Cards from UWorld Flashcards
1
Q
What type of symptoms would occur if the artery with the arrow was occluded?
A
Contralateral leg/foot, urinary incontinence.
this is an ACA stroke
2
Q
What investigations are helpful when diagnosing tentanus?
A
No investiagations needed; this is a clincial diagnosis based on hx and PE
3
Q
Flaccid bullae with ++Nicolsky are assocaited with which condition? What autoantibodies do you expect to find?
A
Pemphigus vulgaris; anti-desmoglein 1 and 3
4
Q
What are the symptoms of rabies? How does it enter the host?
A
Nonspecific flu like symptoms with paresthesias radiating from a known wound progressive to rabies encephalitis (pharyngeal spasms, mental status changes, autonomic dysfunction, muscular rigidity).
Rabies enters the host by binding to nicotinic ACh receptors on the NMJ
5
Q
How would you differentiate Klebsiella from Pseudomonas ?
A
Klebsiella is a lactose-fermenting gram-negative rod
Pseudomonas is a non-lactose-fermenting, oxidase-positive, gram-negative rod.
6
Q
What MEN type is associated with hypercalcemia? What other cancers do you need to screen for?
A
MEN-1: primary hyperthyroidism, pituitary tumors and pancreatic tumors
7
Q
What is the diagnosis based on this barium swallow study? What is the most likely cause? What symptoms would you expect to find?
A
This is a zenker diverticulum; likely caused by cricopharyngeal motor dysfunction.
Symptoms include halitosis, regurgitation and aspiration pneumonias
8
Q
How is ejection fraction calculated?
A
(Preload - afterload) / preload
9
Q
What is the cause of warfarin-induced skin necrosis?
A
protein C or S deficiency >> depletion leads to microvascular occlusion due to hypercoagulation.
10
Q
What are the differences between the toxins produced by EHEC, Shigella, Pseudomonas and diptheria?
A
EHEC and Shigatoxin have A/B subunit -> B binds and lets it in, A blocks tRNA binding to 60S subunit
Pseudomonas exotoxin A and diptheria toxin block elongation factor 2 (EF-2) leading to inability to bind the next tRNA.
11
Q
What drugs are useful to prevent recurrence of colon cancer?
A
Low-dose aspirin as a COX-inhibitor; since adenocarcenoma is typically dependent on prostaglandins for proliferation.
12
Q
What is the difference between a synergistic and a permissive effect?
A
Synergism requires both drugs to have independent response, whereas in a permissive effect, it can allow an existing drug to exert more of an effect despite the additive not having an effect when dosed on its own.
13
Q
What is the cause of an IV blanching with induration and pallor when running norepinephrine?
A
Extravasation / leakage causing alpha-1 activation. Treat with phentolamine (an alpha-blocker).
14
Q
Where does renal cell carcinoma originate?
A
The proximal renal tubules
15
Q
What are the causes of red and white patches in melanoma?
A
Red - vessal ectasia (dilatation) and inflammation
White - Melanocyte regression due to recognition of neoplastic cells by NK cells.
16
Q
What bacteria would be positive to pyrrolidonyl arylamidase?
A
Strep pyogenes (GAS); this test is more sensative than bactracin sensitivity.
17
Q
What is the effect of beta-blockers on ECG?
A
Lengthening of the PR interval due to slowing of conduction.
18
Q
What mutation would result in anti-EGFR resistant colorectal cancer?
A
activating KRAS mutation (downstream of EGFR)
19
Q
What is the mechanism of the defect caused by holoprosencephaly?
A
Incomplete division of the forebrain into the telencephalon and diencephalon (5wks gestation). It is a field defect (multiple malformations) caused by combination of genetic (T13, SHH mutation) and environmental factors.
20
Q
Which cytokines have anti-inflammatory effects? What cells produce them?
A
Th2: IL-4 and IL-10
Treg: IL10 and TGF-beta
21
Q
What are the early and late-phase type 1 reactions on repeat exposure?
A
Early: igE x-link leading to histamine and leukotrienes: wheal and flare
Late: TH2 cells release IL-5 -> eosinophils -> major basic protein -> tissue damage and induration.
22
Q
What differentiates induration due to type I and type IV hypersensitivity reactions.
A
Late-phase type 1 manifests as induration hours after exposure to allergen
Type IV is cell-mediated and takes several days to develop
23
Q
What drugs require methylation to be bioactivated?
A
azathioprine and 6-mercaptopurine
24
Q
What drugs require acetylation for bioactivation?
A
isoniazid, dapsone, hydralazine, procainamide
25
What is the arterial supply to the inferior surface of the heart?
right coronary artery \> posterior descending artery
26
What does the left circumflex coronary artery supply?
Lateral posterior and superior walls of LV
27
What does the left anterior descending artery supply?
Anterior 2/3rds of intervenricular septum, anterior wall of LV and anterior papillary muscle
28
Midshaft fracture of the humerus would most likely cause what type of neuropathy?
Radial nerve injury leading to wrist drop and sensory loss over posterior forarm and dorsum of the hand.
29
What are the two locations where the ulnar nerve can be injured?
Medial epicondyle of the humerus or Guyon's canal near the hook of the hamate and the pisiform bone.
30
What are the enveloped DNA viruses?
Hepadna (hep B), herpes, pox
31
what are the non-enveloped DNA viruses?
adenovirus, Papova (HPV), polyoma (JC, BK)
32
What is the most common cause of colitis in an individual with advanced AIDS? What are the histological characteristics?
CMV reactivation: multiple ulcers, mucosal erosions with large cells with basophilic intranuclear and intracytoplasmic inclusions.
33
What part of the GI tract is affected by cryptosporidium? What findings on microscopy?
Small intestine -- acid fast oocytes in stool. with basophilic parasites on the brush border.
34
Which viral proteins are affected by HIV protease inhibitors?
gag / pol polyproteins (functional viral proteins)--NOT envelope proteins (env).
35
What is the most likely diagnosis in this patient who has acute painless vision loss since "a few hours ago"?
retinal artery occlusion
36
What changes on PFT are expected in the setting of COPD?
Air trapping (obstructive pattern) so higher TLC and higher FRC, lower expiratory and inspiratory reserve volume. RV/TLC increases, FEV1/FVC \<0.7
37
Which autoantibodies would be associated with symmetrical proximal muscle weakness?
ANA; anti-histidyl-tRNA-synthetase (anti-Jo-1); this is polymiositis.
38
What are the effects of acetazolamide on electrolytes?
Reduced sodium, potassium and bicarbonate.
39
What are the key features of drug-induced acute interstitial nephritis?
Rash/fever, new drug exposure in last 1-3 weeks
AKI, inflammatory interstitial infiltrate and urinary eosinophils + eosinophilia are characteristic.
40
What 3 medications are used for anaesthesia induction? What are their pro/s cons
Propofol - GABA-agonist reduces airway resistance and causes vasodilation
Etomidate - GABA agonist hemodynamically neutral but causes adrenocortical suppression (avoid in septic shock)
Ketamine - NMDA antagonist preserves respiratory drive and provides analgesia, increases HR, contractility and cerebral blood flow
41
what structure represents the division between the anterior 2/3rds and posterior 1/3 of the tongue? what is the sensory innervation respectively? What is the innervation for taste
Terminal sulcus + foramen cecum.
Anterior = sensory V3 (mandibular) and taste chorda tympani branch of CN7.
posterior = sensory + taste glossopharyngeal and vagus at the tongue root.
42
What infection presents with heterophile antibodies?
Infectious mononucleosis (EBV) - either monospot (horse) or paul-bunnell (sheep).
43
What is the most important treatment for diptheria?
diptheria antitoxin
44
What lung lobe is most likely to develop aspiration pneumonia if the patient is standing? supine? prone?
Standing -\> basilar segments of lower lobes
Supine -\> posterior segment of upper lobs and superior lower lobe segments.
Prone -\> middle lobe and lingula
Generally R \> L
45
What are some mechanisms to improve drug delivery to CNS?
Disrupt tight junctions, inhibit p-glycoprotein (efflux pump)
46
What virus increases the risk of head and neck cancer?
HPV 16 or 18
47
What are 2 signs of irreversible cellular injury?
Mitochondrial vacuolization and phospholipid-containing densities inside mitochondria.
48
What is the diagnosis? recommended treatment?
CMV retinitis; treat with ganciclovir
49
What urine osmolarity abnormalities can occur with lithium? carbamazepine?
Lithium - ADH resistance and nephrogenic DI (low urine osmolarity)
Carbamazepine - SIADH and high urine osmolarity (low serum sodium)
50
Describe the proression of paget disease of bone
originally osteolytic phase (osteoclast-dominated), then transitioning to an osteosclerotic phase (osteoblast-dominated).
51
What is the mechanism of action of sumatripan for migraine?
it is a serotonin *agonist* which stimulates trigeminal vascular receptors and reduces vasoactive neuropeptides (substance P and calcitonin gene-related peptide).
52
How does the coagulase test differentiate between staphylococci?
Coag +ve = Staph aureus
coag -ve = staph epidermidis, hemolyticus or saprophyticus.
53
What is the cause of these sskin lesions?
Erythema multiforme usually co-occuring with HSV or mycoplasma pneumoniae due to transmission of pathogen DNA fragments to keratinocytes and subsequent cytotoxic T-cell recognition of these fragments.
54
What type of brain hemorrhage are pre-term infants \< 32wks gestation at higher risk?
Germinal matrix hemorrhage leading to bleeding into the lateral ventricles.
55
What is the route of infection and symptoms of Cryptococcus neoformans infection?
Pigeon dropping inhalation into lung.
Spherical yesat with thick capsules; india ink stain.
Initial infection is asymptomatic but can lead to meningitis in immunocompromised patients.
56
What changes to heart function occur in acute /massive PE?
RV obstruction and increase in pressure leads to hypokinesis (decr. O2 supply) and dilatation (stretch increases O2 demand), leading to RV infarct and failure
57
What additional PFT tests are useful for the diagnosis of asthma?
Bronchoprovocation with methacholine
Response to bronchodilators (e.g. levalbuterol).
58
What impact does CKD have on phosphate levels? what is the treatment & mechanism of action?
CKD impairs phosphate secretion in kidney leading to hyperphosphatemia.
Sevelamer binds oral phosphate and it is eliminated in feces.
59
Describe the compensatory mechanisms operating during asympomatic heart failure
Decreased CO triggers decrease in renal perfusion (RAAS stimulation) and lower baroreceptor stretch (sympathetic outflow, increased norepinephrine). Resulting vasoconstriction and salt/water retention increases preload and afterload.
60
What is the presentation of congenital hydrocephalus?
Macrocephaly with poor feeding progressive to developmental delay, spacticity and hyperreflexia (UMN signs).
61
Where in the lymph node does isotype switching occur?
In the germinal centres
62
What are the clinical manifestations and inheritance of the condition shown in the blood smear below?
hereditary spherocytosis: small RBCs with no central pallor.
Clinical manifestations: hemolytic anemia, jaundice and splenomegaly
AD inheritance.
63
What are the symptoms of major concern in theophylline intoxication?
Tachyarrythmias and seizures.
64
Which blood vessels are affected by nitrates?
large veins (via cGMP-mediated smooth muscle relaxation)
65
What are examples of true and false diverticula? What layers are present?
True diverticulum = 3 layers (mucosa, submucosa and muscularis) e.g. Meckel's, appendix
False diverticulum = 2 layers (mucosa and submucosa only), zenker or diverticulosis.
66
How would you differentiate between CML and AML?
AML = 25%+ blasts
CML has myelocytes / metamyelocytes predominantly and low leukocyte ALP
67
What is the mechanism of action of anastrozole, letrozole and exemestane?
Aromatase inhibitors; stop conversion of testosterone into estradiol.
68
Gram positive rods with a narrow beta-hemolytic zone that can grow well in the cold...what are they?
Listeria monocytogenes
69
What are the common intracellular bacteria?
What immune response is required to get rid of these?
Obligate: Really Chilly and Cold (Rickettsia, Chlamydia and Coxiella)
Facultative: Some Nasty Bugs May Live FacultativeLY (Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis)
Cell-mediated immunity
70
How would you differentiate between enterococcal endocarditis and viridans endocarditis?
Enterococcal typically eluderly men with cytoscopy or colonoscopy. No hemolysis, grows in bile & hypertonic saline
Viridans is associated with dental extraction and typically colonizes abnormal heart valves. Does not grow in hypertonic saline or on bile.
71
What are the causes of infectious mononucleosis? How do you distinguish between them?
Immunocompetent: EBV (heterophile +ve, sore throat, lymphadenopathy) or CMV (heterophile -ve, associated with transfusion of non-irradiated blood containing WBC).
Immunodeficient and heterophile negative: HHV-6, HIV, toxoplasmosis.
72
What is the classic triad of congenital toxoplasmosis?
chorioretinitis, hydrocephalus, diffuse intracranial calcifications
73
What are the symptoms and cause of age-related cataracts?
Gradual loss of visual acuity, excessive glare, halos, myopic, loss of red reflex.
Age-related oxidative injury or inability to metabolize sorbitol (diabetes)
74
What excretes brain natriuretic peptide
BNP is produced by the ventricles in response to increased wall stress.
75
What is the treatment for metatstatic prostate cancer or castration-resistant cancer?
17-alpha hydroxylase inhibitor (abiraterone)
76
What are the symptoms and treatment of drug-induced parkinsonism?
Rigidity, bradikinesia, tremor and masked facies
Decrease/discontinue drug or add anticholinergic (trihexyphenidyl or benztropine).
77
What is the pathogenesis of narcolepsy with cataplexy?
Low levels of hypocretin 1 (orexin-A) in CSF.
78
What is the mechanism of action of etoposide? Which cancers is it typically used for?
Inhibits topoisomerase II leading to double-strand breaks. Used for testicular and small cell lung carcinoma
79
Where are the common sites for obstructive hydrocephalus and what is the result?
Cerebral aqueduct (lateral + 3rd ventricle enlargement)
Foramen of monro (unilateral ventricular enlargement)
Foramen of Magendie, Foramen of Luschka (all 4 ventricles)
80
What vasoocclusive symptoms present early in patients with sickle cell disease? What serum abnormalities are expected?
dactylitis (hand/foot syndrome) with swelling, tenderness and erythema of the affected extremities
increased unconjugated bilirubin, LDH and haptoglobin
81
What differentiates exudative and transudative pleural effusion? What are common causes of each?
Light criteria: exudative if 1 of
plerual protein / serum protein \> 0.5
plerual LDH / serum LDH \> 0.6
or plerual LDH \> 2/3 upper NL of serum
Typically infectious, malignant or rheumy
Otherwise transudative due to HF, cirrosis or nephrotic syndrome.
82
What colour does a reticulocyte stain under wright-giemsa? Why?
Blue due to residual rRNA
83
What is the diagnosis in a patient who wears gloves indoors and has fingers that turn blue when cold and has retrosternal burning and regurgitation when supine.
CREST syndrome:
She has features of Raynaud's, esophageal dysmotility (reflux), and sclerodactyly (initial presentation is non-pitting edema progressive to thickened, tight, shiny skin).
84
Muscle fasciculation is most characteristic of what type of motor neuron lesion? What other signs accompany it? Where is the lesion?
Lower motor neuron;
Hypotonia, hyporeflexia or flaccid paralysis. Anterior horn or distal.
85
What is the histopathology of HIV dementia?
infected microglial cells cluster around necrotic areas (microglial nodules) and form multinucleated giant cells.
86
What are the complications of congenital CMV infection?
Chorioretinitis, sensorineural deafness, seizures, jaundice, hepatosplenomegaly and microcephaly
87
How do you estimate carrier frequency for a rare condition which affects 1 in x individuals?
Carrier frequency = 2sqrt(x)
88
What are the 3 pathogens that cause HIV associated-esophagitis?
Candida albicans, HSV-1 and CMV
89
How is CMV esophagitis diagnosed endoscopically? Microscopically?
Endoscopy shows linear ulcerations
Microscopy shows intranuclear and cytoplasmic inclusions
90
What is the difference beteen a hazard ratio and an odds ratio?
Hazard ratio is defined as the risk of an event in the treatment group vs the control group at a particular time t. Odds ratios are cumulative through the entire study
91
What is Loeffler syndrome? What is the cause?
Eosinophilic pneumonitis caused by migration of roundworms (Ascaris) through lungs.
92
What are the vascular regions most susceptible to atherosclerosis? Why?
Lower abdo aorta and coronary arteries due to turbulent flow.
93
What is the impact of hypovolemia on hematocrit, albumin and uric acid?
All increased; uric acid follows increased sodium resorption.
94
How does the weber lateralize in sensorineural and conductive hearning loss?
Conductive: lateralizes to affected ear (as decreased air conduction makes the vibrations easier to hear)
Sensorineural loss: lateralizes to unaffected ear.
95
What is the impact of von Willebrand disease on clotting tests?
Normal platelets, increased bleeding time, normal/increased aPTT (vWF is a factor VIII carrier protein), normal PT.
96
What injection location can cause a trendelenberg gait?
Superomedial buttock injection which injures the superior gluteal nerve.
97
What are the symptoms and cause of roseola?
3-5 days high fever followed by blanching macropapular rash that starts on the trunk and spreads outwards to face and extremities
commonly caused by HHV-6
98
What would cause adalimumab or infliximab efficacy to decline in a patient?
Development of an antidrug antibody.
99
What lung pathology is shown below? What substance drives the development of this lesion?
Granulomatous inflammation (note langerhans giant cell);
interferon-gamma
100
What sleep stage does sleepwalking occur in? What brainwaves are characteristic of this stage?
Non-REM stage 3;
Delta waves
101
What brain waves characterize the first 2 stages of sleep?
N1: theta
N2: sleep spindles & K complexes
102
What is hartnup disease?
AR metabolic disorder due to impaired transport of neutral AAs, esp. tryptophan.
Symptoms of niacin deficiency.
103
How do you calculate Vd?
How do different drug properties relate to the volume of distribution?
Vd = amount of drug given / plasma concentration of drug
Low Vd 3-5L suggests charged / large / tightly bound to plasma protein and remains in blood
Medium Vd 15-16 L means it's small and hydrophilic and distributes into the interstitium
High Vd = intracellular or tissue preferential uptake (e.g. 40+L Vd).
104
What is the presentation of carnitine deficiency?
Low muscle carnitine, hypoketotic hypoglycemia due to inability to beta-oxidize FA, muscle weakness/cardiomyopathy.
