Week 5

Question 1

What are the important enzymes involved in gluconeogenesis?

Answer 1

Glycogenolysis is the primary source of glucose for the first 12-18h after fasting; once hepatic glycogen stores become depleted, gluconeogenesis becomes major process used by body to keep blood glucose levels w/in normal range;

Hexokinase, phophofructokinase, and pyruvate kinase are unidirectional and must be bypassed by distinct gluconeogenic enzymes

Important enzymes:

Pyruvate to oxaloacetate (mitochondria) - pyruvate carboxylase

Oxaloacetate to phosphoenolpyruvate (cytosol) - phosphoenolpyruvate carboxykinase (PEPCK)

Phosphoenolpyruvate to glucose (cytosol) - glycerol 3 phosphate

Question 2

Where are leads placed in a biventricular pacemaker?

Answer 2

First two leads are placed in right atrium and right ventricle via the left subclavian vein and SVC.

Third lead for LV is passed from the right atrium into coronary sinus, which resides in atrioventricular groove on posterior aspect of the heart.

Question 3

What is echinococcosis?

Answer 3

Pathogenesis: Echinococcus granulosus is the most common cause of hydatid cysts. Resides w/in sheep and dog (participate in tapeworm life cycle);

Presentation: liver is often affected; lungs or muscles can be involved

Histology: inflammation involving monocytes and eosinophils; encapsulated and calcified cyst (“eggshell calcification”) containing fluid and budding cells that will eventually become daughter cysts; outer wall composed of gelatinous sheets surrounded by thick fibrous capsule

Dx: imaging (US, CT, MRI) and serology; cyst manipulation (surgery, aspiration) should be performed w/ caution, as spilling of cyst contents causes anaphylactic shock

Question 4

What is small cell carcinoma of the lung (oat cell carcinioma)?

Answer 4

Most aggressive type of lung cancer; central location

Presentation: produces ACTH, SIADH, antibodies against presynaptic Ca2+ channels or neurons (Lambert Eaton); amplification of myc oncogenes common

Histology: neoplasm of neuroendocrine Kulchitsky cells –>small, dark blue cells; positive for - chromogranin A, neuron-specific enolase, neuron cell adhesion molecule (NCAM, also known as CD56), synaptophysin

Tx: chemo +/- radiation

Question 5

What is renal papillary necrosis?

Answer 5

Presentation: gross hematuria, acute flank pain, and passage of tissue fragments in urine

Most commonly seen in patients w/ sickle cell disease or trait, DM, analgesic nephropathy (NSAIDs), or severe obstructive pyelonephritis

Gray-white or yellow necrosis of distal two-thirds of renal pyramids, coagulative necrosis; sloughed papillae

Question 6

What is syphilis?

Answer 6

Causative agent: treponema pallidum; spirochetes are motile and helical

Presentation: single, painless ulcer at inoculation site w/ heaped up borders and clean base

Dx: VDRL/RPR, dark-field microscopy or fluorescent antibody testing (gold standard)

Question 7

What is genital herpes?

Answer 7

Causative agent: HSV

Presentation: multiple, painful superficial vesicles or ulcerations w/ erythematous base; latent in dorsal root (sensory) ganglia

Histology: multinucleated giant cells and intranuclear inclusions (Cowdry type A)

Dx: PCR, Tzanck smear

Tx: daily treatment w/ oral acyclovir, valacyclovir, or famciclovir to reduce recurrence; short course (7-10d) w/ oral acyclovir during primary genital HSV infection to reduce duration of viral shedding

Question 8

What is chancroid?

Answer 8

Causative agent: Haemophilus ducreyi

Presentation: deep, purulent, painful ulcers w/ matted/suppurative lymphadenitis

Histology: organisms often clump in long parallel strands (“school of fish”)

Dx: graim stain and culture; PCR

Question 9

What is granuloma inguinale (donovanosis)?

Answer 9

Causative agent: Klebsiella granulomatis

Presentation: painless, progressive, red serpiginous ulcerative lesions

with NO lymphadenopathy; base may have granulation-like tissue

Dx: gram-negative stain and culture (difficult); biopsy (Donovan bodies)

Complications: elephantiasis

Question 10

What is human placental lactogen?

Answer 10

It increases maternal insulin resistance during the 2nd and 3rd trimesters, leading to a rise in serum glucose and proteolysis that help provide adequate nutrition to the growing fetus.

Increase in lipolysis: produces free fatty acids and ketones to provide energy to mother (preserving glucose and aa for the fetus).

Gestational diabetes occurs when the compensatory rise in maternal insulin is inadequate to prevent serum glucose levels from reaching excessively high levels.

