UWorld Flashcards
1
Q
Which type of signals work via
(a) Intracellular receptors
(b) Membrane-bound receptors coupled w/ G-protein
(c) Transmembrane ligand-gated ion channel
(d) Transmembrane receptor associated w/ intrinsic tyrosine kinase
A
(a) Steroid hormones, thyroid hormone, and vitD
(b) Responding to serum levels of ions
- ex: parathyroid calcium sensing receptors
- glucagon receptors
(c) Neurotransmitters: ACh, 5-HT, GABA
(d) Insulin and insulin-like growth factor stimulate intrinsic tyrosine kinase
2
Q
In a pt w/ cerebellar ataxia, what does a positive Romberg’s sign help you differentiate
A
Cerebellarataxia- not sure if it’s a proprioception or a motor coordination problem
+Rombergs (can’t stay balanced w/ eyes closed feet together) = sensory ataxia
-classically tabes dorsalis, B12 deficiency, defect in posterior columns or peripheral nerve
-Rombergs = ataxia 2/2 impaired motor coordination = central
3
Q
Chronic alcoholic p/w hepatomegaly, increased JVP, and pitting edema w/ scattered ecchymoses
Plts 120k, PT 26s, aPTT 38s
Results unchanged after dose of vitamin K repletion
Cause of lab abnormality?
A
Factor VII deficiency: factor VII is a part of the extrinsic pathway => causes abnormal PT
-not factor VIII deficiency, factor VIII produced by endothelial cells and prolongs aPTT not PT
4
Q
19 yo p/w gradual worsening of blurry vision
- tall and thin
- pectus excavatum on physical exam
(a) Dx
(b) Mutation
(c) Most likely cause of death
A
(a) Marfan syndrome: key involvement of eyes, skeleton, and CV system
(b) Mutation in fibrillin-1 gene
(c) CV lesions, specifically aortic disease
5
Q
Risks of erythropoiesis-stimulating agents in pts w/ CKD
A
EPO and darbapoetin alpha can help the anemia, but increased risk for HTN and thromboembolic events
Increased thromboembolic events 2/2 increased blood viscosity from increased red cell mass, HTN mechanism unclear
6
Q
64 yo M p/w urinary frequency/dribbling x6mo, given drug then notices increases in hair growth over scalp
Which drug was he given?
A
Given finesteride = 5alpha reductase inhibitor- inhibits peripheral conversion of T –> DHT
-pts w/ androgenic alopecia have higher 5alpha reductase
7
Q
Macroorchidism + ID
A
Fragile X = 2nd MC cause of MR in males, characteristic macroorchidism
8
Q
What embryologic layer do the following arise from?
(a) Internal genitalia
(b) Salivary and sweat glands
(c) Sensory ganglia
(d) Adrenal cortex
(e) Adrenal medulla
A
Embryologic layer
(a) Internal genitalia from mesoderm
(b) Salivary and sweat glands (and mammary glands) from surface ectoderm
(c) Sensory ganglia (PNS) from neural crest of the ectoderm
(d) Adrenal cortex from the mesoderm
(e) Adrenal medulla from neural crest of the ectoderm
9
Q
Group of malignant epithelial cells w/ decreased surface expression of MHC class I antigen
(a) Which immune cell will kill these transformed epithelial cells?
(b) Mechanism of death
A
(a) Natural killer cells: NK cells destroy cells w/ decreased or absent MHC class I (which is seen in virally infected and tumor cells)
(b) Perforins pop hole in target cell membrane, granzymes induce target cell apoptosis
- death by causing apoptosis (not by directly lysing cells)
10
Q
Lymphoma that produces a protein that works by
(a) Apoptosis inhibition
(b) DNA repair
(c) Regulation of G1 to S-phase transition
A
(a) Bcl2 = apoptosis inhibitor upregulated by t(14,15) seen in follicular lymphoma
(b) Mutations in DNA repair enzymes cause BRCA breast cancer, Lynch syndrome, xeroderma pigmentosum
(c) Cyclin D1 translocation w/ Ig heavy chain (t11,14) = mantle cell lymphoma
11
Q
Distinguish mechanism of risedronate and raloxifene in the tx of osteoporosis
A
Risendronate (bisphosphonate) binds to binding sites on bone to inhibit bone resorption by mature osteoclasts
While SERMs (selective estrogen receptor modulators) like raloxifene slow bone loss by inhibiting osteoclast differentiation
12
Q
What’s better to dx type I diabetes: OGTT or fasting blood glucose
A
Fasting blood glucose over 126 is diagnostic (also get HbA1C w/ it)
No need for expensive and annoying OGTT
13
Q
2 MC causes of acute otitis media
A
Haemophilis influenza and Strep pneumo
14
Q
CSF gram stain shows bean-shaped gram negative cocci in pairs
(a) Organism
(b) Mode of transmission
A
(a) Gram negative cocci in pairs = neisseria species, if causing meningitis (sample is from CSF)- assume neisseria meningitides (instead of neisseria gonorrhea)
(b) Respiratory droplets- carriers have nasopharyngeal colonization
15
Q
Differentiate DNA polymerase I and III
A
DNA pol I in bacteria removes RNA primer via 5’ to 3’ exonuclease activity
DNA pol III elongates new DNA strand: has 5’ to 3’ polymerase and 3’ to 5’ exonuclease (proofreading) activity
16
Q
What artery supplies the inferior surface of the heart
A
Posterior descending artery, derived from the RCA (in 85-90%)
17
Q
62 yo F p/w ST segment elevation in inferior leads w/ BP 90/60 and HR 42. Initial tx started, BP now 120/70 w/ HR 76
(a) What tx was given?
(b) How this might cause eye pain
A
(a) Inferior MI (2/2 RCA blockage) often associated w/ bradycardia since RCA supply SA and AV node
- treat bradycardia w/ atropine (blocks vagal influence to increase HR)
(b) Atropine in the eye dilates the pupil, which can precipitate angle-closure glaucoma
Explains eye pain after pt who presents w/ inferior MI is treated
18
Q
Nerve that travels thru obturator canal
(a) Motor control
(b) Sensory control
A
Obturator nerve = only major nerve that exits pelvis thru obturator foramen
(a) Controls thigh adduction
(b) Sensory over distal medial thigh
- supply thigh adductor muscles: adductor longus, brevis, magnus
19
Q
Glomerular deposits seen in
(a) Post-strep GN
(b) Lupus nephritis
(c) Rapid proliferative GN
(d) Diabetic nephropathy
A
(a) C3b-Ig (immune complex)
(b) Lupus nephritis = IgE
(c) Crescentic (rapid proliferative) GN = fibrin deposits
(d) Hyaline accumulation = acellular deposits of plasma proteins
20
Q
Holosystolic murmur best hard at apex of the heart that radiates to the axilla
(a) What is the murmur?
(b) Which auscultative finding is the best indicator of severity?
A
(a) Mitral regurg
(b) Presence of audible S3
- S3 indicates LV volume overload, increased LV filling of regurg flow that enters the ventricule duirng diastole
21
Q
Key clinical feature of severe aortic insufficiency
A
Widened pulse pressure causes head bobbing and bounding pulses (palpitations, head pounding)
Ex: Pt experiences head pounding accompanied by involuntary head bobbing with exercise
22
Q
Lymphoma that presents w/ thymic mass in a teenager
A
8 yo boy w/ fever, throat pain, dysphagia to solid foods has bloodwork revealing blasts in peripheral smear
Most likely cause = T-cell ALL
-thymic mass compressing esophagus => dysphagia
23
Q
Two drugs for malaria tx and their actions
A
- Chloroquine to eradicate plasmodia from bloodstream
- Primaquine to eradicate hyponozoites responsible for latent hepatic infection
- specifically P viva and P ovale (and not P falciparum) form intrahepatic stage (hypnozoites) responsible for relapse
24
Q
21 yo F started on new medication yesterday experiences facial flushing, HA, N/V, abdominal cramps after moderate EtOH use
What is the new med treating her for?
A
Recall that metronidazole (flagyl) can cause disulfram (antabuse)-like reaction due to acetaldehyde buildup
So pt being treated for trichomonas vaginalis or bacterial vaginosis w/ metronidazole, causing disulfram-like reaction w/ EtOH
Hence why we tell ppl on flagyl to avoid EtOH
25
20 yo p/w intractible vomiting and abdominal pain after weeks of anorexia and wt loss
- h/o hypothyroidism tx appropriately
- BP 80/40, HR 120, generalized hyperpigmentation, FS 60
(a) Dx
(b) Immediate step in tx
(a) Acute adrenal insufficiency = adrenal crisis
- hypotension/shock w/ N/V/abdominal pain, weakness, fever
- wt loss and hyperpigmentation suggestive of Addison's disease (primary adrenal insufficiency)- also fits w/ h/o hypothyroidism (increased risk of other autoimmune stuff)
(b) Aggressive fluid resuscitation and immediate glucocorticoid supplmentation
26
Elevated C3 in what kidney d/o?