105
What is the mechanism of action of desmopressin?
it is a synthetic analogue of vasopressin/ADH which causes vWF release from endotheleal cells.
106
How do you calculate positive predictive value?
Test positive / (test positive + false positive)
107
What are the symptoms of riboflavin (vitamin B2) deficiency? What enzymes are afffected?
Angular stomatitis, cheilitis, glossitis, seborrheic dermatitis, eye changes and anemia.
Succinate dehydrogenase (as riboflavin makes FAD)
108
What is the timing cutoff for symptoms which differentiates acute stress disorder from PTSD?
PTSD duration of symptoms is greater than 1 month
109
How do opiates provide analgesia?
Activation of the mu receptor blocks calcium influx and reduces excitatory release on the presynaptic membrane and increases potassium efflux on the postsynaptic membrane to induce hyperpolarization.
110
What causes the appearance of lamellar bodies and acid-fast staining of material accumulating in alveoli?
Pulmonary alveolar proteinosis (PAP) due to an imbalance between surfactant production and clearance, due to compromise of the alveolar macrophages.
111
What is the inheritance of neurofibromatosis type 1? Which chromosome is the gene located on?
single gene autosomal dominant; chromosome 17
112
What is the diagnosis of this tonsilar lesion? What is the most likely cause?
Keratin pearls, atypical mitotic figures -\> head and neck mucosal squamous cell carcinoma. Caused by HPV exposure.
113
How would you distinguish between Cryptococcus and Candida?
Candida will grow true hyphae in serum at 37C "germ tubes"; Cryptococcus does not form hyphae.
114
how would you diagnose respiratory failure in the setting of DKA?
Higher than expected PaCO2 i.e. mixed metabolic + respiratory acidosis due to resp. fatigue and hypoventlation.
115
What is the cause of an S4?
Blood from atrial contraction hitting a stiff ventricle. Always pathologic in younger patients or if especially louder.
116
What is the change in renal venous pressure in the setting of CHF?
Renal venous pressure *increases* due to volume overload.
117
How does diptheria become toxigenic?
Infection with corynephage beta inserts the tox gene, resulting in production of diptheria AB toxin.
118
Describe the steps of base excision repair?
Glycosylase detects and removes uracil. Endonuclease cleaves 5' and lyase cleaves 3' sugar-phosphate.
Dna pol fills gap and ligase seals nick.
119
What is the histology of a cutaneous wart?
epidermal hyperplasia
hyperkeratosis
papilloma formation
and koilocytosis (cytoplamic vacuolization
120
What is the function of factor VIII?
Links factor IXa (protease) with factor X (substrate).
121
What are the symptoms of primary hyperaldosteronism?
Hypertension & hypokalemic alkalosis w muscle weakness and paraesthesias.
NO edema / or hypernatremia due to increased RBF/GFR and ANP.
122
What is the genetic cause of fragile X syndrome?
trinucleotide repeat expansion \>200 causes hypermethylation of FMR1 leading to inactivation of gene.
123
What drugs improve survival in decompensated HF?
Beta blockers.
124
A fever, grayish exudate and partial soft palate paralysis would suggest what infection?
Diptheria!
125
Pneumobilia and small bowel obstruction suggests what condition?
Gallstone ileus.
126
When should you suspect SCID?
Lack of a thymic shadow, frequent infections, agammaglobulinemia (i.e. you have *both **B and T cell dysfunction*****).**
127
Wha tis osler-weber-rendu syndrome? What is the inheritance?
Hereditary hemorrhagic telangiectasias of the skin and mucous membranes + severe nosebleeds.
AD
128
What is the mechanism by which physiologic stress leads to chnages in serum K+ levels?
High levels of catecholamines activate B2 receptor -\> increased Na/K pump activity + Na/K/2Cl transporter activity
Net shift of K+ into cells results in hypokalemia.
129
What is the first-line treatment for glaucoma? What is their mechanism of action?
Prostaglandins eg. latanoprost.
Increases outflow of aqueous humor (decrease collagen in uveoscleretal outflow pathway)
130
What is the function of tazobactam?
It is a beta-lactamase inhibitor
131
What are the most comon organisms that cause acute otitis media?
Strep pneumoniae, H flu (nontypeable), Moraxella catarrhalis.
132
What medications can you use to address AFib? What are their mechanism of actions and side-effects?
Calcium channel blockers e.g. diltiazem and verapamil.
Slow sinus rate + conduction through AV node.
Complications include AV block, negative inotropic effect (don't use if CHF), constipation (esp. verapamil).
133
What might you be concerned about if intubating a patient with long-standing RA?
vertebral subluxation of C-spine causing cord compression (absent reflexes, flaccid paralysis).
134
What are the acute and late tissue reactions of radiation?
Acute: erythema, desquamation, hair loss and sterility
Late: fibrosis (homogenization of collagen), necrosis, vascular bnormality.
Can also cause carcinogenesis/teratogenesis.
135
What vitamin deficiency is associated with measles complications?
Vitamin A is depleted by measles; suppleentation prevents karatitis and corneal ulceration and reduces comorbidities and recovery time
136
What is the best way to ensure that the correct operation is done on the correct body part & patient?
Dual independent verification by 2 different providers through the use of a surgical time out.
137
Where on the tRNA is the amino acid attached?
to the CCA-OH-3' tail
138
When treating a migraine with metoclopramide or prochlorperazine, what drug do you want to also co-administer and why?
dopamine receptor blockers can cause extrapyramidal symptoms -\> add dyphenhydramine for anticolinergic activity.
139
What is the ABGs expected when people travel to high altitudes?
persistent hypoxemia
respiratory alkalosis
metabolic alkalosis (compensatory - full normalization \> 72 hrs)
140
What pathway for nitric oxide synthesis and vasodilation in endothelium?
Arginine + O2 is converted by endothelial nitric oxide syntase into NO -\> diffusion to smth muscle
Smooth muscle guanlyate cyclase activated by NO produces cGMP == vasodilation
141
What is the location of a lesion with pure hemisensory loss?
contralateral ventral posterior lateral nucleus in the thalamus.
142
What does lipohyalniosis and microatheromas cause
lacunar infarcts within the basal ganglia, posterior limb of internal capsule, pons or cerebellum
143
Name the arteries indicated on this femorial angiogram
A) external iliac
B) inferior epigastric
C) common femoral
144
describe the differences between the pathophys of Salmonella enterica versus Salmonella typhi
S typhi produces capsular Vi antigen which suppresses neutrophil response, allows intracellular replication in macrophages and systemic spread -\> typhoid fever (proressive fever, rose spots, abdo pain, hepatosplenomegaly, GI bleed)
Enterica = self-limited watery diarrhea. Enterica has animal vectors, typhi is only fecal-oral from other humans
145
What is the mechanism of action of ethosuximide?
Blocks thalamic T-type Ca2+ channels.
146
Describe characteristics reactive neutrophils.
Dohle bodies (cytoplasmic blue inclusions of RER), toxic granulations, cytoplasmic vacuoles.
147
Hypersegmented neutrophils (\>6 lobes) are found in what diserase?
Vitamin B12 or folate deficiency (megaloblastic anemia).
148
What are the characteristics of buspirne? what is it used for?
Partial 5HT-1A agonistused for generalized anxiety disorder.
No risk of dependence, slow onset of action.
149
What happens when you take a fluoroquinolone with calcium carbonate or iron pills?
Insoluble compounts form resulting in impaired absorption
150
Where does collagen hydroxylation occur?
in the rough endoplasmic reticulum.
151
Which AA is a recursor to serotonin?
Tryptophan
152
Identify A-E
A) hippocampus
B) cerebellum
C) corpus callosum
D) pons
E ) thalamus
153
what do bats transmit?
rabies
154
What are the symptoms, key characteristsics and transmission of bubonic plague?
Symptoms: fever and swollen, painful, erythematous lymph nodes.
Yersinia pestis; gram-negative coccobacillus, reservoir is rodents, transmitted by flea bite.
Endemic to SW USA
155
What is this pattern of IF characteristic of in kidney?
glomerular basement membrane disease (e.g. Goodpasture)
156
What is somatomedin C?
IGF-1
157
What is the mechanism of hyperacute rejection of transplanted organs?
preformed recipient antibodies against graft antigens causing gross mottling and cyanosis & thrombotic occlusion.
158
Where are very long chain and branched-chain fatty acids metabolised? What syndromes occur when peroxisomes are defective?
Peroxisomes;
Zellweger syndrome: craniofacial abnormalities, hepatomegaly, profound neurological defects. Death within months.
X-linked adrenoleukodystrophy (defective tranport of VLCFAs into peroxisomes) presenting with neuro symptoms and adrenal insufficiency.
159
What are the causes and presentation of biotin (B7) deficiency?
What reactions are affected?
Cause acquired (raw egg whites due to avidin) and congenital.
Presentation: altered mental status, myalgias, anorexia, derm changes, metabolic acidosis (due to conversion of pyruvate \> lactate).
Pyruvate carboxylase (gluconeogenesis), acetyl-CoA carboxylase and Propionyl-CoA carboxylase req biotin.
160
what happens to ABGs when gas exchange is diffusion limited?
Large alveolar - capilary gradient for O2 (normally would be the same approx 104 mmHg)
CO2 diffuses much faster than O2 therefore CO2 levels stay the same.
161
What is the treatment for recurrent calcium kidney stones?
Thiazide diuretic (reduces urinary Ca2+)
162
How does a patent ductus arteriosus initially affect CO, SVR, and atrial filling?
PDA shunts from systemic to pulmonary circulation, lowers SVR resulting in compensatory ncrease in CO.
As more blood enters pulmonary circulation, LA filling increases.
163
What is the presentation of trochlear nerve palsy?
Up and out eye; diplopia that is worse when looking down and nasal e.g. when walking down stairs or reading up close.
164
Identify A-E
A - descending aorta
B - esophagus
C - trachea
D - aygos vein
E - pulmonary artery
165
What is bacillary angiomatosis?
Red-purple papular skin and/or visceral lesions caused by Bartonella henselae infection in immunocompromised pt
166
What is the cause of the acid-fast stain seen on this liver slide?
a1-antitrypsin deficiency; granules composed of unsecreted AAT polymers which cannot be digested.
167
Describe the 3 mechanisms of action and examples of direct-acting antiviral therapy for HCV infection
Sofosbuvir - RNA-dependent RNA polymerase inhibitor
Simeprevir - HCV protease inhibitor
Ledipasvir - NS5A inhibitor (prevents viral replication and assembly)
168
What would you use to manage bradycardia + hypotension associated with inferior wall MI?
Atropine - blocks vagal tone which contributes to bradycardia
169
Describe the morphology of the mature HepB virion
enveloped, partially double-stranded circular DNA in a hexagonal capsid.
170
Which antibiotic can precipitate serotonin syndrome? What infections is it commonly used for?
Linezolid due to MAOI activity.
MRSA and VRE
171
What are some examples, mechanism of action and side effects of stimulant laxatives?
Bisacodyl and senna
Stimulates peristalsis
Causes cramping, electrolyte disturbances.
172
What type of laxative is docusate?
A surfactant laxative (stool softener).
173
What is the cause and presentation of osmotic demyelination syndrome?
Cause is too-quick correction of chronic hyponatremia causing apoptosis and demyelintaion of the pons.
Pseudobulbar palsy, quadriparesis, horizontal gaze paralysis, obtundation or "locked-in" syndrome.
174
In what order do you give antidoes for organophasphate toxicity?
Atropine first (block muscarinic receptors), then pralidoxime due to the latter's transient AchE inhibition.
175
What is reverse T3?
Inactive T3 generated from peripheral conversion of T4
176
What happens to extracellular potassium concentrations in DKA? Why?
Increased due to loss of free water via increased plasma osm and due to lack of insulin to shift K+ into cells.
177
Describe the imaging
Bilateral ground glass opacification and air bronchograms; atelectasis.
178
Describe how ventilation and perfusion change in the lung when standing?
Ventilation is highest at the apex and lowest in the base
Perfusion is highest in the base and lowest in the apex (due to gravity).
179
What is the difference between projection and displacement?
Projection is attributing your own feelings to others.
Displacement is transferring your feelings to a less threatening object or person
180
What is the presentation of tyrosinase deficiency?
Albinism due to inability of melanocytes to to synthesize melanin.
181
What is the enzyme responsible for classic PKU? What if there is also a dopamine deficiency?
Classic PKU: deficiency of phenylalanine hydroxylase.
PKU + downstream deficiencies of neurotransmitters is caused by dihydrobiopterin reductase, which makes the cofactor needed for phenylalanyne hydroxylase and tyrosine hydroxylase (both are req'd to make DOPA).
182
Which muscles insert on the lateral epicondyle of the humerus? what is the presentation of tendinitis at this location?
Extensor carpi radialis previs & extensor digitorum.
Weakness or pian with wrist extension = tennis elbow.
183
What are the origins and insertions of the 3 major hip flexors?
Iliopsoas (T12-L4 & iliac fossa -\> lesser trochanter of femur)
Rectus femoris (AIIS -\> base of patella (quad tendon))
Sartorius (ASIS -\> pes anserine)
184
How does damage to the intervertebral disc present?
What causes anterior displacement of the vertebral body?
Disc damage -\> herniation, loss of space between vertebrae.
Bilateral pars interarticularis fractures -\> spondylolisthesis
185
What is the difference between primary infection and reactivation of HSV-1
Primary herpetic gingivostomatitis; multinucleated cells on Tzanck smear, more severe.
Reactivation generally mild perioral vesicles.
186
What are the most common infectious bacteria that are associated with septic abortion?
Staph aureus, E coli or other gram-neg bacilli, GBS
187
How does mitral stenosis affect LV end-diastolic pressure? What change in LVEDP suggests aortic valve disease?
Mitral stenosis LVEDP is normal or low due to reduced outflow from LA. If LVEDP is increased, think aortic valve pathology (i.e. stenosis)
188
What is the mechanism of action by which trinucleotide repeats in huntingtin gene cause disaese?
CAG repeat -\> polyglutamine expansion -\> GoF mutation in huntingtin -\> histone deacetylation -\> transcriptional silencing.
189
What medication is lowest-risk pharmacological intervention for insomnia in the elderly?
Ramelteon (binds melatonin receptors in superchiamatic nuc)
190
What is the mechanism of action of the combined OCP?
Suppression of GnRH -\> lowers FSH/LH and prevents ovulation.
191
What is the presentation of PSGN on IF and EM?
IF - granular staining of C3 along GBM
EM - Subepithelial humps .
"Lumpy bumpy"
192
What is the function of JAK2 (mutated in polycythemia vera)?
JAK = Janus Kinase 2, a non-receptor, cytoplasmic tyrosine kinase which mutations result in constitutive activation (i.e. in the absence of erythropoetin).
193
What is the most common cause of hypoketotic hypoglycemia?
Deficiency of acyl-coA dehydrogenase.
194
What are the adverse effects of steroid use?
Skin MSK: Central obesity, buffalo hump, skin atrophy and proximal muscle weakness
GI: peptic ulcer or GI bleed due to suppression of prostaglandins
Endocrine: HPA suppression, hyperglycemia, hypogonadism, osteoporosis
Immune: Neutrophilia due to demargination, immunosuppression
Nervous: Hypomania or psychosis, sheep disturbance
Resp: Increased surfactant production.
195
What is the typical presentation of HUS?
often follows EHEC infection; bloody diarrhea
triad: hemolytic anemia + schistocytes, thrombocytopenia, AKI.
196
What is the primary animal reservoir of EHEC?
Cattle GI tract
197
What is the superficial lymphatic drainage from the lower limb?
Medial to superficial inguinal nodes
Lateral to popliteal nodes and then to deep inguinal nodes.
198
what types of hallucinations occur in schizophrenia?
Most commonly aural - tactile or olfactory more likely to be due to concomittant substnace use.
199
What are the criteria for the diagnosis of schizophrenia? Can you have positive and negative symptoms at the same time?
\>=6months of continuous impairment with functional decline
2 or more of: delusions, hallucinations, disorganized speech, disorganized or catatonic behaviour or negative symptoms (apathy & flat affect).
200
What are the etiologies of syncope?
Vasovagal (think trigger, prodrome)
carotid hypersensitivity (drop in SVR due to tactile stimulation of carotid sinus)
autonomic dysfunction (orthostasis, existing disease)
hypovolemia (volume loss, orthostasis)
LV outflow obstruction (assoc. with exertion, systolic murmor)
VTach (no warning symptoms, cardiomyopathy, ischemic heart disease, long QT)
Conduction impairment (fatigue, lightheadeness, ECG abnormality)
201
Which nerve can be compressed by parotid gland tumors? What is the presentation?
The facial nerve (CN VII) which provides motor innervation to the muscles of facial innervation. Non forehead-sparing facial droop.
202
What are the rapid-acting insulin analogs?
Lispro, aspart or glulisine
203
What are the long-acting and intermediate-acting insulin analogs?
Long-acting: Glargine, detemir, degludec
Intermediate: NPH (twice daily)
204
Name the 5 hypothalamic nuclei which have "homestatic" functions
Ventromedial (satiety) and Lateral (hunger)
Anterior (heat dissipation) and Posteerior (hypotherma)
Suprachiasmatic: circadian rhythm, pineal gland
205
Name the 5 hypothalamic nuclei that secrete hormones
Arcuate: dopamine, GHRH
Medial preoptic: GnRH, sex
Paraventricular: oxytocin, CRH, TRH
Supraoptic: ADH
206
What is the mechanism of transmission of Campylobacter jejuni
contaminated food (e.g. undercooked poultry) and domesticated animals (esp puppies!)
207
What types of food are associated with Vibrio parahaemolyticus gastroenteritis? What individuals are more prone to developing sepsis?
Contaminated seafood e.g. shelfish. Can cause sepsis in people with liver disease or hemochromoatosis.
208
Does insulin contribute to the disease process of T2DM?
No, it is elevated as a result of insulin resistance associated with obesity or high levels of FA
209
What proteins are bound by von Willebrand factor?
platelet Gp1b to exposed collagen under damaged endothelium
and factor VIII (as a carrier, preventing proteolytic degradation)
210
What are the 3 types of prostatic hyperplasia? Which one responds best to finasteride? Alpha blockers?
Epithelial predominant - finasteride
Smooth-muscle predominant - alpha blocker
Collagen-predominant
211
What is the innervation, origin and insertion of latissimus dorsi? What are the primary movements?
