2015.04.11

Question 1

Adrenal Medulla

Answer 1

Contains chromaffin cells (modified postganglionic sympathetic neurons that release catecholamines into the bloodstream in response to acetylcholine released by preganglionic sympathetic neurons) with deeply basophilic cytoplasm.

Question 2

Abnormal migration of neural crest cells through the primitive truncus arteriosus and bulbus cordis

Answer 2

Tetralogy of Fallot

Transposition of the great vessels

Truncus arteriosus

Question 3

Endocardial cushion defects

Answer 3

Defects of the AV septum. Initially manifest as an acyanotic form of congenital herat disease because they form a L-R shunt.

Over time, the increased right-sided blood flow leads to pulmonary hypertension, reversal of the blood flow through the shunt (Eisenmenger syndrome) and development of cyanotic symtpoms.

Question 4

Meningiomas

Answer 4

Located adjacent to the cerebral surface.

Parasagittal meningiomas cause contralateral spastic paresis of the leg due to compression of the leg-foot motor area.

Concentrically-arranged meningothelial cells. Psammoma bodies (concentric laminar calcifications) are characteristic.

Question 5

Rolling

Answer 5

Neutrophils: Sialyl Lewis X or L-selectin

binds to

Endothelium: E-selectin/P-selectin

Cytokine stimulation greatly increases expression of endothelial selectins.

Question 6

Tight Adhesion and crwling

Answer 6

Neutrophils: CD18 beta 2 integrins (Mac-1 and LFA-1)

binds to

Endothelium: ICAM-1

Question 7

Transmigration

Answer 7

Neutrophils migrate out of vasculature by squeezing in between the cells via integrin attachments and adherence to platelet endothelial cell adhesion molecule 1 (PECAM-1)

this protein is found at peripheral intercellular junctions of endothelial cells

Question 8

LAD type 1

Answer 8

Leukocyte adhesion deficiency (LAD) with absence of CD18 (no synthesis of beta-2 integrins Mac-1 and LFA-1) results in defective tight adhesion, crawling, and transmigration.

Recurrent skin infections without pus formation, delayed detachment of the umbilical cord, and poor wound healing.

Question 9

Femoral Nerve Injury

Answer 9

Due to pelvic fracture or mass involving iliopsoas/iliacus muscle (hematoma or abscess)

Weakness of quadriceps muscles develop - flexion of thigh, extensions of leg

Loss of sensation over anterior and medial thigh and medial leg.

Question 10

Brachiocephalic veins

Answer 10

Drains the ipsilateral internal jugular and subclavian veins.

The bilateral brachiocephalic veins combine to form the SVC.

Obstruction causes symptoms similar to SVC syndrome, but on one side of the body. (Right obstruction: Venous congestion of structures drained by external jugular and right lymphatic duct)

Question 11

Kussmaul sign

Answer 11

Paradoxical rise in jugular venous pressure (JVP) due to volume-restricted right ventricle unable to accomodate the inspiratory increase in venous return.

JVP should normally drop during inspiration.

Constrictive pericarditis can be cause.

Question 12

Most common side effect of aspirin

Answer 12

Increased GI blood loss.

GI bleeding due to loss of gastric cytoprotection (PGE2 and PGI2 - made by vascular endothelial cells) in addition to impaired platelet aggregation (Thromboxane A2 - made by platelets).

Question 13

Equilibrium potential

Answer 13

electrical potential difference that moves ions into the cell at the same rate as they leave the cell along the concentration gradient.

When a specific ion channel opens, the respective ions will flow across the membrane in a direction that brings the resting membrane potential closer to that ion’s equilibrium potential.

Question 14

Amphotericin B

Answer 14

Drug of choice for systemic mycoses.

Side effect: nephrotoxicity - decrease in GFR and direct toxic effects on tubular epithelium.

Hypokalemia (causes weakness and arrhythmias - T-wave flattening, ST depression, prominent U waves, premature atrial and ventricular contractions) and hypomagnesemia are common due to increase in membrane permeability of the distal tubule.

Question 15

Carbamazepine

Answer 15

Treatment of simple partial, complex partial, and generalized tonic-clonic seizures.

Blocks voltage-gated sodium channels in neuronal membranes.

Side effects: Bone marrow suppression, hepatotoxicity, and increase in ADH secretion may result in SIADH.

Question 16

Subacute sclerosing panencephalitis

Answer 16

Complication of measles infection that occurs several years after recovery from initial infection.

Oligoclonal bands of measles virus antibodies are found in the CSF.

Caused by a form of measles virus with mutated/absent matrix protein (important for viral assembly) that prevents mature virion particles from forming. Virus continues to replicate intracellularly, leading to persistant, nonproductive infection. Accumulation of viral nucleocapsids within neurons and oligodendrocytes results in formation of intranuclear inclusions.