C3 is elevated in post-strep GN
-C4 can be decreased, but not always
27
Why does HepD need another Hep virus
HepD needs HepB- hepD alone is replication-defective => can only cause infection when encapsulated w/ HBsAg
28
Which thionamide is safe during pregnancy
Thionamides (antithyroid drugs): methimazole, propylthiouracil
PTU safe during pregnancy, while methimazole is a 1st trimester teratogen
29
Name two organisms that use a polysaccharide capsule as a virulence factor?
(a) Mechanism of virulence
Both Haemophilus influenzae and Strep pneumo have polysaccharide capsule
(a) Polysaccharide inhibits phagocytosis by macrophages and neutrophils (innate immunity) => need to wait for adaptive immunity to recognize capsular antigens to effectively phagocytose encapsulated organisms
30
Differentiate the mechanism of the two main BPH drugs
Finesteride (5alpha reductase inhibitor, inhibits T --> DHT) reduces size of the prostate
- b/c DHT stimulates prostate growth
- b/c of this it can take 6-12 months to have max effect
While Alpha-blocker (Tamsulosin) relaxes smooth muscle of bladder, doesn't change size of the prostate
31
Increased risk of which two malignancies in Down's syndrome
AML (acute myelogenous leukemia) and ALL (acute lymphoblastic leukemia) b/c both involve translocations w/ chromosome 21
32
MC location of pancreatic pseudocyst
(a) Explain why they form
Lesser peritoneal sac = just posterior to the stomach, is the most common location of a pancreatic pseudocyst
(a) Pancreatic enzymes induce inflammatory reaction, forming granulation tissue that encapsulates fluid collection (fluid is leakage of pancreatic secretions out of damaged pancreatic ducts)
33
53 yo w/ COPD and cor pulmonale- why doesn't he have peripheral edema?
Core pulmonale 2/2 COPD: increased CVP (RA pressure) increases capillary hydrostatic pressure, which is offset by increased tissue lymphatic drainage
As interstitial fluid pressure increases (from the hydrostatic capillary pressure) so does lymphatic drainage which can compensate for moderate CVP elevations
34
Describe the mechanism of hepatic encephalopathy
Increased ammonia and neurotoxins =>
- increased inhibitory neurotransmission (so increased GABA)
- impaired excitatory nt release
35
How do cranial nerves VII-X exit the skull?
CN VII and VIII exit the internal acoustic meatus
CN IX, X, XI exit out the jugular foramen
36
Mechanism of NSAIDs
(a) How this may interfere w/ furosemide effect
NSAIDs work by inhibiting prostaglandin synthesis
(a) Furosemide inhibits NaK2Cl symporter at ascending loop of Henle to increase Na, Cl, fluid excretion
- furosemide (and other loop diuretics) also secrete PGE to cause vasodilation and increase GFR (enhancing diuretic effect)
- so NSAIDs blunt diuretic response by interrupting prostaglandins
37
How would a pt w/ trochlear nerve palsy present?
Trochlear nerve (CN VI) innervates superior oblique that intorts and depresses the eye => vertical diplopia worsened by looking down (ex: when pt walking down stairs) or in towards the nose (intorting, ex: harder to read morning newspaper)
38
Mechanism of desmospressin therapy for
(a) Bleeding d/o
- which bleeding d/o?
(b) Central DI and nocturnal enuresis
(a) Desmopressin (DDAVP) for mild hemophilia A and type 1 von willebrand diseases increases circulating factor VIII and endothelial secretion of vWF to step bleeding
(b) DDAVP binds to V2 receptors in renal tubular cells, increasing aquaporin channels to increase water reabsorption and decrease urine output
39
Enzyme mutated in Xeroderma pigmentosum
UV-specific endonuclease
-so endonuclease complex that recognizes and cleaves deformed helix (due to thymine dimers formed in response to UV light) is mutated => these kids are super sun sensitive and have a super high risk of skin cancer
40
Explain how the following increase risk for nephrolithiasis
(a) Primary hyperparathyroidism
(b) Crohn disease
High Ca, oxalate, uric acid promote salt cystallization. High urinary citrate and fluid intake prevent calculi formation
(a) Hypercalcemia- excess calcium precipitates (b/c supersaturated) in urine
(b) Crohn disease- hyperoxaluria (intestinal malabsorption of Ca available to bind/trap oxalate in gut)
41
Pt's neutrophils fail to turn blue following exposure to nitroblue tetrazoium
Dx?
Characteristic test for chronic granulomatous disease
2/2 X-linked mutation in NADPH oxidase => inability of phagocytes to do oxygen-dependent intracellular killing => recurrent bacterial and fungal infections, especially w/ catalase-positive organisms that destroy H2O2
42
Carotid bodies vs. central chemoreceptors in what they react to
(a) Impact of COPD on this response
```
Carotid bodies (peripheral chemoreceptor): react to mostly PaCO2, but also PaO2 when it's low enough
(a) Pts w/ long-standing COPD have decreased sensitivity to PaCO2 (since they're chronic retainers). If severe they have profound hypoxemia, so arterial PaO2 becomes a more significant contributor to respiratory drive
```
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Central chemoreceptors (located in medulla) respond to pH of surrounding CSF, major stimulus = PaCO2
-not effected by blood pH b/c BBB is impermeable to H+, instead reacts to arterial PaCO2
```
43
Main molecular mediator in paraneoplastic cachexia
Aka why do ppl w/ cancer undergo weight loss, malaise, and generalized wasting
=TNFalpha
- produced by macrophages
- works by suppressing appetite and increasing basal metabolic rate
44
Phenytoin indications
(a) CNS side effect
(b) Peripheral side effect
Phenytoin = anti-epileptic that blocks voltage-gated sodium channels to tx grand-mal seizures, partial seizures, and status epilepticus
(a) Ataxia and nystagmus
(b) Gingival hyperplasia 2/2 excess PDGF expression
45
Mode of inheritance of hyper-IgM syndrome
X-linked recessive: CD40L deficiency
-recall CD40L deficiency causes failure of Ab class switching in B cells (b/c B cells can't stimulate helper T cells to secrete IL4/5 to cause class switching) so all T cells remain as immature form which secrete IgM
46
Cells contributing to destruction in emphysema
It's activation of macrophages and neutrophils (macrophages activated by chemicals in cig smoke, then macrophages attract neutrophils)
Macrophages and neutrophils both release proteases that destroy acinar walls = permanent destruction of airspaces
47
Would monomeric beta-hemoglobin have a higher or lower affinity for oxygen than HbA?
HbA (tetramer of 2A and 2B units) has a much lower affinity for O2 than myoglobin (single monomer, used to store O2 in skeletal and cardiac muscle tissue)
Single Hb units have similar characteristics to myoglobin => a single beta-Hb unit would have a much higher affinity for O2 than HbA
48
How does the pancreatic ductal system differ in pancreatic divisum?
When the dorsal and ventral pancreatic buds fail to fuse (pancreatic divisum): accessory duct (instead of main duct) drains the majority of the pancreas
49
Location of carotid sinus
(a) Afferent limb of carotid sinus reflex
Carotid sinus = dilation of internal carotid artery just above the bifurcation of the common carotid artery
(a) Afferent limb: baroreceptor signals travel back to vagal nucleus and medullary centers via glossopharyngeal nerve (CN IX)
- while efferent limb carries parasympathetic fibers via the vagus
But carotid massage works via glossopharyngeal
50
Features of atypical depression
Increased appetite and sleep
Leaden paralysis- heavy feelings in arms/legs
Rejection sensitivity
Mood reactivity
Particularly benefit from MAOIs
51
TEE probe anteriorly visualizes left atrium, what does it visualize posteriorly?
Posteriorly see descending aorta
Trachea runs btwn the LA and the descending abdominal aorta
52
Heart failure medication that can cause hearing difficulty
Furosemide (loop diuretic- inhibits NKCC transporter at ascending loop) blocks similar symporters in inner ear => ototoxicity
53
Possible explanation for the on-off phenomenon of levodopa tx in Parkinson disease
Consequence of progressive nigrostriatal pathway degeneration => decreased therapeutic window for levodopa
54
How to diagnose legionella
Legionella urine antigen
55
Test has specificity of 80% and sensitivity of 90%
| P that pt truly doesn't have disease if they test negative?