Innervation: thoracodorsal nerve
Origin: iliac crest and lumbar fascia to spinous processes of T7-12 and lower ribs
Insertion: bicipital groove of humerus
Primary functions: extension, adduction and medial rotation of humerus
212
What type of cardiac cell makes this tracing? What phase of the action potential is affected by class IV antiarrhythmic drugs?
slow-response tissues (pacemaker cells) of SA and AV nodes.
phase 0 (upstroke) is slowed by verapamil / diltiazem due to their effect on L-type calcium channels.
213
What are the characteristics of edwards syndrome (trisomy 18)?
Dysmorphic features: micrognathia, low-set ears, prominent occiput, rocker bottom feet
Hyertonia, e.g. clenched hands, overlapping fingers.
Heart, GU, GI abnormalities
IUGR
214
What is the function of dystrophin?
links actin to the cytoskeleton, stabilizes the sarcomere. Loss of dystrophin leads to myonecrosis.
mutated in DMD / BMD
215
What is medical therapy for symptomatic gallstones?
Ursodeoxycholic acid (hydrophilic bile acids)
Improves cholesterol solubility & helps dissolve gallstones
216
What is the impact of chronic alcoholism on TCA?
Thiamine deficiency, blocks pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase complex.
NAD+ depletion; all steps which consume NAD+ are inhibited
217
Why do patients with CF have dehydrated mucus, yet have salty sweat?
CFTR inhibition means loss of chloride leaving the cell (i.e. inside is more -ve), which means that there is more sodium flux via ENaC. Increased sodium flux pulls water into the cell.
CFTR is reversed in sweat glands, normally absorbing luminal chloride and pulling sodium and water out of the sweat.
218
How do you calculate cumulative incidence?
Number of cases that develop over a given time period / number of susceptible people in the population at the beginning of the period.
219
How can a venous embolus bypass the lungs and end up causing a stroke?
Patent foramen ovale (PFO); present in 25% of adults, but functionally closed due to LA \> RA pressure. Valsalva release can transiently open the PFO.
220
What is the most common complication of adult rubella?
polyarthritis / polyarthralgias
221
What are the 3 biologic suffixes?
- mab/pab is a monclononal antibody
- nib is a tyrosine kinase inhibitior
- cept is a receptor molecule
222
What is the mechanism of action of etanercept?
It is a decoy receptor for TNF-alpha
223
what is the innominate artery?
the (right) brachiocephalic artery.
224
What is subclavian steal syndrome?
When either subclavian artery is occluded, bloodflow in the ipsilateral vertebral artery is reversed and "steals" from the contralateral artery, diverting blood away from the brainstem.
Symptoms include arm ischemia and vertebrobasilar insufficiency (dizziness, vertigo etc.)
225
identify the pathogen in this lung biopsy. What are the key characteristics?
coccidioides immitis
mold in the cold.
thick-walled sperules with and w/o endospores.
Culture on sabouraud agar.
226
Testicular swelling and tenderness localized to the posterior and superior areas is suggestive of what diagnosis?
Epididymitis; typically caused by Chlamydia or Gonorrhea in younger men or colonic flora in older men.
227
What is the cause of kidney disease in multiple myeloma?
Free light chains from Ig enter through glomerulus and form obstructive casts causing kidney injury.
228
What leads to rebound "rhinorrhea"? how do you manage it?
use of topical decongestants \>3 days. Stop decongestents to restore normal norepinephrine production.
229
How do you treat primary hypergonadism?
replace estrogen or testosterone.
230
What is the cause of splenomegaly in the setting of hemolysis?
Red pulp hyperplasia
231
What drugs cause a use-dependent prolongation of the QRS complex without QTc prolongation?
Class 1C antiarrhythmics: Flecainide, propafenone
232
How do you differentiate between bulimia nervosa, binge-eating disorder and body-dysmorphic disorder?
Bulimia: binge eating +compensatory behaviour to prevent weight gain and excessive worrying about body shape and weight
Binge-eating disorder is bulemia without compensatory behaviours
Body-dismorphic disorder: intense preoccupation with a perceived defect in physical appearnce, significant functional impairment, *does not meet criteria for eating disorder*.
233
Identify the lesion. What is the presentation of the nerve most likely affected?
This is a retroperitoneal hematoma, common in patients that are anticoagulated.
Femoral nerve compression can occur (note the psoas muscle is squished) leading to quadriceps weakness, decreased patellar reflexes and sensory loss over anteromedial thigh.
234
What inherited cause explains a loud S2 and right axis deviation on ECG? What is the causative mutation and inheritance pattern?
pulmonary arterial hypertension due to inactivating mutation in BMPR2; AD with variable penetrance.
235
Which cells express MHC II? How does it work?
Antigen presenting cells phagocytose extracellular pathogen in lysosomes (acidic) and then fused onto an MHC class II molecule which is sent to the cell surface for presentation to a CD4+ T cell.
236
Where is the AV node located?
on the endocardial surface of the RA, near the coronary sinus and the septal leaflet of the tricuspid valve.
237
How does diastolic pressure, afterload and contractility change in mitral valve stenosis?
Intially, all 3 are normal. Contractility may increase in advanced disease due to decreases in diastolic pressure and afterload (due to decreased filling).
238
What is the presentation of acute or chronic arsenic poisoning? What is the treatment?
Acute: garlic breath, vomiting, diarrhea and QTc prolongation
Chronic:skin changes (pigmentation, keratosis), stocking-glove neuropathy.
Treatment: dimercaprol
239
What are the non-enveloped RNA viruses?
Reoviruses, Picornaviruses (PERCH), hepevirus (HEV), calicivirus (norovirus)
240
What is a glomangioma? What is the characteristic appearance?
A benign tumor originating from smooth muscle cells that control thermoegulation via glomus bodies. Characteristic appearance is a red/blue small lesion under a nail bed.
241
Which drug interactions can cause a methadone overdose?
Inhibitors of CYP3A4: azoles, fluvoxamine, ciprofloxacin, clarithromycin and cimetidine.
242
What is first-line therapy for essential tremor?
Non-selective beta blocker (e.g. propranolol)
243
What tuberculosis drug produces red-orange body fluids? What is its mechanism of action?
Rifampin; inhibits bacterial DNA-dependent RNA pol
244
chronic, treatment-refractory rhinosinusitis with nasal polyps and failure to thrive is most likely...
CF
245
What is itchthysosis vulgaris?
inherited disorder with mutation of the filaggrin gene leading to defective desquamation and dry, scaly skin with loss of barrier function. Extensor surfaces most commonly affected with flexural sparing.
246
What is the most likely diagnosis? What would you see on histology?
Mesothelioma
On histology: either epithelial-like or spindle cells with staining for cytokeratins and calretinin.
247
What is the diagnosis? What are the key characteristics?
Lichen planus: 5Ps it is pruritic, purple or pink, polygonal, papules & plaques.
Wickam striae; Kôbner phenomenon
Found on skin, oral mucosa, and genitalia
248
What is the major toxicity of trastuzumab?
reversible cardiotoxicity associated with decreased contractility without destruction or fibrosis.
249
Describe the biochemistry of alkaptonuria.
Lack of homogentisic acid dioxygenase blocks conversion of tyrosine to furmarate; accumulation of homogentisic acid which turns black when oxidized.
250
What causes the electrolyte abnormalities seen in thiazide diuretics?
volume depletion causes activation of RAAS, increases urinary excretion of K+ and H+ (so serum hypokalemia and metabolic alkalosis)
251
Identify the substances 1-5 in the graph of proximal tubule concentrations.
1. creatinine
2. urea
3. Na+, K+
4. HCO3-
5. Glucose and AAs
252
This chronic alcoholic has oculomotor dysfunction, ataxia and encephalopathy (cofusion and anterograde amnesia). What is the diagnosis and what structure on the diagram is most affected?
Wernicke encephalopathy due to thiamine deficiency; mamillary body (B) will demonstrate atrophy or hemorrhage.
253
Describe the immune response in leprosy.
Initial tuberculoid leprosy characterized by TH1 response ( IL-2, IFN-gamma, IL-12), +ve lepromin skin test.
Lepromatous leprosy characterized by humoral immnity (TH2: IL-4, IL-5 and IL-10) response and a negative lepromin skin test.
254
What is the pathogenesis of COPD?
1. alveolar macrophages are activated due to irritants
2. Macrophages recruit neutrophils; which produce neutrophil elastase and MMP9
3. Macrophages secrete cytokies to recruit CD8+ T cells which destroy alveoli.
255
What are the electrolyte changes in tumor lysis syndrome?
Hyperphosphatemia, hyperuricemia, hyperkalemia and elevated LDH
256
What is the drainage from internal hemorrhoids? External hemorrhoids?
Internal: superior rectal vein -\> inferior mesenteric vein
external: inferior rectal veins -\> internal pudendal
257
What is the first sign of uncal herniation?
ipsilateral oculomotor nerve palsy starting with a fixed+dilated pupil.
258
What is the difference between somatic mosaicism and germline mosaicism
Germline mosaicism affects offspring, but not parent. Heritable.
Somatic mosaicism affects body cells manifesting disease.
Sometimes you get both.
259
What is the diagnosis? What is the presentation?
Hairy cell leukemia
Infiltration of the bone marrow causes fibrosis and failure -\> pancytopenia.
Infiltration of red pulp -\> massive splenomegaly, LUQ pain, fatigue ,weakness, fever and recurrent infections.
260
Label A-F
A - ischiocavernosus
B - bulbospongiosus
C - perineal body
D - levator ani
E - external anal sphincter
F - anococcygeal body
261
In what stage of sleep do nightmares occur? What about sleep terrors?
Nightmares - REM sleep.
Night terrors occur during slow-wave sleep
262
Label A-G
A - trapezium
B - capitate
C - scaphoid
D - lunate
E - pisiform
F - trapezoid
G - hamate
263
What is the most frequently injured abdominal organ in MVAs? What does it predispose individuals to?
The spleen; asplenia predispose to sepsis from encapsulated bacteria e.g. Strep pneumo, H flu, N meningitidis.
264
Name the bug. What is the treatment?
Aspergillus fumigatus;
V shaped, narrow septated hyphae.
Treatment is amphotericin B
265
This person presents with proximal muscle weakness. What is the diagnosis? What conditions are associated with it?
Diagnosis: dermatomyositis (perifascicular inflammation), muscle shows grotton papules over bony prominences.
May occur due to paraneoplastic syndrome of adenocarcinoma (ovary, lung, pancreas).
266
Differentiate between the two types of heparin-induced thrombocytopenia.
Type 1: non-immun-mediated caused by platelet clumping, generally milder course with thrombocytopenia \>100,000-/mm3. Typically occurs \<2 days post-heparin.
Type 2: heparin causes conformational change in platelet factor 4, which creates an antigen. IgG antibodies form, causing agglutination. Typically occurs \>5 days post-heparin.
267
What would you see in active MS on histology?
Focal demyelination with plaques with perivenular inflammatory infiltrates (largely T-cells and macrophages).
268
What are the 3 openings through which each division of CN V passes through?
Superior **orbital** fissure - V1 **o**pthalmic
Foramen rotundum - V2 maxillary
Foramen ovale - V3 mandibular
269
Acute recurrent flank pain and hydroureter; what is your #1 differential? What would you see on urinalysis?
Ureterolithiasis.
Free RBCs on urinalysis (RBC casts = glomerular bleeding).
270
What is diphenoxylate used for? what is the mechanism of action?
Anti-diarrheal agent, binds opioid mu-receptors in gut and slows motility.
271
What drug is the blue line?
Lidocaine or mexiletine (class 1B antiarrhythmic, weaker Na+ channel binding)
272
What are the contraindications of testoosterone replacement therapy and potential adverse effects?
Contraindicated if prostate cancer, hematocrit \> 50% or severe OSA
Adverse effects include erythrocytosis and VTE.
273
What cardiac pathology occurs in acromegaly?
LV hypertrophy due to stimulation of GH.
274
What is the diagnosis in this child with nephrotic syndrome? What will you find on EM?
Minimal change disease (normal LM glomeruli, no immune deposits)
EM effacement of podocyte processes.
275
What is the difference between familial chylomicronemia and familial hypercholesterolemia?
Familial chylomicronemia due to defect in lipoprotein lipase or ApoC-II: presentation is elevated chylomicrons (hypertriglyceridemia), acute pancreatitis, lipemia retinalis and eruptive xanthomas.
Familial hypercholesterolemia due to defect in LDL receptor or ApoB-100 presentation is elevated LDL, premature heart disease, corneal arcus, tendon xanthomas and xanthelasmas.
276
Why would someone with STEMI present with eye pain?
If they are treated with atropine for bradycardia, it will cause mydriasis and blockade of aqueous humor outlflow, leading to glaucoma.
277
What is the cause of high-altitude pulmonary edema?
Hypoxic vasoconstiction -\> increased pulmonary pressure -\> patchy edema, bilateral crackles.
278
What is associated with abacavir hypersensitivity reaction?
HLA-B\*57-01
Abacavir binds it, causing self-peptide presentation and cytotox T-cell response.
Delayed rash, fever, malaise, GI symptoms
279
What lesion would produce a medial rectus palsy?
Ipsilateral medial longitudinal fasciculus lesion.
280
What is the sensory distribution of the tibial nerve?
plantar surface of the foot.
281
What brain pathology is associated with autosomal dominant polycystic kidney disease (ADPKD)? What is the presentation?
Berry aneurysms of the circle of Willis -\> subarachnoid hemorrhage
"Worst headache of my life"
282
What is the difference between tenofovir-induced nephrotoxcitiy and TMP-SMX nephrotoxicity?
Tenofovir: interferes with mitochondrial DNA + cellular damage in the proximal tubule (phosphaturia, glucosuria, proteinuria) with loss of brush border, giant mitochondria (eosinophilic inclusions)
TMP-SMX (used in advanced AIDS): interstitial nephritis and AKI, not focal cellular damage to prox tubule.
283
What virulence factor leads to necrotizing pneumonia from Staph aureus?
Panton-Valentine leukocidin (PVL), acquired by bacteriophage. Causes tissue necrosis and destroys leukocytes.
284
What is this finding? What procedure was recently performed on this individual? What other symptoms might they present with?
Livedo reticularis
Microangiopathy due to cholesterol emboli dislodged by invasive vascular procedures esp if atherosclerosis.
Can also present with blue toe syndrome, bowel ischeimia, stroke or renal infrct.
285
Which immune cells are associated with sarcoidosis? What cytokines are important in the progression of disease?
CD4+ T-cells and macrophages.
interferon-gamma and TNF-alpha
286
What substance causes hepatic encephalopathy?
Ammonia (NH4+) in blood
NOT urea.
287
What are the adverse effects of PDE-5 inhibitors?
Hypotension
Blue discoloration of vision, sudden monocular vision loss (due to PDE6 inhibition in retina)
Priapism
Flushing, headache, hearing loss.
288
Activation of which receptors would produce this pattern of changes?
Alpha 1 adrenergic receptors
289
What organism can cause a flu-like illness with bilateral conjunctival suffusion that is culture negative on routine media? What is the source of exposure?
Leptospira (spirochete)
Water contaminated by animal urine
290
How would you differentiate hypersensitivity pneumonitis from idiopathic pulmonary fibrosis?
Both present with a restrictive pattern, BUT idiopathic fibrosis does not have biopsy findings (granulomas) and typically presents much older \>50yo.
291
Why do peripheral neurons regenerate when CNS neurons cannot?
After transection in PNS, schwan cells degrade myelin and recruit macrophaqges to clear debris & secrete trophic factors.
In CNS the oligodendrocytes undergo apoptosis and microglia are slow to remove myelin debris, which suppress neuron growth. Astrocyte proliferation leads to a glial scar, further blocking regenreation of the neuron.
292
What enzyme changes in stool is diagnostic for pancreatic insufficiency
Decreased elastase levels in stool.
293
What is the first-line pharmacotherapy for patients with sarcoidosis?
Glucocorticoids
294
very high ALP with insidious onset severe pruritis in the setting of autoimmune disease is suggestive of...
Primary biliary cholangitis
295
What is this cell? What are the key features? What is the pathogenesis?
Koilocyte: immuature squamous cell, perinuclear halo, "raisin nucleus"
HPV infection
296
What is the treatment for genital HSV infection? Does treating the initial infection result in less recurrance?
Oral daily valacyclovir, acyclovir, or famciclovir
No; treating the first infection does not alter recurrance rates.
297
In tranesophageal echo, when the probe is facing forward, which chamber is it closest to?
The left atrium
298
What ABGs are expected in the 3rd trimester of pregnancy?
Hyperventilation due to progesterone -\> subjective SOB -\> respiratory drive.
Respiratory alkalosis with metabolic compensation
299
What are the genital lesions present in each stage of syphilis?
1. painless chancre
2. condyloma lata
3. gummas (necrotizing granulomas that are white-gray rubbery lesion).
300
What fungal infections are caspofungin and TMP-SMX used for?
Caspofungin - aspergillosis
TMP-SMX - pneumocystis
301
Describe the steps in the pathogenesis of cholecystitis
Persistent gallstone obstuction (biliary colic) -\> disruption of mucus layer -\> chemical irritation, inflammation of mucosa & deep tissues -\> hypermotility with increase in internal pressure -\> ischemia -\> bacterial invasion of necrotic wall.
302
What condition would cause subcutaneous crepitus on lung exam?
Pneumothorax (esp. traumatic)
303
What changes in absorption of nutrients are expected in a patient on PPIs?
Malabsorption of calcium, iron, magnesium & B12
Lower acidity improves fat absorption for pts on pancreatic enzyme replacement by preventing lipase degradation in the stomach.
304
Why does retching and vomiting cause mallory-weiss tears? What is a strong associated predisposing factor?
Increased intraabdominal pressure; hiatal hernia.
305
What is the difference between dofetilide and dobutamine? What are their adverse effects?
Dofetilide is a class III antiarrhythmic which slows repolarization by blocking potassium channels. Leads to prolongation of QT and increased risk of polymorphic ventricular tachycardia
Dobutamine is a beta-1 agonist used for congestive heart failure; can cause HTN, angina, arrhythmia and tachycardia
306
What does immunoreactivity of synaptophysin indicate?
Neuronal origin of tumor (or neurectoderm or neuroendocrine).
307
Which tumors stain with GFAP?
Gliomas (astrocytomas, oligodendrogliomas and ependymomas).
308
What is the presentation of contrast-induced nephropathy?
Acute rise in creatinine and BUN subsequent to contrast administration, ATN with muddy brown casts on UA
309
What are the key pharmacokinetic differences in the neonate vs the adult?
