6/17 UWorld

Question 1

What is the damage caused to DNA by UV light

Answer 1

Thymine dimers

Question 2

What is first line treatment for BPH?

Do they affect size of prostate

Answer 2

Alpha-1 antagonists (“-zosin”)

Do not change size of prostate

Question 3

Which drug is used to decrease size of prostate

Answer 3

5-a reductase inhibitors (e.g. Finasteride)

Question 4

Diagnostic criteria of pre-eclampsia

Answer 4

HTN

+

Protenuria OR signs of end-organ damage

Question 5

Describe presentation of Neurofibromatosis type 1

Answer 5

• Neurocutaneous disorder characterized by café-au-lait spots, cutaneous neurofibromas, optic gliomas, pheochromocytomas, Lisch nodules (pigmented iris hamartomas)
• Neurofibromas consist of proliferation of Schwann cells, fibroblasts, and neurites

Question 6

What is the most common renal stone?

Answer 6

Calcium stone

Question 7

What are the 2 radioopaque kidney stones (seen on X-ray)

Answer 7

Calcium

Ammonium magnesium phosphate

Question 8

What are the 2 radiolucent (not seen on XR) stones?

Answer 8

Uric acid

Cysteine

Question 9

In internuclear ophthalmoplegia, is the affected eye (the one that cannot adduct) ipsilateral or contralateral to the MLF lesion?

Answer 9

Ipsilateral

• E.g. if there is a lesion of the right MLF, when you look L, the R eye will not be able to look medially

Question 10

What is the MOA and uses of Cilostazol

Answer 10

• Inhibition of phosphodiesterase leads to increases cAMP within the platelet which will activate protein kinase A, and impairing platelet function and aggregation n
  
  • = sign UP for cAMP = increased camp
• Causes arteriole vasodilation (due to increased cAMP)
  
  • =dilated red sleeves
• Can treat symptoms of claudication due to peripheral artery disease
  
  • = dirt clods hitting leg

Question 11

Adverse effect of Cilostazol

Answer 11

• Can cause coronary steal
  
  • = stolen heart base
• When there is stenosis in an artery, the body is already vasodilating, try to restore blood to that area
• So if you give a vasodilator, all the other normal vessels will dilate even more, leading to even less blood going to the stenotic area, exacerbating ischemia
  
  • = dilated red hat crown = coronary artery vasodilation

Question 12

Most commonly affected area in Crohn’s

Answer 12

Terminal ileum

Question 13

AST and ALT indicate function of what organ?

Answer 13

Liver

Question 14

Adverse effects of Methotrexate

Answer 14

• Folate deficiency
• Megaloblastic anemia
• Myelosuppression and Pancytopenia
• Increased risk of infection due to immunosuppression
• _Pulmonary fib_rosis (restrictive lung disease)
• Hepatotoxicity (should monitor LFTs)
• Alopecia
• Mucositis/oral ulcerations

Question 15

What is the effect of an arteriovenous shunt on preload and afterload

Answer 15

Increased preload and decreased afterload due to shunting of blood out of arteries and into veins, bypassing arterioles

Question 16

Presentation of Pick disease

Answer 16

Aka frontotemporal dementia

• Early = Behavior/personality changes (frontal lobe) and/or aphasia (temporal lobe)
• Late = Dementia

Question 17

Lesion of subthalamic nucleus

Answer 17

• Hemiballismus (involuntary flailing of limbs)

Question 18

What nucleotide binds to what (A, G, T, C)

Answer 18

A binds to T with 2 bonds

G binds to C with 3 bonds

Question 19

How do you get fromc cytosine (in DNA) to uracil (in RNA)

Answer 19

Uracil is a deaminated cytosine

Question 20

Do purines/pyrimidines synthesis start with a base or ribose sugar

Answer 20

Purine starts with a sugar

Pyrimidine starts with a base

Question 21

Rate limiting step in pyrimidine synthesis

Answer 21

Carbamoyl phosphate synthetase II (in cytosol)

Vs. CPSI used in urea cycle in mitochondria

Question 22

What is the cause of megaloblastic anemia that does not respond to B12 or folate

Answer 22

Orotic aciduria

• Failure to thrive
• Developmental delay
• Megaloblastic anemia refractory to folate and B12
• No hyperammonemia

Question 23

What is the enzyme responsible for GMP/IMP salvage, preventing the formation of uric acid

Answer 23

Hypoxanthine-guanine phosphoribosyl transferase (HGPRT)

• Deficient in Lesch Nyhan

Question 24

What is a common cause of SCID

Answer 24

Adenosine deamine deficiency

• Increased dTAP = toxicity to lymphocytes

Question 25

Describe mismatch repair What disorder is it defective in

Answer 25

Occurs during synthesis Mismatch is recognized and removed, along with everything downstream of the mismatch; and then starts over Defective in Lynch syndrome