Question is asking for the negative predictive value of the test
NPV = (ppl who test negative and don't have disease) / (ppl who test negative overall)
NPV = specificity / all negative tests
-all negative tests = specificity + (100-sensitivity)
So NPV = 80 / 90 = 89%
56
Function of the following cell junctions
(a) Gap jxns
(b) Tight jxns
(c) Adherens jxn
(d) Desmosomes and hemidesmosomes
Cell junctions have different functions (lolz that rhymes)
(a) Gap jxns for intracellular communication
(b) Tight jxns as a paracellular barrier (barrier btwn cells)
(c,d) Adherens, desmosomes, and hemidesmosomes are cellular anchors
57
What type of infarction is seen in pulmonary embolism?
Hemorrhagic infarction (not ischemic infarction) is seen b/c the lung has dual blood supply
58
MC renal neoplasm
(a) MC subtype of this renal neoplasm
(b) Cell of origin
(c) Macroscopic appearance
MC renal neoplasm = renal cell carcinoma (RCC)
(a) MC subtype of RCC = clear cell carcinoma
(b) Clear cell carcinoma arises from the epithelium of the proximal renal tubules
(c) Yellow fatty appearance b/c of high lipid content
59
Explain the importance of gap junctions in a gravid uterus
Communicating (gap) junctions important for coordination and synchronization of myometrial cells for contractions during labor
-estrogen stimulates upregulation of gap junctiosn btwn individual myometrial smooth muscle cells to allow synchronized myometrial excitability
60
12 yo M found to have wide, fixed splitting of S2
Do surgical repair of present congenital heart defect to prevent irreversible changes of what part of the cardiopulmnary circuit?
Wide, fixed splitting of S2 = ASD (atrial septal defect)
-surgery to prevent irreversible changes in pulmonary vessels
Starts w/ L to R shunt, increasing blood flow thru pulm arteries which can lead to Eisenmenger syndrome = reversal of shunt as a result of chronic pulmonary HTN
61
Differentiate sexual development influences of testosterone and dihydrotestosterone
T: internal male genitalia development, spermatogenesis, male differentiation at puberty (muscle mass, libido, deepened voice)
DHT: development of male external genitalia, prostate growth, male-pattern hair growth
So in 5alpha reductase (catalyzes T --> DHT) deficiency- have normal internal genitalia w/ small phalus and hypospadias, raised as female until puberty when masculinize
62
Coagulase and catalase negative
PYR test positive
Which pathogen?
Pathogen = strep pyogenes (group A strep)
- catalase is how to differentiate staph (catalase negative) vs. strep (catalase positive) species
- PYR test is rather specific for step pyogenes (group A strep)
63
Differentiate the formulas for relative risk vs. relative risk reduction
Relative risk = (tx rate/control rate)
Relative risk reduction = ARR / (control rate)
-while ARR = control rate - tx rate
64
What is a complete AV canal defect?
(a) Feature of what disease
Complete AV canal defect = basically ASD and VSD 2/2 failure of endocardial cushion fusion
(a) MC type of cardiac defect in Down syndrome
65
Differentiate etiology of male infertility in CF vs. Kartagener syndrome
CF- b/l absence of vas deferens (azoospermia)
Kartagener syndrome => impaired sperm motility
66
Rank fastest to slowest conduction: AV node, atrial muscle, ventricular muscle, Purkinje system
Fastest: Purkinje system
Atrial muscle
Ventricular muscle
Slowest: AV node
-conduction speed in atrial master is faster than that of ventricular muscle
67
PTH levels in osteoporosis
Normal PTH, calcium, and phosphorus
It's not due to bone breakdown, just age (and maybe estrogen) causing low bone mass
68
Which HIV drugs directly impair the following steps
(a) cDNA synthesis
(b) fusion of viral and host membranes
(c) mRNA transcription
(d) polyprotein cleavage
(e) viral attachment
(a) Reverse transcriptase inhibitors (AZT)
(b) Fusion inhibitors bind HIV's transmembrane envelope protein gp41 (ex: enfuvirtide)
(c) mRNA transcription inhibited by integrase inhibitors b/c HIV DNA can't integrate into host genome = Raltegravir
(d) Protease inhibitor = saquinavir, ritonavir
(e) HIV envelope protein gp120 must bind to CD4 and chemokine receptor (CXCR4 or CCR5) => CCR5 antagonists block attachment so HIV cells can't get into CD4" T cells or macrophages = maraviroc
69
What type of organism responsible for
(a) Severe coughing spells w/ post-tussive emesis
(b) MC cause of community acquired pneumonia
(a) Paroxysmal phase of pertussis (whooping cough)- can present in adults who didn't get vaccine booster
Type of organism = gram negative coccobacillus
(b) Strep pneumo is a gram positive diplococci
70
Overall mechanism of general anesthesia
(a) Effect of general anesthesia on blood flow to key organs
Works by inhibition of neuronal activity by increasing the inhibitory action of GABA
(a) Decreased hepatic and renal blood flow (decreased GFR), decreased cardiac output, hypotension, buttttt
* *increased in cerebral blood flow (2/2 decreased vascular resistance)- causing undesirable effect of increased ICP
71
Location of DBS to treat Parkinsonism
Subthalamic nucleus
-or also globus pallidus internus, both which promote thalamo-cortical disinhibition to improve mobility
- inhibited normally by globus pallidus externus
- while subthalamic nucleus excites globus pallidus internus and substantia nigra
72
28 yo M post-op p/w fever and muscle rigidity, BP 190/100 HR 130, muscle stiffness and cyanotic skin mottling
(a) Dx
(b) Mechanism of disease
(c) Tx
(a) Malignant hyperthermia
(b) Defective ryanodine receptors on SR that cause excess Ca2+ release in response to anesthetic, excess Ca2+ needs to be pumped back in (uses ATP, generates tons of heat) and damages muscle cells => rhabdo
(c) Tx w/ dantrolene to decrease Ca release from ryanodine receptors
73
3 steps to treatment of peripheral artery disease that manifests as intermittent claudication
Tx for peripheral artery disease
1. Graded exercise regimen
2. Cilostazol = PDE inhibitor that inhibits platelet aggregation and directly causes arterial dilation
3. Aspirin for secondary prevention of heart disease and stroke
74
Minimal change disease
(a) Mechanism of pathology
(b) Light microscopy finding
(c) Electron microscopy finding
Minimal change disease = nephrotic syndrome in children
(a) Systemic T cell dysfunction causes production of cytokine (glomerular permeability factor) that damages podocytes
(b) Normal glomeruli on light microscopy
(c) Podocyte food process effacement and fusion on electron microscopy
75
What is beta-lactamase?
(a) Clinical significance
Beta-lactamase = enzyme produced by bacteria to break up the beta-lactam in the wall of lactam antibiotics (ex: penicillin)
(a) Lead to creation of penicilinase-resistant penicillins (methicillin, oxacillin, nafcillin) and beta-lactamas inhibitors (clavulante, tazobactam, sulbactam)
76
Differentiate genital ulcers seen from Haemophilus ducreyi vs. poxvirus
Haemophilus ducreyi causes chancroid = painful ulcers w/ grey exudate and inguinal lymphadenopathy (ducreyi = you cry)
Poxvirus causes granuloma inguinale: painless, ulcerative lesion w/o lymphadenopathy
77
Allergic bronchopulmonary aspergillosis
(a) MC organism
(b) CT finding
(c) Lab findings
ABPA = hypersensitivity response to aspergillus fungus
(a) MC 2/2 aspergillus fumigatus
(b) CT: proximal bronchiectasis (abnormal airway dilation)
(c) Lab: eosinophilia and hyper-IgE
78
2 actions of Cilostazol
Cilostazol = first line medication for peripheral artery disease causing intermittent claudication
1. inhibits platelet aggregation
2. causes direct arterial vasodilation
79
Mechanism of fenofibrate therapy
Fenofibrates reduce TG by reducing hepatic VLDL production
-activate PPAR-gamma to decrease hepatic VLDL production and increase LPL (TG and VDL to TGs)
Similar to omega-3 FAs that they decrease VLDL production
80
Receptors needed for HIV virus to infect cell
(a) Envelope protein
(b) T-cell proteins
(a,b) HIV outer envelope protein gp120 binds both CD4 and CCR5 on T-cells
-if CD4 cells don't express CCR5 protein, HIV virus binds CD4 but is unable to enter the cell => pts w/ both CCR5 receptor genes deleted are resistant to HIV
81
15 yo boy presents w/ poor exercise intolerance
-severe muscle cramping and urine discoloration and exercise strain, improved by oral glucose solution before strenuous activity
(a) Dx
(b) Enzyme deficiency
(a) McArdle disease
(b) Deficiency in glycogen phosphorylase => inhibited breakdown of glycogen during exercise
poor exercise tolerance, muscle cramps, rhabdo, no rise in lactate after exercise
82
Severe right sided eye pain and ipsilateral HA, pt seeing 'halos' around objects
(a) Dx
(b) Explain mechanism of acetazolamide for tx
(a) Acute angle-closure glaucoma
(b) Tx w/ acetazolamide = inhibits carbonic anhydrase, found mostly in proximal tubule and needed for NaHCO3 absorption
=> acetazolamide tx results in diuresis w/ highly alkaline urine
83
2 indications for Linezolid
MRSA and VRE
```
MRSA = methicillin-resistant staph aureus
VRE = vancomycin resistant enterococcus
```
84
22 yo p/w fever and sore throat
- PMH: Graves disease, on antithyroid meds
- PE: erythematous pharynx
Next step?
