Usmle Step 1 - April 18

Front 1

HPV-associated oncogenesis is attributed to which viral proteins?

Back 1

E6 & E7
HPV strains responsible for CIN (intraepithelial neoplasia of the cervix) = 16, 18, 31, 33, 35

Front 2

Which tumor suppressor is targeted in cervical cancer?

Back 2

E6 gene products target p53

Front 3

Risk factors for cervical dysplasia?

Back 3

#1 = Multiple sex partners
- Smoking
- Early sexual intercourse
- HIV infection

Front 4

What cell is a sign of HPV infection? What are its characteristics?

Back 4

Koilocyte = Immature squamous cell with:
- Dense, irregularly staining cytoplasm
- Perinuclear clearing ("halo")
- Pyknotic nucleus ("raisinoid")

Front 5

What is a pyknotic nucleus?

Back 5

The chromatin has condensed in the nucleus as part of the process of apoptosis.
Seen in koilocytes in cervical condyloma / HPV infection.

Front 6

What are Clue Cells and when are they seen?

Back 6

Clue cells are squamous cells covered with bacilli.
They are seen in Pap smear specimens from women with bacterial vaginosis (Gardnerella vaginalis)

Front 7

What are Parabasal Cells? When do you encouter them?

Back 7

Paraasal cells are round cells with:
- Basophilic cytoplasm
- Finely granular chromatin
- No visible nucleoli
- High N/C ratio

They are found in Pap smears from post-menopausal and post-partum women.

Front 8

What type of cell is present in a normal Pap smear and what are its characteristics?

Back 8

Glandular endocervical cells.

They are columnar cells with:
- Vacuolated or granular cytoplasm
- Prominent cell borders
- Occasional nucleoli
- Form "honeycomb pattern" in clusters

Front 9

What drugs slow the progression and reduce the mortality in patients with CHF? How?

Back 9

Beta-blockers, particularly CARVEDILOL (non-selective ß + α1).
Beta-blockers decrease cardiac work by:
- Slowing ventricular rate
- Decreasing afterload

Front 10

What is the cause and what are the common characteristics of Turner Syndrome?

Back 10

Cause: Loss of parental X during MITOSIS; can be complete monosomy (45XO), mosaicism, or partial deletion of one X chromosome.

Commonly = Short, webbed neck, low posterior hairline
Urogenital = Streak ovaries, horseshoe kidney
Cardiac = Coarctation of the aorta, bicuspid aortic valve
Lymphatic = Lymphedema in feet/hands, cystic hygroma

Front 11

What are examples of trinucleotide repeat expansion diseases?

Back 11

Huntington (CAG)
Fragile X (CGG)
Myotonic dystrophy (CTG)

Front 12

What genetic diseases feature uniparental disomy of the same chromosome?

Back 12

Chromosome 15:
- Prader-Willi (2 x maternal)
- Angelman (2 x paternal)

AngelMAN = 2 copies from MAN

Front 13

What type of mutation is associated with Familial hypercholesterolemia?

Back 13

Frameshift mutation

Front 14

What is a major source of nosocomial infections for patients w/ implanted foreign bodies like replacement heart valves (or indwelling catheters)?

Back 14

Staphylococcus epidermidis.

Normal skin flora. Can colonize by producing polysaccharide slime that allows them to adhere to foreign-body surfaces.

Tx = Vancomycin (empirically) w/ or w/o Rifampin/Gentamycin

In heart valve, can cause indolent endocarditis and if untreated --> intracardial abscess, dehiscence of valve, and septic embolization.

Front 15

Injury sustained when falling on outstretched hand and results in pain, flattening of the deltoid, and sensory loss over the deltoid?

Back 15

Anterior dislocation of the humerus.

This causes axillary nerve to be injured (innervates deltoid and teres minor, sensation overlying the lateral arm & deltoid)

Front 16

What 2 nerves are possibly injured after falling with an outstretched hand?

Back 16

Axillary and Radial Nerves.

Axillary d/t anterior dislocation of the humerus.

Radial d/t spiral mid-shaft fractureo of the humerus.

Front 17

What are the components of the Rotator Cuff?

Back 17

SItS
S = Supraspinatus
I = Infraspinatus
t = teres minor
S = Subscapularis

Front 18

A newborn with lethargy, vomiting, tachypnea and labs that show large anion gap metabolic acidosis, ketosis, hypoglycemia, and markedly elevated methylmalonic acid in serum and urine?

Back 18

There is a problem with the isomerization reaction that converts Methylmalonyl CoA --> Succinyl CoA (which enters the TCA cycle).

The reaction uses Methylmalonyl CoA Isomerase and B12.

Front 19

Most common congenital heart disease to cause early cyanosis?

Back 19

Tetrology of Fallot

Front 20

What are the 4 parts of the Tetrology of Fallot?

Back 20

imPROVe
(patients squat to imPROVe symptoms)
P = Pulmonary Stenosis*
R = RVH
O = Overriding aorta
V = VSD

* extent of pulmonary stenosis is most important determinant of prognosis

Front 21

Embryological cause of the Tetrology of Fallot?

Back 21

Tetrology of Fallot is caused by anterosuperior displacement of the infundibular septum.

Front 22

A stab wound in the 5th intercostal space at the mid-clavicular line would strike what structure?

Back 22

Left lung.

The lateral border of the heart comes to that point too, but it is behind the lung and the left ventricle would only be injured if the stab wound was deep.

Front 23

What congenital abnormality is associated w/ Valproate use?

Back 23

Neural tube defects.

Inhibit maternal folate absorption in the intestine.

Valproate is an anti-epileptic.

Front 24

What congenital abnormality is associated with Down Syndrome?

Back 24

Duodenal atresia.