Question 11

What is the form of candida albicans at 20 and 37 degrees?

Answer 11

20: pseudohyphae and budding yeasts
37: germ tubes (true hyphae from yeast) in the body

Question 12

What is the pudendal nerve block?

Answer 12

A pudendal nerve block is performed by injecting an anesthetic intravaginally, medial to the ischial spine, through the sacrospinous ligament. Provides anesthesia to most of the perineum.

Question 13

What is CREST syndrome?

Answer 13

Occurs in the limited form of scleroderma that primarily affects the skin (face, forearms, and fingers) + CREST

Pathogenesis: chronic autoimmune inflammation, vascular endothelial injury resulting in chronic ischemic tissue damage (fingertip ulcers) and excessive activation of fibroblasts leading to progressive tissue fibrosis

Presentation: Calcinosis, anti-Centromere antibody, Raynaud phenomenon, Esophageal dysmotility, Sclerodactyly, Telangiectasia

Esophageal dysmotility: result of atrophy and fibrous replacement of muscularis layer in lower esophagus; can cause GERD w/ increased risk of Barrett’s esophagus and stricture formation; pulmonary HTN is a common complication of systemic sclerosis

Diffuse form: widespread skin involvemnt; antiScl70 (anti DNA topo I) antibody

Question 14

What is a strawberry-type capillary hemangioma (juvenile hemangioma)?

Answer 14

Cutaneous, common, benign, congenital tumors; composed of unencapsulated aggregates of closely packed, thin walled capillaries

Presentation: initially grow in proportion to growth of child, eventually regress; in 75-95% of cases, vascular tumor will regress completely by 7yo

Question 15

What are the selective estrogen receptor modulators?

Answer 15

Raloxifene: estrogen agonist in bone; antagonist in breast and uterus; no increased risk for endometrial cancer, good for osteoporosis

Tamoxifen: estrogen antagonist in breast; agonist in bone and uterus; increased risk for endometrial hyperplasia/cancer; not appropriate for use in osteoporosis

Question 16

What is essential tremor?

Answer 16

Pathogenesis: common movement disorder; referred to familial tremor as it follows AD inheritance

Presentation: slowly progressive, symmetric postural and/or kinetic tremor that commonly affects the upper extremities; worsens while maintaining a particular posture (when holding an object); symptoms improve with Etoh consumption

Tx: propranolol (non-selective Beta adrenergic antagonist) is first line

Question 17

What is arsenic poisoning?

Answer 17

Mechanism: binds to sulfydryl groups; disrupts cellular respiration via inhibition of pyruvate dehydrogenase, and gluconeogenesis and glutathione metabolism

Sources: pesticides/insecticides; contaminated water (often from wells); pressure-treated wood

Presentation: acute - garlic breath or stool, vomiting, watery diarrhea, QTc prolongation, hypotension from dehydration; chronic - hypo/hyperpigmentation, hyperkeratosis, stocking-glove neuropathy

Tx: dimercaprol; DMSA (meso dimercaptosuccinic acid, succimer)

Question 18

What is vitamin E deficiency?

Answer 18

Function: scavenger of free radicals (antioxidant)

Pathogenesis: may occur in pts w/ fat malabsorption and abetalipoproteinemia

Presentation: hemolytic anemia;

Neurologic dysfunction (due to free radical damage of cell membranes); ataxia (due to degeneration of spinocerebellar tracts), loss of position and vibration sense (due to degeneration of dorsal columns), and loss of deep tendon reflexes (due to peripheral nerve degeneration); neurologic sx closely mimic Friedrich ataxia

Question 19

What is an accessory nipple?

Answer 19

The most common congenital breast anomaly resulting from failed regression of mammary ridge in utero; asymptomatic; can occur anywhere along the embryonic milk line between axilla and perineum; bilateral in 50% of patients

Presentation: may swell or become tender similar to normal breast tissue before or during menses, pregnancy, and lactation;

Histology: hyperpigmented, epidermal thickening

Question 20

What structures are derived from the pharyngeal pouch?

Answer 20

1: epithelium of middle ear and auditory tube; pharyngeal membrane - tympanic membrane; pharyngeal groove - epithelium of external ear canal
2: epithelium of palatine tonsil crypts
3: thymus, inferior parathryoid glands
4: superior parathyroid glands, ultimobranchial body

Question 21

What is neurocysticerosis?