Need to be aware of the rare but serious complication of thionamides (PTU and methimazole) of agranulocytosis
Next step = WBC count w/ differential b/c agranulocytosis would present w/ sudden fever and sore throat
-stop drug immediately then get CBC w/ diff
Overall: rare but serious side effect of thionamides is agranulocytosis
85
How do the cranial nerves I - VI exit the skull
- CN I exits the cribiform plate
- CN II exits the optic canal
- CN IIII, IV, V1, VI exit the superior orbital fissure
- V2 (maxillary) out foramen rotundum
- V3 (mandibular) out foramen ovale
86
Mechanism of exocrine release in
(a) Acne
(b) Breast feeding
(c) Salivary glands
(d) Sweat glands
(a) Acne: sebaceous glands secrete sebum by holocrine release: release entire content of cells via cell lysis
(b) Breast feeding: mammary glands are apocrine glands that secrete stuff by membrane-bound vesicles
(c,d) Salivary glands and both eccrine and apocrine sweat glands are merocrine glands- release contents by exocytosis
87
Supplementation of which amino acid may improve vasodilation in stable angiona
Arginine, b/c arginine is a prescursor to nitrous oxide
NO is synthesized from arginine by NO synthase, so arginine supplementation may play an adjunct role of tx of conditions that improve w/ vasodilation (ex: angina)
88
Explain mechanism of Risperidone induced amenorrhea
Risperidone = atypical antipsychotic that inhibits D1 and D2 receptors
=> loss of tonic inhibition of dopamine on prolactin => hyperprolactinemia. Thru negative feedback prolactin inhibits GnRH (gonadotropin releasing hormone) secretion => decreased LH/FSH secretion
89
What organism uses coagulase as a virulence factor?
(a) Mechanism of coagulase as virulence factor
Coagulase = enzyme produced by S. aureus
(a) Coagulase activates prothrombin which converts fibrinogen --> fibrin, causing fibrin-coating of the organism and resistance to phagocytosis
- activates prothrombin to resist phagocytosis
90
Which cells are directly responsible for synthesizing fibrous cap of atheroma?
Vascular smooth muscle cells synthesize ECM proteins (collagen, elastin, proteoglycan) forming the fibrous cap
-NOT fibroblasts, there aren't any fibroblasts in the intima
As the plaque enlarges and vascular smooth muscle cells die, plaque gets more vulnerable = higher risk of rupture
91
3 lines of tx for CDiff infection and their mechanism
1. Oral Metronidazole- disrupts DNA structure in anaerobes (bacteriocidal)
2. Oral vancomycin- inhibits cell wall synthesis (bacteriostatic against CDiff at doses given)
3. Oral Fidaxomicin- inhibits sigma subunit of RNA polymerase (bacteriocidal against CDiff) good for recurrent CDif or pts at increased risk of recurrence
92
Differentiate mechanism of polyene and azole antifungals
Polyenes (amphotericin B and nystatin) attack ergosterol (component of fungal cell membrane) to poke a hole in the membrane and cause cell lysis
Azoles (fluconazole, ketoconazole, voriconazole) also target cell wall, but do so by inhibiting ergosterol synthesis
93
Landmark to distinguish indirect and direct inguinal hernia
Inferior epigastric vessels
Indirect inguinal hernia (thru internal inguinal ring) arise lateral to the inferior epigastric vessels
Direct inguinal hernia (thru Hasselbach triangle) arise medial to the inferior epigastric vessels
94
Brown-Sequard Syndrome
(a) Contralaterally
(b) Ipsilaterally
Brown-Sequard = Hemicord syndrome
(a) Contralateral loss of pain/temp and lt touch 2/2 damage of spinothalamic tract
(b) Ipsilateral loss of vibration/proproception (dorsal column) and loss of motor fxn (corticospinal tract)
95
Which muscle(s) abduct the humerus
Supraspinatus (MC injured during rotator cuf injury) initiates movement for first 10-15 degrees
Then after the deltoid provides the abductive force while supraspinatus stabilizes the joint
96
Name 2 G+ cocci that are catalase negative and undergo
(a) Alpha-hemolysis
(b) Beta-hemolsysis
(c) Gamma-hemolysis
Staphyloccocus
(a) Alpha-hemolysis = partial green hemolysis
- strep viridans
- strep pneumo
(b) Beta-hemolysis = complete green hemolysis
- strep pyogenes (GAS)
- strep agalactae (GBS)
(c) Gamma-hemolysis = no hemolysis
- enterococci (nosocomial UTI)
- strep bovis
97
Differentiate clinical presentation of 5alpha-reductase vs. aromatase deficiency
5alpha-reductase converts testosterone --> DHT needed for development of male external genitalia => male w/ normal internal genitalia w/ abnormal external genitalia
-often raised as females until they have high T at puberty => voice deepening, penile/scrotal growth, testicular descent
Aromatase converts androgens to estrogens => p/w virilization in females, while males usually unaffected
98
24 yo F w/ severe pain and swelling in R knee, L elbow
- afebrile
- joint aspirate: opaque exudate w/ high neutrophil content and intracellular organisms
Dx?
Dx = disseminated neisseria gonorrhea infection
- neisseria gonorrhea is a facultative intracellular oragnism in PMNs (neutrophils)
- disseminated infection causes septic arthritis in sexually active young adults
99
What embryologic layer do the following arise from?
(a) Middle ear
(b) Bladder and urethra
(c) Kidneys and urether
Embryologic layer
(a) Middle ear from the endoderm
(b) Bladder and urethra from endoderm
(c) While kidneys and ureter are from mesoderm
100
Kid updated on vaccines gets otits media from Haemophilis influenza, why?
Strain kid infected with is nontypable (no capsule)
90% of H. influenzae (oxidase positive gram negative rod/bacilli) are untypable (no capsule), the other 10% are H. influenza B that the vaccine covers for
101
Rash seen in infection with
(a) parvovirus
(b) togavirus
(c) paramyxovirus
(d) HHV-6
(a) Parvovirus (fifth disease) causes slapped-cheek rash- redness of cheeks, followed by macpap of body
(b) Togavirus (rubella, German measles): macpap rash starting on face then rapidly progressing to body
- postauricular tender lymphadenopathy
(c) Paramyxovirus (rubeola, measles): macpap rash that more gradually progresses to body
(d) HHV-6 (roseola): transient macpap rash on chest/trunk for a few days after fever subsides
102
Insulin release
(a) Most important stimulator
(b) What activates K+ cells that depolarizes the membrane
Insulin release
(a) Most important stmulant = glucose, facilitated diffusion inwarsd by GLUT2
(b) ATP-sensitive K+ channels, so glucose intake --> pyruvate undergoes TCA cycle => increase intracellular ATP to activate K+ channels, K+ rushes out which depolarizes membrane and opens Ca2+ channels to let Ca2+ in
- Ca2+ then causes insulin release
103
RLS for pentose phosphate pathway
(a) Mode of inheritance for deficiency in this enzyme
(b) Clinical presentation of deficiency
RLS for pentose phosphate pathway = glucose-6-phosphate dehydrogenase (G6PD)
(a) X-linked recessive
(b) Episodes of hemolytic anemia during times of increased oxidative stress (b/c need G6PD to generate NADPH and deal w/ oxidative stress in RBCs)
Ex of increased oxidative stress = infxn, sulfa-drugs, antimalarials
104
Beta-blocker overdose
(a) Clinical features
(b) Tx and mechanism of tx
Beta-block overdose
(a) depression of cardiac contractility, bradycardia, varying degrees of AV block
(b) Glucagon to increase HR and contractility independent on adrenergic receptors by activating G-protein coupled receptors on cardiac myoctes, raising intracellular cAMP
105
Differentiate the three progressive lesions of a melanocytic nevi
1st junctional nevi = nevus cells limited to the dermoepidermal jxn
-flat brown/black macules w/ more color in the center, preserved skin margins
2nd compound nevi where nevus cells spread into the dermis (so both dermal and epidermal involvement)
-raised paples, uniform brown/tan pigmentation
3rd (oldest) are intradermal nevi where epidermal nests are lost and remaining dermal nevus cells lose tyrosinase activity so don't produce pigment
-skin/tan colored, dome-shaped
106
34 yo F w/ h/o severe bronchial asthma p/w recurrent transient pulmonary infiltrates
- CBC: eosinophilia
- CT: proximal bronchiectasis
(a) Dx
(b) Organism responsible
(a) Bronchiectasis and eosinophilia in asthmatic (or CF pt) = ABPA = allergic bronchopulmonary aspergillosis = hypersensitivity response to aspergillus fungus
(b) MC aspergillus fumigatus
107
Clinical features of minimal change disease
(a) Tx
Generalized edema, hyperlipidemia (high TG), hypoalbuminemia, massive proteinuria = nephrotic syndrome, MCD is the MC type of nephrotic syndrome in young children
(a) Tx = corticosteroids
108
34 yo M p/w heart palpitations, particularly at night
-w/ exertion: head "pounding" w/ involuntary head bobbing
(a) Mechanism
(b) Dx
(a) Widened pulse pressure- buzzword here is head bobbing
| (b) Super widened pulse pressure typical of Aortic insufficiency/regurgitation
109
Describe the reaction of pts w/ SCID to the candida skin test
Candida skin test- used to test T cell immune response (b/c everyone has been exposed to candida, so ppl w/ intact T cell response will mount type IV hypersensitivity)
Basically if negative rxn (mainly CD4/CD8 and macrophages) = SCID
110
What arises from the dorsal vs. ventral pancreatic bud?