Neonates have:
higher % body water & an immature BBB
Lower CYP activity and glucuronidation
Lower renal blood flow and GFR
Lower plasma protein levels
310
What is the structure in the rectangle? What CN exits at this level?
The middle cerebellar pedicle (pons) -\> CN V trigeminal nerve
311
What does the t(15;17) translocation responsible for acute promyelocytic leukemia code for? What is used for treatment of APML?
PML-RARA, an abnormal retinoic acid receptor which inhibits differentiation.
Use all-trans retinoic acid for treatment.
312
What ligaments attach to the stomach? What is their composition
Lesser omentum (hepatogastric & hepatoduodenal ligaments, double fold of peritoneum)
Greater omentum (visceral peritoneum)
313
What the gram-positive rods in blood cultures?
Corynebacterium
Listeria
Actinomyces
Nocardia or
Clostridium
314
What are the virulence factors that are unique to Listeria monocytogenes?
Listerolysin O: makes pores in phagosome membranes to allow bacteria to escape
Actin-based transcellular spread
315
what characterizes a the fluid in a pericardial effusion in the context of malignancy?
Often hemorrhagic fluid with atypical malignant cells.
Subacute accumulation over weeks until volumes exceed stretch capacity, causing cardiovascular dysfunction.
316
What is this malformation? How does it present in infancy?
Dandy-walker malformation
Hypoplasia of cerebellar vermis, and dilatiation of 4th ventricle with posterior fosa enlargement.
Presents with head enlargement and developmental delay
317
What is this malformation? What is the presentation?
Chiari malformation
can cause syringomyelia and headaches or movement problems but can also be asymptomatic.
318
What is the pathophysiology of a ganglion cyst?
Mucoid degeneration of periarticular tissue which collects fluid via 1-way valve.
319
What should you do to further workup an unknown metabolic alkalosis?
Assess volume status and urine chloride.
Low urine chloride = vomiting, suctioning, hypovolemia
High urine chloride = loop diuretic overuse, aldosterone-mediated H+ loss
320
What is the pathophysiology which would explain hemolytic anemia, hypercoagulability and pancytopenia?
PIGA mutation leading to loss of CD55 and CD59 on RBCs -\> complement-mediated hemolysis esp. at night.
Paroxysmal nocturnal hematuria.
321
How does the kidney pathology reflect hypertension? Analgesic nephropathy?
HTN -\> medial hypertrophy and intimal proliferation of arterioles, glomerulosclerosis. Advanced disease may present with proteinuria
NSAIDs -\> papillary necrosis and tubulointerstitial nephritis.
322
What is the treatment of choice for anaphylactic shock?
Epinephrine
323
What is the difference between norepinephrine and epinephrine?
norepinephrine: alpha-1 adrenergic effect, vasoconstriction
epinephrine: vasoconstriction (contracts shock), beta-1 incr cardicac output. Beta-2 bronchodilation.
324
What is the reaction that is inhibited by methotrexate
Inhibits DHF reductase
Blocks folic acid -\> DHF and DHF -\> THF
325
what are the side effects of colchicine?
diarrhea, nausea, vomiting or abdo pain (due to disruption of microtubule formation in GI mucosal cells.
326
Identify A-E (this is a section at L2). What direction are you facing when you look at the CT?
A - descending duodenum
B - IVC
C - abdo aorta
D - duodenum (4th part)
E - L renal vein
Looking up from the patient's feed towards their head.
327
What is the presentation of myotonic dystrophy? What is the presentation?
difficulty relaxing muscles (e.g. problems with handshake or releasing doorknob)
AD, due to CTG repeat for myotonia-protein kinase with anticipation
Weakness, atrophy, cataracts, frontal balding, gonadal atrophy
328
Why would anticholinergic (amitriptyline, scopolamine) medications predispose to heat stroke?
They inhibit sweating.
329
What is the pathophysiology of infectious endocarditis?
Turbulent flow -\> focal adherence of fibrin and platelets -\> bacterial colonization -\> further coagulation.
330
What is the most common way that legionella spreads?
Through aerosolization of contaminated building water systems eg. showers, cooling towers, ventilators, nebulizers etc.
331
What is the most common side effect of ethambutol?
optic neuropathy: decreased acuity, central scotoma, colour blindness.
332
Which enzymes are affected by grapefruit juice? Where?
CYP3A in intestine.
333
What is the difference between ghrelin and leptin with respect to meals?
Ghrelin stimulates hunger (spikes leading up to a meal) and leptin suppresses hunger (goes up after a meal)
334
What is the diagnosis? What are the key characteristics?
Cryptosporidium parvum
Blunting of brush border, cystic appearing acid-fast organisms on the brush border.
335
What is the typical organism and presentation of bronchiolitis?
RSV in age \< 2 infants
Nasal congestion / discharge + cough
followed by wheezing, crackles and resp distress.
336
How does carbergoline work for prolactinoma?
It is a dopamine agonist which reduces prolactin secretion (it is under negative regulation by the hypothalamic neurons).
337
What pathology leads to lower extremity clubbing and cyanosis?
Large PDA + eisenmenger syndrome (revesal of shunt)
338
What is the cause and presentation of malignant hyperthermia?
Mutation of ryanodine receptors and triggered by inhaled anaesthetic + succinylcholine.
Once triggered, causes massive Ca2+ release from SR leading to masseter spasm, rigidity, hypercarbia, hyperthermia
339
What is the cause and presentation of retinitis pigmentosa?
Progressive dystrophy of retinal pigment epithelium (rods first).
Initially presents with night blindness and peripheral vision loss.
340
Where is the greater saphenous vein located?
Branch off the femoral vein located superficially in the leg surfacing 3-4 cm inferolateral to the pubic tubercle and running down the medial leg, in front of the malleolus and to the medial foot.
341
What would you see on labs for aplastic anemia?
High EPO, pancytopenia with low retics but normal appearance and MCV
342
What is the cause of wrinkles?
Decreased fibril production of collagen.
343
Why does peau d'orange rash develop?
Due to lymphatic obstruction
344
What genetic factor predisposes individuals to drug-induced SLE?
Slow acetylators (low expression of N-acetyltransferase) which increase concentrations of procainamide, hydralazine or isoniazid.
345
Which drugs cause medcation-induced esophagitis?
Tetracyclines, NSAIDs, Bisphosphonates, KCl and Fe.
346
What are side effects from bisphosphonate use?
osteonecrosis of jaw, atypical bone fractures.
347
What is the mechanism of action of cromolyn and nedocromil?
Prevent mast cell degranulation used prophylactically for asthma.
348
What is the presetnation of pituitary apoplexy?
AKA acute pituitary hemorrhage, usually assoc with adenoma.
Severe headache, bitemporal hemianopsia, opthalmoplegia, hemodynamic instability / altered senses.
349
A patient presents with arthralgias, fatigue low-grade fever and weight loss, SOB and cough. CT below. What is the diagnosis? What would you see on biopsy? What marker is associated?
Granulomatosis with polyangiitis (note cavitary lesion on CT)
necrotizing vasculitis with granuliomas, no immunoglobulin or complement deposition.
PR3-ANCA / c-ANCA
350
What interventions reduce iron absorption in the GI tract? What other nutrient deficiencies must you watch out for in these cases?
Gastric bypass or gastrojejunostomy (decreased acidity)
Also can cause thiamine, folate, B12, fat-soluble vitamines esp D or calcium deficiency.
351
Describe the 3 stages of diabetic nephropathy
Initially presents with glomerular hypertrophy and hyperfiltration (GFR goes up).
Incipient DN is accompanied by albinuria, HTN, mesangial expansion, GBM thickening and arteriolar hyalinosis
Overt DN is kimmenlstiel wilsonlesions, tubulointerstitial fibrosis and overt proteinuria (nephrotic syndrome). GFR goes down.
352
What is endothelin 1? What drug interacts with it?
Endothelin-1 is a potent vasoconstrictor released by endothelial cells
Bosentran is an endothelin-1 receptor antagonist used to treat pulmonary HTN
353
How do you treat infants with nephrogenic diabetes insipidus?
Freqent water supplementation with thiazide administration (!) which reduces water loss by inducing volume depletion and increasing water and Na+ absorption in prox tubule.
354
What is the pathology? What caused it?
Subdural hematoma
Rupture of the bridging veins
355
What is the effect of alpha 1, alpha 2 beta 1 and beta 2 receptors on their second messengers?
Alpha -1 increaes IP3 (Gq)
Alpha 2 decreases cAMP (Gi)
beta-1 / beta-2 increases cAMP
356
What is the mechanism of action of triamterene and amiloride?
Block lumenal/epithelial NA+ Channel (ENaC) in the distal nephron.
Poassium sparing
357
What causes vision changes in Graves disease?What medications are indicated to treat Graves opthalmopathy?
Ocular fibroblasts are activated by thyrotropin receptor antibodies causing glycosaminoglycan deposition, T-cell activation and inflammation.
Treat with glucocorticoids
358
How does a ruptured AAA present? What are the risk factors?
Initial resentation is hyperacute onset severe abdominal and back pain. Rupture into the peritoneal cavity produces syncope, hypotension and shock. Rupture into retroperitoneum can delay hemodynamic instability.
May also present with distension, pulsatile midline mass or umbilical / flank hematoma.
Age \> 60, smoking, male, hx of atherosclerosis, connective tissue disease are risk factors.
359
how would you differentiate cardiogenic shock due to RV failure from anaphylactic shock & septic shock?
RV failure causes a drop in PCWP and elevated RA pressure & CVP.
Sepsis or anaphylaxis will produce reduction of *both* CVP and PCWP and will produce compensatory increase in CO.
360
What are the indications for use of trazodone? What are the side effects?
Serotonin modulator indicated for antidepressant, but used off-label for insomnia.
Side effects: priapism (use with caution in sickle cel), orthostatic hypotension, and sedation.
361
What predisposes the myocardium to hypoxia? Where is the location of blood with the lowest oxygen tension in the body?
Very high oxygen demand and extraction; increased demand can only be met with more flow, perfusion only during diastole to LV.
Carotid sinus.
362
What causes the esophageal dysmotility in CREST syndrome?
atrophy and fibrous replacement of the muscularis of the lower esophagus.
363
What drugs are helpful to correct electrolyte changes in the context of SIADH?
SIADH results in excessive free water reabsorption.
Block with V2 receptor antagonists (\*vaptans).
364
How would you differentiate between CF and Kartagener syndrome?
Kartagener syndrome does not present with bilateral absence of the vas deferens in males.
365
What signs suggest acute pancreatitis with alcohol abuse?
What explains the changes in Ca2+ levels that occurs in severe pancreatitis?
Macrocytosis, \>2 AST:ALT ratio, absence of gallstones on abdo U/S.
Severe pancreatitis can result in saponification (due to lipase release) of the omentum and retroperitoneal fat which causes Ca2+ to be pulled from circulation.
366
How does serum thyroglobulin change with Graves, subacute thyroiditis, exogenous thyroid or central hyperthyroid?
Increases with increasing production of thyorid or destruction of thyroid follicles (graves, subacute thyroiditis, central hyperthyroidism)
Decreases with exogenous thyroid use
367
What changes in glucose level are caused by catechloamines and cortisol?
Hyperglycemia
368
What causes hypoglycemia in insulin-dependent patients?
intense exercise (due to GLUT4 translocation), inadvertent insulin overdose, decreased carbohydrate intake.
369
What process leads to increased risk of gallstones in Crohn disease? Kidney stones?
Inflammation of terminal ileum leads to bile acid loss in feces and overall increase in cholesterol:bile acid ratio, increasing the risk of cholesterol **gall**stones.
Increased oxalate absorption in the intestines leads to calcium oxalate **kidney** stones
370
What immune modulator is most important for the pathogenesis of giant cell arteritis? What drug can be used to treat it?
IL-6 secreted by CD4+ T cells.
Treat with IL-6 inhibitor, tocilizumab
371
What is the difference between phenoxybenzamine and phentolamine?
phenoxybenzamine irreversibly inhibits alpha-1 or alpha-2 receptors whereas phentolamine is a competitive antagonist which can be overcome by high enough norepinephrine concentrations.
372
What are the side effects common to protease inhibitors?
Lipodystrophy (buffalo hump, central obesity), hyperpglycemia, cytochrome P450 inhibition (replace rifampin with rifabutin if treating tb in a pt on PIs)
373
What is the most specific imaging for diagnosis of acute or chronic cholecystitis?
Hepatobiliary scan: radiotracer taken up by hepatocytes and excreted into bile; failure to visualize the gallbladder means obstruction.
374
What is the cause of isolated systolic hypertension?
Increased arterial stiffness (decreased compliance)
Or due to severe aortic regurg or systemic causes with increased CO.
375
What is the predominant cell type found in fatty streaks (the earliest atherosclerotic lesions)
Lipid-laden macrophages (foam cells)
376
Why might a person with a testicular tumor present with hyperthyroidism?
hCG and TSH share homology; a choriocarcinoma produces high levels of hCG causing paraneoplastic hyperthyroidism.
377
What intracranial hemorrhage is chracterized by a lucid interval?
Epidural hematoma caused by rupture of the middle meningeal artery.
378
What is the diagnosis of this lung specimen? What does this pathology predispose this patient to?
Bronchiectasis (note thick, widened airways with mucous plugging)
Bronchial artery hemorrhage
379
What is the differential for elevated CK myopathy?
Statin-induced
Inflammatory (polymyositis, dermatomyositis) associated with skin rash or arthritis
Hypothyroid
380
What is the pathophysiology of duodenal and jejunoileal atresias?
Duodenal: due to failure of recanalization at 8-10wks
Jejunum or ileum: due to vascular occlusion with ischemia
381
How does the HBV vaccination protect against infection?
Generates anti-HBs antibodies against the surface antigen glycoproteins which bind virions and prevent entry.
382
How do the kidneys excrete acid?
Renal ammoniagenesis (excretion of H+ via NH4+) which occurs thorugh glutamine -\> glutamate -\> alpha-ketoglutarate metabolism.
383
What organism is responsible for this presentation? What would you see on a KOH slide?
Tinea versicolor, caused by Malassezia yeasts.
Spaghetti and meatball appearance under LM/KOH
384
How do adenosine and acetylcholine affect the SA node action potential?
They decrease the slope of phase 4; adenosine via A1 receptors, both by increasing K+ outflow and inhibiting L-type Ca2+ channels & funny Na+ channels.
385
What is the diagnosis? How would this present? What is the causative organism?
Scabies
Intense pruritis which begins on the hands, flexor surfaces of wrist, lateral fingers and finger webs and can spread up to the elbow and axilla, which is worse at night.
Sarcoptes scabiei mite
386
What stains red with mucicarmine?
The polysccharide capsule of Cryptococcus
387
What does amantidine / amatoxins block?
Bind and inhibit RNA pol II, which stops RNA synthesis. Tends to manifest with liver failure due to concentration of the toxin there after absorption via portal circulation.
388
Label A-E
A - Bladder
B - prostatic urethra
C - membranous urethra
D - bulbous urethra
E - penile urethra
389
What is thromboangiitis obliterans? Who is affected most commonly?
Inflammatory thrombi blocking small/medium vessels leading to digital ulcers, ischemia, gangrene and limb claudication.
Typical in young smokers.
390
What class of antiarrhythmic drugs would produce the following ion changes?
Class III antiarrhythmic (amiodarone, sotalol, dofetilide). Blockage of potassium channels slows repolarization and prolongs the AP.
391
What is the pathogenesis of ankylosing spondylitis? What cytokines are associated?
What is the treatment?
Originates in gut where defective mucosal barrier causes IL-17 mediated response leading to TNF-alpha and prostaglandins.
Characterized by bridging syndesmophytes and fusion of the apophyseal and SI joints.
Treatment is NSAIDs, anti-TNF-alpha (e.g. etanercept and infliximab) or anti-IL-17 (secukinumab).
392
Label the gastric histology
A - simple columnar epithelial cells
B - upper glandular layer (incll clear parietal cells)
C - deeper gastric glands (delta and chief cells)
D - Muscularis mucosae
E - Submucosa
393
What is the mechanism of action of abciximab?
It is a GPIIb/IIIa receptor antagonist
394
what is the mechanism of action of clopidogrel?
bocks platelet P2Y12 on platelet ADP receptors
395
How would you differentiate reactive arthritis from disseminated gonorrhea?
Reactive arthritis is associated with the classic triad (can't see, can't pee, can't bend my knee) and shigella, salmonella, yersinia, campylobacter and enterococcus infection.
S aureus can cause septic arthritis, but in the setting of recent STI, gonorrhea is more likely. These patients present with a septic joint; classic triad is polyarthralgia, tenosynovitis (wrist) and dermatitis (pustules)
396
What is the most common cause of sudden cardiac death in the setting of MI?
VFib or VTach due to electrical instability of the myocardium.
397
What is this? What exogenous stimulus can cause it to form?
Granuloma; can form in response to a foreign body (cannot be digested by macrophages).
398
What organism forms neurocystercosis in immunocompetent hosts? Where is it endemic? What is the mechanism of spread?
Taenia solium (pork tapeworm)
Central / south america due to consumption of infected feces.
399
What causes on-off phenomenon in patients with parkinson disease on long-term treatment?
Progressive nigrostriatal neurodegeneration leading to a narrowing of the therapeutic window for levodopa.
400
Describe the 5 steps of leukocyte chemotaxis and associated proteins.
1. Margination
2. Rolling (PSGL-1 binding by L-selectin on neuts or E/P-selectin on endothelial cells)
3. Activation
4. Tight adhesion / crawling (CD18 beta2 integrins (Mac1 and LFA-1) binding ICAM-1 on endothelial cells)
5. Transmigration (PECAM-1)
401
What are the mood stabilizers used for bipolar disorder?
Lithium, valproate, carbamazepine and lamotrigine
402
What are the risk factors for AAA?
Male, smoking, \>65 yo.
403
What disease would present in a young adult with neurologic symptoms, ataxia, and elevated AST?
Wilson disease.
404
What serum marker is associated with active HBV replication and infectivity?
HBeAg
405
Which nerve cells are affected first by hypoxia?
CA1 pyramidal neurons of the hippocampus, followed by cerebellar purkinje cells and neocortex pyramidal neurons.
406
Which tumors are characterized by biphasic growth and S-100 staining? What tumors are also S-100 positive?
Schwannoma; melanoma
407
What medications predispose patients to serious hypoglycemia? What is the mechanism that explains this effect?
