Mini 2: Biochemistry And Genetics

Front 1

Albumin plays an important role in the following ways:

Back 1

1. Colloid osmotic pressure
2. Transport (of fatty acids, bilirubin)
3. Drug Transport (of aspirin, sulfonamides)

Front 2

What is the difference between plasma and serum?

Back 2

Serum is the liquid part of blood AFTER coagulation, therefore devoid of clotting factors as fibrinogen. plasma is the liquid, cell-free (by centrifugation, for example) part of blood, that has been treated with anti-coagulants.

Think of serum = plasma - fibrinogen

Front 3

With the exception of albumin, all proteins contain _______________

Back 3

N-linked oligosaccharides ending with sialic acid bound to galactose

Front 4

What happens during the lifetime of a plasma protein?

Back 4

During the lifetime of the plasma protein, the terminal sialic acid residues are gradually chewed off by endothelial neuraminidases

After the loss of the sialic acid, the exposed galactose at the end of the oligosaccharide binds to an asialoglycoprotein receptor on the surface of hepatocytes, followed by receptor-mediated endocytosis and lysosomal degradation.

Front 5

If the serum electrophoresis shows a single intensity in the gamma globulin range, what does it mean?

Back 5

The patient is suffering from monoclonal gammopathy. The single intensity means that only one immunoglobulin is in play while the remaining four are inactive.

Front 6

Drugs in their free state are dangerous to the patient. Which protein is involved in inactivating drugs? How is it accomplished?

Back 6

Albumin has multiple receptor sites on its surface through which it can bind to numerous drugs and thus inactivating them

Front 7

In arteries, what does albumin provide?

Back 7

Albumin, due to its large molecular weight, helps the arteries re-absorb and maintain water through its large colloid oncotic pressure

Front 8

What is a drop in albumin concentration called?

What occurs during this period of time?

Back 8

Hypoalbuminemia

Water leaks out of the arteries and into the interstitial space (edema)

Front 9

What are the four abnormalities of albumin metabolism?

Back 9

1. Reduced synthesis
Liver does not produce enough albumin because the patient is malnourished


2. Increased catabolism
IL-6


3. Altered distribution
Immune system components vasodilate arteries to fight infection which can lead to loss of albumin through the arterial wall


4. Abnormal losses
Diseased kidneys will release protein (and albumin) into the urine

Front 10

What is the inherited form of hypoalbuminemia?

What is used to test it? How does it show itself in that test?

Back 10

Analbuminemia

* You can test it using protein-gel electrophoresis and find that this condition is marked by a missing albumin band near the cathode and an increase in the alpha 2 band.

* The increase in the alpha 2 band shows compensation by the body for the missing Albumin

Front 11

It signifies that the patient is suffering from hypoalbuminemia because:

* The filled in circle is the missing albumin band

* The arrow points to an increased band of alpha 2 proteins

Back 11

What does this protein-gel electrophoresis signify?

What is missing and what is elevated?

Front 12

What is it called when an individual has too much albumin protein?

Back 12

Hyperalbuminemia

Front 13

How does one become hyperalbuminemic?

Back 13

1. Dehydration
2. Excessive stasis during venepuncture

Front 14

Name each of the bands of the serum electrophoresis

Back 14

Look at the boxes for the answers

Front 15

What proteins do you see in each of the electrophoresis bands?

α1-Globulins
α2-Globulins
β1-Globulins
β2-Globulins
γ-Globulins

Back 15

α1-Globulins: α1-antitrypsin, α-lipoprotein

α2-Globulins: haptoglobulin, ceruloplasmin, α2-macroglobulin

β1-Globulins: transferrin, β-lipoprotein

β2-Globulins: C3 (complement protein), fibrinogen (plasma), β2-microglobulin

γ-Globulins: immunoglobulins (MADGE)

Front 16

Plasma proteins besides Albumin are specialized carriers of small molecules.

Name them and their function.