Dorsal pancreatic bud (larger) gives rise to tail, body, most of head, and accessory pancreatic duct
Ventral pancreatic bud (smaller) gives rise to uncinate process (rest of head) and main pancreatic duct
111
Differentiate the three types of exocrine sweat glands
Merocrine glands secrete by exocytosis
Apocrine secrete thru membrane-bound vesicles
Holocrine secrete by cell lysis releasing entire contents of cytoplasm and cell membrane
112
If a murmur is heard louder in left lateral decubitus position, name another way to make the murmur loduer
L lateral decubitus works by bringing the heart closer to the chest wall, can make similar murmurs louder by listening at end expiration where lung volume is decreased so heart is closer to the chest wall
113
What embryologic layer do the following arise from?
(a) Peritoneum
(b) Thymus
(c) Lymphatics
(d) Spinal cord
Embryologic layer
(a) Peritoneum, all serosa linings, from mesoderm
(b) Thymus from endoderm
(c) Lymphatics (and blood) from mesoderm
(d) Spinal cord from neural tube of the ectoderm
114
Which way do the following shift the Hb dissociation curve?
(a) Hypothermia
(b) Chronic high-altitude
(c) Hypoventilation
(a) Low temps stabilize bonds btwn O2 and Hb => hypothermia shifts the Hb dissociation curve to the right (increased affinity of Hb for O2)
- while hyperthermia would shift right
(b) Chronic high altitude = O2 availability reduced which increases 2,3-BPG (also increased in chronic lung disease) which decreases Hb-O2 affinity
(c) Hypoventilation increases CO2, increased acid shifts Hb curve right (decreases Hb affinity for O2)
115
Lower extremity reflexes mediated by what nerve root
(a) Knee jerk
(b) Ankle reflex
(a) Knee jerk: L3/L4
| (b) Ankle reflex: S1/S2
116
46 yo M p/w recurrent nosebleeds
- h/o EtOH and chronic mental illness
- PE: swollen gums, scattered ecchymoses, hyperkeratosis, chronic ulcer
(a) Dx
(b) Mechanism of findings
(a) Scurvy 2/2 vitamin C deficiency = weak CT
- weak capillary walls => easy bruising, mucosal bleeding
- poor wound healing => chronic ulcer
- hyperkeratotic follicles w/ corkscrew hairs
(b) Abnormal proline hydroxylation
- leads to defective collagen synthesis
117
78 yo M w/ progressive SOB, weakness, tingling numbness LE b/l
- poor diet
- third heart sound, high volume collapsing carotid pulses, b/l basal crackles, 2+ b/l peal edema
- normal CBC
Deficiency of which vitamin
B1 (thiamine) deficiency = beriberi = peripheral neuropathy and heart failure
118
Explain what part of the nephron is responsible for
(a) Majority of water reabsorption
(b) Concentrating urine
(c) Titrating urine concentration to body volume status
(a) Regardless of fluid status, over 60% of filtered water is reabsorbed in the proximal convoluted tubule
(b) Urine is concentrated as it descends thru the water-permeable descending loop of Henle b/c of the osmotic gradient of the renal interstitium
(c) Anterior pituitary releases ADH in response to volume status, ADH then controls amount of aquaporins on the collecting duct and distal DCT, controlling final water reabsorption
119
1st and 2nd line tx for acute gouty attack
(a) Mechanism of 2nd line
1st line = NSAIDs
(a) But if pts have contraindications to NSAIDs (renal insufficiency, PUD): give colchicine = inhibits microtubule formation- inhibits migration and phagocytosis by neutrophils to decrease inflammation
Not allopurinol!!! (xanthine oxidase inhibitor) which can actually mobilize urate stores and exacerbate acute gouty attack
120
How does high urinary citrate help prevent kidney stones
Citrate binds to free (ionized) calcium, preventing its precipitation and facilitating excretion
121
What structures run thru the foramen magnum?
- Spinal roots of CN XI run up
- brainstem
- vertebral arteries
122
9 yo boy w/ beta-thalassemia s/p numerous transfusions and chelations has liver biopsy:
Kupffer cells w/ coarse, yellowish-brown cytoplasmic granules
What are the granules composed of?
Hemosiderin from iron deposition (Prussian-blue stain) b/c of iron overload from all the RBC transfusions
-not lipofuscin that is yellow-brown but associated w/ aging
123
Differentiate the infectious dose of salmonella vs. shigella
Salmonella has a much higher infectious dose (lot more particles required to get infection) than shigella
-as few as 10 shigella organisms can cause disease
124
A branch of what artery lies behind the junction of the frontal, parietal, temporal, and sphenoid bones
Junction of these 4 bones = pterion = area of weakness in the skull b/c the skull is thin
Middle meningeal artery lies under the pterion, if rupture => epidural hematoma
Key is that the middle meningeal artery is a branch of the maxillary artery (one of the terminal branches of the external carotid)
125
1st and 2nd line tx for acute gouty attack
(a) Mechanism of 2nd line
1st line = NSAIDs
(a) But if pts have contraindications to NSAIDs (renal insufficiency, PUD): give colchicine = inhibits microtubule formation- inhibits migration and phagocytosis by neutrophils to decrease inflammation
Not allopurinol!!! (xanthine oxidase inhibitor) which can actually mobilize urate stores and exacerbate acute gouty attack
126
Differentiate the autoantibodies seen in drug-induced lupus erythmeatosus and SLE
Both often have positive ANA
Drug-induced lupus: 95% have anti-histone abs (only 50% in SLE)
Anti-dsDNA in 80% SLE, rarely in drug-induced
127
Pretreatment with what agent could eliminate the vasodilation and tachycardia effects of epinephrine
Epinephrine (beta agonist at low dose, alpha agonist high dose)
Overall: increases systolic BP (alpha1 and beta1), increases HR (beta1), and decreases diastolic BP at low dose (beta2) yet increases diastolic BP at high dose (alpha1)
Pretreatment w/ propranolol (beta blocker) eliminates the vasodilation and tachycardia, leaving only alpha effects of vasoconstriction (increase diastolic BP, HR doesn't elevate)
128
12 yo M found to have wide, fixed splitting of S2
Do surgical repair of present congenital heart defect to prevent irreversible changes of what part of the cardiopulmnary circuit?
