360 - Lipids & Cardiac Markers

Question 1

these transport lipids in the plasma

Answer 1

lipoproteins

Question 2

typical lipoprotein structure

Answer 2

core of triglycerides and cholesteryl ester and a shell composed of apolipoprotein, unesterified cholesterol, and phospholipid

Question 3

linear hydrocarbon chains that terminate in a carboxyl group

Answer 3

fatty acids

Question 4

beta oxidation of free fatty acids

Answer 4

forms acetyl-CoA which enters the Kreb’s cycle to produce energy

Question 5

triglycerides

Answer 5

many types
- composed of 3 fatty acid molecules and one molecule of glycerol; they are classified as neutral lipids

Question 6

describe cholesterol

Answer 6

• amphipathic molecule
• esterified form of cholesterol = cholesteryl ester, is conjugated to fatty acids and is classed as a neutral lipid
• used to synthesize many hormones, including mineral corticoids, and sex hormones

Question 7

amphipathic molecules composed of two esterified fatty acids, glycerol, and a phospholipid group

Answer 7

phospholipids
- found in cell membranes

Question 8

T or F. Apolipoproteins are amphipathic.

Answer 8

T!

Question 9

how are lipoproteins classified

Answer 9

• by their densities
• 6 categories: chylomicrons, very low-density lipoproteins (VLDL), intermediate density lipoproteins (IDL), low-density lipoproteins (LDL), high-density lipoproteins (HDL) and lipoprotein (a)

Question 10

T or F. As the density of lipoproteins increases the proportion of triglycerides decreases and the proportion of cholesteryl ester increases

Answer 10

T

Question 11

how are lipoproteins measured?

Answer 11

immunoturbidimetry and immunonephelometry

Question 12

these transport dietary lipid to the liver and peripheral cells

Answer 12

chylomicrons

Question 13

the largest lipoprotein and the least dense

Answer 13

chylomicrons
- form the creamy layer that settles on serum; Apolipoprotein B-48 is only found in chylomicrons

Question 14

where is VLDL primarily produced?

Answer 14

liver

Question 15

this carries endogenous triglycerides from the liver to peripheral cells

Answer 15

VLDL

Question 16

these are used for energy during fasting periods

Answer 16

triglycerides

Question 17

the primary component of VLDL apolipoprotein

Answer 17

Apolipoprotein B-100

Question 18

formed by the lipolysis of VLDL

Answer 18

LDL
- contains apolipoprotein B-100

Question 19

T or F. LDL is readily taken up by the liver and peripheral cells

Answer 19

T
- LDL can move into the extracellular space of blood vessel walls
- LDL is oxidized and ingested by macrophages
- laden with lipid evolve into foam cells
- foam cells are components of fatty streaks, which can develop into atherosclerotic plaques

Question 20

the densest lipoprotein

Answer 20

HDL

Question 21

where is HDL synthesized?

Answer 21

in the liver and intestine

Question 22

what does HDL do?

Answer 22

transports cholesterol away from the peripheral cells, back to the liver

Question 23

Its anti-atherogenic properties are attributed to its ability to remove cholesterol

Answer 23

HDL

Question 24

this component may be measured to determine anti-atherogenic status of HDL

Answer 24

apolipoprotein A-1

Question 25

Coronary heart disease is characterized by ...

Answer 25

narrowing of the small vessels that carry oxygenated blood to the heart

Question 26

Atherosclerosis

Answer 26

a pathologic process characterized by cholesterol deposits on vessel walls, macrophage invasion, and plaque formation

Question 27

interferences in triglycerides enzymatic assay

Answer 27

- Endogenous free glycerol can participate in the reaction, reagent blank may correct this interference - Bilirubin and vitamin C may interfere, but enzymes may be added to eliminate this interference - Hemolysis may cause positive interference

Question 28

specimen used for triglycerides enzymatic assay

Answer 28

- 12hr fasting (triglyc incr after meals) - aviod alc for 24 hrs before test (transient increase in trigly) - smoking increases trigly - increase when go from lying down to standing