Nonselective beta-blockers (e.g. propranolol)
Blockage of normal epinephrine signalling (stops hepatic gluconeogenesis and peripheral glycogenolysis)
Masking of epinephrine-related symptoms of hypoglycemia including jitters, tachycardia, anxiety/arousal.
408
What enzymes are associated with rupture of an atherosclerotic plaque?
Metalloproteinases produced by macrophages (results in thinning of the fibrous cap)
409
What is the diagnosis?
Metastatic liver disease (note multiple nodules)
hcc is much less common than mets
410
What viruses are susceptible to Acyclovir? How does its mechanism explain the spectrum of activity?
HSV-1, HSV-2 and VZV
These viruses make thymidine kinase, which converts acyclovir to active form via phosphorylation.
411
What is the most common cause of lobar hemorrhage in children? Older adults?
Children - arterovenous malformation, typically single lesion.
Adults \>60 - amyloid angiopathy associated with AD. May present with multiple lesions.
412
What eye change leads to myopia?
Increase in AP diameter of the eyes leading to an image that is focussed in front of the retina.
413
What is the diagnosis? What does the fluid contain? What are the walls made up of?
Pancreatic pseudocyst containing pancreatic enzymes. Walls are made up of granulation tissue and fibrosis occurs over time.
414
What is the pathogenesis of alpha-1-antitrypsin deficiency?
Lack of AAT activity -\> cannot suppress neutrophil elastase -\> panacinar emphysema (esp. with smoking exposure).
415
What drug can be used to minimize gynecomastia in men undergoing antiandrogenic prostate cancer treatment?
Tamoxifen
416
How would you distinguish between degenerative/OA back pain and spinal mets?
OA back pain is positional and relieved with rest; spinal mets present with constant back pain that is worse at night irrespective of position or analgesics.
417
What is the most common cause of age-related aortic stenosis? What is the pathogenesis?
Calcific aortic valve disease
due to atheroma development triggering inflammtion and differentiation of fibroblasts into osteoblast-like cells with bone matrix deposition and calcification.
418
What is the difference between aspirin and other NSAIDs e.g. ibuprofen, diclofenac, indomethacin?
Aspirin acetylates COX-1 and COX-2 leading to irreversible inhibition. Other NSAIDs have reversible inhibition of these enzymes.
419
What kind of brain pathology is associated with large infarcts? Small infarcts?
Cardiac embolism or carotid artery atherosclerosis = medium or large vessel occlusion.
HTN leads to atherosclerosis and lipohyalinosis and narrowing of the vessels -\> lacunar infarct.
420
What is the function of S-100 protein?
Homodimeric calcium binding proteins -\> protein phosphorylation and cell growth / differentiation.
Present in cells derived from the neural crest.
421
What 2 conditions could produce this presentation?
G6PD defienciency and glutathione reductase deficiency.
422
What are the non-selective alpha-1 blockers?
doxazosin, prazosin and terazosin
423
What is superior mesenteric artery syndrome? What are risk factors for it?
Entrapment of transverse duodenum by SMA and aorta resulting in obstruction.
Risk factors are rapid weight loss / catabolism, pronounced lordosis, scoliosis surgery
424
What is the genetic structure of HBV?
Enveloped, icosahedral core with partially dsDNA and reverse transcriptase.
425
What hormone is primarily responsible for growth and development of bone, cartilage and soft tissue? Where is it produced?
IGF-1 produced by liver under the influence of GH.
426
What are the two origins of ascending aortic dissection and descending aortic dissection, respectively?
Type A dissection usually starts from the sinotubular junction
Type B originates from the left subclavian artery
427
What gram-positive nonhemolytic bacteria produces a "medusa's head" when cultured? What are its virulence factor?
Bacillus anthracis
Bacteria has a D-glutamic acid polypeptide capsule that prevents phagocytosis and produces exotoxin complex of edema factor, lethal factor and protective antigen.
428
What are the typical causes of COPD exacerbation?
Viruses: rhinovirus, influenza and parainfluenza
Bacteria: H flu, Moraxella catarrhalis, Strep pneumo
Other: Air polution or PE
429
What is this tissue? What factor is responsible for producing it?
Granulation tissue; VEGF release.
430
What valve pathology corresponds to this tracing? Where will the sound be loudest? What's different compared to a normal tracing?
Aortic regurg; C (i.e. shortly following closure of the valve)
Note loss of dicrotic notch at closure of the aortic valve and steep diastolic decline in aorta pressure.
431
How does the bone marrow look in primary myelofibrosis? How would you differentiate that presentation from aplastic anemia?
Neoplastic megakaryocytes which stimulate fibroblasts to fill the space with collagen. Blood smear will show dacrocytes
Aplastic anemia: bone marrow replaced with fat; extracellular hematopoesis is minimal thus does not present with hepatosplenomegaly.
432
What drugs cause ototoxicity?
Loop diuretics (furosemide), aminoglycosides, salicylates and cisplatin
433
What is the most common cause of lobar pneumonia? What is its virulence factor and the target of vaccination?
Streptococcus pneumoniae
Anti-phagocytic polysaccharide capsule that blocks complement binding. Many antigenic variants, but vaccine against most common strains.
434
Label A-E binding sites
A/B: Antigen binding site
C: Disulfide bonds
D: C1 attachment site
E: Fc receptor binding site
435
What antiviral therapy for CMV does not need to be activated by viral-encoded enzymes?
Foscarnet (pyrophosphate analog) - CMV
436
Which muscles participate in external rotation of the arm?
Infraspinatus & teres minor
437
What movements does the subscapularis do?
Adduction and internal rotation of the arm
438
Where are thrombi most likely to be formed in Afib?
The left and right atrial appendages
439
Which valves are vulnerable to thrombosis?
Mechanical or bioprosthetic valves require anticoagulation
440
What are the local and systemic effects of diptheria toxin. What is the target of the vaccine?
Local: pseudomembranous pharyngitis
Systemic: myocarditis, neuritis
Target is exotoxin B subunit (for binding)
441
What function does the Hep D virus need to borrow in order to replicate?
Requires Hep B surface antigen to coat the Hep D virus before it can infect hepatocytes.
442
What is DRESS syndrome? What drugs are at risk?
Drug Reaction with Eosinophilia and Systemic Symptoms
Anticonvulsants (phenytoin, carbamazepine), allopurinol, sulfonamides, antibiotics (vanco, minocycline)
443
What is the piriform recess? What nerve runs just deep to it? What reflex does it participate in?
Cavities on either side of the laryngeal opening which divert food through to the esophagus.
Internal laryngeal nerve -\> afferent limb of cough reflex from mucosa superior to vocal cords.
444
What is the effect of C difficile toxins?
Toxin A and B inactivate rho proteins and disrupt cytoskeleton structure. Disruption of tight junctions + increased paracellular fluid secretion leads to watery diarrhea
Toxins also cause inflammation + apoptosis, leading to pseudomembrane formation
445
What is this cell? What do the granules contain? What infections trigger it?
reactive lymphocyte
Granules contain perforin and granzymes to punch holes and trigger cell death of infected cells
Infectious mononucleosis (EBV)
446
What should be suspected in the patient that has cyanosis that does not improve with supplemental O2? What is the pathophysiology? Risk factors? Management?
Acquired methemoglobinemia due to oxidation from Fe2+ to Fe3+ (unable to bind O2)
Causes include dapsone, local (benzocaine) and nitrates/nitrites
Treat with methylene blue.
447
What are the indications for and adverse effects of clozapine?
Schizophrenia refractory to treatment or with suicidality.
Adverse effects: agranulocytosis, seizures, myocarditis, metabolic syndrome.
448
How would you differentiate a cereballar tremor from a parkinsonian tremor?
Key characteristcs of cerebellar: low frequency, coarse, intention tremor
Parkinsonian: resting tremor which improves with intentional movement.
449
What are the effects of digoxin on the heart?
Blocks Na/K ATPase pump
Reduces AV nodal conduction via increased PNS tone.
Inotropic effect on the ventricles (increasing intracellular Ca2+)
450
What is the anastomosis between the SMA and IMA?
The marginal artery of Drummond
451
What is the characteristic oncogenic mutation in glioblastoma?
EGFR overexpression.
452
What test helps differentiate between different etiologies of an elevated ALP?
GGT - it is specific to hepatocytes and biliary epithelium so r/o bone origin for ALP.
453
What causes a dupuytren contracture?
overstimulation of Wnt leading to fascial thickening and formation of nodules due to proliferating fibroblasts making type III collagen and resulting in fibrosis and limitation of ROM
454
What vitamin deficiency can lead to squamous metaplasia?
Vitamin A
455
What are the adverse effects of lithium?
Diabetes insipidus, hypothyroidism, tremor, ebstein anomaly (teratogen)
456
What are the criteria for myelodysplastic syndrome? How is it differentiated from myelofibrosis?
Criteria: 1+ cytopenia, dysplastic cells on peripheral or bone marrow biopsy with hypercellularity
Hepatosplenomegaly and lympadenopathy uncommon (no secondary erythropoesis, unlike myelofibrosis)
457
What process leads to horseness in the setting of heart failure?
Ortner syndrome: left recurrent laryngeal nerve impingement by LA and associated structures
458
What are the 5 virulence factors of E coli and associated presentations
LPS - activates macrophages and release of IL-1 , Il-6 and TNF alpha
K1 capsular polysaccharide - neonatal meningitis
verotoxin (shiga-like) - blocks protein synthesis leading to bloody gastroenteritis
Enterotoxins - fluid secretion from GI epithelium = watery gastroenteritis
Fimbriae - UTIs
459
What tests are used to distinguish streptococci?
460
How do you culture Haemophilus influenzae? What is its virulence factor?
Lysed blood agar or regular agar + factor V and X.
Virulence factor is polysaccharide capsule which binds factor H and degrades C3b, preventing phagocytosis.
461
What are the effects of aldosterone and ADH on electrolytes in the collecting duct?
Aldosterone increases Na/K+ ATPase pumps and promotes K+ and H+ secretion
ADH: increases urea reabsorption to concentrate urine
462
How would you differentiate between primary syphilis and L-type chlamydia?
NB: syphilis testing is commonly false negative due to slow development of antibodies.
L-type Chlamydia is rare in the US and usually presents with painful lymphadenitis
463
This patient presents with cough and weight loss? What is the diagnosis?
Active TB (note cavitary lesion)
464
What is the mechanism of staphylococcal toxic shock syndrome?
Pyrogenic toxic shock superantigens bind MHC-II APC complex and then trigger T cells to release massive amounts of cytokines.
465
What bacterial virulence factor activates toll-like receptors? What results?
Endodoxin in gram negative bacteria. Fever & hypotension result.
466
What receptors are stimulated for tocolysis?
Beta-2 receptors
467
What other cancers are associated with Zollinger-Ellison syndrome?
Hyperparathyroidism & pituitary tumors
468
What is the most common benign lung tumor? What is it made of?
Hamartoma / pulmonary chondroma often containing hyaline cartilage, fat, smooth muscle and clefts lined with resp epi.
469
What is biliary sludge?
Commonly caused by gallbladder hypomotility; dehydrated bile can be associated with colic (due to transient blockage) and precipitate stone formation.
470
What is glyburide? What is the mech of action & sitde effects?
Insulin secreatagogue can cause hypoglycemia and weight gain
471
What are the SGLT2 inhibitors? What are their side effects?
Cana**glif**lozin or dapagliflozin. Can cause UTIs and hypotension
472
What are the key findigns of prerenal azotemia?
BUN/Cr \>20
FENa \< 1%, low urine Na+ \< 20 mEq/L
Hyperosmolar urine, hyaline casts
473
Describe the pathogenesis of ascites due to cirrhosis of the liver.
Cirrhosis causes portal hypertension and increases splanchnic capillary pressure. Meanwhile, NO production in those vessels increases, lowering their resistance and causing blood to pool; this reduces effective arterial volume leading to RAAS+ADH activation and resultant water and sodium retention.
Furthermore, hypoalbuminemia contributes to ascites by lowering osmotic pressure
474
How does pulmonary edema affect the lung?
Impaired ventilation, intrapulmonary shunting, decreased lung compliance (due to interstitial edema)
475
What is the lymph node drainage from the uterus, cervix, vagina and vulva?
Uterus -\> external iliac
Cervix -\> internal iliac
Vagina -\> prox to internal iliac, distal to inguinofemoral
Vulva -\> inguinofemoral
476
What is cilostazol? What is its mechanism of action?
Inhibits platelet phosphodiesterase (can't break down cAMP) and is a direct vasodilator, used for PAD
477
What bacteria is associated with contaminated seafood and lives in water? What are its characteristics? What are the stool findings?
Vibrio cholerae; oxidase-positive, gram-negative, comma-shaped. Requires salt for growth.
Noninvasive & causes diarrhea by cholera toxin - no fecal leukocytes or RBCs
478
What is the difference between ectopy and metaplasia?
Ectopy = microscopically and functional normal tissue found in an abnormal location due to embryonic development.
Metaplasia is *replacement* of one tissue type for another and occurs during adult life rather than during embryogenesis.
479
How would you differentiate between scleroderma, achalasia and diffuse esophageal spasm on manometry?
Scleroderma: low middle & lower eso tone, low lower sphincter tone
Achalasia: globally low eso tone with high sphincter tone
Spasm: affects middle/lower eso, low sphincter tone
480
What class of drugs does fenofibrate belong to? What is the mechanism of action?
Fenofibrate is a fibrate (like gemfibrozil) that activates PPAR-alpha -\> lowers VLDL production with increased lipoprotein lipase activity
481
What bicarbonate level is expected in acute respiratory acidosis? Chronic respiratory acidosis?
Acute - approx 24 meq/L
Chronic - high (30++ meq/L) due to compensation
482
How does the spleen change over time in individuals with sickle cell disease?
Initially splenic congestion can occur during sequestration crisis due to vaso-occlusion of the cords of Billroth + pooling of erythrocytes.
Repeated splenic infarcts eventually result in fibrosis and atrophy of the spleen by adolescence.
483
What is the mechanism of action of statins?
Inhibit HMG-CoA reductase, reducing cholesterol biosynthesis and increasing clearance of LDL by hepatocytes, pulling cholesterol out of the serum.
484
A patient presents after liver transplant with skin rash and ulcerations of the intestinal mucosa. What is the cause?
Graft versus host disease due to activation of donor T cells against host MHC
485
How would you differentiate between squamous cell carcinoma and adenocarcinoma of the esophagus? What is the characteristic histology for each? Characteristic mets?
SCC - associated with alcohol, smoking and foods contaning n-nitroso. Typically found in the middle 1/3 (most common) or prox. 1/3. Presents with sheets of eosinophilic squamous cells, keratin pearls, intercellular bridges. Lymphatic spread is to the mediastinal nodes.
Adenocarcinoma - associated with GERD and preceded by Barrett esophagus. Typically found in the distal 1/3, with drainage of lymphatics to gastric and celiac nodes. Characterized by irregular glandular cells.
486
What are the direct Xa inhibitors? What is their impact on PT and PTT? Thrombin time?
Rivaroxaban or apixaban
Prolonged PT and aPTT, but no effect on thrombin time (IIa)
487
What drug can be added to combat the change in acid/base status caused by someone on loop diuretics?
Furosemide -\> metabolic alkalosis
Treat with carbonic anhydrase inhibitor (acetazolamide) which stops HCO3- resorption in kidney
488
What is the classic presentation of PICA stroke?
Lateral medullary syndrome: vertigo and nystagmus (vestibular nuclei), ataxia and dysmetria (inferior cerebellar peduncle), ipsilateral face (spinal trigeminal) and contralateral body (lateral spinothalamic tract) loss of pain/temp sensation, bulbar weakness (nucleus ambiguus) +/- ipsilateral Horner (sympathetic fiber)
489
What is the impact of the arterovenous concentration gradient on anaesthetics?
High AV gradient = high distribution of anaesthetic into tissue
Takes longer to reach induction concentrations in brain (slower onset).
490
What cholesterol therapy results in elevated levels of triglycerides?
Bile-acid binding resin (e.g. cholestyramine) inhibit reuptake of bile and increase hepatic triglyceride production.
491
What are the 4 main classes of antifungal medications and their mechanism of action?
1. Polyenes (amphotericin B, nystatin) bind ergosterol and create pores in cell membrane
2. Triazoles (ketoconazole, fluconazole, itraconazole, voriconazole) inhibit ergosteral synthesis
3. Echinocandins (capsofungin, micafungin), inhibit glucan synthesis which is used for fungal cell wall
4. Pyrimidines (flucytosine) interfere with fungal DNA/RNA synthesis
492
What mutation starts of the classical adenoma to carcinoma sequence in sporadic colon cancer? What about Lynch syndrome?
inactivating APC mutation. Lynch syndrome is due to DNA repair mismatch gene mutations causing microsatellite instability (MLH1 and MSH2)
493
How are FSH LH and estradiol affected in athlete's triad or anorexia nervosa?
All are decreased (this is hypothalamic amenorrhea). Caused by inhibition of pulsatile GnRH release.
494
What are the causes of DIC in obstetrics?
Placental tissue factor release due to abruption, amniotic fluid embolism. Ascending infection -\> sepsis
495
Why is sarcoidosis accompanied by hypercalcemia / hypercalciuria?
Activated macrophages in lung/lymph nodes secrete 1-25-OH-vit-D causing increased intestinal absorption *independent of parathyroid level* (which is typically low in sarcoidosis)
496
What organism that lives in salt water produces rapidly progressive septicemia and cellulitis with necrotizing fasciitis in people with iron overload or liver disease? What are its characteristics?
Vibrio vulnificus: curved, gram-negative rod
497
What is the appearance of the intestinal mucosa in the setting of rotavirus?
blunting of the villi in the duodenum and proximal jejunum
498
What infection presents with flask-shaped ulcers (see below) on intestinal biopsy?
Entamoeba histolytica
499
Identify the organism. What are the key characteristics and typical presentation?
Mucor, Rhizopus or Absidia: nonseptate hyphae branching at 90 degree angles
Affects paranasal sinuses of people with DKA or underlying immunosuppression
500
What medications trigger QT prolongation?
Antiarrhythmics (Ia / III)
Antibiotics (macrolides, fluoroquinolones, azoles)
Antipsychotics
Antidepressants (TCA)
Antiemetics (odansetron)
and methadone
501
What does cryoprecipitate contain vs fresh frozen plasma?
Cryoprecipitate = factor VIII, XIII, VWF and fibrinogen
Fresh flozen factor contains all coagulation factors and proteins
502
How do you treat rat poison injestion?