Answer 21

Microbiologiy: ingestion of Taenia solium (pork tapeworm) eggs excreted in feces of human carriers

Presentation: common in Central and South America, sub-Saharan Africa, Asia; prolonged incubation (months to years); seizures, focal neurologic symptoms, intracranial hypertension (CSF obstruction)

Dx: CT/MRI - cysts, scolex; eosinophilia, increased ESR

Tx: albendazole

Question 22

What is cutaneous small vessel vasculitis?

Answer 22

Pathogenesis: it is associated w/ medication (e.g., penicillins, cephalosporins, sulfonamides, phenytoin, and allopurinol) use

Presentation: palpable purpura in lower extremities

Histology: Marked perivascular inflammation of small blood vessels with fibrinoid necrosis and a predominance of neutrophils and fragmented neutrophilic nuclei (leukocytoclastic vasculitis); mononuclear cells predominant in older lesions

Question 23

What is phencyclidine (PCP)?

Answer 23

MOA: an N methly D aspartate (NMDA) receptor antagonist; less effects on reuptake inhibition of NE, D, and SE; also has effects on sigma opioid receptors

Presentation of overdose: agitation, hallucinations; loss of coordination, horizontal/vertical nystagmus; memory loss, disorientation, poor judgment; hypertensive, tachycardic; delirium; psychosis, seizures

Fatalities due to related violent trauma due to combative behavior

Question 24

What is idiopathic intracranial hypertension?

Answer 24

Pathogenesis: increased ICP transmitted through CSF in subarachnoid space, which is continuous w/ optic nerve sheath; pressure compresses optic nerves which impairs axoplasmic flow w/in optic nerves causing bilateral optic disc edema (papilledema)

Presentation: young obese woman with daily headache, bilaterally symmetric papilladema, and transient visual disturbances related to impaired cerebral venous outflow and elevated ICP; sx worsen during valsalva (bending down, coughing, lifting objects) as ICP increases; HA, tinnitus, diploplia

[Female, tetracyclines, obesity, vit. A excess, Danazol (female TOAD)]

Fundoscopy: optic disc is elevated w/ blurred disc margins

Lumbar puncture reveals increased opening pressure and provides temporary HA relief

Tx: weight loss, acetazolamide, invasive procedure for refractory cases (e.g., CSF shunt placement, optic nerve sheath fenestration surgery for visual loss)

Question 25

What is acute hemolytic transfusion reaction?

Answer 25

An antibody-mediated **(type II) hypersensitivity** reaction caused by **pre**-**existing** anti-ABO antibodies that bind antigens on transfused donor erythrocytes. Presentation: **complement activation** results in erythrocyte **lysis**, vasodilation, and symptoms of shock; fever, hypotension, chest and back pain, hemoglobinuria

Question 26

What is extramedullary hematopoiesis?

Answer 26

The presence of erythroid precursor cells in the **liver** and **spleen** is indicative of **extramedullary hematopoiesis**. Characterized by EPO-stimulated, hyperplastic marrow cell invasion of extramedullary organs. Extramedullary hematopoiesis is most frequently caused by severe **chronic** **hemolytic** **anemias**, such as **Beta** **Thalassemia**.

Question 27

What is tetralogy of fallot?

Answer 27

Pathogenesis: abnormal **neural** **crest** **cell** migration leading to anterosuperior **deviation of the infundibular septum;** results in a **malaligned** **VSD** and an **overriding** **aorta** Findings: Pulmonary infundibular stenosis, Right ventricular hypertrophy, Overriding aorta , VSD Presentation: **cyanosis** due to right to left shunt, harsh, systolic ejection murmur **Squatting** increases peripheral SVR (afterload) and decreases degree of right ot left shunt across **VSD**

Question 28

What is phenylephrine?

Answer 28

A selective alpha 1 adrenergic receptor agonist that **increases peripheral vascular resistance (vasocontrictor) and systolic blood pressure**; **decreases pulse pressure and heart rate**.

Question 29

What is Zollinger Ellison Syndrome?

Answer 29

**Gastrin** secreting tumor of **pancreas** or **duodenum** Pathogenesis: Gastrin-secreting **neuroendocrine** tumors (**gastrinomas**); commonly located in the SI or pancreas; gastrin leads to **_increased gastric acid production_** resulting in peptic ulcers that are located **beyond duodenal bulb**; refractory to therapy Presentation: **abdominal pain** and **acid reflux**; **diarrhea** due to acidic damage to intestinal epithelial cells and inactivation of pancreatic enzymes, **preventing** **nutrient** **absorption** Histology: **_rugal thickening_** Dx: measuring basal and stimulated gastrin levels (**positive** **secretin** stimulation test; gastrin levels **remain** **elevated**, secretin does not work to decrease gastrin); Associated w/ **MEN 1**

Question 30

What is a cricothyrotomy?