Back 16

1. PREALBUMIN and RETINOL-BINDING PROTEIN

* RETINOL-BINDING PROTEIN has retinol bound to it during its release from the liver

* Retinol in turn binds to PREALBUMIN in the blood and is transported to other tissues


2. THYROXINE-BINDING GLOBULIN

* The major transporter of thyroid hormones in the body

* Binds to thyroxine with 100 times greater affinity than PREALBUMIN

* However, PREALBUMIN'S congenital absence leads to abnormally low levels of thyroid hormones


3. CORTISOL-BINDING GLOBULIN (TRANSCORTIN)

* Glucocorticoids are bound to this protein

* Androgens and estrogens have their own sex hormone-binding globulin


4. HAPTOGLOBIN

* Binds free hemoglobin released from erythrocytes with high affinity and thereby inhibits its oxidative activity. The haptoglobin-hemoglobin complex will then be removed by the reticuloendothelial system (mostly the spleen)


5. HEMOPEXIN

* Binds to any free heme/hematin in the blood to prevent the loss of iron

* The hemopexin-heme or hemopexin-hematin complex is removed in the liver

Front 17

If blood is seen in urine, what two conditions can we readily assume that the patient is suffering from?

How can we diagnostically detect this internal bleeding?

Back 17

We can assume that the patient is suffering either from HEMOGLOBINURIA or MYOGLOBINURIA

We can diagnostically detect HEMOGLOBINURIA by measuring the level of HAPTOGLOBIN -- we will see that this level is depressed. [Why will we see this?]

The same cannot be said of MYOGLOBINURIA as HAPTOGLOBIN does not bind to the myoglobin released from muscles

Front 18

What is the function of α1-antitrypsin?

How does one go about measuring it in the blood?

Back 18

α1-antitrypsin is a serine protease inhibitor (serpin) and trypsin inhibitor (trypin). It protects tissue from enzymes released from inflammatory cells, especially elastase from WBC.

Its activity can be measured as the TRYPSIN INHIBITORY CAPACITY (TIC)

Front 19

What are the two types of alleles (normal and mutant) coding for α1-antitrypsin?

What conditions arise because of homozygosity of the mutant allele?

Back 19

Z is the mutant allele coding for α1-antitrypsin. As a result, homozygosity for the Z allele causes early-onset of pulmonary emphysema.

NOTE: α1-antitrypsin deficiency suggests that excessive proteolytic activity is an important mediator of tissue damage in chronic bronchitis and emphysema. Furthermore, these diseases then lead to hepatic disorders.

Front 20

Where is the activity of α1-antitrypsin seen?

Back 20

Mostly in lung tissue

Front 21

Please describe the diseases associated with each of the protein-gel electrophoreses.

Back 21

Plasma protein electrophoresis in various disease states. A, Normal. ALB, albumin. B, Immediate response pattern. C, Delayed response pattern. D, Liver cirrhosis. E, Protein-losing conditions (nephrotic syndrome, protein-losing enteropathy). F, Monoclonal gammopathy ("paraprotein").

Front 22

If and when cell damage or cell proliferation occurs, we will see:

A. an increase in enzyme concentration in the blood

B. a decrease in enzyme concentration in the blood

Back 22

A. an increase in enzyme concentration in the blood

Front 23

Why are enzymes measured?

Back 23

Most of the diagnostically useful serum enzymes are intracellular enzymes
that are released into the blood only when the cells get damaged. The enzymes are cleared
from the circulation with half-lives of one to several days. A diagnostically useful enzyme
should have higher or lower concentration due to a specific disease or condition.

Front 24

During what conditions do cells release enzymes?

Back 24

1. Tissue necrosis: Myocardial infarction, hepatitis, acute pancreatitis.

2. Increased membrane permeability: Muscular dystrophy, dermato-myositis, angina pectoris.

3. Increased Tissue Source or Release from Tissue: Neoplasms, psoriasis, Paget’s disease, healing fractures.

4. Impaired Enzyme Excretion: duct obstruction, reduced urinary excretion

Front 25

How does one choose which enzyme test to administer?

Back 25

* Has tissue damage occurred?
- If so, to what extent?

* Which tissues have been damaged?

Front 26

What are isoenzymes?

Back 26

They are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. These enzymes usually display different kinetic parameters (i.e. different KM values), or different regulatory properties (pH or isoelectric point)

Front 27

Name an example of a critical isoenzyme used in:

* Skeletal muscle
* Cardiac muscle
* Brain

Back 27

Creative Kinase

CK-MM (skeletal muscle)
CK-MB (cardiac muscle)
CK-BB (brain)

Front 28

What is the significance of α-fetoprotein?