"Super-warfarin" reverse with fresh frozen plasma + vitamin K
503
What diuretic improves survival in patients with CHF?
Mineralocorticoid receptor antagonists (spironolactone and eplenerone) by blocking remodeling due to aldosterone and improving Na+ and water excretion in kidney
504
What is the medical management of aortic dissection?
1) esmolol (beta-1 blocker) to reduce contractility and shear stress
2) vasodilators (nitroprusside, nicardipine) to reduce BP
505
Why is carbidopa added to levodopa treatment of Parkinson disease ? What side effects persist and which ones are improved?
Carbidopa blocks peripheral conversion of L-DOPA to dopamine, which reduces N/V, tachyarrhythmias or postural hypotension and hot flashes.
Anxiety, agitation, insomnia, confusion or hallucinations (central symptoms) can be worsened by carbidopa
506
What are the key adverse effects and toxicities of isoniazid?
INH Injures Neurons and Hepatocytes
as well, inhibits cytochrome P450, can cause seizures, drug-induced SLE, AGMA, B6 deficiency (supplement with B6).
507
What are maternal risk factors for toxoplasmosis?
Undercooked meat (contaminated farm animals, unwashed produce (soil contamintaion), cat feces
508
What are the physiological causes of nausea and their associated treatments
GI enteritis - seretonin antagonist
Vestibular (motion sickness, vertigo) antihistamines (diphenhydramine) or anticholinergics (scopolamine).
Migraine - dopamine agonists (e.g. metoclopramide, prochlorperazine)
509
What is the structure and difference of MHC I and MHC II molecules?
MHC I - all cells, heavy chain and B2 microglobulin
MHC II alpha and beta chain.
510
What is the mechanism of action of tamiflu / oseltamivir?
Neuraminidase inhibitors stop mature viral release from cells via agglutination and sticking to host cell membrane
511
What are the 2 classes of calcium channel blockers and their respective effects?
Dihydropyridines (amlodipine, felodipine, nifedipine) = peripheral vasodilation (targets smooth muscle)
Verapamil = reduced heart rate and contractility (targets cardiac muscle)
Diltiazem = both
512
What is the cause of a false positive or false negative tuberculin skin test?
False positive - due to nontuberculous mycobacteria or previous BCG vaccination
False negative - recent infection, T cell anergy, immunocompromise or improper injection technique.
513
What medications should be given to improve outcomes after subarachnoid hemorrhage?
Nifedipine to reduce cerebral vasospasm & cerebral ischemia
514
Which metabolic pathways occur in the cytosol? The mitochondria?
Cytosolic: glycolysis, fatty acid synthesis, pentose phosphate pathway
Mitochondrial: beta-oxidation of FAs, TCA, carboxylation of pyruvate (gluconeogenesis)
515
What is the most common karyotype in a complete hydratidiform mole?
46 XX (due to fertilzation with 1 sperm and subsequent duplication of paternal chromosomes)
516
Which nerve root is responsible for hip extension? What is its sensory distribution?
S1
Posterior calf, sole & lateral foot
517
What are the two fates of homocysteine?
Methylation from methyl-THF in the presence of B12 to methionine (via methionine synthase)
Transsulfation to cystathionine and then to cysteine via cystathionine synthase / cystathionase + B6.
518
What type of epithelium is infected by HPV? Where is it found?
Stratified squamous epithelium
Anal canal, vagina and cervix as well as the true vocal cords
519
When a patient presents with hypercortisolism, what should you check first?
Medications / PMH to see if they are taking an exogenous steroid.
520
What is the positive and negative regulation of the lac operon?
+ve via binding of catabolite activator prtein to CAP site
-ve via binding fo repressor (binds lactate) to operator site.
521
How do alkaline phosphatase levels correlate with bone remodeling?
ALP increases with osteoblast activity.
522
What causes a cleft palate to form?
Failure of the intermaxillary segment to fuse with the maxillary prominence
523
What drugs are affected by chelation binding?
Tetracyclines, fluoroquinolones, levothyroxine
524
How does arbon monoxide poisoning affect oxygen delivery to tissues?
CO bound carboxyhemoglobin increases, which reduces the amount of hemoglobin available to bind oxygen, but not the PaO2 (i.e. the oxygen levels in blood).
CO poisoning does NOT cause methemoglobinemia
525
How does carotid massage affect the electrical conduction of the heart?
Increased baroreceptor firing rate (via CN IX) -\> increased vagal tone -\> temporary inhibition of SA activity, slower AV node conduction and increased refractory period.
526
What are the signs and symptoms of benzodiazepine withdrawl?
Rebound anxiety, tremor, insomnia, sympathetic hyperactivity
Severe: psychotic symptoms, seizures, death.
527
What is the rapid urease test used for? How does it work?
Detects H pylori in peptic ulcers. Urease made by bacteria splits urea into ammonia and CO2; the former increases pH locally and improves bacterial survival
528
What is lipofuscin? Where would you find it?
Insoluble pigment made of lipid polymers and protein-complexed phospholipids.
Sign of ageing, free radical injury and lipid peroxidation. Heart / liver cells as intracytoplasmic, yellow-brown granules.
529
What is the cause and presentation of short bowel syndrome?
postprandial large-volume diarrhea, weight loss and B12 deficiency (if terminal ileum involved)
Cause is surgery or Crohn disease.
530
What causes painless bleeding in diverticular disease?
Exposure of the vasa recta with thinning of the vascular media -\> ulceration & rupture of the vessels.
531
What enzyme metabolizes statins? Which drugs are associated with statin myopathy?
CYP3A4
Macrolide antibiotics, ketoconazole, verapamil & diltiazem, protease inhibitors
532
What is the cause and presentation of beta-blocker withdrawal?
Upregulation of the beta receptors -\> increased sensitivity to catecholamines when medication is withdrawn.
Presentation is increased HR, CO and BP with angina for selective beta-1 blocker withdrawal.
533
What is the differential for pancreatitis?
1. Gallstones
2. Alcoholism
3. Surgery
4. Drugs (azathioprine, sulfsalazine, furosemide, valproic acid)
5. Infections (mumps, Coxackie virus, M pneumoniae)
6. Structural defect of pancreatic duct or ampulla
7. Hypercalcemia
8. Hypertriglyceridemia
GAS-DISHH
534
What is imiquimod used for? What is its mechanism of action?
Topical immunomodulation for dermatologic disorders with abnormal proliferation (warts, BCC and actinic keratosis)
Activation of TLR-7 -\> NFkappaB causing TH1 response, inibition of angiogenesis and induction of apoptosis (via BCL-2) in tumor cells
535
What is preferred therapy for focal onset seizures?
Carbamazepine, phenytoin (can treat seizures that generalize)
Lamotrigine, Levetiractetam
536
What is preferred treatment for generalized (involviing both hemispheres) onset seizures?
Tonic-clonic or myoclonic: levetiracetam or valproic acid
Absence: ethosuxamide, valproic acid
537
What is the key metabolite that needs to be measured for carcinoid syndrome? What are the clinical manifestations?
5-hydroxyindoleacetic acid
Skin flushing, telangiectasias or cyanosis
Watery crampy diarrhea
Bronchospasm, dyspnea and wheezing
Valvular fibrous plaques found on the right heart endocardium presenting with tricuspid regurg
538
What is the presentation of a granulosa cell tumor? What does it secrete?
Call-exner bodies with cuboidal granulosa cells forming rosette-like structures with a glandular appearance.
Secrete estrogen (may present with endometrial hyperplasia).
539
What microscopic findings would you see on skin biopsy of these lesions?
Henoch Schonlein purpura
IgA and C3 deposition on IF
On LM damaged small vessels with fibrinoid necrosis, perivascular neutrophilic inflammation
540
What are the GLP-1 agonists and DPP-4 inhibitors? What is their mechanism of action?
GLP-1 is secreted by L cells in intestine with food intake -\> increases glucose-dependent insulin release
GLP-1 agonists: exenatide, liraglutide and dulaglutide
DPP-4 inhibitors block degradation of GLP-1: sitagliptin, saxagliptin and linagliptin
541
What is the diagnosis?
Lichen planus
542
What are the 3 routes of infection for a hepatic abcess?
Direct from adjoining area e.g. choecystitis
via biliary tract (enteric bacteria)
Hematogenous spread
543
What is the diagnosis? What is the culprit? Where does the infection occur?
Tinea corporis
Dermatophytes - trichophyton rubrum is most common
Infects the superficial epidermis (stratum corneum) no deeper invasion
544
An itchy papulopustular rash with recent exposure to pool water (e.g. resort, cruise ship) is suggestive of what infection?
P aeruginosa folliculitis
545
How woul dyou distinguish between IgA vasculitis and TTP?
IgA vasculitis presents with normal platelets, palpable purpura, arthritis/arthralgia and renal disease
TTP presents with hemolytic anemia (schistocytes) and thrombocytopenia with normal PT/PTT and can sometimes show up with renal failure, fever, and neurologic symptoms.
546
How does hemithorax volume change in the context of pneumothorax?
Increased due to loss of collapsing force from lungs (expansion is unopposed)
547
How would you differentiate constrictive pericarditis from cardiac tamponade?
Constrictive pericarditis takes weeks to develop due to scarring and loss of elasticity - does not occur accutely.
548
What is the cause and presentation of Jarisch-Herxheimer reaction?
Rapid lysis of spirochetes (syphilis, Lyme or lepto) due to antibiotic initiation.
Presents within hours to 2 days of treatment onset with acute onset fevers, chills, myalgias and sometimes rash due to inflammatory response to lipoproteins.
549
What is the characteristic presentation and associated neurotoxic proteins for frontotemporal dementia?
Disinhibition, loss of empathy, compulsive behaviors, hyperorality
Hyperphosphorylated tau and TDP-43 ubiquitination
550
What immunodeficiency presents with trombocytopenia and abnormal platelets?
Wiskott-Aldrich syndrome
551
What is the pathogenesis of vitiligo?
Depigmentation due to absence of melanocytes - autoimmune or neurohumoral toxicity
552
What is the pentad of symptoms for TTP?
Fever, neurologic symptoms, renal failure, anemia and thrombocytopenia.
553
Where is the lesion in temporary vs permanent central diabetes insipidus?
Temporary: posterior pituitary
Permanent: hypothalamus, specifically the paraventricular nucleus.
554
What is the diagnosis? What is the stain positive for?
Myeloblasts with auer rods: APL
Myeloperoxidase stain
555
What are the nonnucliotide reverse transcriptase inhibitors?
Nevirapine and efavirenz
556
What heart pathology leads to a steeper LV end-diastolic PV curve?
Restrictive / infiltrative cardiomyopathy
557
What predisposes individuals to this esophageal pathology?
Barrett's esophagus and esophageal adenocarcinoma:
Chronic GERD, Obesity, smoking, meds that lower eso tone (nitroglycerin) and nitroso foods (deli meat).
558
What are the symptoms of digoxin toxicity? How is it cleraed?
Arrhythmias, anorexia n/v, abdo pain, fatigue, confusion, weakness and color vision alterations
Renal clearance
559
What is the indication for raloxifene?
Estrogen-specific activity on bone, and estrogen antagonist for breast and endometrium
560
What common cause of meningitis in a very young child would not be covered by cefotaxime?
Listeria monocytogenes
561
What infection is associated with a chancroid? How does it look?
Haemophilus ducreyi
Deep ulcer, may be multiple, base may have grey membrane.
562
How would you differentiate between blastomyces and cryptococcus infection?
Blastomyces is a broad-based budding yeast that infects immunocompentent patients
Cryptococcus is variable-sized, narrow based yeast with thick polysaccharide capsule that infects immunocompromised patients
563
What is the diagnosis in this immunocompromised patient? What is the most common causative organism?
Ecthyma gangrosum, caused Pseudomonas aeruginosa
564
What is the preferred vasodilator for hypertensive emergency? What is its mechanism of action?
Fenoldopam, a selective D1 agonist, leads to renal vasodilation
565
What is the vector for dengue and chikungunya fever? Presentation for each?
Aedes aegypti mosquito
dengue: fever, headache, retro-orbital pain, muscle + joint pain
chikungunya: fever, flu-like symptoms, diffuse macular rash, polyarthralgias
566
What is the most likely interpretation of someone who has anti hep A IgG but not IgM
Previous infection—often silent in childhood (not reinfection, as they would have IgM)
567
What is the best empiric treatment for a patient with HIV who presents with neurologic symptoms and 2 ring-enhancing focal lesions on brain MRI?
Pyrimethamine and sulfadiazine to treat Toxoplasma gondii
568
What should you do if your HIV test results are discordant or indeterminate yet you have a high pre-test probability of HIV/AIDS?
Check if it's HIV-2 using an immunoassay. Don't treat with NNRTIs or fusion inhibitors.
HIV-2 is endemic to West Africa
569
Which cell types are recruited by C3a? What are the common downstream effects of C3a, C4a and C5a?
Basophils and eosinophils
Anaphylaxis, histamine release, vasodilation, enhanced vascular permeability.
570
Which patients have a relative contraindication to fibrates? Why?
Those with existing gallbladder disease as the inhibition of 7-alpha hydroxylase reduces bile production which increases the risk of stones forming.
571
What are the risk factors for cataract formation?
Age, DM, chronic sunlight exposure, tobacco, occular trauma or immunosuppression (viruses / drugs)
572
What are the main adverse effects expected in patients treated with nitrates?
Headaches, flushing, lightheadedness, cutaneous flushing and reflex tachycardia
573
What is the pathway by which glucocorticoids affect bone?
Suppress osteoblasts precursors and increases osteoblast apoptosis
Increased osteoclast differentiation as NFKappaB acts as a decoy for osteoprotegerin, which normally inhibits RANK. Furthermore glucocorticoids increase RANK/RANK-L expression.
574
What lab investigations do you need to do before starting someone on a statin or niacin?
Liver function tests due to potential for hepatitis / hepatotoxicity
575
How do beta blockers work to decrease intraocular pressure? What other drug has a different mechanism but achieves the same goal/target?
Decrease secreation of aqueous humor by ciliary epithelium
Also acetazolamide.
576
What is the mechanism of action of ipatropium?
Anticholinergic effect decreases parasympathetic tone to bronchi (leading to bronchodilation) and reduces mucus production
577
What is the primary mechanism that mediates anemia of chronic disease? How would you differentiate it from iron deficiency anemia?
Hepcidin -\> inactivates iron channels on enterocytes and macrophages, leading to increased iron sequestration in the latter and decreased iron absorption from gut.
Key differentiators: in ACD TIBC/transferrin is down, ferritin is normal or increased
578
What cancer can be treated by all-trans-retinoic acid?
Acute promyelocytic leukemia
579
In addition to urine that turns black when oxidized in air, what other visible signs or symptoms point to a diagnosis of alkaptonuria?
Severe adult-onset arthritis of large joints and spine with blue-black deposits in sclerae and ear cartilage.
580
What is the defective enzyme and substance that accumulates in Tay-Sachs disease? How would you differentiate it from other presetnations with "cherry-red macula"
Hexosaminidase A deficiency, buildup of GM2 ganglioside
Key differentiator is that tay-sachs does *not* have hepatomegaly.
581
What organelle is necessary for heme synthesis?
mitochondria
582
What is the most common cause of a communicating hydrocephalus?
Disruption of subarachnoid villi (arachnoid granulations)
583
How does a vitamin D deficiency (other than due to renal disease) present in terms of serum calcium, phosphate and PTH?
Ca2+ and PO4 - decreased
PTH - increased
584
What is the most likely cause of heart failure in a patient who presents after viral prodrome?
Viral myocarditis leading to dilated cardiomyopathy
585
What finger movements are impaired in a volar lunate displacement? Which nerve is involved?
Thumb abduction, flexion and opposition, weakness of the lumbricals of the 1st and second digits (for joint extension) due to medial nerve compression
586
what is the sensory innervation of the musculocutaneous nerve?
Lateral forearm
587
What is the mechanism of action of nucleoside reverse transcriptase inhibitors?
They lack a 3'-OH group, so when incorporated they block the formation of the next phosphodiester bond resulting in chain termination
588
What muscle passes through the greater sciatic foramen? The lesser sciatic foramen? Where do they insert & what is their function?
Greater - piriformis
Lesser- obdurator internus
Insert on greater trochanter of femur and allow external rotation of thigh when extended and abduction when flexed
589
Where does hematogenous osteomyelitis in children invade the bone? In adults?
Metaphysis of long bones in children
Adults in the vertebral bodies
590
What should you suspect in a patient with upper extremity HTN with diminished lower extremity pulses? What murmur or extra heart sounds will you hear?
Coarctation of the aorta with continuous murmur over the back due to collateral blood vessels
S4 due to LVH
591
What neoplasm are individuals with Sjogren syndrome at increased risk for?
non-Hodgkin lymphoma, due to chronic B cell stimulation
592
Which nerve(s) are disrupted in a supracondylar humeral fracture? What type of fracture results in an ulnar nerve injury?
Anterolateral displacement affects the radial nerve, anteromedial nerve affects the median nerve.
Posterior displacement of the proximal humerus or fracture of the medial epicondyle due to a fall onto a flexed elbow
593
What is the characteristic appearance of focal nodular hyperplasia of the liver? Does it require treatment?
Pale nodules with cords of normal hepatocytes with a central stellate scar with fibrous septae
Benign, usually asymptomatic, dosesn't need treatment.
594
What is the characteristic appearance of head and neck squamous cell carcinoma? What are the key risk factors?
Sheets of polygonal cells with eosinophilic cytoplasm; intercellular bridges and keratin pearls.
Risk factors age \>40, alcohol, tobacco, immunocompromise, HPV infection
595
What is the ID50 for Shigella? What other organisms can cause diarrhea with a very low innoculate?
10-500 organisms - Shigella
Campylobacter jejuni, Entamoeba histolytica and Giardia lamblia are also in this ballpark for ID50
596
What is the structure of the major virulence factor for S pyogenes? What is its function?
M protein - alpha helical coiled-coil with structural similarity to tropomyosin and myosin.
Prevents phagocytosis, inhibits complement binding, helps with bacterial adherence
Cross-reactivity against myosin due to M protein leads to rheumatic carditis
597
How do nitrates help with stable angina?
By causing venous dilation which reduces preload (i.e. LV EDV) which results in reduced oxygen demand.
598
What HBV antigen present in the mother represents the highest congenital infection risk?
HBeAg; \>90% will be infected
599
What is the diagnosis based on the imaging? How would you differentiate this presentation from a large pleural effusion?
