Mon July 13

Question 1

how are pyrimidine dimers removed?

Answer 1

nucleotide excision repair

Question 2

what type of DNA repair is defective in xeroderma pigmentosum?

Answer 2

nucleotide excision repair

Question 3

abiraterone MOA?

Answer 3

Inhibits 17-alpha-hydroxylase, thus decreasing DHEA production. -Useful in prostate cancer

Question 4

which enzyme is defective in PKU?

Answer 4

phenylalanine hydroxylase or BH4 cofactor

Question 5

Presentation of PKU?

Answer 5

Intellectual disability
Growth retardation
Seizures
Fair complexion
Eczema
Musty body odour

Question 6

Treatment of PKU?

Answer 6

Avoidance of phenylalaine
Increased tyrosine intake
Tetrahydrobiopterin supplementation

Question 7

Which sweetener must patients with PKU avoid?

Answer 7

aspartame - contains phenylalanine

Question 8

Which enzyme is defective in alkaptonuria?

Answer 8

homogentisate oxidase

Question 9

Which pathway is disrupted in alkaptonuria?

Answer 9

Conversion of tyrosine to fumarate

Question 10

presentation of alkaptonuria?

Answer 10

blue-black connective tissue, ear cartilage and sclera - urine turns black on prolonged exposure to air
-arthralgias

Question 11

proopiomelanocortin is cleaved to produce which substances?

Answer 11

beta-endorphins, ACTH and MSH

Question 12

what is aripiprazole?

Answer 12

An antipsychotic drug used in schizophrenia and bipolar I

Question 13

which enzymes require the cofactor thiamine?

Answer 13

pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase and transketolase

Question 14

inheritance of VHL?

Answer 14

autosomal dominant

Question 15

what is systemic mastocytosis?

Answer 15

Clonal mast cell proliferation in the bone marrow, skin and other organs

Question 16

systemic mastocytosis is associated with which mutation?

Answer 16

mutations in the KIT receptor tyrosine kinase

Question 17

pathophys of systemic mastocytosis?

Answer 17

Mast cells overproduce tryptase

• they have excessive histamine release leading to flushing, syncope, hypotension, urticaria, etc.
• the histamine induces gastric acid secretion leading to ulceration
• the excess acid also inhibits pancreatic and intestinal enzymes, leading to diarrhea

Question 18

what type of virus is the west nile virus?

Answer 18

Arbovirus (+ RNA virus)

Question 19

what receptor does glucagon act on?

Answer 19

g protein coupled receptors - Gs

Question 20

what is the first line treatment for essential tremor?

Answer 20

Beta-blocker

Question 21

the acidic environment of the stomach helps with the absorption of which substances?

Answer 21

Ca, Fe, Mg and B12

Question 22

the acidic environment of the stomach activates which pancreatic enzymes?

Answer 22

amylase and protease

Question 23

the acidic environment of the stomach INactivates which pancreatic enzymes?

Answer 23

lipase

Question 24

Someone who has been prescribes a PPI will have increased absorption of what?

Answer 24

dietary fats - loss of H leads to decreased INactivation of pancreatic lipases - thus promoting lipase activity and fat absorption

Question 25

giant multinucleated tumour cells are consistent with which grade of cancer?

Answer 25

High-grade

These are found in anaplastic tumours

Question 26

retinal hemorrhages in a baby are highly suggestive of….

Answer 26

abusive head trauma (shaken baby syndrome)

Question 27

pathophys of shaken baby syndrome (abusive head trauma)?

Answer 27

Vigorous shaking leads to tearing of the bridging veins and subdural hemmorhage and retinal hemorrhage. The baby may have accompanying posterior rib fractures from the perpetrators grasp.

Question 28

under normal conditions, the extracellular space has a high concentration of which ions?

Answer 28

Na and Cl

Question 29

how may macrophages in an atheroma lead to instability of the plaque?

Answer 29

The plaque is constantly being remodelled, and macrophages may secrete MMPs which breakdown extracellular matrix proteins leading to plaque instability and risk of rupture

Question 30

In myocardial ishemia, how soon will loss of contraction of the affected tissue occur?

Answer 30

Less then 60 seconds due to rapid depletion of ATP

Question 31

after how long does myocardial ischemia lead to irreversible damage?

Answer 31

30 minutes

Question 32

Under hypoxic conditions what is ATP in the myocardium broken down into?

Answer 32

ATP - > ADP -> AMP ->adenosine, which can cross the cell membrane and act as a vasodilator

Question 33

what structures run through the superior orbital fissure?

Answer 33

CN III, IV, Va, VI, opthalmic veins and sympathetic fibers

Question 34

what structure goes through the foramen rotundum?

Answer 34

CN Vb

Question 35

what structure goes through the foramen ovale?

Answer 35

CN Vc

Question 36

formula for total peripheral resistance in a parallel circuit?

Answer 36

1/resistance = 1/R1 + 1/R2 + 1/R3 + 1/R4

Question 37

Blood supply to the femoral head?

Answer 37

Branches from the median circumflex humeral artery

Question 38

what type of vaccine is the post-prophylactic exposure vaccine for rabies?

Answer 38

inactivated

Question 39

which measure is sensitive to changes in prevalance of disease?

Answer 39

positive predictive value

negative predictive value

Question 40

does sensitivity change with changes in prevalence of disease?

Answer 40

no

Question 41

where does the radial nerve enter the forearm?

Answer 41

anterior to the lateral epicondyle

Question 42

which two nerves does the radial nerve split into?

Answer 42

superficial and deep branches. The superficial branch is sensory and the deep branch is motor

Question 43

which muscle does the deep branch of the radial nerve travel through?

Answer 43

the supinator muscle - making it vulnerable to injury from repeated supination/pronation

Question 44

under which condition is chronic hyperventilation normal?

Answer 44

Pregnancy - the progesterone stimulates a sensation of shortness of breath and stimulates hypothalamus to increase respiratry drive