Answer 30

Indication: when an emergency airway is required and orotracheal or nasotracheal intubation is either **unsuccessful** or **contraindicated** (due to massive hemorrhage, vomiting, facial trauma, or airway obstruction) Procedure: incision made between **thyroid and cricoid cartilages**; passes through skin, **superficial cervical fascia** (including subq fat and platysma muscle), investing and pretracheal layers of **deep cervical fascia**, and the **cricothyroid membrane**

Question 31

What is glucagonoma?

Answer 31

Pathogenesis: rare tumor arising from the **alpha cells** of pancreatic islets of Langerhans Presentation: **necrolytic migratory erythema** (painful, pruritic rash that affects the **face**, **groin**, and **extremities**); **erythematous papules/plaques** on face, perineum and extremities (crusts and scaling at borders/central areas of brownish induration); **hyperglycemic or overt diabetes mellitus**; **GI distress** (diarrhea, anorexia, abdominal pain) [Ds: **Dermatitis**, **Diabetes**, **DVT**, **Declining** weight, **Depression**] Dx: **elevated glucagon levels** Tx: **octreotide**, surgery

Question 32

Where can pulsus pardoxus occur?

Answer 32

Seen in: asthma, COPD, cardiac **tamponade**, **pericardial** effusion/**constrictive** **pericarditis**

Question 33

What is polymyositis?

Answer 33

Pathogenesis: **autoantibodies** against **_endomysium_** Presentation: **symmetrical proximal muscle weakness**, increasing difficult climbing stairs, getting up from a chair, carrying heavy objects; **_NO skin findings_** Histology: **endomysial mononuclear infiltrate (CD8)**, **patchy necrosis** Labs: elevated muscle enzymes (CK, aldolase); autoantibodies (**anti-histidyl tRNA synthethase (anti Jo1**)); anti-nuclear antibody (ANA)); **anti-SRP**, **anti-Mi2** Associated complications: **interstitial** **lung** **disease**, **myocarditis**; parenoplastic **malignancies** (adenocarcinoma) Tx: steroids, followed by long-term immunosuppresant therapy (methotrexate)

Question 34

In the **absence** of ADH, where is tubular fluid most concentrated? Most dilute?

Answer 34

ADH acts primarily on the collecting ducts, increasing their permeability to water. In the **absence** of ADH, the tubular fluid is most **concentrated** at the **junction** between the descending and ascending limbs of the **loop of Henle;** Most **dilute** in the **collecting ducts**.

Question 35

What is the purpose of the Sudan III stain?

Answer 35

The **Sudan III** stain can quickly and easily identity **unabsorbed fat** and **confirm** **malabsorption**. Fats are the earliest and most severly affected nutrient in generalized malabsorption; so testing for fat malabsorption is the most **sensitive** strategy for **screening** for **malabsorptive** **disorders**.

Question 36

What are the key defense mechanisms?

Answer 36

[**Immature**; includes primitive and neurotic] **Acting out**: expressing unacceptable feelings through actions **Denial**: behaving as if an aspect of reality does not exist **Displacement**: **transferring** feelings to a more acceptable object **Intellectualization**: using intellect to avoid uncomfortable feelings **Passive** **aggression**: avoiding conflict by expressing hostility covertly **Projection**: **misattributing** one's own unacceptable feelings to others who don't actually share them **Rationalization**: justifying behavior to avoid difficult truths **Reaction** **formation**: repsonding in a manner **opposite** to one's actual feelings; **replacing**/**transforming unacceptable** feelings or impulses into their **extreme opposites** **Regression**: reverting to earlier developmental stage **Splitting**: seeing others as **all bad** or **all good**; unable to integrate mixed feelings [**Mature**] **Sublimation**: channeling impulses into socially **acceptable** behaviors **Suppression**: putting unwanted feelings aside to cope with reality

Question 37

What is thromboangiitis obliterans (Buerger's Disease)?

Answer 37

A vasculitis of medium and small sized arteries, principally the **tibial** and **radial** arteries Pathogenesis: direct **endothelial** **cell** **toxicity** from **tobacco** **products** or from **hypersensitivity** to them Presentation: **heavy cigarette smokers** with onset before age 35yo; calf, foot, or hand intermittent **claudication**; superficial **nodular** **phlebitis** and cold sensitivity (**Raynaud's** phenomenon; severe distal pain due to neural involvement Histology: acute and chronic inflammation of arterial walls, often with **thrombosis** of the lumen, which can undergo **organization** and **recanalization**; segmental thrombosing vasculitis extends into **_contiguous veins and nerves_** Tx: smoking cessation

Question 38

What is panic disorder?