Wide, fixed splitting of S2 = ASD (atrial septal defect)
-surgery to prevent irreversible changes in pulmonary vessels
Starts w/ L to R shunt, increasing blood flow thru pulm arteries which can lead to Eisenmenger syndrome = reversal of shunt as a result of chronic pulmonary HTN
129
Proteins that make up
(a) Gap jxns
(b) Tight jxns
(c) Adherens
(d) Desmosomes
(e) Hemidesmosomes
Proteins that make up
(a) Gap jxns = connexins (important for intracellular communication
(b) Tight jxns = claudins
(c,d) Adherens and desmosomes are made of cadherins
(e) Hemidesmosomes are made of integrins
130
8 yr old immigrant w/ rash that started on face then spread rapidly down body
-postauricular tender lymphadenopathy
(a) Dx
(b) Causative organism
(a) Rash starting on face and spreading to body is characteristic of measles (rubeola) and German measles (rubella)
- key here is that child is immigrant => prob unvaccinated
- rash of rubella typically spreads faster than rash of rubeola and rubella typically associated w/ postauricular lymphadenopathy and tenderness
(b) Rubella- causative organism is togavirus
(while causative organism for rubeola is paramyxovirus)
131
7 yo F p/w diffuse lace-like erythematous rash that started on cheeks
- congestion HA and fever 3 days ago
- brother had same symptoms that spontaneously resolved
(a) Dx
(b) Where does this agent replicate?
(a) Fifth's disease (classic slapped cheek rash) from parvovirus B19
- slapped cheek rash classically sparing nasolabial folds develops after initial symptoms resolve, then get diffuse lacy reticular rash over trunk/extremities
(b) Parvovirus B19 replicates in erythrocyte precursors in bone marrow
- b/c these erythrocyte precursors have group P antigen (globoside) that act as parvovirus B19 cellular receptor
132
Lymphoma that produces a protein that works by
(a) Transcription activation
(b) Tyrosine kinase upregulation
Lymphoma
(a) Transcription activation: c-myc oncogene w/ Ig heavy chain (t8,14) of Burkitt lymphoma
- jaw of African Americans, abdomen in other childrne
(b) BCR-ABL fusion gene increases tyrosine kinase activity, t(9,22) seen in CML (chronic myelogenous leukemia)
133
2 most common causes of central venous catheter infections
Both are gram positive cocci:
- coagulase negative staph (staph epidermidis)
- staph aureus (coagulase positive)
134
Sputum specimens showed pneumonia-causative organism required complex acellular medium enriched with cholesterol to grow
(a) Which organism?
(b) Xray findings
(a) Mycoplasma pneumoniae (causes walking pneumonia)
- require cholesterol to grow b/c cell membrane is composed of a single cholesterol-rich phospholipid bilayer (no peptidoglycan cell wall, envelope, or capsule)
(b) Xray findings much worse than clinical appearance
135
What embryologic layer do the following arise from?
(a) Thyroid/parathyroid
(b) Pituitary
(c) Retina
(d) Blood
Embryologic layer
(a) Thyroid/parathyroid from endoderm
(b) Pituitary from ectoderm
- anterior pituitary (Rathke pouch) from surface ectoderm, vs. posterior pituitary from neural tube
(c) Retina from neural tube (ectoderm)
(d) Blood from mesoderm: and lymph, and CV system
136
Embryologic derivative of what layer?
(a) Lens and cornea
(b) Epidermis
(c) Spleen
Embryologic layer
(a) Lens and cornea come from the ectoderm
- specifically surface ectoderm (not neural tube or neural crest)
(b) Epidermis comes from the ectoderm
- again from surface ectoderm
(c) Spleen from mesoderm
- the one GI organ that's from mesoderm (others are from endoderm)
137
Langerhans cells
(a) Location and function
(b) Key electron microscopy finding
(c) From what precursor cell line
Langerhans cells
(a) Form of dendritic cells (professional APCs) in skin and mucus membranes
(b) 'Racquet shaped' intracytoplasmic granule = Birbeck granule- unknown function but specific for Langerhans cell
(c) Myeloid cell line => demonstrates myeloid surface markers
138
Clinical presentation of familial pulmonary arterial hypertension
(a) Tx while waiting for lung transplant
Dyspnea, weakness, exercise intolerance in women 20-40
(a) Bosentan = endothelial-receptor antagonist that blocks endothelin (potent vasoconstrictor) effects to allow for vasodllation
139
Neurocysticercosis vs. Toxoplasma gondii
(a) Mode of transmission
(b) Imaging finding
(c) Type of pt
Neurocysticercosis
(a) Transmitted by taenia soluium (pork tapeworm) eggs in feces of human carriers
(b) Single cysts
(c) Endemic to Central and South America
Toxoplasma gondii
(a) Cat feces
(b) Multiple ring-enhancing lesions
(c) Immuncompromised
140
MC cardiac defect seen in
(a) Downs
(b) DiGeorge
(c) Friedreich ataxia
(d) Marfans
(e) Turners
MC cardiac defect (so wide range can be seen but these are the buzzwords)
(a) Downs = complete AV canal defect (ASD and VSD)
(b) DiGeorge = ToF
(c) Friedreich ataxia = hypertrophic cardiomyopathy
(d) Marfans = aortic pathology
(e) Turners = bicsupid aortic valve (second is coarctation of aorta)
141
Clinical features of malignant hyperthermia
Malignant hyperthermia = fever and muscle rigidity in response to anesthetic due to defect in Ryanodine (Ca2+ channel) receptors on SR that cause huge increase in Ca2+ intracellular release
Tachycardia, hypertension, rhabdo => myoglobinemia and hyperkalemia
142
Differentiate the lining of a true cyst from a pancreatic pseudocyst
(a) How long after episode of acute pancreatitis do you expect mature pseudocyst
True cyst is lined by epithelial cells, walls of pseudocyst made of fibrous and granulation tissue
(a) 4-6 weeks after episode of acute pancreatitis the firm fibrotic pseudocyst wall ('mature wall') is fully formed
143
Name 2 G+ cocci that are catalase negative and undergo
(a) Alpha-hemolysis
(b) Beta-hemolsysis
(c) Gamma-hemolysis
Staphyloccocus
(a) Alpha-hemolysis = partial green hemolysis
- strep viridans
- strep pneumo
(b) Beta-hemolysis = complete green hemolysis
- strep pyogenes (GAS)
- strep agalactae (GBS)
(c) Gamma-hemolysis = no hemolysis
- enterococci (nosocomial UTI)
- strep bovis
144
Main 3 places where copper accumulates in Wilsons disease
Liver => transaminitis, cirrhosis
Basal ganglia => Parkinsonism, gait disturbance
Cornea => Kayser-Fleisher rings
145
What embryologic layer do the following arise from?
(a) Liver
(b) Lungs
(c) Spleen
Embryologic layer
(a,b) Lung and livers are from endoderm
(c) Spleen from mesoderm
146
Metformin
(a) Mechanism of action
(b) Contraindication
Metformin = oral diabetes med
(a) Inhibits hepatic gluconeogenesis and increases peripheral glucose utilization
(b) Contraindicated in pts w/ renal insufficiency 2/2 increased risk of lactic acidosis
147
Volume status in pt w/ SIADH
SIADH (ex: excess ADH from small cell lung carcinoma) => euvolemic hyponatremia
SIADH transiently increases total volume status, which suppresses RAAS and increases natruiertic peptides which increases Na+ excretion
So get euvolemic state (no crackles, JVD, edema) w/ hyponatremia
148
Which anticoagulants have the following mechanism
(a) Bind to thrombin active site
(b) Blocks glutamate residue carboxylation
(c) Block ADP receptors
AC
(a) Direct thrombin inhibitors = hirudin, lepirudin, argatroban
(b) Vitamin K is needed to carboxylate glutamic acid residues of clotting factors II, VII, IX, and X- so Warfarin inhibits this
(c) Blocks ADP receptors (preventing plt aggregation) = Clopidogrel
149
Pt w/ h/o HTN and depression treated for cellulitis develops altered mental status, febrile to 102.6, BP 180/100, HR 120, tremulosis w/ mydriasis, b/l hyperreflexia and ankle clonus
What was she given to treat the cellulitis?
Linezolid = abx w/ MAOI effects, so when combined w/ SSRI (given pt h/o of depression) can cause serotonin syndrome
Serotonin syndrome = autonomic instability, altered mental status, neuromuscular irritability
150
Mechanism of pioglitazone
Pioglitazone = oral diabetic tx that activates PPAR-alpha transcription factor to regulate transcription of target genes
- upregulates GLUT4 => increases uptake of glucose by adipocytes and skeletal myocytes
- upregulates adiponectin
B/c alters transcription, takes a few days-weeks to have significant affect
151
8 yo boy p/w enlarging mass of the right mandible w/ palpable lymphadenopathy
-biopsy: diffuse infiltrate of lymphoid cells, macrophages surrounded by clear spaces
(a) Dx
(b) Associated virus
(b) Gene translocation causes what fusion gene
(a) Burkitt lymphoma = typically affects children, African form presents w/ maxillary or mandibular mass
(b) Strong association w/ EBV
(c) t(8,14): translocation btwn c-myc and Ig heavy chain region producing overactive c-myc = transcription activator
152
Murmur produced by small VSD
(a) Best heard where
Small VSD = more turbulent than large VSD = loud holosystolic murmur
(a) Best heard at left sternal border around 4th rib
153
What structures exit the skull thru the superior orbital fissure?