Back 28

Fetus: It is an immune system regulator but also a prenatal diagnostic for:

Down's syndrome -- low concentration

Open neural tube -- high concentration


Adults: It only appears in trace amounts in adults

Good indicator/marker of HEPATOCELLULAR CARCINOMA

Front 29

Is copper an anti-oxidant or pro-oxidant?

Back 29

Anti-oxidant

Front 30

Ceruloplasmin can be found in low concentration and as such is a diagnostic tool for finding this disease.

Back 30

Wilson's disease

Front 31

What is a physical symptom of Wilson's disease?

Back 31

The most characteristic symptom of Wilson's Disease is the Kayser-Fleisher ring – a rusty brown ring around the cornea of the eye that can best be viewed using an ophthalmologist’s slit lamp

Front 32

What does C-reactive protein attack?

Back 32

It attacks the pneumococcal cell wall of bacteria

Front 33

What is scoline apnea?

Back 33

The inability of CHOLINESTERASE to breakdown succinylcholine, an anesthetic, after surgery and thus lengthening the recovery period

Front 34

Why would a surgeon want to measure a patient's recovery from succinylcholine administration?

Back 34

If the patient has an allele which codes for little or no ChE activity, then the degradation of anesthetic is slow and thus dangerous to the patient

Front 35

Which plasma cholinesterase allele codes for the silent protein (no activity)?

Back 35

E1s

Front 36

Graph A: Acute myocardial infartion (increased LDH1, LDH2)

Graph B: Acute hepatitis (increased LDH5)

Back 36

Looking at the lactate dehydrogenase levels for graph A and B above, what disease does each indicate?

Front 37

What is the main component of Heme?

Back 37

Protoporphyrin IX

Front 38

What element is added to Protoporphyrin IX to yield Heme?

Back 38

Iron (Fe2+)

Front 39

What type of bonding is prominent with the Fe2+ in the heme group?

Back 39

Coordinate covalent bonds (6 total/group)

Front 40

Where in the protoporphyrin is the Fe2+ located?

Back 40

In the center.

Front 41

How many molecules of oxygen bind to each heme group?

Back 41

1

Front 42

When does the heme group no longer bind oxygen?

Back 42

Interaction with oxygen oxidizes Fe (II) to Fe (III). Fe (III) in the heme group is called methemoglobin (which is useless in binding oxygen)

Front 43

Where specifically does oxygen bind on the protoporphyrin?

Back 43

Sixth ligand of Fe (II) out of the plane of the heme.

Front 44

Name two primary functions of globin.

Back 44

1. Modulate oxygen binding affinity

2. Make reversible oxygen binding possible

Front 45

Once globin surrounds the heme, what is the only component of the heme that is exposed to the solvent?

Back 45

propionic acid side chains, which contribute to the solubility of hemoglobin

Front 46

What is the fn of MYOglobin?

Back 46

oxygen storage in muscles

It facilitates rapidly respiring muscle tissue

Front 47

What effect does detergent treatment have upon Mb?

Back 47

heme and globin come apart, due to the breaking of hydrophobic interactions holding the two together.

Front 48

What contributes to slow diffusion of oxygen from capillaries to tissue?

Back 48

oxygen's solubility (Mb increases oxygen's solubility and facilitates oxygen diffusion)

Front 49

Where is hemoglobin found?

Back 49

RBC

Front 50

What makes up the quarternary structure of hemoglobin?

Back 50

2 alpha/beta dimers, a total of 4 polypeptide chains.

The association of the dimers contributes to the quarternary structure.

Front 51

Is the binding of oxygen to a free heme group reversible or irreversible?

Back 51

Irreversible (enclosure in a protein allows reversible binding)

Front 52

What basically is the reason that we see color differences between oxygenated and deoxygenated blood?

Back 52

Oxygen binding alters heme electronic structure (changes in the electronic spectrum)

Front 53

How is C reactive protein important diagnostically?