Question 26

Describe the steps in base excision repair

Answer 26

1. Glycosylase removes base, creating empty nucleotide 2. Endonuclease removes the empty nucleotide 3. DNA polymerase fills the gap 4. Ligase seals it

Question 27

What is the only DNA repair that causes double-strand repair

Answer 27

Non-homologous end-joining

Question 28

What is the defect in Ataxia telangiectasia

Answer 28

Mutated ATM gene = defective nonhomologous end-joining

Question 29

What are the Gram + bugs covered by 1st gen and 2nd gen Cephalosporins

Answer 29

* 1st gen - PEcK * Proteus, E. Coli, Klebsiella (UTI bugs) * 2nd gen = HENS PEcK * H. Flu, Enterobacter, Neisseria, Serratia + PECK

Question 31

What are the stop codons

Answer 31

UGA, UAA, UAG * U Go Away * U Are Away * U Are Gone

Question 32

What causes removal of repressor protein and activation of transcription factor in lac operon

Answer 32

No glucose = activation of transcription factor (CAP) Lactose present = removal of repressor protein

Question 33

Where does transcription and translation occur

Answer 33

* Transcription occurs in the nucleus to mature mRNA * Only 5' capped, 3' tail, and spliced mRNA can leave the nucleus * Translation occurs in the cytosol

Question 34

What is the signal for Poly-A polymerae to add a tail

Answer 34

AAUAAA

Question 35

Does aminoacyl tRNA synthesis work at the 5' or 3' end of tRNA, and what codon is at that end

Answer 35

3' end with a CCA sequence THINK: CCA = Can carry amino acids

Question 36

Where are ribosomes synthesized

Answer 36

Nucleus

Question 37

What is the functino of initiation factors

Answer 37

Part of translation Assembe the smaller RNA subunit with tRNA IF's are released when the larger RNA subunit attaches

Question 38

What acid-base disorder (resp/met alk/acid) will occur during high altitude? Will you see high or low: * pH * pO2 * pCO2 * HCO3

Answer 38

Respiratory alkalosis (body starts hyperventilating in order to compensate for low O2) * pO2 = low (due to altitude) * pCO2 = low (due to hyperventilation) * pH = high (due to respiratory alkalosis) * HCO3 = low (due to compensation for alkalosis)

Question 39

What is the purpose of V(D)J recombination

Answer 39

Antibody diversity

Question 40

What is the presentation of galactokinase deficiency

Answer 40

* Deficiency in galactokinase = mild condition * Leads to accumulation of galacticol * Symptoms: * · Infantile cataracts * · Galactosemia and galactosuria

Question 41

Describe the deficiency and presentation in Classic galactosemia

Answer 41

* Classic galactosemia – severe condition * Deficiency in galactose-1-phosphate uridyltransferase * Symptoms: * · Infantile cataracts * · Failure to thrive * · Jaundice * · Vomiting * · Hepatomegaly * · Renal dysfunction * · Intellectual disability * · E. Coli sepsis

Question 42

What is Rett syndrome (inheritance, presentation)

Answer 42

* X-linked dominant, almost exclusively in females (males die in utero) * Symptoms become apparent between 1-4 y/o * Regression: loss of development, loss of verbal abilities, intellectual disability, ataxia, stereotyped hand-wringing

Question 43

What inheritance pattern do most enzyme deficiencies follow?

Answer 43

Autosomal recessive E.g. Classic galactosemia

Question 44

Will there be neutrophil or lymphocytic predominance present in the stool of a patient with V. cholera?

Answer 44

Neither - Vibrio is non-invasive Toxin activated adenylate cyclase to increase cAMP, enhancing Cl- efflux and decreased Na+ reabsorption Stool microscopy will show flecks of mucus and sloughed epithelial cells because toxin induces mucus ejection from goblet cells

Question 45

Inserts of the ACL and PCL

Answer 45

ACL = originates on the lateral femoral condyle and courses anteriorly and medially to insert on the anterior intercondylar area of the tibia PCL = originates from medial condyle of femur and courses posteriorly to insert into posterior head of tibia

Question 46

What disorder presents with diplopia that worsens with use?

Answer 46

Myasthenia gravis * Clinical features: * Ptosis, diplopia, weakness * Worsens with muscle use

Question 47

What is the formula for Fick's Principle for cardiac output?

Answer 47

* CO = (Rate of O2 consumption) / (arterial O2 content – venous O2 content)

Question 48

Compression of what nerve causes Saturday night palsy

Answer 48

Radial Recall that presentation includes inability to extend wrist

Question 49

What nerve is responsible for arm flexors (biceps, coracobrachialis)

Answer 49

Musculocutaneous