Question 29

total cholesterol enzymatic assay interferences

Answer 29

- Bilirubin and vitamin C can cause false DECREASES because they react with H2O2 - Hemolysis may cause positive interference

Question 30

total cholesterol enzymatic assay specimen collection

Answer 30

- 12hr fasting specimen (IF part of lipid panel) - chol DECREASEs w exercise - smoking increases chol - prolonged toueniquet = increases chol - chol increases from lying to standing

Question 31

HDL methodology

Answer 31

- direct HDL cholesterol = homogenous assay - does not require pretreatment/centrifugation - depends on a unique detergent which solubilizes only HDL lipoprotein particles & releases HDL cholesterol to react with chol esterase and chol oxidase in presence of chromogens - the detergent also inhibits the reaction of the cholesterol enzymes with LDL, VLDL, and chylomicron lipoproteins by adsorbing to their surfaces

Question 32

HDL methodology: A ____________ contained in the reagent enhances the selectivity for HDL cholesterol assay by complexing ____, _____, and _____________ lipoproteins

Answer 32

polyanion; LDL, VLDL, chylomicrons

Question 33

T or F. In HDL direct method, the change in absorbance at 560 nm is directly proportional to the concentration of cholesterol in the sample

Answer 33

T, (Beckman Coulter LX 20 manual).

Question 34

Friedewald formula for calculating LDL cholesterol

Answer 34

Total cholesterol - [Triglyceride÷2.2] - [HDL cholesterol]

Question 35

the result of an obstruction in the circulatory pathway of the heart resulting in necrosis of the heart muscle

Answer 35

myocardial infarction

Question 36

cardiac markers of choice for MI

Answer 36

troponins

Question 37

this occurs when the heart is unable to pump blood to maintain oxygenation of the tissues

Answer 37

congestive heart failure

Question 38

congestive heart failure is characterized by ...

Answer 38

edema, due to sodium and water retention, and breathlessness

Question 39

congestive heart failure cardiac markers of choice

Answer 39

B-type natriuretic peptide (BNP) and a catabolic product of pro-BNP: NT-pro-BNP

Question 40

a protein molecule composed of three subunits, TnC, TnT, and TnI and is a part of the actin-myosin contractile unit of muscle

Answer 40

troponin

Question 41

where are cardiac troponins found?

Answer 41

found only in the heart and are released into the blood during cell death

Question 42

Troponin I (cTnI) and Troponin T (cTnT) rise approximately _-_hours after the onset of symptoms.

Answer 42

2-6 hrs

Question 43

T or F. cTnI is more specific than cTnT for myocardial infarction

Answer 43

T!!

Question 44

Troponin remains elevated in the blood ______ to ____days after an MI.

Answer 44

four to ten days

Question 45

these may interfere with troponin I performance

Answer 45

heparin, heterophilic antibodies, autoantibodies, fibrin/hemolysis, and rheumatoid factors NOTE: Barricor tubes may reduce interference

Question 46

AHS recommends the collection of a Troponin I sample at __ hours and again ___ hours later to rule out an MI

Answer 46

0; 6

Question 47

a hormone secreted by the ventricles of the heart

Answer 47

B-type natriuretic peptide (BNP)

Question 48

BNP synthesis

Answer 48

- synthesized as a preprohormone (preproBNP) - preprohormone is cleaved into proBNP, which is further cleaved into two parts: the N-terminal portion (NT-proBNP) and the C terminal, the active portion (BNP) - NT-proBNP and BNP are found in the circulation

Question 49

an excellent measure of cardiac stretch

Answer 49

BNP

Question 50

used for identifying individuals with moderate to severe congestive heart failure and for risk assessment

Answer 50

BNP

Question 51

the only acceptable sample for BNP

Answer 51

EDTA in a PLASTIC tube

Question 52

NT-proBNP acceptable sample

Answer 52

Serum or heparin plasma in a glass or plastic tube

Question 53

high sensitivity C reactive protein

Answer 53

values above normal but below those seen in infection can be detected by the hsCRP assay and are indicative for atherosclerosis, a risk factor for heart disease