CN III, IV, V1, VI
| Along w/ opthalmic vein and sympathetic fibers
154
3 D's of pellagra
(a) What vitamin deficiency
(a) Vit B3 (niacin) deficiency => Pellagra = dermatitis, dementia, diarrhea
155
Name some common medical conditions w/ polygenic inheritance
Androgenetic alopecia (male pattern baldness)
Epilepsy
HTN
DM II
Schizophrenia
-basically bunch of genetic loci => variable expressivity
156
First line medical tx for Wilson disease vs. acute iron overdose
D-penicillamine: contains free sulfhydryl group to function as a copper chelator
Acute iron overdose can be treated w/ an iron chelatig agent = Deferoxamine
157
Most likely knee injury 2/2
(a) Deceleration and pivot injury
(b) Blow to lateral knee
(a) Deceleration and pivot injuries => ACL injury
(b) Blow to lateral knee => injury to tibial (medial) colalteral ligament
- contra-coup injury kind of thing
158
# Define number needed to treat
(a) Formula
NNT = number of pts needed to take intervention to prevent one adverse event
(a) NNT = 1 / ARR
ARR = absolute risk reduciton = control rate - tx rate
159
Which cells are the regenerative source of
(a) alveolar lining
(b) ciliated cells in bronchioles
(a) Alveolar lining (type I pneumocytes) are regenerated by type II pneumocytes
- type II pneumocytes = stem cells of the alveoli
(b) Ciliated cells in the bronchioles by Club (Clara) cells
160
How do cranial nerves X-XII exit the skull
CN IX, X, XI exit out the jugular foramen
CN XII exits out the hypoglossal canal
161
What do the following auscultative findings indicate?
(a) Mid-systolic click
(b) Long S2 to opening snap time interval
(a) Mid-systolic click is characteristic of mitral valve prolapse
- sudden tensing of chordae tendinae
(b) S2 to opening snap interval = time btwn aortic valve closing and abrupt opening of stenotic mitral valve
- indicates severity of mitral stenosis
162
Which blood vessels are most susceptible to nitroglycerin
Large veins are the most suscepitible to nitroglycerin (much more than arteries/arterioles)
-venodilator of large veins causes blood to collect in venous system, decreasing preload => decreasing cardiac oxygen demand
Nitroglycerin is primarily a venodilator (VENOdilator)
163
Which disease is a result of IgM antibodies against the following:
(a) Mitochondrial extract
(b) Fc portion of human IgG
(c) Nuclear basic proteins
(d) Centromeres
(e) Sheep erythrocytes
(f) dsDNA
(a) Mitochondrial extract = primary biliary cirrhosis
(b) Fc portion of human IgG = rheumatoid factor seen in RA
(c) Nuclear basic protein = non-specific finding in many CT d/o
(d) Anti-centromeres = CREST syndrome
(e) Sheep erythrocytes: used in monospot test to diagnose mono
(f) anti-dsDNA is specific for SLE
164
MIcroorganism demonstrates slow growth on buffered charcoal yeast extract medium
(a) What organism?
(b) What stain for sputum culture?
(c) How is this organism spread?
(a) Growth on BCYE medium = legionella pneumophilia (pneumonia)
(b) Use silver stain for visualization, b/c very faint on gram stain since it's intracellular so gram stain shows neutrophils w/o bacteria
(c) Spread via water
165
MC cause of retinitis in HIV pts
(a) Associated CD4 count
(b) Tx
CMV = MC cause of retinitis in HIV-positive pts
(a) Most frequently affects AIDS pts w/ CD4 under 50
(b) Tx w/ ganciclovir = guanine nucleoside analogue w/ high activity against CMV DNA polymerase
166
Fxn of the following enzymes in immune-system regulating drugs
(a) Adenosine deaminase
(b) Dihydrofolate reductase
(c) Hypoxanthine-guanin phosphoribosyl transferase
(d) Xanthine oxidase
Enzymes
(a) Adenosine deaminase converts adenosine to inosine in purine metabolism, enzyme is deficiency in SCID
(b) DHT is inhibited by methotrexate to block DHT --> Tetrahydrofolate and disrupt thymidine synthesis
(c) HGPRT converts 6-MP to active metabolite (drug used to inhibit purine synthesis, tx of ALL)
(d) Xanthine oxidase breaks down 6-MP into inactive metabolites, so need xanthine oxidase to get rid of 6-MP
167
How to change 6-mercaptopurine dose in patients on allopurinol
6-mercaptopurine (purine analog to inhibit de novo purine synthesis) is metabolized by Xanthine oxdiase in the liver
-when xanthine oxidase is inhibited (by allopurinol), more of the drug is converted to it's active form => increased toxicity
So need to decrease the drug concentration of 6-MP by a ton (like 75%) in pts on allopurinol
168
GI tract congenital abnormality associated w/ Down's syndrome in addition to duodenal atresia
Hirschsprung disease
169
Give overview of how excess nitrogenous groups are excreted from the body- start in the skeletal muscle
Alanine = major AA to transfer excess nitrogen from periphery (ex: skeletal muscle) to liver
Alanine gives amino group to alpha-ketoglutarate to form glutamate, then glutamate can enter urea cycle forming urea excreted by the kidney
170
68 yo F w/ crampy abd pain and vomiting
- h/o acute calculous cholecystitis a few months ago
- tympanic abdomen on exam
- Xray: air in GB and biliary tree
Where is the gallstone lodged?
Gallstone ileus = large gallstone thru cholecystenteric fistula (btwn GB and gut, MC duodenum) due to pressure necrosis and erosion, ultimately causes obstruction in ileus which is the narrowest part of the intestines
P/w sos SBO, see air in GB and biliary tree (pneumobilia)
171
S/p TAHBSO for invasive cervical carcinoma, 46 yo F experiences left-sided flank pain that radiates to the groin
-PE: ballotable left flank mass
Dx
Dx = ureteral obstruction (potentially ligation during surgery) causing hydronephrosis
-flank pain 2/2 distention of the ureter and renal pelvis
172
Clinical presentation of paramyxovirus in children
Parainfluenza (class including paramyxovirus) causes croup (laryngotracheitis): brassy, barking cough w/ difficulty breathing
173
Clinical presentation of
(a) Calcivirus
(b) Togavirus
(c) Actinomyces israelii
(a) Calcivirus = Norwalk virus- causes viral gastroenteritis
(b) Togavirus causes rubella (german measles)
(c) Actinomyces israelii = G+ component of normal oral flora that can cause cervicofacial abscess after dental procedures
174
35 yo s/p tooth extraction p/w hard mass under jaw of growing size and draininag yellow pus
(a) Organism
(b) Tx
(a) Organism = actinomyces israelii = G+ component of normal oral flora that can cause cervicofacial actinomycosis = chronic face/neck abscess complicated by cutaneous sinus tract (aka drains out the skin)
(b) Tx = surgical debridement and penicillin
175
1st line med for MDD that doesn't cause sexual dysfunction
Buproprion = atypical antidepressant that inhibits both NET and DAT w/ no effect on 5-HT
- so inhibits NE and DA reuptake w/o impacting serotonin activity
- no impact on serotonin activity = no sexual dysfunction
176
67 yo M p/w SOB and chest tightness
- at 120mmHg intermittent Korotkoff sounds are heard only during expiration
- at 100mgHg Korotkoff sounds are ehard throughout the respiratory cycle
(a) Name of finding
(b) Dx
(a) Pulses paradoxus = over 10mmHg drop in systolic BP during inspiration (so w/ inspiration Korotkoff sounds are heard only at lower mmHg)
(b) Pericardial disease
- impaired expansion of pericardial space => increase in RV volume w/ inspiration causes bowing of IV septum into LV, decreasing LVEDV and stroke volume, decreasing systolic BP during inspiration
177
Ddx for pulsus paradoxus
(a) Explain mechanism
Pulsus paradoxus (systolic BP drops by more than 10mmHg w/ inspiration) MC seen in cardiac tamponade
Also asthma, COPD, constrictive pericarditis
(a) When RV can't expand to accomodate increased right heart filling during inspiration it moves over the IV septum into the LV and decreases stroke volume
178
Sympathetic manipulation used to tx acute COPD exacerbation
(a) Mechansim
Use beta-agonist to control acute asthma and COPD exacerbation
(a) G-s coupled protein increases intracellular cAMP => bronchial smooth muscle relaxation
179
67 yo M p/w R tibial pain and progressive hearing impairment x12 mo
-tibial biopsy shows numerous multinucleated cells
Dx
Dx = Paget's disease of bone- deformity of long bones and hearing loss (due to bony deformity of the skull)
-both 2/2 high bone turnover w/ replacement by disorganized bone
Ostoclasts form when several precursor cells fuse to form multinucleated mature cell- can have up to 100 nuclei in Pagets disease (vs. 2-5 nuclei in normal osteoclasts)
180
Name the two purely ketogenic amino acids
(a) Increasing these in diet is useful in what condition?
