lecture 5 - enzymes as biomarkers

Question 1

what are enzymes

Answer 1

protein catalysts

Question 2

what are the definitions of enzymes

Answer 2

type of protein that accelerates the speed of chemical reaction

by binding to a substrate to form a complex

lowers activation energy in the reaction without being consumed, or changing equilibrium of reaction

Question 3

why do we use enzymes as markers

Answer 3

amplification of signal over time

Question 4

what are the two ways you can measure enzyme activity

Answer 4

stop the reaction and measure product formed (kinetic fixed time)

repeatedly measure product formation(kinetic continuous time)

Question 5

what does ELIZA stand for

Answer 5

Enzyme-linked immunosorbent assay

Question 6

what are isoenzymes

Answer 6

enzymes that differ in amino acid sequence yet catalyse the same reaction

Question 7

what are biomarkers

Answer 7

biological molecules who’s concentration changes in response to a specific disease or intervention

Question 8

what do biomarker lead to when in disease state

Answer 8

moderate or extensive tissue damage

Question 9

what happens to the cardiac myocyte after SOME tissue damage

Answer 9

membrane ruptures

this damage can be repaired

enzyme levels are only elevated while damage persists

Question 10

what happens to the cardiac myocyte after MORE tissue damage

Answer 10

cell dies

cellular necrosis

cell contents released

test blood for specific enzymes

Question 11

what is the aetiology for cardiac disease

Answer 11

blockage of blood vessels supplying to the heart

Question 12

what does the blockage of blood vessels lead to

Answer 12

deficiency of oxygen (ischemia)

Question 13

what is non reversible damage that leads to cell death called

Answer 13

infarction

Question 14

what is acute myocardial infarction

Answer 14

a heart attack

Question 15

what does angina cause

Answer 15

heart pain

Question 16

what is the aetiology of angina

Answer 16

reduced blood flow to the heart

Question 17

what is the development of heart disease

Answer 17

1. plaques form on the artery wall
2. macrophages accumulate in the endothelial lining
3. narrowing of the artery
4. 70% reduced blood flow -> ischemia

Question 18

what are the stages leading to myocardial infarction

Answer 18

1. Tear or erosion of the plaques
2. Cause an intraplaque thrombus
3. Platelets accumulate to repair the damage
4. Aggregated platelets break off and are swept downstream
5. Aggregated platelets block downstream vessels

Question 19

what is the treatment for platelet aggregation

Answer 19

antiplatelet

antithrombotic

Question 20

what is the treatment for after clot formation

Answer 20

thrombolytic drugs

catheterisation and angioplasty

Question 21

what are the cardiac biomarkers

Answer 21

aspartate amino transferase - elevated 12 hours

lactate dehydrogenase - elevated 36 hours

creatine kinase - elevated 4-6 hrs

Question 22

what is the product of creatine + atp?

Answer 22

creatine phosphate + ADP

Question 23

what are the sources of creatine kinase

Answer 23

skeletal muscle

brain

cardiac muscle

Question 24

what can mask myocardial infarction

Answer 24

more skeletal muscle than cardia muscle

Question 25

what is the specimen for CK anaylsis

Answer 25

non - hemolyzed serum storage in refrigerator or freezer

Question 26

what are the sources of error in CK analysis

Answer 26

sample not fresh or exposed to heat anticoagulants such as citrate or fluoride

Question 27

what is lactate dehydrogenase inhibited by

Answer 27

mercuric ions

Question 28

what are sources of lactate dehydrogenase

Answer 28

heart liver kidney skeletal muscle

Question 29

what is the clinical significance of Lactate dehydrogenase

Answer 29

myocardial infarction hemolytic conditions malignancies renal disease

Question 31

what does troponin T do

Answer 31

binds to myosin

Question 32

what does troponin I do

Answer 32

inhibit actin-myosin binding

Question 33

what does troponin C have

Answer 33

Binding sites for ca2+

Question 34

what happens in the absence of calcium

Answer 34

troponin prevents myosin from interaction with actin prevents contraction

Question 35

what are the advantages of troponin-tropomyosin

Answer 35

sensitive - able to detect cardiac troponin T and troponin I in more than 50% of individuals better detection than CKMB/total CK

Question 36

what tests are required to detect AMI

Answer 36

electrocardiogram detection of enzymes released into the blood

Question 37

what is rhabdomyolysis

Answer 37

rapid breakdown of damaged muscle tissue

Question 38

what are the biomarkers for skeletal muscle

Answer 38

Rhabdomyolysis Spills over into the urine myoglobin

Question 39

what are natriuretic peptides

Answer 39

small circular peptides (cardiac hormones) that PROMOTE loss of sodium from the kidneys

Question 40

what are the key aims of future biomarkers

Answer 40

predicting the rupture of placques detecting ischemia prior to cell death (necrosis)