbalances, renal failure

Question 19

Hyperlipidemia

Answer 19

increase in both cholesterol & triglycerides

increased risk for CHD- coronary heart disease

Question 20

Lipoprotein A (LpA)

Answer 20

presence can indicate increase risk for CHD
similar to plasminogen in structure - competes for fibrin binding sites & increases plague formation!!
cholesterol drugs do not help - need niacin & estrogen replacement
measure by immunoassay
independent risk factor for CHD

Question 21

Enzymatic Cholesterol methods

Answer 21

patient sample has cholesterol esters & cholesterol so in order to measure total cholesterol; must first convert cholesterol esters in serum to free cholesterol
Substrate: cholesterol esters
Enzymes: Cholesterol esterase, cholesterol oxidase, Peroxidase
read colored product

Question 22

HDL cholesterol methods

Answer 22

various precipitation reagents -> the supernatant analyzed by enzymatic cholesterol method
direct methods for HDL include specific antibody to apo B (APO B is is on all but HDL)
block activity of VLDL, LDL in sample
use alpha-cyclodextrin to select for HDL

Question 23

Precipitating reagents for HDL analysis

Answer 23

MgCl2 & Dextran Sulfate
Polyethylene Glycol (PEG)
etc

Question 24

Hyperalphalipoproteinemia

Answer 24

increased HDL ( over 100 mg/dL)
very rare & shows decreased risk of CAD

Question 25

Hypoalphalipoproteinemia

Answer 25

decreased HDL & increased risk for CAD

Question 26

Tangier’s Disease

Answer 26

absence of HDL w/ low to absent A-I & A-II (need these apoproteins to form HDL)
increased risk of developing atherosclerosis

Question 27

Triglyceride methods

Answer 27

Substrate: triglycerides (VLDL, LDL, HDLs- mostly VLDL)
Enzymes: bacterial lipase (no interference w/ endogenous lipase), glycerol kinase, glycerolphosphate oxidase, peroxidase
Read: colored product @ 500 nm
NEED FASTING SAMPLES

Question 28

Triglyceride method glycerol interference

Answer 28

10-20 mg/dL of glycerol in normal samples: can do a ‘glycerol’ blank to subtract interference or most commonly just set calibration to offset

Question 29

Hyperlipoproteinemias

Answer 29

elevated triglycerides seen secondary to DM, nephrosis, biliary obstruction, endocrine disturbances , fatty liver

Question 30

Hormone sensitive lipase

Answer 30

lipase that has to do with fat cells & move triglycerides into storage

Question 31

Calculating LDL

Answer 31

T cholesterol - ( HDL + [Triglycerides/5])

calculation is invalid if triglyceride value is over 500 mg/dL

Question 32

Measuring LDL

Answer 32

measure apoproteins, apo A-1 & B-100

use antibodies to apo E & A to remove other lipoproteins & measure residual

Question 33

Additional markers for cardiovascular disease

Answer 33

Lp(a), homocysteine, C-reactive protein, & Hs C reactive protein