USMLE STEP 1 - UWORLD HIGH YIELD EXAM |
QUESTIONS AND ANSWERS | 2024
What are the two major microtubular motor proteins? Which does anterograde axonal
transport, which does retrograde axonal transport? - Kinesin, Dynein
Kinesin: Anterograde
Dynein: Retrograde`
What do you think, immunologically speaking, when you see someone with recurrent
Neisseria infections? - Inability to form the membrane attack (MAC) complex
this is a common complement deficiency
What is the defect in Chronic Granulomatous disease? What is the pathophysiology? -
NADPH Oxidase deficiency leads to the inability to kill intracellular organisms
Characteristic triad of ataxia telangiectasia? - cerebellar ataxia, telangiectasias,
increased risk of sinopulmonary infections
What is the major immune deficiency of ataxia telangiectasia? - IgA deficiency, which
predisposes to infections of the upper and lower airways (and other mucous
membranes)
There's a useful mnemonic for Ataxia Telangiectasia and the gene that's mutated. What
is it? - ATM
Ataxia
Telangiectasia
Mutated
ATM gene is responsible for DNA break repair
What is one reason that lead intoxication causes hypochromic anemia? - Mitochondrial
iron transport is important for Heme synthesis! It's inhibited by lead. So you don't make
heme in your mitochondria and you get hypochromic anemia.
What is the biochemical problem in Lesch-Nyhan syndrome? (And, only if you got that
right, what are the really cool symptoms of it?) - Defective purine catabolism, so buildup
of purines. It's an X-linked recessive disorder with mutated HGPRT gene (hypoxanthine-
guanine phosphoribosyltransferase, if you want to impress people).
,Now, if you got HGPRT and purine catabolism right, you can say: self-mutilating
behavior on top of mental retardation, choreoathetoid (think Chorea) movements and
spasticity.
What is the defect in Niemann-Pick disease?
What causes that?
What is the common macular finding? - Sphingolipid degradation is defective
Caused by an autosomal recessive defect in sphingomyelinase
Cherry Spot on the macula? Niemann Pick's or Tay Sach's.
If a baby gets exposed to an unclean knife (...) and subsequently develops rigid
paralysis, what is the diagnosis, where do we think this might happen, and how do we
prevent it? - Neonatal Tetanus
Developing Countries
Maternal immunization with tetanus toxoid is the best way to prevent it
an adeuately immunized mom will transfer IgG's across the placenta to the neonate
Which microtubule associated protein aids in anterograde transport of intracellular
vesicles and organelles? Which end of the microtubule do they go towards? - Kinesin.
Towards the (+) rapidly growing end.
What is an early BRAIN finding of Ataxia-Telangiectasia and how does it manifest itself?
- Cerebellar atrophy
manifests as ataxia in the first years of life.
High yield path association for Alzheimer's disease? - Neurofibrillary tangles in the
neocortex
High yield path association for Parkinson's disease? - Loss of neurons in the substantia
nigra
High yield path association for Huntington disease? - Atrophy of caudate nucleus
What are the major manifestations of Ataxia-telangiectasia? - cerebellar ataxia,
oculocutaneous tenlangiectasias, repeated sinopulmonary infections, and an increased
incidence of malignancy
If you heard: amenorrhea, bitemporal hemianopsia, and enlargement of the pituitary
gland on brain imaging, what would you be thinking? - Prolactinoma, the most common
pituitary adenoma.
What embryological layer is the anterior pituitary derived from? - Surface ectoderm
,What is the most common congenital abnormality associated with the use of Sodium
Valproate during pregnancy? - neural tube defects, e.g., meningocele
because valproate inhibits intestinal folic acid absorption resulting in teratogenicity
What is the characteristic histology of a craniopharyngioma? - On light microscopy,
cysts are lined by stratified squamous epithelium, possibly with Keratin perals. Cysts are
usually filled iwth a yellow, viscous fluid that's rich in cholesterol crystals.
Where do craniopharyngyomas arise from? - Craniopharyngiomas are calcified cystic
tumors that arise from remnants of Rathke's pouch (embryonic precuros of the anterior
pituitary)
Failure of what process leads due neural tube defects? What can be seen in the
amniotic fluid due to leakage of fetal cebebrospinal fluid? - Failure of fusion of the
neuropores.
Alpha-fetoprotein and Acetylcholinesterase may appear in the amniotic fluid
Can a competent patient refuse healthcare? Can a competent patient refuse knowledge
of their potential health situation? - yes and yes
What is the consensus and professional standard regarding the receiving of gifts from
patients? - Don't do it. It's unethical to accept individual gifts from patients, especially of
signficant value.
AMA doesn't have clear cut answer, but they recommend careful consideration be used.
some general guidelines:
-cash gifts should never be accepted (this includes gift certificates)
-a gift should never influence treatment
-no specific dollar value is given; but as a rule of thumb, it shouldn't be above patient's
or physician's means
-psychiatrist must be super careful even with small gifts
-maintain consistency among all patients
-if physician would be embarrassed or uncomfortable if his colleagues found out about
the gift, don't accept it
Is displacement a mature or immature defense mechanism? What is displacement? -
Immature. A patient redirects emotions from the person or object that's causing the
emotions (e.g., wife), but who it woudl be completely unacceptable to direct those
emotions toward, to a more acceptable, but still inappropriate, person or object (e.g., a
wall or a vase).
, Is sublimation a mature or immature defense mechanism? How does it work? - Mature.
Unacceptable drives are redirected toward completely acceptable targets. (Workout
hard if you're angry)
Is projection a mature or immature defense mechanism? What is it? - Immature.
Unacceptable or personally disagreeable impulses are attributed to others; e.g., a
student who wants to cheat on a test accuses his classmates of cheating. Or the
gayness thing
Is reaction formation immature or mature defense mechanism? what is it? - immature,
where unacceptable feeligns are IGNORED and the opposite sentiment is adopted
(forced). man who's mad at his wife instead compliments her dress
Is splitting a mature or immature defense mechanism? what is it? - immature.
frequently employed by patients with borderline personality disorder, everything is either
"good or bad."
What do you do if you suspect child abuse? Ask the parents or call child protective
services? - Call Child Protective Services immediately!
Psychologically speaking, what phenomenon is "white coat syndrome" associated with?
- Classical Conditioning. In classical conditioning, a reflexive response normally elicited
by an unconditioned stimulus becomes evocable by a second, formally neutral
(conditioned) stimulus.
What three things can patients with bulimia develop (hint: one isn't weight loss because
bulimia doesn't work.)? - (1) bilateral partodi gland enlargement
(2) erosion of tooth enamel*
(3) irregular menses
What is the pulmonary capillary wedge pressure and what does it indirectly measure? -
Pressure in the pulmonary artey distal to the point of its occlusion by an inflated
intravascular balloon.
Since there's no significant blood flow towards the left atrium (LA) beyong this point of
occlusion, the pressure at the tip of the "wedged" pulmonary artery catheter is an
indirect measurement of LA Pressure.
What would we expect, in a normal patient, the relationship to be between LA and LV
pressure during diastole? - We would expect them to be nearly equale (both <12) since
the open mitral valve offers minimal resistance to flow between the 2 chambers
What is the characteristic finding via cardiac catheterization in a patient with mitral valve
stenosis? I.e., if we see what value elevated while the other remains normal, when do
we think "Mitral Valve Stenosis." - Cardiac Catheterization will reveal a LA end diastolic