Answer 38

Pathogenesis: strong genetic component; increased risk of suicide Presentation: recurrent episodes of chest pain, tachycardia, shortness of breath, sweating, and tremulousness in a young, otherwise healthy patient w/ **normal EKG**; not assoc. w/ a known trigger; a. periods of intense fear and discomfort peak in 10 min; recurrent and unexpected panic attacks w/ **4 or more of the following** - Palpitations, paresthesias, dePersonalization/derealizaiton Abdominal distress or Nausea Intense fear of dying, Intense fear of losing **control** or "**going** **crazy**", light-headedness Chest pain, Chills, Choking Sweating, Shaking, Shortness of breath Sx are systemic **manifestations** of **fear**; **negative** work up b. dx: attack followed by 1mo or more of 1 or more of the following: **worrying** about additional attacks, **avoidance** behavior, worrying about **consequences** of attack Tx: **immediate**: **benzodiazepines**; long-term: SSRI/SNRI(venlafaxine) and/or cognitive behavioral therapy

Question 39

Where is the deep brachial artery found? What runs along side it?

Answer 39

The **deep brachial** (profunda brachii) artery and **radial nerve** run together along the **posterior aspect of the humerus**. **Midshaft fractures** of the humerus risk injury to these structures.

Question 40

What is phenotypic mixing?

Answer 40

Occurs when a host cell is **coinfected with 2 viral strains** and progeny virions (1st set released) contain **unchanged parental genome** from one strain and **nucleocapsid (or envelope) proteins** from the other strain. B/c there is **no change** in underlying viral genomes (no genetic exchange), subsequent progeny will **revert to their original**, unmixed phenotypes (will have the s**ame envelop proteins and genome**).

Question 41

What are the consequences of patent ductus arteriosus?

Answer 41

**Eisenmenger** **syndrome**: **Cyanosis** and **clubbing** most pronounced in LE (**differential cyanosis and clubbing** - difference in O2 sat between arms and legs) b/c PDA delivers unoxygenated blood distal to the left subclavian artery. Shunt is reversed from L to R to R to L

Question 42

What is congenital torticollis?

Answer 42

Pathogenesis: birth **trauma** (e.g, breech delivery) or **malposition of head** **in utero** (due to fetal **macrosomia** or **oligohydramnios**), both of which can result in **sternocleidomastoid** **injury** and **fibrosis** Presentation: develops by 2-4w; head is **tilted** **toward** affected side with **chin** pointed **away** from contracture; soft tissue mass palpable in inferior 1/2 of the affected SCM; **plagiocephaly** and **facial** **asymmetry** in severe cases Dx: made clinically Tx: resolves with conservative therapy and stretching exercises

Question 43

What is the femoral nerve?

Answer 43

Nerve roots: L2-L4 Route: descends through fibers of the psoas major muscle, emerges laterally b/n **psoas** and **iliacus** muscle, then runs **beneath** inguinal ligament Neuropathy due to: trauma, compression from hematoma or abscess; Presentation: **weakness** involving quads; difficulty w/ stairs and frequent falling secondary to "**knee** **buckling**"; diminished **patellar** **reflex**; **sensory loss** over **anterior and medial thigh, medial leg;** motor deficit - flexion of thigh, extension of leg at the knee

Question 44

What is infectious mononucleosis?

Answer 44

Pathogenesis: caused by EBV and associated with serum **heterophile** antibodies (positive Monospot test); replicates in B lymphocytes; Also caused by **CMV** (**negative** Monospot test) in immunocompetent patients w/ **heterophile antibody-negative** mononucleosis like syndrome; CMV can be acquired during **transfusion** of leukocyte-laden blood products, as the virus infects leukocytes of granulocyte-macrophage lineage; can also be caused by **Toxoplasma** Presentation: teenager/young adult, sore throat, fever, palatal petechiae, fatigue, anterior and posterior lymphadenopathy, splenomegaly, **atypical** **lymphoctyosis** Histology: **(atypical) CD8 T** cells dominate on blood smear; larger than quiescent lymphocytes w/ abundant cytoplasm, an **eccentrically** placed nucleus and a cell membrane that appears to **conform** to borders of neighboring cells; they expand in response to EBV infected B lymphocytes in effort to **destroy** virally infected cells Serum **heterophile antibodies agglutinate** with RBCs from unrelated species (horse RBCs in Monospot test; sheep RBCs in Paul-Bunnell test) Associated malignances: **Burkitt** **lymphoma** (endemic African type), **naospharyngeal** **carcinoma**; causes **CNS** **lymphoma** in HIV pts and post-transplant lymphoprolierative disorder (PTLD) in allograft recipients

Question 45

What is hairy cell leukemia?