Question 17

Congenital Adrenal Hyperplasia

Answer 17

21-hydroxylase deficiency (Progesterone to 11-Deoxycorticosterone; 17-hydroxyprogesterone to 11-deoxycortisol)

Affected female presents at birth with ambiguous (virilized) genitalia.

Male infants have normal genitalia and present later with salt-wasting or precocious puberty.

Diagnostic: Elevated 17-hydroxyprogesterone.

Question 18

Congenital Rubella

Answer 18

congenital cataracts (white pupils), sensory-neural deafness, and patent ductus arteriosus.

Neonatal defects of the head (microcephaly, mental retardation), eyes (cataracts), ears (deafness), and heart/CV system (patent ductus arteriosus, peripheral pulmonic stenosis).

Question 19

Achondroplasia

Answer 19

Autosomal dominant

Gain-of-function mutation in the FGFR3 gene (fibroblast growth factor receptor 3).

Occurs as a sporadic mutation in 85% cases and inherited in 15% cases.

Question 20

Staphylococci

Answer 20

Gram+ cocci, catalase-positive (Streptococci are catalase-negative).

Ability to clot blood plasma (coagulase) separates Staphylocci into 2 groups:

Coagulase + : S. aureus (mannitol fermentation, yellow pigment production)

Coagulase - : S. epidermidis (most common cause of infective endocarditis in patients with prosthetics; novobiocin sensitive), S. haemolyticus, S. saprophyticus (novobiocin resistance)

Question 21

Brain Natriuretic Peptide (BNP)

Answer 21

Elevated in patients with heart failure.

Released by the ventricles when they are stretched due to increased blood volume (as they are in CHF from systolic dysfunction).

Acts along with ANP to cause vasodilation (decreased preload) and diuresis.

ANP and BNP activate guanylate cyclase, which increases intracellular cGMP.

Question 22

Hyperammonemia in Hepatic encephalopathy

Answer 22

Depletion of alpha-ketoglutarate during process of ammonia detoxification, causing inhibition of the Krebs cycle.

Depletion of glutamate, an excitatory neurotransmitter, and causes accumulation of glutamine, resulting in astrocyte swelling and dysfunction.

Question 23

Migraine Headaches

Answer 23

Unilateral, have pulsating or throbbing quality, and associated with photophobia, phonophobia, and nausea.

Triptans are serotonin 5-HT1B/5-HT1D agonists (inhibit the release of vasoactive peptides, promoting vasoconstriction, and blocking pain pathways in the brainstem) used as abortive therapy during acute migraine.

Beta-blockers, antidepressants, and anticonvulsants are used for prophylaxis.

Question 24

Glucagonoma

Answer 24

Rare tumor arising from alpha-cells

Diabetes mellitus (due to hyperglycemia), necrolytic migratory erythema (bronze-colored induration) and normochromic normocytic anemia.

Diagnosis: Elevated glucagon levels

Question 25

Pure red cell aplasia

Answer 25

Severe hypoplasia of marrow erythroid elements in the setting of normal granulopoiesis and thrombopoiesis.

Associated with thymoma, lymphocytic leukemias, and parvovirus B19 infection.

Question 26

Facial pain, headache, black necrotic eschar in the nasal cavity in a patient with diabetic ketoacidosis

Answer 26

Suggestive of mucormycosis.

Fungi show broad nonseptate hypahe with right-angle branching.

Treatment: surgical debridement and antifungal therapy (amphotericin B)

Question 27

Poststreptococcal glomerulonephritis prognosis

Answer 27

cola-colored urine and facial edema

associated with age.

worse in adults (95% children recover completely, only 60% in adults)

Question 28

Piperacillin-tazobactam

Answer 28

Combination of extended-spectrum penicllin with B-lactamase inhibitor.

Effective against most gram - enteric rods (including Pseudomonas aeruginosa and Bacteroides fragilis)

Question 29

Atrophic gastritis

Answer 29

Results in profound hypochlorhydria, inadequate intrinsic factor production, vitamin B12 deficiency and elevated methylmalonic acid levels.

Reticulocyte count increases dramatically once vitamin B12 replacement therapy is initiated in an individual with pernicous anemia.

Question 30

Papillary thyroid cancer

Answer 30

Most common type of thyroid cancer.

Diagnosis: fine-needle aspiration by characteristic cell morphology showing large cells with nuclei containing finely dispersed chromatin with a ground-glass appearance (Orphan Annie eye).

Numerous intranuclear inclusions and grooves can be seen due to invagination of nuclear membrane.

Psammoma bodies (laminated calcium deposits) found within tumor.

Question 31

Ebstein’s anomaly

Answer 31

Apical displacement of tricuspid valve leaflets, decreased right ventricular volume, and atrialization of the right ventricle.

Cause: Lithium (anti-manic medication used to treat bipolar disorder) exposure in utero

Question 32

Fetal Alcohol Syndrome

Answer 32

Midfacial anomalies

Growth retardation

Mental retardation