Right mainstem bronchus obstruction - trachea deviates *towards* affected side
Large PE or hemothorax -\> trachea deviates *away from* affected side.
600
What is the differential for lactic acidosis with an anion gap?
High metabolic rate due to seizures/exercise
Low O2 due to heart failure, lung failure or ischemia/infarct
Low lactate metabolism due to liver failure
Low oxygen utilization due to cyanide poisoning
Enzyme defects e.g. glycogen storage disease, mitochondrial myopathy
601
What is CD31? What is the most likely diagnosis for a tumor that stains positive for this marker? What risk factors increase the likelihood of such a tumor?
CD31 = PECAM1 (platelet endothelial cell adhesion molecule) implies endothelial origin for cancer
Liver angiosarcoma due to arsenic, thorotrast or PVC exposure.
602
What is the pathology present in this slide? Key features?
Carcinoid tumor - uniform size and shape of neuroendocrine cells forming islands with eosinophilic cytoplasm and round/oval strippled nuclei.
Most often benign, found at the tip of the appendix, but can produce liver mets -\> carcinoid syndrome
603
What is the most common virus associated with pure red cell aplastic crisis in sickle cell patients?
Parvovirus B19
604
What is the cause of these lesions in this patient that presents with a Virchow node and B symptoms?
Seborrheic keratoses (rapid-onset) due to GI malignancy e.g. gastric adenocarcinoma
605
What BP is expected in the context of opioid intoxication?
Hypotension due to opioid-induced histamine release from mast cells
606
What is another name for enterovirus? What diseases are associated with it?
Coxsackievirus
Herpangina, Hand-foot-and-mouth disease, asceptic meningitis, myocarditis
607
What are the characteristic pathological findings in fibromuscular dysplasia?
Fibromuscular webs with aneurysmal dilatation and loss of internal elastic lamina
"String of beads" in multifocal disease on angiography
608
How would you treat a boy with bilateral lens subluxation, developmental delay and marfinoid body habitus?
This is homocysteinuria -- can treat with high-dose pyridoxine (B6) suplementation and dietary restriction of methionine.
609
What is the mechanism of pathogenesis of headache and vision changes in preeclampsia?
Placental ischemia causing endothelial dysfunction and vasospasm with decreased perfusion and leaky capillaries.
610
What condition would produce painless nodules on lips and tongue, thyroid mass, marfinoid habitus with joint laxity?
MEN-2B due to RET mutation:
flesh-coloured nodules = mucosal neuromas
medullary thyroid cancer
Marfinoid habitus
May also have pheochromocytoma and intestinal ganglioneuromas
611
What is the cause of this testicular pathology?
Testicular torsion, often associated with inadequate fixation of the lower pole of testis to tunica vaginalis
612
Which virus is associated with postherpetic neuralgia?
VZV post-shingles
NOT HSV!
613
What is the impact of dilated cardiomyopathy on pressures in the heart?
Initially increased left-ventricular volume is compensated for by starling forces and hypertrophy followed by decompensation which results in elevated LV end diastolic pressure.
As a result, this increased pressure is "back-ported" and results in pulmonary edema and right heart failure with elevated right atrial pressure indicated volume overload.
614
What brainstem nucleus is disrupted by bilateral pontine hemorrhage? What neurotransmitter does it make? What are its functions?
Locus ceruleus - norepinephrine.
Functions in reticlar activating system and blood pressure control.
615
What are the risk factors for spontaneous non-traumatic gas gangrene? What is the invading organism?
Colon cancer, inflammatory bowel disease, immunosuppression
Clostridium septicum
616
What is the most common cause of impulse control disorders in Parkison patients?
Dopamine agonists: e.g. pramipexole, ropinirole.
617
Which patients present with centriacinar vs panacinar emphysema?
Centriacinar = due to extensive (\>30p-y) smoking
panacinar = alpha-1-antitrypsin deficiency
618
How would a patient with absent HLA-DP, HLA-DQ or HLA-DR genes present?
Severe combined immunodeficiency (due to inability for APCs to present antigens with MHCII) with normal levels of B and T cells in circulation.
619
What would produce a midsystolic click followed by a late-systolic murmur that disappears with squatting?
Mitral valve prolapse (most commonly sporadic due to connective tissue problems).
620
In a patient in DKA, what is the enzyme that metabolizes glycerol for gluconeogenesis?
Glycerol kinase (Liver)
621
How would you distinguish between a patient who has a thiamine deficiency and a cobalamin deficiency?
B1 / thiamine deficiency: Beriberi (peripheral neuropathy +/- **HF**) or Wernicke-Korsakoff syndrome?
B12 / cobalamin deficiency is typically **macrocytic anemia** and neurologic involvement with sensory peripheral neuropathy
622
Name the 4 posterior foramina of the skull and the nerves that exit through them.
Internal acoustic meatus: VII and VIII
Jugular Foramen IX, X, XI and jugular vein
Hypoglossal canal: VN XII
Foramen magnum: spinal roots of CN XI, brain stem and vertebral arteries
623
What is the primary mediator for niacin's side effects? What medication can help manage these side effects?
Prostaglandins cause flushing, warmth and itching
Give aspirin 30-60min before niacin dose.
624
What is the mechanism of action of terbinafine? What is it used for?
Inhibits ergosterol by suppressing squalene oxidase
Used for dermatophytosis e.g. tinea
625
What does neprilysin do? What is the phamacological approach that targets it?
Neprilysin cleaves ANP and BNP and angiotensin II
Due to these combined effects, a neprilysin inhibitor (sacubitril) must be combined with an ARB (valsartan)
626
What is the typical presentation of aortic regurg?
"uncomfortable heartbeat" esp. if lying on left, bounding femoral/carotid pulses and head bobbbing.
Blowing diastolic decrescendo murmur in the LLSB.
627
What is the function of RNA Pol I, II and III?
I - rRNA (most components)
II - mRNA, snRNA, microRNA
III - tRNA and 5S rRNA (makes 60S subunit)
628
Which receptors increase or decrease insulin secretion?
Increase: M3, B2, glucagon and glucagon-like-peptide 1 (via Gs and Gq)
Decrease: A2 and somatostatin 2 (via Gi)
629
How would you differentiate an ASD murmur from a PDA murmur?
**continuous machine-like** murmur, loudest at S2 in the left infraclavicular region = PDA
Pulmonic systolic ejection murmur or **fixed split S2** = ASD
630
When someone has recurrent Ca2+ kidney stones, aches and pains, and a high serum Ca2+ level, what is the most likely diagnosis? What would their bones look like?
Primary hyperthyroidism (adenoma or malignancy)
subperiosteal resorption with cortical thinning
631
What is the characteristic feature of cardiomyopathy caused by Chagas disease?
Dilated cardiomyopathy with localized apical wall thinning and development of a large apical aneurysm in the LV
632
Describe the dose-dependent adrenergic effects of dopamine.
Low: D1 receptor stimulation results in vasodilation which increases RBF, mesenteric, cerebral and coronary vascular flow
Medium: B1 effects predominate, increasing CO HR and BP
High: alpha-1 receptor effect predominate, leading to generalized vasoconstriction and reducing CO
633
What nucleotide supplementation enables continued DNA synthesis in the absence of folate?
Thymidine (dT)
634
What type of diarrhea is associated with foodborne outbreaks of E coli O157:H7
Hemorrhagic colitis (bloody diarrhea)
635
What is the signalling mechanism used by TNF-alpha? How does it affect insulin signalling?
Activates serine kinases which phosphorylate the insulin receptor & substrate, blocking tyrosine pohosphorylation.
This results in insulin resistance
636
What is the impact of preeclampsia on VEGF?
Overall, placental ischemia is antiangiogenic, so decreases VEGF and placental growth factor.
637
Describe the primary ion flows for each letter on the cardiomyocyte action potential curve
A- nothing
B- Na+ IN
C - K+ OUT
D - K+ OUT and CA++ IN balanced
E - K+ OUT
638
What drug acts as an agoist of PPAR-gamma? What is its effect?
Thiazolidinedione drugs (e.g. pioglitazone).
Results in decreased insulin resistance by activating GLUT-4 and adiponectin (stimulates FA oxidation)
639
How is HCV able to produce chronic infections despite high antibody titres?
Continuous antigenic variation of the envelope proteins
640
What is the 1st line therapy for PCOS-caused infertility? What is its mechanism of action?
Clomiphine - SERM that prevents -ve feedback by estrogen on the HPG-axis, leading to increased FSH & LH and then ovulation
641
What enzyme deficiency results in underproduction of dopamine, melanin and catecholamines?
PKU - phenylalanine hydroxylase
642
What is the characteristic presentation and causative mutation of epidermolysis bullosa? What are the complications?
Bullae with minor trauma or friction; intraepidermal cleavage on histology
Due to mutations in keratin genes that impede assembly.
Can be complicated by malnutrition or infection
643
What pathologies result in concentric vs eccentric LVH?
Concentric = pressure overload due to HTN or aortic stenosis
Eccentric = volume overload due to aortic or mitral regurg, ischemic heart disease or dilated cardiomyopathy.
644
How would you treat a gram-negative oxidase-positive non-lactose-fermenting bacterial infection in a burn patient?
Pseudomonas aeruginosa
Cefepime or ceftazidome or carbapenem
645
What bacterial virulence factor should you suspect in an infection of a foreign object placed in the body? What is one example of a bacterium that does this?
Biofilm formation - Staphylococcus epidermidis
646
What is the pattern of inheritance of G6PD deficiency?
X-linked recessive
647
What is the cause of skin hyperpigmentation due to chronic venous insufficiency?
Stasis dermatitis due to deposition of hemosiderin from RBC breakdown.
648
What bacterial structure is penicillin most similar to?
D-ala-D-ala - the peptidoglycan terminus. Normally bound by transpeptidase to cross-link chains in the cell wall.
649
In cancer immunotherapy, what is the cellular target on T cells which can be blocked to improve NK destruction of tumor cells? What is the medication that targets this protein?
Programmed death (ligand) receptor -1 (PD-1 / PD-L1)
Blocked by pembrolizumab and atezolizumab
650
What is milrinone used for?
It is a PDE-3 inhibitor (it increases cAMP levels downstream of beta-1 or beta-2 receptor) used in the setting of LV dysfunction.
Increases contractility in heart
Induces vasodilation in veins
651
What patients is succinylcholine relatively contraindicated for?
Patients with significant denervation due to quadriplegia or GBS, crush or burn injuries or myopathies.
Danger of hyperkalemia due to upregulation of the target for succinylcholine (nAChRs) being non-selective for sodium.
652
What therapy is indicated for TIA?
Low-dose aspirin, BP control, statin
653
What is the complication that can result when a chronic hyponatremia is rapidly corrected?
Cerebral demyelination due to uncontrolled cell shrinkage.
654
What causes a patient to be "slow to wake up" from succinylcholine?
Pseudocholinesterase deficiency, leading to inability to rapidly metabolize succinylcholine (can result in paralysis for several hours)
655
How is 2,3-BPG generated in erythocytes?
By bypassing the ATP generation step from 1-3-bisphosphoglycerate to 3 phosphoglycerate.
656
What is the characteristic histology of mesothelioma?
epithelioid type cells with long slender villi and abundant tonofilaments
657
What is the site of colonization for staphylococcus aureus?
The nostrils (nares). Spread is by direct contact producing skin soft-tissue abcess
658
What are the biochemical abnormalities that characterized AD?
Decrease in acetylcholine due to defficiency of choline acetyltransferase in the nucleus basalis of Meynert and hippocampus
659
What electrolyte imbalances occur in the recovery phase of ATN?
Electrolyte wasting due to transient polyuria: **hypokalemia**, hypo Mg++, Ca++ or PO4---
660
What vesel can be penetrated by a posterior duodenal ulcer?
The gastroduodenal artery
661
What is the pathogenesis of decreased glucose secretion in T2DM?
Islet amylin (amyloid) deposition
662
How would you prevent a rapid increase in creatine subsequent to high-dose IV acyclovir?
Aggresssive IV hydration, reduce drug infusion rate if needed
663
Describe the presentation of superior, middle and inferior trunk lesions of the brachial plexus. Which nerve roots are involved?
Superior - C5/C6 presents with Erb palsy (waiter's tip)
Middle = C7 mixed radial + median neuropathy with diminished triceps reflex
Inferior - C8/T1 - Claw hand
664
How would you differentiate malignant hyperthermia from succinylcholine overdose?
Malignant hyperthermia would present with widespread rigidity / spasm and rhabdo
Succinylcholine overdose is going to be floppy paralysis.
665
What is the expected pattern of gastrin and pH in patients with autoimunne gastritis?
Destruction of parietal cells leads to a drop in gastric acid secretion (pH goes up) and stimulates gastrin release by G cells
666
What explains a rise in prevalence over time despite incidence of a disease not increasing?
Improved quality of care (i.e. more people living with the disease)
667
Which structure is at greatest risk of injury in a posterior hip dislocation?
Sciatic nerve
668
What is the most common cardiac malformation in patients with Turner syndrome?
Bicuspid aortic valve
669
What is appropriate prophylaxis for close contacts of a confirmed case of Neisseria meningitidis?
rifampin
670
What paraneoplastic syndromes are associated with renal cell carcinoma?
Erythrocytosis (due to elevated erythropoetin production), IVC obstruction, hypercalcemia
671
How is glycogen metabolism regulated in muscle and liver?
Glycogen phosphorylase breaks down glycogen
activated by phosphorylase kinase (and deactivated by phosphoprotein phosphatase)
In liver epinephrine and glucagon -\> Gs -\> cAMP -\> PK
In muscle, primarily Ca2+ -\> PK (although epinephrine has a smaller effect)
672
What is the most likely primary location of a tumor that presents with middle ear effusion and neck mass?
Nasopharynx obstructing eustachian tube (HNSCC)
673
Describe the signalling cascade of the phosphoinositol system
Gq receptor activation -\> phospholipase C
PIP2 -\> DAG (direct stimulation of PKC) + IP3 (Ca2+ mediated activation of PKC)
674
What bacteria should be cultured for CF exacerbation? What media do you need?
Staph aureus, Haemophilus influenzae (nontypable), Pseudomonas aeruginosa and Burkholderia cepacia complex (esp. advanced disease)
Cultures plated on blood, chocolate, MacConkey, mannitol salt and B cepacia selective agars
675
Nerve compression of the facial nerve would present with what changes to hearing or vision?
Hearing - hyperacusis due to paralysis of stapedius
Vision - loss of efferent limb of corneal reflex
676
Bacteria that grow as parallel chains on culture medium demonstrates which virulence factor?
Cord factor (surface glycolypid) which prevents phagolysosomal destruction and causes caseating granuloma formation.
Mycobacterium tuberculosis
677
What are two identifying charcteristics of EHEC O157:H7? What is the mechanism of the shiga-like toxin that it produces?
Does not ferment sorbitol or produce glucuronidase (unlike other E. coli)
Shiga-like toxin stops protein synthesis by disabling 60S subunit of ribsome.
678
What is the diagnosis based on this kidney slide?
Hypertensive nephrosclerosis - note "onion-skin" appearance
679
What are the two types of systemic sclerosis? What serology is involved? What are the symptoms?
CREST syndrome with distal sclerosis, sometimes evolving to pulmonary hypertension; anticentromere antobidies
Diffuse cutaneus sclerosis on trunk and proximal extremities; progressive to interstitial lung disease and scleroderma renal crisis; anti-SCL-70
680
What is the underlying biochemistry and microscopic appearance of prion disease?
Prion proteins normally in a-helix undergo change to b-pleted sheet: this form is able to cause conformation changes in other proteins and produces neurotoxic fibrils.
Spongiform degeneration of gray matter with microscopic vacuoles.
681
What is the presentation of cutaneous angiosarcoma / Stewart-Treves syndrome? What are the risk factors for it?
red-violet lumps/nodules on the affected limb.
Risk increased by chronic lymphedema e.g. due to a radical lymph node dissection.
682
What is the mechanism of action and indication of dobutamine?
Beta-adrenergic agonist with B1\>B2 activity used for cardiogenic shock / severe LV dysfunction
683
What is the appearance of HbS, HbC and alpha thalassemia on western blot relative to normal hemoglobin?
In order of migration towards anode:
Alpha-thal
Normal Hb
HbS (V -\> E)
HbC (E -\> K)
684
Which maneuvers decrease LV preload? Which increase afterload?
Decrease preload: Valsalva (straining), abrupt standing, nitroglycerin
Increase afterload: sustained hand grip, squat (higher preload and afterload, passive leg raise
685
What is the circulating iron level vs iron in bone marrow in anemia of chronic disease?
Low circulating iron, high iron in bone marrow (due to sequestration in macrophages
686
What structural characteristic of elastin allows it to stretch?
Lysyl oxidase cross-links the elastin monomers, which have lots of hydrophobic amino acids
687
How would a mutation in methylmalonyl-CoA-mutase present?
High methylmalonic and propionic acid -\> **metabolic acidosis**
Hypoglycemia -\> increased fatty acid oxidation, high ketones, **worse acidoses**
Organic acids inhibit urea cycle -\> **hyperammonia**
688
What does molluscum contagiosum look like? What is the virus that causes it?
Where is it most commonly found?
Firm dome-shaped papule with central umbilication
Caused by poxvirus
Generally presents on trunk / face for kids, and sexually transmitted in adults.
689
What is the lesion?
Molluscum contagiosum (note intracytoplasmic eosinophilic inclusion bodies)
690
What injury causes locked-in syndrome?
Bilateral ischemic injury to the ventral pons
691
What factor delays the development of edema in cor pulmonale?
Venous backlog increases hydrostatic pressure in the interstituim, which increases lymphatic return
692
What infection are patients with a central line receiving parental nutrition at greatest risk for?
Candidemia
693
What increases the risk of developing cholera from injestion of Vibrio cholerae?
(low stomach acid / achlorhydria
694
What is the final step / effector in nitrate-mediated vasodilation?
myosin light-chain phosphatase (activated by lower Ca++ levels) -\> dephosphorylates myosin light chain
695
Why does postmenopausal obesity increase risk of endometrial cancer?
Androgens are converted to estrogen via adipose tissues, but ovaries aren't producing progesterone so this is unopposed estrogen which stimulates endometrial proliferation
696
Which step of the TCA results in generation of GTP?
Succinyl-CoA -\> Succinate
697
Electrical stimulation of which nerve is most likely to be helpful in OSA?