Answer 45

Pathogeneisis: Mature B cell tumor; infiltrates the BM and reticuloendothelial system Presentation: middle-aged men; peripheral lymphadenopathy is **uncommon** (trapped in BM and spleen, **can't** **leave**); causes marrow fibrosis (**dry tap** on aspiration); **massive** **_splenomegaly_**, **pancytopenia**; **LUQ** pain, fatigue, weakness, fever, and recurrent infections Histology: cells have **filamentous**, hair-like cytoplasmic projections Dx: BM biopsy and flow cytometry Labs: stains **TRAP** (tartrate-resistant acid phosphatase) **positive** Tx: **cladribine**, **pentostatin**

Question 46

How does left sided heart disease cause pulmonary hypertension?

Answer 46

It **increases** pulmonary **venous pressure** and **congestion**. This leads to passive increase in pulmonary arterial pressure, which is made worse by **reactive** **constriction** and **structural** **remodeling** of pulmonary vasculature secondary to **impaired** **nitric oxide** availability and **increased** **endothelin** expression.

Question 47

What is epiglottitis?

Answer 47

Pathogenesis: infection with **H. influenza type B**; major virulence factor is **polysaccharde** **capsule**, which is composed of **_polyribosylribitol phosphate_** (PRP); PRP capsule protects bacterium against phagocytosis and complement mediated lysis by **binding factor H**, a circulating regulator protein that normally prevents (C3b) deposition on host cells Presentation: inflammed epiglottis, which causes **inspiratory** **stridor**, fever, dyspnea Imaging: **"thumbprint sign"** (**swollen** **epiglottis**) Tx: conjugate Hib vaccine composed of **PRP** **conjugated** to **protein** **toxoid**

Question 48

What is hepatic encephalopathy?

Answer 48

Pathogenesis: increased levels of ammonia and other neurotoxins in circulation that lead to **increased** **inhibitory** **neurotransmission** (**GABA**) and **impaired** **excitatory** **NT** **release** (glutamate, catecholamines) Precipitating factors: **drugs** (sedatives, narcotics), **hypovolemia** (diarrhea), electrolyte changes (hypokalemia), increased N2 load (e.g., GI **bleeding**), **infection** (pneumo, UTR, spontaneous bacterial peritonitis), **portosystemic** **shunting** (TIPS) [GI bleed: NH3 is normally produced by GI tract as result of enterocytic catabolism of **glutamine** and colonic bacterial catabolism of **dietary** **protein**. Bleeding increases NH3 delivery to gut in form of Hgb, which is converted into NH3 and absorbed into blood. NH3 enters liver through portal vein and is detoxifed to urea.] Presentation: sleep pattern changes, altered mental status, ataxia, asterixis Tx: correct precipitating causes (fluids, antibiotics); decrease blood ammonia concentration (e.g., **lactulose**, **rifaximin**) Lactulose: acidifies colonic contents, which converts absorbable NH3 into **nonabsorbable** NH4+ (ammonium ions), trapping it in stool and increasing fecal nitrogen excretion

Question 49

What is endocarditis?

Answer 49

Pathogenesis: s aureus (high virulence: adheres to normal valves); s virdans (low virulence: adheres to damaged valves) Presentation: fever, Roth spots, Osler nodes, murmur, Janeway Lesions, Anemia, Nail-bed hemorrage, emboli (not large enough to cause acute renal failure); associated w/ **glomerulonephritis**, septic arterial or pulmonary emboli; **mitral** valve commonly involved; tricuspid assoc. w/ s. aureus; infection may be complicated with **deposition of _immune complexes_ in glomerulus** [**Flu-like** **symptoms**, **fever**, and **new** **systolic** **murmur** are **suggestive** of **infective endocarditis**.] Dx: multiple blood cultures

Question 50

What is biolar disorder?

Answer 50

Presentation: **1 week or more** of **elevated or irritable mood** and **increased energy/activity** **3 or more** of the following sx (4 if mood is irritable only) = **Manic episode** **Distractibility** **Impulsivity**/indiscretion, risky behavior **Grandiosity** **Flight** of ideas/racing thoughts Increased **activity**/psychomotor agitation Decreased need for **sleep** **Talkativeness**/pressured speech Dx: Pts w/ 1 or more **_lifetime_** manic episodes = **bipolar I disorder**; manic episodes can occur w/ or w/o psychotic features (delusions, hallucinations)

Question 51

What is familial hypocalciuric hypercalcemia?

