Lipids and Lipoproteins Flashcards
Constitutes the body’s “petroleum industry.”
Lipoproteins
are large, lipid-rich transport vessels that ferry their cargo of dietary triglycerides throughout the circulatory system to peripheral tissues, until arriving at the liver as chylomicron remnants when nearly empty.
Chylomicrons
most abundant lipid
phospholipid
where does phospholipid originate
liver and intestines
formed from conjugation of two fatty acids and phosphorylated glycerol
Phospholipid
lipids with both hydrophilic and hydrophobic parts
amphipatic lipids
phospholipids are produced in the lungs by
type II pneumocytes in the form of lamellar bodies
Ref value of phospholipid
150 - 350 mg/dL
alters fluid surface tension (surfactant)
phospholipid
Phospholipids are important substrates of ?
LCAT and LPL
Forms of phospholipids
- Lecithin/phosphotidyl choline – 70%
- Sphingomyelin – 20%
- Cephalin – 10%
the only phospholipid that is NOT derived from glycerol
Sphingomyelin
amino alcohol of Sphingomyelin
sphingosine
essential component of RBCs and nerve sheath
Sphingomyelin
unsaturated steroid alcohol containing 4 rings with a single C-H-side chain tail
Cholesterol
cholesterol is synthesized where
liver
cholesterol should be measured in all adults at — years old at least once every — years
20 yrs old
every 5 yrs
cholesterol is important in the assembly of …
cell membranes, bile acids, and steroid hormones
transport and excretion of cholesterol is promoted by
estrogen
cholesterol evaluates the risk of..
evaluates the risk of atherosclerosis, CAD (coronary artery disease) and Myocardial infarction (heart attack)
forms of cholesterol
cholesterol ester 70%
unesterified/free cholesterol – 30%
cholesterol ester is esterified by
Lecithin-Cholesterol Acyl Transferase (LCAT)
inactive form of cholesterol is
cholesterol ester. stored in cells
active form of cholesterol is
unesterified/free cholesterol. cytotoxic property
fasting hours needed for cholesterol lab work. and what specimen
12 to 14 hours
serum
principle of colorimetry
dehydration and oxidation of cholesterol to form a colored compound
end product of Salkowski reaction and color
cholestedienyl disulfonic acid
red
Liebermann-Burchard end product and color
monosulfonic acid
green
color developers of colorimetry/chemical method
glacial acetic acid, acetic anhydride, conc. sulfuric acid
Pearson, Stern, and Mac Gavack method
colorimetry
Bloor’s extraction
E + C
Abell – Kendall
saponification (s) + E + C
Schoenheimer, Sperry, Parekh, and Jung
S+E+C+Precipitation
effect of hemolysis on cholesterol level
falsely increases
reagent of colorimetry
Leibermann-Burchard
reagent for extraction
petroleum ether
reagent for saponification
alcoholic potassium hydroxide
reagent for precipitation
digitonin
most common method of quantifying the cholesterol oxidase reaction
is to measure the amount of hydrogen peroxide produced
reference method for cholesterol and what color
abell, levy, broolie method;
end color:green
gold standard for cholesterol
isotope dilution mass spectrometry
Mod risk, age 2 - 19
> 170
high risk, age 2 - 19
> 155
mod risk, age 20 - 19
> 200
high risk, age 20 - 19
> 220
mod risk, age 30 - 39
> 220
high risk, age 30 - 39
> 240
mod risk, age 40 - 49
> 240
high risk, age 40 - 49
> 260
Main storage lipid in man
Triglyceride/Triglycerol (neutral fat)
triglyceride components
three fatty acids and one glycerol
Exogenous TAG
chylomicron
endogenous TAG
VLDL
what is laboratory measurement of TAG based on
hydrolysis of FAs to produce glycerol
specimen and fasting hours for TAG
serum
12 - 14 hours fasting
what might interfere in TAG results?
ascorbic acid, bilirubin, hemolysis
level of TAG that is clear serum
<200 mg/dL
level of TAG that is turbid serum
> 300 mg/dL
level of TAG that is milky/opaque serum
> 600 mg/dL
colorimetric for TAG and what is end color
van handel and zilversmith
– blue
what is flurometric method for TAG and end color
hantzsch condensation
– yellow
major interference in enzymatic method for TAG
glycerol
specific, rapid, easy to use for TAG measurement
enzymatic method
COC tag level <150 mg/dL
normal
COC tag levels 150 - 199
borderline high
COC tag levels 200 - 499
high
COC tag levels ≥500
very high
transports lipid throughout the body
lipoproteins
are the major sites of protein synthesis
hepatocytes and enterocytes
used in the assessment of atherosclerosis and CAD
lipoproteins
main purpose of lipoproteins
transport TAG and Cholesterol to sites of energy storages and utilization
hydrolyzes TG to glycerol and FA
lipoprotein lipase
hydrolyzes TG and phospholipids from HDL (high density lipoprotein)
Hepatic lipase
converts free cholesterol to cholesteryl ester
Lecithin-cholesterol acyltransferase (LCAT)
hydrolyzes HDL for the release of TG
Endothelial lipase
largest and least dense lipoprotein
chylomicrons
delivers exogenous/dietary TAG
chylomicron
major apolipoprotein of chylomicron
APO B-48
non-atherogenic lipoproteins
chylomicrons, HDL
atherogenic lipoproteins
VLDL, LDL
Density of chylomicron
<0.95 kg/L
AKA pre-beta lipoprotein
VLDL (very low density lipoprotein)
transports endogenous TAG: atherogenic
VLDL (very low density lipoprotein)
major apolipoprotein of VLDL
APO B-100
density of VLDL
0.95 – 1.006 kg/L
AKA beta – lipoprotein
LDL
Major catabolic end-product of VLDL
LDL
Primary marker for CHD (congenital heart disease) risk
LDL
most atherogenic lipoprotein
LDL
Major apolipoprotein of LDL
APO B-100
density of LDL
1.019 – 1.063 kg/L
AKA alpha lipoprotein
HDL
smallest and most dense lipoprotein
HDL
how is antiatherogenic conc. related to cardiovascular disease risk
inversely
most cardioprotective form of HDL
HDL2
Density of HDL
1.063 – 1.21 kg/L
COC ref method for HDL
ultracentrifugation precipitated with heparin MnCL
HDL level <40 mg/dL
low
HDL level <35 mg/dL
Hgb risk factor for CHD
HDL protective level
60 mg/dL
specific and sensitive indicator of cholestasis
Lipoprotein X
Lipoprotein X is sensitive indicator of
cholestasis
lipoprotein X is found in..
obstructive jaundice and LCAT deficiency
AKA floating beta lipoprotein
B - VLDL
floating beta lipoprotein is found in what type of ◦ hyperlipoproteinemia/dysbetalipoproteinemia
type 3
similar density to VLDL
B – VLDL
product of VLDL catabolism – “VLDL remnant”
IDL (intermediate density lipoprotein)
apolipoprotein of IDL
APO B-100
AKA sinking Pre-beta lipoprotein
Lpa or lipoprotein a
increased levels of lipoprotein a means
premature CHD and stroke
density of lipoprotein a
1.045 – 1.081 kg/L
lab specimen for lipoprotein
plasma
chelating agent for lipoprotein lab analysis
EDTA
order from most to least dense
HDL, LDL, IDL, VLDL, CM
order from most anodic/fastest
HDL, VLDL, IDL, LDL, CM
amount of aliquot of plasma for standing plasma test
2 mL
accumulates overnight as a floating “cream” layer and can be detected visually
chylomicrons
A plasma sample that remains turbid after standing overnight contains excessive amounts
VLDL
