UWorld Test Reviews Flashcards
most African Plasmodium species are _______ resistant and require treatment with ________ or __________
most African Plasmodium species are chloroquine resistant and require treatment with atovaquone-proguanil or artemisinins
where is ventilation and perfusion highest/lowest in the lungs?
ventilation and perfusion are both lowest in the apex and highest in the base - gravity pulls lungs downward, expanding alveoli and increasing blood flow at the base
however, gravitational effect on perfusion is greater than ventilation —> V/Q ratio is LOWEST at the BASE and highest at the apex
large pulmonary arteriovenous malformations (AVMs) may cause:
a. alveolar diffusion impairment
b. decreased alveolar ventilation
c. increased pulmonary vascular resistance
d. increased R to L shunting
AVM allows direct artery to vein anastomosis —>
d. increased R to L shunting
deoxygenated blood is directly arterialized without participating in gas exchange —> hypoxemia
what is the function of O6-methylguanine-DNA methyltransferase (MGMT)?
converts O6-methylguanine (naturally occurring alkylation product) back to guanine
what are the clinical features of 22q11.2 deletion?
aka DiGeorge Syndrome, CATCH-22:
Cardiac outflow tract anomalies (tetralogy of Fallot, truncus arteriosus)
Anomalous face (prominent nasal bridge, low-set ears, micrognathia)
Thymic aplasia (decreased T cell immunity)
Cleft palate
Hypoparathyroidism (hypoCa2+)
which of the following as a structure most closely resembling endorphins?
a. prolactin
b. TSH
c. ACTH
d. growth hormone
e. vasopressin
f. somatomedin C (insulin like growth factor)
c. ACTH
endorphins, ACTH, and MSH are all derived from POMC (proopiomelanocortin) - suggests physiological relationship between stress axis and opioid system
what can be used to distinguish cardiogenic vs no cardiogenic pulmonary edema?
noncardiogenic pulmonary edema (ARDS, high altitude pulmonary edema) has a normal pulmonary capillary wedge pressure
[clinical history of pneumonia/sepsis or pancreatitis is also suggestive of ARDS]
cardiogenic pulmonary edema (decompensated LVHF, volume overload) will have elevated PCWP
where would lipofuscin granules be found, and in which patients?
lipofuscin: insoluble granules composed of lysosomal breakdown products (lipid polymers, phospholipids) resulting from free radical injury and lipid peroxidation
wear-and-tear products that accumulate with age in low-turnover cells (heart, liver, CNS) of elderly
what is the mechanism for glucose entry into cells?
carrier-mediated (facilitated) transporter - does NOT require ATP
heparin induced thrombocytopenia type 2
formation of IgG Abs to complexes of heparin + endogenous platelet factor 4
—> thrombocytopenia, typically 5-10 days after heparin initiation due to destruction of antibody-coated platelets by splenic macrophages
what is the effect of angiotensin II on GFR?
angiotensin II preferentially constricts efferent arteriole —> increased hydrostatic pressure, increased net filtration pressure
which 2 proximal carpal bones articulate with the radius?
scaphoid (lateral) and lunate (medial)
scaphoid more often affected by FOOSH
characterized by epithelial and myoepithelial cells lining fibrovascular cores in cyst walls or ducts in the breast
intraductal papilloma - most common cause of bloody nipple discharge, typically presents without breast masses or skin changes
gingival hyperplasia is a common side effect of:
a. lithium
b. prednisone
c. cocaine
d. phenytoin
e. clozapine
f. methimazole
d. phenytoin - causes increased expression of PDGF, which causes proliferation of gingival tissue and alveolar bone
phenytoin toxicity mainly affects cerebellum and vestibular system —> ataxia, nystagmus
which 2 bacteria cause a purely toxin-mediated watery diarrhea?
- Vibrio cholerae
- enterotoxigenic Escherichia coli
modify electrolyte handling by enterocytes but do not cause cell death - no erythrocytes or leukocytes are noted in stool microscopy
patients with deficiency of propionyl-CoA carboxylase are unable to utilize which amino acids for energy production?
propionyl-CoA carboxylase required for conversion of propionyl-CoA to methylmalonyl-CoA
propionyl-CoA is derived from metabolism of valine, isoleucine, methionine, threonine, and odd-chain fatty acids
deficiency —> proprionic acidemia, presenting with lethargy, poor feeding, vomiting, hypotonia 1-2 weeks after birth
contrast the effect of CFTR functioning in sweat ducts vs respiratory/intestinal glands
sweat ducts - reabsorb luminal Cl-, stimulate ENaC Na+ absorption from lumen [mutation —> sweat with high Cl- and Na+ content]
resp/intestinal glands - secrete Cl- ions, inhibit ENaC opening to decrease Na+ reabsorption —> retains water in lumen to form hydrated mucus
in preparation for labor, increasing estrogen stimulates production of:
a. adherens junctions
b. desmosomes
c. fenestrae
d. gap junctions
e. hemidesmosomes
f. tight junctions
d. gap junctions - via upregulation of connexin proteins
increase in gap junction density allows for coordinated labor contractions
what is the effect of nitrites on respiration?
nitrites - cause poisoning by inducing conversion of heme iron (Fe2+, ferrous) to oxidized iron (Fe3+, ferric) —> methemoglobin, unable to bind O2
affinity of residual ferrous iron is increased, causing left shift as well
look out for “dusky” discoloration of skin and state of functional anemia
what is the function of interferon alpha/beta vs gamma
IFN alpha/beta (Type I) —> halt protein synthesis and promote apoptosis of infected cells, induce MHC I expression, stimulate NK and cytotoxic T cells
IFN gamma (Type II) —> produced by NK and T cells, promotes TH1 differentiation, induces MHC II expression on APC, enhances macrophage function
coronary dominance is determined by…
… which coronary artery supplies blood to the posterior descending artery (PDA)
right dominant (most people) = right coronary artery
left dominant = left circumflex artery
what type of host immune factors are responsible for mediating the response to monoclonal antibody therapy?