Back 53

It is a good diagnostic for bacterial infection

Front 54

Cyclooxygenase helps to create which proteins?

Back 54

Prostaglandins
Thromboxane (TXA2)
Prostacyclin (PGI2)

Front 55

What is the function of the following proteins?

* Prostaglandins
* Thromboxane (TXA2)
* Prostacyclin (PGI2)

Back 55

* Prostaglandin: Maintain normal hemostasis

* Thromboxane: a potent vasoconstrictor
and inducer of platelet aggregation that functions by binding to receptors that
function through the PLC-g pathway

* Prostacyclin: a vasodilator and an inhibitor of platelet aggregation

Front 56

What inhibits cyclooxygenase activity?

By virtue of this, what other activities are also inhibited?

Back 56

Aspirin (COX-1 inhibitor) inhibits cyclooxygenase (COX) activity.

** Aspirin is an important inhibitor of platelet activation. By virtue of
inhibiting the activity of cyclooxygenase, aspirin reduces the production of thromboxane (TXA2).

Aspirin also reduces endothelial cell production of prostacyclin (PGI2), an
inhibitor of platelet aggregation and a vasodilator. Localized to the site of
coagulation is a balance between the levels of platelet derived TXA2 and
endothelial cell derived PGI2. This allows for platelet aggregation and clot
formation but preventing excessive accumulation of the clot, thus maintaining
blood flow around the site of the clot.

Endothelial cells regenerate active cyclooxygenase faster than platelets because mature platelets cannot synthesize the enzyme, requiring new platelets to enter the circulation (platelet half-life is approximately 4 days). Therefore, PGI2 synthesis is greater than that
of TXA2. The net effect of aspirin is more in favor of endothelial cell-mediated
inhibition of the coagulation cascade. This reflects the cardiovascular benefits to
low dose administration of aspirin.

Front 57

Platelets will only adhere to this type of tissue?

Back 57

Subendothelial tissue

Front 58

Instead of directly attaching to collagen on the subendothelial tissue, platelets attach to this protein.

Back 58

vWF

Front 59

Of the following, which is produced by platelets and which by endothelial cells?

* Prostacyclin (PGI2)
* Thromboxane (TXA2)

Back 59

Platelets: Thromboxane

Endothelial: Prostacyclin

Front 60

Activated platelets produce which proteins?

Back 60

* ADP
* Thromboxane (TXA2)
* Serotonin and Phospholipids

Front 61

vWF binds to this receptor on platelets.

Back 61

Glycoprotein (GP) Ib-IX

Front 62

What two pathways lead to the formation of a fibrin clot?

Back 62

Intrinsic and extrinsic

Front 63

What is the difference between the intrinsic and extrinsic pathways?

Back 63

The formation of a red
thrombus or a clot in response to an abnormal vessel wall in the absence of tissue injury is the result of the intrinsic pathway.

Fibrin clot formation in
response to tissue injury is the result of the extrinsic pathway.

Front 64

Low levels and high levels of thrombin have these kinds of effects on the coagulation cascade.

Back 64

Low thrombin levels activate V -> Va and VIII -> VIIIa

High thrombin levels deactivate Va and VIIIa

Front 65

How is thrombin created from the prothrombinase complex?

Back 65

Within the prothrombinase complex, prothrombin is cleaved at 2 sites by factor Xa. This cleavage generates a 2-chain active thrombin molecule containing an A and a B chain which are held together by a single disulfide bond.

Front 66

Thrombin plays a role in platelet aggregation and leukocyte adhesion AND impairment of plasminogen activation.

Specific the steps for each of these pathways.

Back 66

* Thrombin - PAR 1,2,3
IL1 and IL6 released
Secretion of ICAM-1, VCAM-1
>> Platelet aggregation and leukocyte adhesion

* Thrombin - TAFI
Modulates degradation of fibrin clots
Removal of C-terminal lysines
Impairment of plasminogen activation and reducing rate of fibrinolysis

Front 67

In what ways is the activity of thrombin regulated?

Back 67

1. Heparin - Antithrombin III [MOST IMPORTANT]

Complex leads to altered conformation and increased affinity for thrombin. It is specifically a SERINE PROTEASE INHIBITOR (serpin).