Answer 51

Pathogenesis: benign, autosomal dominant; caused by a defective calcium-sensing receptor (CaSR) in the parathyroid gland and kidneys; **higher** serum Ca levels are required to **suppress** the secretion of PTH raising set point of Ca-induced regulation of PTH secretion Presentation: mild asymptomatic **hypercalcemia**, **reduced urinary excretion of calcium**, high normal or mildly elevated PTH CaSR is a **transmembrane G protein coupled (metabotropic) receptor**

Question 52

What is a vasectomy?

Answer 52

It involves transection of the vas deferens; blocks transport of new sperm from epididymis, but has no effect on sperm distal to ligation Vas deferens: transport duct from epididymis to ejaculatory duct; stores and protects sperm following spermatogenesis Pts can still have **viable** sperm in **distal** vas for **3mo** and **at least 20 ejaculations** following vasectomy; **little** **effect** on **volume** of ejaculate

Question 53

What is an orbital fracture?

Answer 53

Fracture to orbital floor (composed of zygomatic bone and maxilla) result from direct frontal trauma to orbit. Assoc. nerve: **infraorbital nerve** (continuation of **maxillary** nerve (CN5.2)) runs along the orbital surface of maxilla in infraorbital groove before traversing infraorbital canal and exiting skull via infraorbital foramen (below orbit). Presentation: numbness and paresthesia of u**pper cheek, upper lip, and upper gingiva**; displacement of orbital contents through floor may cause enophthalmos, and entrapment of inferior rectus muscle impairing vertical gaze

Question 54

What is nursemaid's elbow?

Answer 54

Pathogenesis: **radial head subluxation**; results from a sharp pull on hand while the forearm is outstretched and pronated and the elbow is extended; **annular ligament tears** from periosteal attachment at the radial neck and is **displaced** over the head of radius and slides into radiohumeral joint where it becomes trapped Presentation: injured arm is held close to body with **elbow extended (or slightly flexed)** and **forearm is pronated**; child in little distress until attempts are made to move elbow Tx: reduction by fully supinating forearm followed by fully flexing elbow

Question 55

What is a cleft lip? a cleft palate?

Answer 55

Cleft lip: results when the **maxillary prominence** **_fails_** to fuse with the **intermaxillary segment/merged medial nasal processes** during the 5-6th week of embryonic development Fusion of the two **medial nasal prominences** forms the midline intermaxillary segment. Cleft palate: occurs when the two lateral **palatine shelves** (secondary palate) fail to **fuse** with one another or failure of fusion of lateral palatine shelves with the nasal septum and/or medium palatine shelf Cleft lip and palate can occur together or in isolation

Question 56

What is the relationship between carbonic anhydrase and the eye?

Answer 56

Carbonic anhydrase is present in the eyes (+ pancreas, GI tract, CNS, and RBCs). In the eyes, it modulates HCO3- **formation** in the **aqueous humor**. Inhibition of CA will **decrease** HCO3- and **aquemous humor formation**. CA inhibitors (**acetazolamide**) are used to **relieve intraocular pressure** in open-angle and angle closure glaucoma. SE of CA inhibitors: somnolence, paresthesia, urine alkalinization; Rare SEs: metabolic acidosis, dehydration, hypokalemia, hyponatremia

Question 57

What is mucormycosis?

Answer 57

Pathogenesis: due to mucor of rhizopus Presentation: facial pain, HA, nasal **eschar** in pt w/ **diabetic** **ketoacidosis** (+dry mucous membranes and unintended weight loss); black necrotic **eschar** in nasal cavity Histology: fungi appear as **broad** **ribbon**-**like** nonseptate hyphae w/ **right angle branching**; tissue invasion seen along **blood** **vessels**, vascular thrombosis and tissue necrosis can occur Dx: **histology** (mucosal biopsy) to confirm diagnosis; blood cultures are **negative** Tx: amphotericin B and surgical debridement

Question 58

What are schistocytes?

Answer 58

**Fragmented** red cells; **Diagnostic** of a traumatic mechanism and **indicate** either **Microangiopathic hemolytic anemia** (HUS, thrombotic thrombocytopenic purpura, DIC, malignant HTN, metastatic carcinoma) or **Mechanical damage** (prosthetic valve, severely calcified valves) Coagulation studies are **normal** in **HUS** and **TTP**.

Question 59

What are the intraperitoneal and retroperitoneal organs?