NK cells and granzymes, mediating antibody-dependent cellular cytotoxicity (ADCC)
IgG (natural or mAb) binds surface antigen —> NK binds Fc portion using CD16 —> triggered granule release (perforin + granzymes/proteases) —> induced apoptosis/osmotic lysis
which virus infects B cells and stimulates them to proliferate continuously (transformation, aka immortalization)?
Epstein-Barr virus (EBV) - EBV-encoded oncogenes activate proliferative and anti-apoptotic signaling in infected B cell
immortalized B cells secrete heterophile IgM antibodies
what would muscle biopsy of focal dystonia show?
focal dystonia: neurological movement disorder characterized by sustained, involuntary muscle contractions
would cause muscle fiber hypertrophy
5 day old with multiple episodes of emesis, tachycardia, hypotension, sunken fontanelle, dry mucous membranes, hepatomegaly, gram negative rods in arterial blood
symptoms started after breastfeeding - which enzyme is impaired?
galactose-1-phosphate uridyl transferase (GALT): converts galactose-1-phosphate to glucose-1-phosphate
patients predisposed to E. coli sepsis
what are normal aortic and LV pressures, respectively?
aortic: 120/80
LV: 120/10
what types of medications are associated with drug-induced neutropenia? (5)
antithyroid: methimazole, propylthiouracil
anti-inflammatory: sulfasalazine, methotrexate
psychotic/anticonvulsant: clozapine, carbamezepine, phenytoin
cardio: anti-arrhythmic (procainamide), ticlopidine
antimicrobial: TMP-SMX, quinine, acyclovir
how does drug-induced neutropenia present?
oropharyngeal ulcers + fever (mucus membrane infection)
lab shows isolated leukopenia (no anemia, thrombocytopenia)
resolves in 1-3 weeks if drug is discontinued
which infectious disease is associated with thatched roofing/ adobe in Latin America?
Trypanosoma cruzi: vector-borne to Triatomine bug, causes Chagas disease
acute phase: asymptomatic or nonspecific
chronic phase: 1-3 decades later, minority develop end-organ disease of heart (cardiomyopathy - ventricular arrhythmias!) or GI system
when are beta-hCG levels first detectable in serum after fertilization?
8 days after fertilization
malignant breast condition characterized by unilateral, painful/pruritic, eczematous rash confined to nipple and areola, associated with scaling/ulceration
Paget disease of the breast (adenocarcinoma) - biopsy shows Paget cells in epidermis of nipple-areolar complex (enlarged, abundant cytoplasm, prominent nucleoli)
most patients have underlying breast malignancy - require diagnostic mammography
forms colonies in culture with multiple curled extensions at the edges that resemble a “Medusa head”
bacillus anthracis: large, nonmotile, nonhemolytic, gram positive rod
facial muscle contractions elicited by tapping on the facial nerve anterior to the ear is indicative of what
hypocalcemia - causes neuromuscular hyperexcitability
becomes clinically apparent when serum calcium drops below 7mg/dL
from where do the gonadal arteries vs gonadal veins arise from?
gonadal arteries arise from abdominal aorta (involved in testicular torsion)
R gonadal vein drains into IVC, L gonadal vein drains into left renal vein (affected by blockage by tumor)
Pt is 24yo F presenting with pruritic rash on her flexor regions (antecubital and popliteal fossa), which has been present on and off for most her life. Examination reveals erythematous patches and papules. What is the diagnosis, and which cytokines are driving the pathology?
atopic dermatitis: inflammatory condition characterized by acute exacerbations of dry, pruritic, erythematous patches, papules, or vesicles in flexural regions
pathology - skin barrier dysfunction increases cutaneous exposure to environmental antigens, which induces Th2 response, triggered by IL-4 and IL-13 —> IgE production, inhibition of Th1
by what mechanism does amiodarone affect digoxin metabolism?
inhibition of P-glycoprotein (transmembrane efflux transporter, aka drug pump) —> increased intestinal absorption + decreased renal clearance
[note amiodarone does inhibit cytochrome P-450, but digoxin is NOT hepatically cleared and therefore unaffected by this]
gingival bleeding + failed ristocetin test + corrected ristocetin test with normal plasma added =
Von Willebrand factor deficiency
vWF binds glycoprotein Ib receptors on platelets following endothelial damage - mediates platelet adherence
ristocetin cofactor assay measures platelet agglutination via binding of glycoprotein Ib receptors to vWF (activates receptors to make them available for binding)
what anatomical landmark should be used to identify the optimal site for lumbar puncture?
iliac crest - needle should be inserted in the L3/L4 of L4/L5 space
[recall spinal cord terminates at inferior border of L1 vertebra in adults, L2/L3 in neonates/infants]
neutrophil micro-abscesses + epidermal hyperplasia (acanthosis) =
psoriasis: erythematous plaques with thick scales on extensor surfaces of extremities
hyperkeratosis + sawtoothed rete ridges =
lichen planus: small, pruritic, purplish, polygonal papules or plaques
typically multi-focal