Leucine and lysine are the two purely ketogenic amino acids, meaning they produce ketone bodies as intermediate to acetyl coA instead of pyruvate or TCA cycle intermediates
(a) Increasing leucine and lysine in diet of pt w/ pyruvate dehydrogenase deficiency helps pt generate energy w/o worsening lactic acidosis
181
5 cofactors required for pyruvate dehydrogenase
Also the same 4 needed for alpha-ketoglutarate dehydrogenase
'TLC for Nancy': thiamine, lipoic acid, coenzymeA, FAD, NAD
182
Supplementation w/ what substance may improve the condition of pt w/ Maple Syrup Urine Disease
Maple Syrup urine disease = defect in alpha-glutarate dehydrogenase = inability to catabolized branched chain AAs (isoleucine, leucine, valine)
Alpha-ketoglutarate dehydrogenase (like pyruvate dehydrogenase) has 5 required cofactors
'TLC for Nancy' = thiamine, lipoic acid, coenzyme A, FAD, NAD
So thiamine supplementation can sometimes improve condition
183
45 yo M w/ CSF w/ positive VDRL complains of severe stabbing pains in extremities and falling at night
(a) Dx
(b) Spinal cord tract involved
(a) Tabes dorsalis of neurosyphilis- longest latency of all forms of neurosyphilis occurring 20-30 yrs after primary infection
(b) Spirochetes damage sensory nerves in dorsal roots, get demyelination and loss of axons in dorsal columns
184
Explain what an Argyl Robertson pupil is?
(a) Another physical exam finding of this condition
Argyll Robertson pupils = b/l small pupils that accommodate but don't react to light
-so pupils get smaller when object gets closure but don't get smaller to bight light
Dx = neurosyphilis
(a) Positive Romberg's b/c over time spirochetes damage dorsal column => loss of proprioception
185
Differentiate class I antiarrhythmics by
(a) Inhibition of phase 0 depolarization
(b) Length of AP
Class IA: Quinidine, Procainamide, Disopyramide
(a) Intermediate inhibition of phase 0
(b) Prolongs AP duration
Class IB: Lidocaine, Mexiletine
(a) Weak inhibition of phase 0
(b) Shortens AP duration
Class IC: Flecainide, Propafenone
(a) Strong inhibition of phase 0
(b) No effect on AP duration
186
Expressive aphasia
Broca's area defect
187
Non-speech feature associated w/ Broca's vs. Wernicke's area injury
Broca's aphasia (expressive) associated w/ R. face and upper extremity hemiparesis
Wernicke's aphasia (comprehensive) associated w/ R. superior visual field defect
188
Pupillary finding seen in uncal herniation
As uncus of the temporal lobe herniates below tentorium it compresses CNIII
Get fixed dilated ipsilateral pupil due to loss of preganglionic parasympathetic fibers
189
Direct vs. indirect inguinal hernia
(a) Relationship to inferior epigastric blood vessels
(b) Form 2/2 incomplete closure of processus vaginalis
Direct inguinal hernias arise medial to the inferior epigastric vessels
-seen in adults 2/2 weakening of abdominal wall
Indirect inguinal hernias arise lateral to the inferior epigastric vessels
- seen in children 2/2 incomplete closure of processus vaginalis
- can extend down into scrotum, increase in size w/ Valsalva
190
53 yo M s/p lung transplant p/w b/l pulmonary infiltrates
-lung biopsy w/ intranuclear and cytoplasmic inclusion bodies
Dx
Dx = CMV pneumonitis
| Pts w/ lung transplant usually put on Valganciclovir for ppx given high risk of CMV pneumonitis
191
ds or single stranded? DNA or RNA? enveloped?
(a) Influenza
(b) Rhinovirus
(c) Adenovirus
(d) CMV
(a) Influenza = enveloped ss RNA
(b) Rhinovirus = nonenveloped ss RNA
(c) Adenovirus = nonenveloped ds DNA
(d) CMV = enveloped ds DNA
192
MC reservoir of rabies in the US
(a) Type of paralysis caused by rabies
(b) Characteristic encephalitic feature
Bats! Eek
(a) Ascending flaccid paralysis
(b) Hydrophobia
193
AED w/ the highest risk of SJS
Lamotrigine- up to 10% of pts develop skin rash, while SJS/TEN can occur in up to 1% of pts, particularly children
194
Absent CD18 antigens on surface of leukocytes
(a) CBC/BMP abnormality
CD18 antigen needed for functional integrins => absence causes leukocyte adhesion deficiency
(a) Get persistent leukocytosis, infections lacking pus and delayed separation of umbilical cord
- leukocytosis b/c leukocytes can't migrate out of BV into tissues
195
Cofactor needed in transfering of nitrogen isotopes to oxaloacetate
Alanine (AA) brings nitrogen from periphery (ex: skeletal muscle) to the liver where the N group is transferred to oxaloacetate by a transaminase that requires B6 (pyridixine)
N group transfers: from alanine to alpha-ketoglutarate forming glutamate. then glutamate transfers N group to oxaloacetate to make aspartate, then aspartate enters the urea cycle
196
Risk of co-administering ganciclovir and trimethoprim-sulfamethoxazole
Ganciclovir interferes w/ human host DNA synthesis => can caues neutropenia
Bactrim inhibits folate production => further suppresses DNA synthesis
So watch out for neutropenia 2/2 bone marrow suppression
197
Antiarrhtyhmic for post-MI ventricular arrhythmia
(a) Explain mechanism
Class IB agents (Lidocaine, Mexilitine) good for ischemia-induced ventricular arrhythmias b/c they preferentially bind Na+ channels in the inactivated state
(a) Ischemic myocardium has higher normal resting potential, delaying voltage-dependent recovery of Na+ channels from inactivated to resting state => more binding of class IB agents to ischemic tissue
198
Explain HPV viral proteins in the high risk strains that make them so oncogenic
viral proteins E6 and E7
- E6 inhibits p53 (tsg)
- E7 inhibits Rb (retinoblastoma gene product)
199
Sample of moist soil is heated to 100 C for 15 mins, which bacteria will be present after heat exposure
Spore forming bacteria commonly found in soil = bacillus and clostridium species!
=> expect bacillus anthracis to still be present
200
Which vessel has the greatest difference in blood oxygen content from the aorta?
Coronary sinus b/c the heart muscle has the highest O2 demand => removes the most O2
Due to the high degree of oxygen extraction, increases in myocardial oxygen demand (ex: exercise) are met nearly proportionately by increasing coronary blood flow
-aka no extra O2 in blood that enters coronary sinus, basically fully depleted of O2
201
Symptoms of vitamin D intoxication
Vit D intoxication causes hypercalcemia which causes symptoms: mental status change, muscle weakness, constipation, polyuria/polydispsia
202
Explain how sarcoidosis can mimic vitamin D intoxication
Activated macrophages in sarcoidosis (and other granulomatous disease) express 1-alpha-hydroxylase that can cause PTH-independent activation of vitD => hypercalcemia
203
Why avoid chlorpheniramine w/ diazepam
Chlorpheniramine (like diphenhydramine, promethazine, and hydroxyzine) are first generation antihistamines => very sedating
Don't want to use two sedating drugs
204
Explain why these abx are contraindicated in pregnancy
(a) Tetracyclines
(b) Chloramphenicol
(c) Bactrim
(d) Aminoglycosides
(a) Tetracyclines (Doxycycline) => teeth staining
(b) Chloramphenicol => gray baby syndrome
(c) Batrim => neural tube defects 2/2 folate synthesis inhibition
(d) Aminoglycosides (Gentamycin, tobramycin, amikacin) => ototoxicity ad vestibulotoxicity
205
Best test to assess for impaired GI nutrient absorption
Stool microscopy w/ Sudan III stain which quickly identifies unabsorbed fat to confirm malabsoprtion- b/c stool should normally contain no measurable fat
206
Pts w/ CKD are at greatest risk of what long-term complication of renal disease
Osteodystrophy, specifically osteitis fibrosa cystica
CKD => hyperphosphatemia and hypocalcemia which stimulates PTH secretion => increased bone resorption over deposition