Hallmark is bilious vomiting w/o abdominal distention in 1st day of life.

Front 25

What congenital abnormality is associated with Turner Syndrome?

Back 25

Coarctation of the aorta & bicuspid aortic valves.

BP elevated in vessels that are proximal to coarctation.

BP and pulse reduced in vessels distal to coarctation.

Front 26

What are the 2 types of Coarctation of the Aorta and what are their causes?

Back 26

Infantile type is PREDUCTAL (stenosis is proximal to the insertion of the ductus arteriosus) and usually d/t Turner Syndrome.
INfantile = IN close to the heart

Adult type is POSTDUCTAL (stenosis distal to ligamentum arteriosum) and is associated with:
- Notching of the ribs
- HTN in upper extremities
- Weak pulses in lower extremities
aDult = Distal to Ductus

Front 27

What congenital abnormalities are associated with Potter Syndrome?

Back 27

Bilateral renal agenesis which leads to Oligohydramnios &:
- Face & limb deformities
- Pulmonary hypoplasia.

d/t malformation of the ureteric bud.

Front 28

What is Ebstein's anomaly and what is it associated w/?

Back 28

It's a congenital heart defect where the tricuspid valve is anteriorly displaced leading to an "atrialization" of much of the right ventricle.

It is associated with use of Lithium in the first trimester.

Front 29

Abused drugs most associated with violent behavior?

Back 29

1) Hallucinogens (Psychotomimetics):
- PCP/Angel Dust = phencyclidine
- LSD
2) Amphetamines
3) Cocaine

Belligerence/psychomotor agitation more common in PCP > LSD

Front 30

What are characteristic signs of Aortic Regurgitation?

Back 30

1) "Water-hammer" pulses (bounding pulses in femorals and carotids; d/t large pulse pressure)

2) de Musset sign = Head bobbing w/ each heart beat (d/t higher stroke volume, LVSV, reaching head/neck)

Front 31

What kind of murmur is heard in a patient with Aortic Stenosis?

Back 31

DIASTOLIC
immediate, high-pitched, "blowing"

(NOTE: Diastolic = ARMS)

Front 32

What is a precaution needed when using inhaled / aerosolized corticosteroids and why?

Back 32

Oral rinsing to prevent oropharyngeal candidiasis.

e.g. Aerosol Flunisolide

Front 33

What are recommendations for patients using systemic glucocorticoid therapy?

Back 33

Low sodium diet.
Fluid restriction.

Front 34

What does an operon contain?

Back 34

At least two regulatory sites:
- the Promoter
- the Regulator (operator)

Front 35

What genes are in the lac operon?

Back 35

Lac i = Repressor protein
Lac p = binding site for RNA polymerase
Lac o = binding site for Repressor protein

3 structural genes:
Lac z = ßgalactosidase (lac --> glu & gal)
Lac y = permease (increase permeability for lactose)
Lac a

Front 36

How is the Lac operon activated?

Back 36

When there is an abundance of lactose, lactose will bind to the Repressor protein.

Front 37

How does the presence of glucose affect the lac operon?

Back 37

Glucose decreases activity of Adenylyl Cyclase and therefore the amount of cAMP in the cell is depleted.

CAP (catabolite activator protein) is unable to complex w/ cAMP and therefore unable to be a (+) upregulator of the operon.

Front 38

What regions of a gene do repressor proteins bind to?

Back 38

Operator region.

Repressor --> Operator

Front 39

What metabolic process is unique to S. aureus of all the Staphylococci?

Back 39

Mannitol fermentation.

Front 40

What property of Staph. saprophyticus allows it to be differentiated from other coagulase-negative Staph?

Back 40

Novobiosin resistance.

The other coagulase-negative Staph are killed by Novobiocin.

Front 41

What is the function of T-tubules and why are they important?

Back 41

T-tubules are invaginations of the sarcolemma (muscle cell membrane).
Fx = transmit depolarization from sarcolemma --> sarcoplasmic reticulum

Absence would lead to uncoordinated contractions of myofibrils.

Front 42

What is Rheumatoid Factor?

Back 42

It's an IgM antibody against self IgG's.

Present in majority of RA pts.

Absent in seronegative spondylarthropathies

Front 43

What are the seronegative spondylarthropathies?

Back 43

Characterized as arthritis w/o rheumatoid factor.

PAIR
- psoriatic arthritis
- ankylosing spondylitis
- IBD
- reactive arthritis (Reiter's)

Front 44

What genetic association do the seronegative spondylarthropathies share?

Back 44

HLA-B27
(an HLA MHC Class I)

e.g. 90% of AS pts are HLA-B27+

Front 45

Ini normal distribution, how many values fall w/in 1 SD of the mean? 2 SD's? 3 SD's?

Back 45

1 SD = 68% (2/3)
2 SD = 95%
3 SD = 99.7%

Front 46

How can you inactivate HAV?

Back 46

- Chlorination
- Bleach (1:100)
- Formalin
- UV
- Boiling (85º, 1min)

Front 47

Characteristics of HAV?

Back 47

Picornavirus (RNA)
Fecal-oral

Alone, Asymptomatic, Acute
- No carrier
- Weeks

No HCC risk

Front 48

What vessels are most affected by Nitroglycerine?

Back 48

Large Veins.

Venodilation allows blood to collect in venous system (redistribution) and thus decrease preload / cardiac workload.

Front 49

What part of the EKG is affected by ß-Blockers?

Back 49

PR Interval (prolonged).

PR = the interval b/w beginning of Atrial depolarization and Ventricular depolarization.

Front 50

What type of immune reaction is responsible for Type I DM?

Back 50

Cellular immunity (destruction by T lymphocytes).

Anti-islet Ab's are present but believed to be d/t destruction of the ß-Cells by T-Cells.