Myocardial Infarction

Question 1

What make a good indicator

Answer 1

1) Tissue Specificity
2) Time of Appearance (shorter!)
3) Time of Disappearance
4) Detection Level (sensitivity)
5) Availability of Test

Question 2

What is an isoenzyme?

Answer 2

an enzymes with identical function but slightly different genetic structure.

Question 3

What is the benefit of isoenzymes? What 3 enzymes are we focusing on for MI?

Answer 3

One form of the enzyme may be more tissue specific.

CK/CPK and LDH

Question 4

What is the function of CK/CPK. For CK to work it need to be ____ by _____ interactions.

Answer 4

enzyme that turns creatine and ATP to creatine phosphate to store energy,
dimerized, Non Covalent

Question 5

Name the two isoforms of CK, the (3) combinations, and tissue origin.

CK1, CK2, CK3??

Answer 5

1) M (muscle) B (brain)

BB - Brain (bowel)
MB - Myocardium
MM - Skeletal mm. & Myocardium

Question 6

Myocardium, Skeletal - What are their isoenzyme [C] in %

Answer 6

Cardiac - CK3 - 85%, CK2 - 15%
Skeletal - CK3 - 98%, CK2 - 2%

CK2 is used to diagnose myocardium problems b/c no other tissue expresses such high levels of MB

Question 7

Summarize the laboratory process of determining isoenzyme concentration

Answer 7

1) isolate and electrophorese samples – > - charges proteins migrate to anode, antibody can detect density of separated proteins (BB, MM most - , + respectively) THINK GRAPH

Question 8

Why is CK2, the best indicator for MI

Answer 8

While MI does produce high levels of CK3, the high level of CK2 produced by MI is specific to MI. Also as opposed to CK3,
CK2 has early appearance, and short duration

Question 9

What is the function of LDH? For it to work it need to be ____ by _____ interactions.

Answer 9

Converts pyruvate to lactate under anaerobic conditions. Tetramer, NC

Question 10

Name the two isoforms of LDH, the (5) combinations, and tissue origin.

LDH1, LDH2, LDH3, LDH4, LDH5?

Answer 10

1) M (Muscle), H (Heart) 
LDH1 - Myocardium+, RBC
LDH2  RBS+, Myocardium
LDH3 - Brain & Kidney
LDH4 
LDH5 - Liver & Skeletal

Question 11

Pneumonic of isoenzyme composition

Answer 11

• 1 = amount of M in isozyme. REMEMBER, you got (2 , 4 components respectively)

Question 12

When using LDH isozymes, MI is diagnosed when LDH1/LDH2 ratio is 1 meaning..

Answer 12

LDH1 is greater or equal to LDH2

Question 13

Name the three cardiac Troponin Types and function

Answer 13

c-Tn-T - Tropomyosin binding
c-Tn-C - Ca++ Binding
c-Tn-I - Inhibitory

Question 14

Which if the troponins have isoforms? What are there normal levels in the blood? After MI or Angina how long till you see elevation in serum concentration?

Answer 14

c-Tn-T1 –> 4 hours, lasting 7-10 days
c-Tn-T2 –> 4 hours, lasting 14 days

*normal levels in the blood are low

Question 15

What is the diagnostic value of c-Tn-T[1,2]?

Answer 15

c-Tn-T1 –> (MI, or Angina)
c-Tn-T2 –> (MI)

*both test are very sensative

Question 16

Rank Test Sensitivity for MI from least to greatest. (4)

Answer 16

1) EKG 10g.
2) CK - 0.2g
3) CK- MB - 0.02g
4) cTn-T - 0.002g

Question 17

What is plamin, plasminogen? Tell me about concentration in blood?

Answer 17

Plasmin - Zymogen enzyme that dissolves blood clots. High concentration in blood

Plasminogen - Activated form

Question 18

__________ are used in emergency cases of MI. Name two types, and the drawbacks of using them.

Answer 18

1) Plasminogen activators

2) a. tissue plasminogen activator (t-PA)
b. Streptokinase

3) Removed from circulation quickly so high doses are needed!