Hypoglossal (tongue moves forward which increases AP diameter of airway)
698
Gout or pseudogout? What are the crystals made of?
Rhomboid positively birefringent crystals of calcium pyrophosphate
pseudogout
699
How does the myocardium differ between hypertensive heart disease and hypertrophic cardiomyopathy?
HTN = uniform thickening of the myocardium
HOCM = eccentric thickening of myocardium primarily the septum + disorganized myocardium with fibrosis
700
How would a fibrinous pericarditis present differently from nonbacterial endocarditis in SLE?
Pericarditis = pleuritic chest pain, friction rub, diffuse ST elevation
Nonbacterial endocarditis doesn't tend to cause valve problems and won't explain a friction rub or pleuritic pain
701
What is the pathology on this lung biopsy?
Adenocarcinoma - frequently affects nonsmokers
702
What pathology is shown on this lung biopsy? What is the
Actinomycosis due to actinomyces infection after aspiration.
Characteristic sulfur granules will appear purple on H&E
703
What is the pertechnetate scan test for? What location would you expect to see increased uptake in Meckel diverticulum?
Pertechnetate = gastric mucosa
Meckel is characterized by painless LGI bleed / intusseception often periumbilical or RLQ +ve
704
What would be the result of failure of hindgut descent?
Imperforate anus
705
Name A-E
What are the two black spots?
A - SVC
B - Ascending aorta
C - pulmonary trunk
D - esophagus
E - descending aorta
Black spots = mainstem bronchi
706
How would you differentiate between undertreatment of Myasthenia gravis and overtreatment (cholinergic crisis)
In undertreatment, edrophonium provides improvement in symptoms
Overtreatment, endrophonium doesn't work because NMJ is overstimulated and refractory, so need to stop AChE inhibitors temporarily
707
What is the minimum time that symptoms need to be present for to diagnose major depressive disorder? What about persistent depressive disorder?
Adjustment disorder + depressied mood?
2 or more weeks (avg is 6 months)
For PDD, 2+ years of depressive symptoms (dysthymia, chronic depression)
Adjustment disorder if they don't meet MDD criteria and there is a significant psychosocial stressor within the last 3 months.
708
What is the characteristic presentation of Rett syndrome? Causative mutation?
De-novo X-linked MECP2 gene mutation.
Characteristically girls that develop normally until 6-18 months followed by loss of motor & language skills and sterotypic handwringing. Decreased HC growth, seizures, autistic features, and breathing abnormalities may also present.
709
How is tay-sachs differentiated from Rett syndrome?
Tay-sachs = regression of motor skills but **earlier** (2-6 months) with **macrocephaly** and **cherry red spo**t on macula.
710
What is the strategy for interpreting multiple physical exam findings?
Correct answer should mechanistically explain all of the signs on PE.
711
If an appendix cannot be localized by palpation during appendectomy, what landmark could be used to locate it?
Following the tenaie coli to the root of the vermiform appendix
712
What stain can be used to identify steatorrhea?
Sudan III stain
713
Which monosaccharide is metabolized most quickly in glycolysis?
Fructose, via fructokinase, aldolase B, and triokinase to glyceraldehyde 3-phosphate.
Bypasses phosphofructokinase.
714
What is the mechanism of action of digoxin?
Blocks Na/K ATPase, resulting in:
1) increased intracellular sodium
2) increased intracellular Ca2+ via Na+/Ca++ exchanger
715
What is the most common cause of familial dilated cardiomyopathy?
TTN mutation (AD) causing defect in cardiac sarcomere protein titin
716
What happens to pulmonary artery pressure in cardiogenic shock?
LVEDP is increased, which causes back-transmission to increased PCWP -\> pulmonary edema and higher pulmonary artery systolic pressure -\> can result in RHF
717
What is the culprit bacteria when people present with abdo pain, N/V hours after eating food?
Likely enterotixgenic Staph aureus due to improper food handling by a carrier followed by storage at room temperature \>2hrs -\> enterotoxin.
718
This individual presents with acalculus cholecystitis. What is the diagnosis based on this biopsy of the submucosal gallbladder vessels?
Polyarteritis nodosa
Note fibrinoid necrosis of arterial wall + luminal narrowing and thrombosis
719
An S4 is a sign of?
Left ventricular hypertrophy (i.e. atrium pushing against less compliant wall)
720
What is the virulence factor in E. coli that results in septic shock?
Lipid A (a component of lipopolysacharide) that is toxic to mammalian cells and leads to cytokine release.
721
What is the primary factor that leads to decompensated HF?
Activation of the sympathetic nervous system and RAAS signalling -\> vasoconstriction and fluid retention -\> remodeling -\> decreased CO.
722
What precipitates calcification of the aortic valve?
Chronic hemodynamic stress or atherosclerosis leads to cell necrosis -\> calcification
723
In the setting of coronary artery disease, why would vasodilation of the coronary arteries lead to worsening ischemia in areas downstream of stenoses?
Stenosed arterioles are often already maximally dilated due to release of local vasodilators. When medications vasodilate the nonischemic / nonstenosed circulation, this results in diversion of flow towards these areas, exacerbating the ischemia downstream of the blockage: coronary steal.
724
What is the biggest risk factor for aortic dissection?
hypertension
cystic medial degeneration (Marfan's) in young patients.
725
What peaks within 1 week of receiving B12 for megaloblastic anemia? How long does it take for hemoglobin to normalize?
Reticulocyte count
Hemoglobin normal within 8 weeks
726
What is kussmaul sign?
What is the cause?
Elevated JVP on inspiration (instead of falling)
Rigid pericardium due to constrictive pericarditis = inability to accomodate extra volume in RH.
727
A lesion in what location would cause a pie in the sky lesion (left homonymous superior quadrantanopia?
Temporal lobe -\> damage to meyer's loop
728
Femoral hernia - what population is most common and which side? Describe their location.
Women on the right side
Lateral to the pubic tubercle, medial to femoral vein and below the inguinal ligament.
729
What are the key characteristics of intestinal or hepatosplenic schistomiasis.
Schistosomiasis - diarrhea, abdo pain, ulceration of intestines leading to iron deficiency, hepatosplenomegaly (esp large splenomegaly) portal HTN (cf eso varices) due to fibrosis.
730
What dietary / lifestyle factors inrease risk of gastric adenocarcinoma? What differentiates ulcers that result from NSAID use or Zollinger-Ellison syndrome from cancerous ones?
High-salt diet, processed meat and tobacco use, obesity.
NSAID / Z-E produce benign ulcers with clean, regular borders, no intestinal metaplasia.
731
Does weight loss worsen acne? What other extrinsic factors exacerbate acne?
No, weight loss does *not* worsen acne.
Excessive friction or trauma due to clothing or scrubbing, or comedogenic hair/skin products can worsen acne.
732
What drugs can produce increased blood pressure with reduced heart rate?
High dose dopamine and epinephrine, norepinephrine or, phenylephrine
Due to alpha-1 stimulation leading to vasoconstriction, with reflex bradycardia.
733
What is the target of maraviroc?
The T-cell chemokine receptor CCR5
734
What is the function of the HIV tat and nef genes?
Nef - downregulates MHC-I expression in infected cells
tat - Transcriptional activator -\> increases viral gene expression.
735
Which regions have high prevalence of chloroquine-resistant malaria? What is the strain? What therapy is indicated?
Africa, tropical south america, middle east, asia
P falciparum
Artemisins or atovaquone-proguanil
736
What are the triggers of secondary lactose intolerance? What is the affected enzyme?
Inflammation (e.g. celiac disease) or infection (giardia) affecting SI
Absent/decrease lactase (converts lactose -\> glucose+galactose)
737
What is the long-term complication of chronic hookworm infection? Which organisms cause it?
Microcytic anemia due to iron deficiency
Necator and Ancyclostoma
738
What cancers occur with increased frequency in celiac patients?
T-cell lymphoma
small bowel adenocarcinoma
NOT COLON CANCER
739
What is the diagnosis?
What are some causes?
Constrictive pericarditis
note thickening and calcification of the pericardium.
Radiation, cardiac surgery, TB
740
How would you distinguish measles from rubella based on physical exam?
Rubella characteristically has **bilateral postauricular lympadenopathy** with a faster-spreading paint-bucket rash that does not darken/coalesce.
741
What are the diseases associated with togaviruses?
Toga CREW
Chikungunya
Rubella
Eastern and Western equine encephalitis.
742
What is the mechanism of pembrolizumab?
Blocks PD-1 (programmed-death ligand 1) thus improving cytotoxic T-cell response and promoting tumor apoptosis
743
What is a desmoplastic repsonse?
Common in cancer -\> excessive connective tissue growth or stroma around hte tumor, producing chemoresistance.
744
What drug produces in creased cardiac contractility and vasodilation?
Isoproterenol (B1 = B2 agonist)
B1 agonism increases contractility
B2 agonism results in peripheral vasodilation
745
What are the characteristic changes to left heart size and function due to amyloiad cardiomyopathy?
Enlargement of the LA and LV
Ventricular wall thickening and stiffening resulting in impaired diastolic relaxation -\> back-transfer of pressure to LA and right heart
746
What cancers are associated with BRAF mutation? What is its function?
Melanoma, non-Hodgkin lymphoma, papillary thyroid carcinoma, hairy cell leukemia.
747
Why must PPIs be slowly tapered?
To reduce risk of gastrin-mediated rebound acid hypersecretion
748
What is the association between prostaglandins and acid production in stomach?
Prostaglandins block histamine signalling downstream and increase HCO3 production from epithelial cells, protecting the walls from acid.
749
What is the diagnosis? What is the cause?
Cirrhosis of the liver due to replacement of the normal lobar architecture by regenerative parenchymal nodules.
750
What are the triggers of nonbacterial thrombotic endocarditis?
Cancer (esp mucinous adenocarcinoma) & SLE most commonly
Antiphospholipid syndrome, DIC and extensive burns may also cause it.
751
Where is the most common location for anal fissures?
Posterior midline (distal to dentate line)
752
What are cholestatomas? What causes them?
Pearly mass of squamous cell debris in the middle ear
Primary due to chronic -ve pressure leading to cystic retractions of tympanic membrane
Secondary due to implanttion of squamous epithelium in middle ear
753
What adverse effects do you need to be concerned about when patients are given fibrinolytics?
Hemorrhage - watch for intracerebral signs including decreased LOC, asymmetric pupils or irregular breathing
754
What antihypertensives are contraindicated in the setting of hyperkalemia?
ACE-i, mineralocorticoid recetor blockers (spironoclactone, eplerenone), and ARBs (losartan) and eNaCs (amloride, triamterene)
755
Which vascular territory of the stomach is vulnerable to ischemia if the splenic artery is blocked?
Short gastric artery (poor anastomoses)
756
What is the localization of the lesion and name of the syndrome that explains a finding of agraphia, acalculia, finger agnosia and left/right confusion?
Angular gyrus; Gerstmann syndrome
757
What is the general pattern of neurons and neurotransmitters in the sympathetic nervous system? What are the two exceptions?
1st neuron synapses via ACh nicotinic receptors onto sympathetic chain. 2nd neuron synapses on organ and releases norepi via a/b receptors.
Exceptions: eccrine sweat glands, 2nd neuron is ACh muscarinic
Adrenal medulla, second neuron releases epinephrine and norepinephrine directly into bloodstream.
758
What are the causes and consequences of extramedullary hematopoesis in children?
Causes: severe chronic hemolytic anemia e.g. beta-thal
Consequences: impaired bone growth, chipmunk facies (maxillary overgrowth, frontal bossing), pathologic fractures
759
Which organ is least susceptible to infarction after occlusion of an artery?
Liver due to portal vein supply.
760
How would you differentiate between pheo and neuroblastoma
Neuroblastoma is kids \<2, abdo mass, opsoclonus-myoclonus syndrome (involuntary jerking movements and nonrhythmic eye movements) bone mets, periorbital ecchymoses
Pheo is adults, no opsoclonus-myoclonus
Both can have elevated catecholamine breakdown products in urine (HVA, MVA)
761
Which enzyme involved in heme synthesis is inhibited in the setting of pyridoxine deficiency? What would you see on blood smear stained with prussian blue?
aminolefulinic acid synthase
ringed sideroblasts (microcytic anemia)
762
Which leukotriene is involved in chemotaxis?
Leukotriene B4
763
What drug can be used to decrease heart rate and reduce vascular resistance while not affecting stroke volume?
Labetalol - alpha and beta blockade results in arterial and venous dilatation that is balanced and beta-1 blockade stops reflex tachy
764
What is the treatment for acute intermittent porphyria? What is the mechanism of action?
Hemin - downregulates aminolevulinic acid synthase thereby reducing bulidup of ALA and porphyrins
765
How would you distinguish HSV-1 encephalitis from Naegleria fowleri infection?
HSV-1 more common - starts with **primary oropharyneal infection** leading to headache, fever mental status changes, CN defects and seizures. Receptive aphasia and personality changes occur if temporal lobes affected
Naegleria fowleri = **swimming** in freshwater, **smell/taste abnormalities**; similar presentation of encephalitis
766
What is the diagnosis? How would the lesion appear grossly?
Leukocytoclastic (small-vessel) vasculitis
Nonblanching palpable purpura of the lower extremities
767
What strains of HIV are effectively treated by maraviroc? Which are not?
R5 (CCR5) or macrophage trophic is blocked by maraviroc
X4 (CXCR4) or T lymphotrophic is not
768
Hypersegmented neutrophils are indicative of what kind of anemia?
Megaloblastic anemia (B12 deficiency)
769
What is the most common cause of watery diarrhea in developed countries? Developing countries?
Developed - norovirus esp. congregate settings
Developing - traveller's diarrhea typically enterotoxigenic E coli.
770
What is the Ddx for cholesterol gallstones?
Increased chol synthesis (diet, genetics, DM, obesity, medications e.g. OCP)
Gallbladder hypomotility (pregnancy, somatostatin, fasting, TPN, spinal cord injury)
Increased calcium or mucin (gastric bypass, very rapid weight loss)
Decreased bile acid synthesis or recirculation (fibrates, Crohn disease, ileotomy)
771
What serum levels do you have to monitor when treating someone with amphotericin B?
Potassium and magnesium (due to hypo K+ and hypo Mg++ due to increased membrane permeability / nephrotoxicity)
772
At what point of time after myocardial infarction do the earliest changes appear? What are the changes?
4-12 hours; early coag necrosis, edema, hemorrhage, \*wavy fibers
\*wavy fibres may be apparent earlier than 4 hrs
773
What is the microscopic appearance of this lesion?
Hives / urticaria
Increased vascular permeability due to IgE -\> degranulation of mast cells -\> dermal edema with mixed inflammatory infiltrate
774
What is acantholysis?
Loss of cohesion between keratinocytes due to pemphigus vulgaris & other similar diseases)
775
What is acanthosis? What conditions would present with this finding?
Diffuse thickening ofthe stratum spinosum
Found in psoriasis, seborrheic dermatitis, acanthosis nigricans.
776
What is dyskeratosis? What is the characteristic cellular appearance? What disease presents with it?
Premature and abnormal keratinization of keratinocytes; eosinophilic with basophilic nuclear remnant
Squamous cell carcinoma
777
Why are aluminum hydroxide and magnesium hydroxide often combined in milk of magnesia?
Magnesium causes diarrhea and aluminum causes constipation; together they offset each other's adverse effects
778
What is the stomach pathology shown on the slide?
Signet-ring carcinoma (as opposed to the intestinal type)
779
What are the common complications of chronic Chagas cardiomyopathy?
Cardiac arrhythmias, ventricular aneurysm + intracardiac thrombus, biventricular HF.
NOT aortic pathology
780
What is the molecular cause of bullous impetigo?
Exfoliative toxin A produced by Staph aureus -\> targeting of desmoglein -1 and formation of flaccid bullaeo
Also causes staphylococcal scalded skin syndrome
781
What is the direction of proofreading exonuclease activity which corrects for errors in transcription?
3'-\>5'
as in DNA is synthesized 5'-\>3'
782
What is the pathogenesis of non-alcoholic fatty liver disease?
Insulin resistance -\> increased lipolysis in fatty tissue -\> FAs taken up by heatocytes -\> oxidative damage
783
What is the diagnosis of this colon polyp?
Villous adenoma
784
What is the diagnosis? What is the microscopic appearance
Psoriasis
Disruption of epithelial barrier -\> activation of dendritic cells -\> T-helper cell activation - \> hyperkeratosis + parakeratosis (retained nulcei in stratum corneum).
perivascular lymphocytes, ilated capillaries and acanthosis can also be seen.
785
What is the diagnosis? What is the microscopic presentation?
Buerger disease (thromboangiitis obliterans)
Small & medium vessel segmental vasculitis with inflammatory intraluminal thrombi which extends into veins & nerves and vessel wall sparing.
Presents with raynaud and superficial erythema and vein tenderness (thrombophlebitis)
786
What is procalcitonin? What does it tell you when it's elevated versus depressed?
Calcitonin precursor made by monocytes + C cells.
High = bacterial toxins
Low = viral infections
787
What bacterial toxins increase cyclic AMP concentrations?
Anthrax exotoxin (edema factor) , pertussis toxin.
788
What are the first line treatments for psoriasis? What is their mechanism of action
Steroids
Vitamin D analgs -\> activation of Vit D receptor -\> inhibition of T cell and keratinocyte proliferation.
789
What is this kidney tumor? If an individual has bilateral tumors like this, what is the most likely diagnosis?
Renal angiomyolipoma
Tuberous sclerosis
790
What spleen changes are expected in alcholic liver disease?
Portal hypertension leading to splenomegaly, conjestion and expansion of the red pulp
791
In a patient who is started on a new medication and then experiences changes in their health, what must be on your differential?
Drug adverse effects or interactions.
792
What histology is characteristic of contact dermatitis?
spongiosis - accumultaion of edema fluid, lymphocyte and eosinophil infiltration,
793
How would you distinguish between the two key types of heart pathology common in Marfan syndrome?
Mitral prolapse & regurgitation - myxomatous degeneration of valve leaflets, midsystolic clic and late systolic apical murmur
Aortic root dilatation and aortic regurg; decrescendo *diastolic* murmur
794
What two structures contribute to LV outflow tract obstruction in HOCM?
Thickened septum and anterior mitral leaflet block aortic valve.
795
What is the diagnosis? What happens when plaques are removed?
How is it differentiated from Lichen Planus?
Plaque psoriasis
Lichen planus 5Ps palpable, polygonal, pruritic, purple/pink, planar, papules/plaques
