UWorld Test 5/30/2014

Question 1

Majority of patients with MG have what kind of mass>

Answer 1

thymoma / thymic hyperplasia

Question 2

The majority of cancers in the head and neck are? Where do they tend to develop?

Answer 2

Squamous cell carcinomas. Oral cavity - ventral dongue, floor of the mouth, lower lip, soft palate and gingivae are the most common locations

Question 3

What is the MOA for nitroglycerin. How does it affect heart rate, contractility, end diastolic volume, blood pressure, ejection time and myocardial oxygen consumption

Answer 3

Decreases angina by overall reduction in myocardial oxygen consumption. Increases vascular smooth muscle relaxation, especially in the veins compared to arteries => vendodilators. => decrease venous return and end diastolic volume. There is reflexive increase in heart rate and contractiliy which can be treated with beta blockers. ejection time and myocardial oxygen consumption decrease

Question 4

What is alleleic heterogeniety?

Answer 4

Different mutations in the SAME genetic locus causes similar phenotypes. Example Duchenne and Becker muscular dystrophy.

Question 5

Superior rectain vein drains into what? Which further drains into?

Answer 5

Superior rectal => inferior mesenteric => splenic vein

Question 6

Splenic vein meets with the superior menesteric vein to form?

Answer 6

Portal vein

Question 7

What is achondroplasia?

Answer 7

Constitutive action of FGFR3 gene => leads to inhibition of chondrocyte proliferation and failure of enchondral ossification which means failure of long bone growth. => dwarfirsm. >85% are sporadic though also shows some a/d inheritance. a/w advanced paternal age

Question 8

What is Bruton’s agammaglobulinemia? What is the inheritance?

Answer 8

B cell disorder. X linked.BTK gene defect => Impaired intracellular messaging. No B cell maturation. Leads to recurrent bacterial and enteroviral infections after 6 months. Lab: absent CD19+ cells, decreased pro-B, decreased Ig of all classes. Abscent/scanty lymph nodes

Question 9

Proteins designated for the ER have what?

Answer 9

N terminal peptide signaling sequences. These N terminal sequences are translated in the cytosol and are rapidly recognized by signal recognition particles which halt translation and target the ribosome to protein pores in the RER. Once bound, the SRP dissaciates, translation continues with the pp being fed into the RER. SRP are hydrophobic and are compose of 15-20 a.a.

Question 10

What is articular cartilage? What kind of cartilage is found in this? What is the main collagen type?

Answer 10

Cartilage found on bone in joint spaces. Hyaline cartilage is found in articular cartilage. The main type of collagen is collagen type II.

Question 11

Collagen can be stained with what?

Answer 11

Safranin O stains CARTILAGE mucin and mast cell granules red.

Question 12

Pheochromocytomas results in elevated levels of?

Answer 12

Serum catecholamines, metanephrine, and vanillymandelic acid.

Question 13

What is the normal range for 1) PaO2 2) PaCO2 3) Bicarb and 4)pH

Answer 13

1) 80-95mmHg 2) 35-45mmHg 3) 22-26mEq/L 4)7.35-7.45

Question 14

What happens with pulmonary embolism

Answer 14

Pulmonary embolism => V/Q mismatch => hypoxemia => hyperventilation => respiratory alkalosis. High pH, low pAO2 and paCO2

Question 15

What kind of expression is NFtype1

Answer 15

A/D, 100% penetrance with variable expressivity

Question 16

Phenoxybenzamine vs phentolamine

Answer 16

Both are non selective alpha blockers. Phenoxybenzamine is NON-COMPETITIVE IRREVERSIBLE alpha blocker with a LONG HALF LIFE (24 hours with effects lasting 3-4 days). Used for pheochromocytomas to avoid hypertensive crisis. Phentolamine is a reversible alpha blocker with a shorter half life.

Question 17

What are the toxicities of amiodarone

Answer 17

Interstitial pneumonitis - progressive dyspnea and nonproductive cough. Causes arrythmias, photosensitivity, hepatic injurity, thryoid abnormalitie (amiodarone is 40% iodine by weight), ocular changes, bluish gray skin discoloration. Corneal deposits.

Question 18

What is palmitoylation?

Answer 18

Process by which fatty acids are covalently anchored to plasma membrane cystein residues => increases hydrophobicity of a protein

Question 19

CFTR function in sweat glands?

Answer 19

Normally reabsorbs NaCl. Mutated CFTR => diminishes this and increases sweat tonicity.

Question 20

CFTR function in respiratory and intestinal epithelieum

Answer 20

Normal CFTR allows for active chloride secretion. Mutated => reduces luminal chloride secretion and increases luminal sodium reabsorption. Water follows sodium => and depletes the water content of the surface fluid layer. Isotonic low volume surface fluid layer leads to production of thick viscous secretions.

Question 21

What is the level of testosterone in the seminferous tubules relative to testosterone in circulation?

Answer 21

Seminiferous tubules and epididymis must have more in order for spermatogenesis and sperm maturation to occur.

Question 22

How is a high concentration of testosterone in the seminferous tubules achieved?