Also, it inhibits factors IX, X, XI, and XII

2. alpha2-macroglobulin

3. alpha1-antitrypsin

4. Heparin cofactor II

Front 68

Fibrinogen consists of the following polypeptide chains.

Back 68

Fibrinogen (factor I) consists of 3 pairs of polypeptides ([A-a][B-b][g])2

Front 69

Is fibrinogen soluble or insoluble in the plasma? Why?

Back 69

Soluble due to the fibrinopeptide A and B associated with the alpha and beta polypeptides

Front 70

How does fibrin become insoluble in the plasma?

Back 70

The fibrinopeptides, A and B, are cleaved prior to the formation of fibrin

Front 71

Which factor involves the cross-linking of fibrin monomers?

Back 71

Factor XIII

Front 72

Factor XIII is able to cross-link fibrin monomers through this reaction.

Back 72

Transglutaminase reaction: covalent linking between the glutamate and lysine residues on two different monomers

Front 73

What are three activators of plasminogen to plasmin?

What are their specificities?

Back 73

1. tPA: In its inactive form, binds to fibrin and is activated at the clot.

[SPECIFIC TO CLOT]

2. Streptokinase: It is less
selective than tPA, being able to activate circulating plasminogen as well as that
bound to a fibrin clot.

3. Urokinase: Urokinase is produced as the precursor, prourokinase by epithelial cells lining
excretory ducts. The role of urokinase is to activate the dissolution of fibrin clots
that may be deposited in these ducts

Front 74

What two inhibitors are there for plasminogen to plasmin?

Back 74

1. α2-antiplasmin

2. PAI 1,2 (plasminogen activator inhibitors)

Front 75

Which bleeding disorder is associated with prolonged bleeding?

Which bleeding disorder is associated with prolonged coagulation?

Back 75

Factor VIII: Prolonged bleeding

Factor IX: Prolonged coagulation

Front 76

Affected individuals suffer easy bruising, prolonged bleeding from wounds and
muscle hemorrhage, what disorder am I?

Back 76

Hemophilia A

Front 77

I am caused by deficiency of vitamin K-dependent procoagulant protein Factor IX, what disorder am I?

Back 77

Hemophilia B

Front 78

It also has a role in stabilizing and increasing plasma concentration of Factor VIII, what factor am I?

Back 78

vWF

Front 79

Presentation is in bleeding from the umbilical cord
stump in neonates, intracranial hemorrhage, or after surgical challenge in children
(often dental extractions), what disorder am I?

Back 79

Fibrinogen and Factor XIII

Front 80

The platelet plug is normally formed with this factor in place.

Back 80

vWF

Front 81

What is contact activation?

Back 81

When blood makes contact with negatively charged surfaces it triggers a series of interactions that involve factor XI, prekallikrein and high molecular weight kininogen leading to blood coagulation

Front 82

Deficiency in factor __?__ confers an injury-related bleeding tendency.

You also witness reduced contact activation.

Back 82

XI

Front 83

These factors require liver Vitamin K for their biosynthesis.

Back 83

Factors II, VII, IX, and X

Front 84

The membrane and calcium associations of these enzymes depend on post-translational
modification of γ-carboxylation of glutamic acids.

Back 84

Precursors of factors II, VII, IX, and X

Front 85

This drug interferes with blood clotting by inhibiting Vitamin K-dependent biosynthesis of the clotting factors

Back 85

Warfarin

Front 86

Warfarin is recognized as a _______?_______

Back 86

Anti-coagulant

Front 87

This lab test tests the function of the 'extrinsic' and final common clotting pathways.

Back 87

Prothrombin Test (PT)

Front 88

This lab test tests the function of the 'intrinsic' and final common clotting pathways

Back 88

Activated partial thromboplastin time (APTT!)

Front 89

What factors does PT measure?

Back 89

Factor VII and common pathway factors (I, II, V, and X)

Front 90

What factors does APTT measure?

Back 90

Factors VIII, IX, XI, and XII and common pathway factors (I, II, V, and X)

Front 91

Diagnosing myocardial infarction has previously followed the serum levels of CK, AST, and LDH.

Recently however, this enzyme has also been measured alongside CK.

Back 91

Troponin I