Answer 22

Sertoli cells synthesize and secrete androgen binding protein. ABP binds to testosterone and DHT and makes them less lipophilic, thereby concentrating them to the luminal fluid

Question 23

Superior cervical sympathetic ganglion innervates

Answer 23

Lacrimal, salivary, radial muscle of iris, tarsal muscle

Question 24

Thoracic cervical sympathetic trunk innervates

Answer 24

Sweat glands among others

Question 25

Metabolic derangements with DKA

Answer 25

Metabolic acidosis, hyperkalemia, hyponatremia, glycosuria, ketonemia, hyperglycemia. Block 2 of UWSA1 Item 5/33 of “correct” answers has amazing explanation

Question 26

What cells synthesize leukotrienes

Answer 26

Eosinophils and mast cells

Question 27

Efflux pumping by resistant bacteria requires

Answer 27

ATP. Relies on H+ gradient for energy to pump drug out

Question 28

Round ligament of the uterus is a remant of what? What does it connect/pass through?

Answer 28

Guburnaculum. Passes through the inguiinal ligament. Connects uterus to labia major. Upper part of the gubuernaculum becomes proper ovarian ligament which connects the uterus to the ovary

Question 29

What is platelet activating factor? What signaling pathway does it use?

Answer 29

Promotes platelet aggregation through the Gq/IP3 pathways. Excess PAF can cause bronchoconstriction, vasocontriction

Question 30

Rapid infusion of what leads to red man syndrome?

Answer 30

vancomycin. Widespread histamine release via nonspecific mast cell degranulation. NOT an IgE mediated reaction.

Question 31

Know what epidural hematoma vs subdural hematoma vs subarachnoid hemorrhage vs intraparenchymal hemorrhage look like

Answer 31

Epidural hematoma = convex shape, subdural hematoma = crescent shape, SAH = blood in the sucli/ventricles, intraparenchymal = intraparenchyma/often basal ganglia

Question 32

SAH usually occurs due to the rupture of? What are they a/w?

Answer 32

Saccular (berry aneuryms) or AVMs. Saccular aneuryms are associated with ADPKD, Marafan’s and ehler’s Danos

Question 33

What is the most common presentation of recurrent hemorrhagic stroke?

Answer 33

Cerebral amyloid angiopathy

Question 34

Recurrent lobar hemorrhages in an elderly patient is most associated with what?

Answer 34

Cerebral amyloid angiopathy. Beta amyloid depsots in vessel walls, weakening them. They are NOT associated with systemic amyloidosis. They tend to occur in the cerebral hemispheres (lobar strokes) and involve smaller areas of the brain parenchyma. VS hypertensive strokes are larger and tend to occur in the basal ganglia

Question 35

What are signs of thalamic syndrome?

Answer 35

Thalamic syndrome is when there is an ischemic or hemorrhage event that affects the VPL and VPM of the thalamus leading to complete contralateral sensation loss. Although there are no motor deficits per say, propioception loss can be so severe it can affect ambulation

Question 36

What is the most common cause of asesptic meningitis?

Answer 36

Enterovirus

Question 37

What are enteroviruses?

Answer 37

SS+RNA, naked, icosahedraol, Picornaviridae - include poliovirus, echovirus, coxsacie virus A and B, hep A. most common cause of aseptic Poliovirus can also affect lower motor function by affecting the anterior horn

Question 38

What presents in von Hippel Landau disease

Answer 38

Cavernous hemangiomas (benign, self involuting tumor of the endothelial cells that line the blood vessels) in skin, organs, mucosa; congenital cysts/neoplasms of kidney, pancreas, liver; bilateral renal cell carcinoma, and HEMANGIOBLASTOMAS in retina, cerebellum, brain stem; pheochromocytomas. A/D.

Question 39

What happens to area of brain infarct following thrombosis or embolism?

Answer 39

Infart => neuronal cell death (macroscopically changes seen within 12 hours) => neutrphils move into start eating up => microglia come in 3-5 days. Microglia eat the disintegrating neurons => abundance of phagocytic myelin breakdown causes abundance of lipids

Question 40

Paraneoplastic syndrome process? How can it affect the brain?

Answer 40

Antibodies against tumor cells start cross reacting against body’s own tissue. Can produce paraneoplastic cerebellar degeneration which is autoimmune. Common places of paraneoplastic cancrs = lung, breast, ovary, uterus, lymphoma

Question 41

What is a rare neurologic complication of measles?

Answer 41

Subacute sclerosing encephalitis. Thought to be a strain of measles that does not that the antigen M protein, therefore antibodies doesn’t effectively clear it. Antibodies to the M protein in titers are missing. There are high titers of antibodies to measles and oligoclonal bands of immunoglobulins

Question 42

What test should be done if one suspects temporal arteritis?

Answer 42

ESR is uniformly elevated often >100mm/hr. biopsy is needed for diagnosis. Steroid treatment should be started asap to prevent vision loss.

Question 43

What do these following viruses bind to? 1) CMV 2) EBV 3) HIV 4) Rabies 5) Rhinovirus

Answer 43

1) cellular integrins 2) CD21 3) CD4, CXCR4, CCR5 4) Nicotinich Ach R 5) ICAM-1 (CD54)

Question 44

Which pediatric tumors arise in the cerebellum?

Answer 44

Pilocytic astromas and medulloblastomas

Question 45

What are the microscopic findings of medulloblastomas?

Answer 45

Sheets of primitive cells with many mitotic figures. They are “primitive neuroectoerdermal tumors” (PNETS).Sheets of small cells with deeply basophilic nuclei and scant cytoplasm (small, round blue cells).