Answer 59

Intraperitoneal: stomach, liver, spleen, transverse colon; lacerations/rupture leads to **hemoperitoneum** (free blood in **peritoneal space**) **Retroperitoneal**: hematomas assoc. with abdominal and pelvic trauma; **pancreatic** injury is frequent source of retroperitoneal hematomas Suprarenal (adrenal) glands Aorta and IVC Duodenum (2-4) Pancreas (**head** and **body**) Ureters and bladder Colon (**ascending** and **descending**) Kidneys Esophagus (thoracic) Rectum (mid-distal)

Question 60

What is a cholesteatoma?

Answer 60

Collections of **squamous cell debris** that form a round, **pearly mass** behind the tympanic membrane in the **middle** **ear**. Pathogenesis: congenital or may develop as either acquired primary lesions or secondary to infection, trauma, or surgery of **middle** **ear** **Primary cholesteatomas**: result of chronic **negative pressure** in middle ear causing retraction pockets in typanic membrane that become **cystic**; cholesteatoma is formed as **squamous** **cell** **debris** accumulates **Secondary cholesteatomas**: occur after squamous epithelium **migrates** to or is **implanted** in middle ear ("skin in the **wrong** **place**") **Presentation**: **painless** otorrhea; **conductive** hearing loss (lytic enzymes erode through ossicles); **vertigo** or **facial** **palsies** (erosion into vestibular apparatus of CN7)

Question 61

What vessel is most vulnerable to injury during a hysterectomy/pelvic surgery in females?

Answer 61

The **ureter**; **Pathogenesis**: distal ureter may be severed during ligation of uterine vesses b/c ureter passes **inferior** and lateral to urterine artery at level of internal cervical os prior to entering bladder (water under the bridge); ureters run **closely** to **pelvic lymph nodes** **Presentation** of injury: **flank pain (**due to distention of proximal ureter w/ urine) and **fever**; hydronephrosis due to ureteric obstruction; Second ureter is uninjured so pts are able to void (**urinate**) **normally**

Question 62

What is androgenetic alopecia?

Answer 62

**Male pattern baldness**; the most common type of hair loss in **males and females.** Pathogenesis: **polygenic inheritance** with variable expressivity; depends on hormonal (circulating androgens) and genetic factors Presentation: hair loss occurs primarily at the **temporal** areas and **vertex** and progresses through life; pattern and severity vary between males and females [Other conditions with **polygenic** **inheritance**: epilepsy, glaucoma, HTN, ischemic heart disease, schizophrenia, type II DM]

Question 63

What is small intestinal bacterial overgrowth (SIBO)?

Answer 63

Pathogenesis: gastric bypass surgery can cause SIBO due to excessive bacterial proliferation in the **blind-ended** gastrodudenal segment; bacteria ferments food that may divert into that segment Presentation: **deficiency** in vit. B12, A, D, E, and iron; **increased** production of _**folic acid** and_ **_vitamin K_;** nausea, bloating, abdominal discomfort, and malabsorption Enteric bacteria can produce **_vit. K and folate_**, inhibit proliferation of surrounding pathogenic bacteria, and digest unabsorbed dietary sugars and convert them to fatty acids

Question 64

What is vitamin A deficiency?

Answer 64

Pathogenesis: insufficient dietary intake; **malabsorption** related to **biliary** **obstruction** (primary biliary cholangitis), exocrine **pancreatic** **insufficiency** or small bowel resection (crohn disease, bariatric surgery) Presentation: **night** **blindness**, severe eye **dryness** and corneal **ulceration**, dry skin (hyperkeratosis); growth retardation Pruritus + signs of vit. A deficiency = **primary biliary cholangitis**

Question 65

What is Ehlers Danlos syndrome?

Answer 65

Pathogenesis: **procollagen peptidase deficiency**, which results in impaired cleavage of **terminal** **propeptides** in the extracellular space Presentation: joint laxity, hyperextensible skin, and tissue fragility due to the formation of **soluble** **collagen** that **does not** properly crosslink

Question 66

What is rifaximin?

Answer 66

MOA: Nonabsorbable antibiotic that alters GI flora to **decrease** intestinal **production and absorption** of ammonia Indications: in pts with **hepatic encephalopathy**, it is used in addition to **lactulose** (which is catabolized by intestinal bacterial flora to short chain FFA lowering colonic pH and increasing **conversion** of ammonia to ammonium); **traveler's diarrhea** - **inhibits bacterial RNA synthesis** through binding with DNA-dependent RNA **polymerase**

Question 67

What are the parts of the urethra are injured in pelvic fracture and straddle injury?

Answer 67

**Anterior urethra**: lies within the bulb and the remainder of the corpus spongiosum; divided into **bulbous and penile** segment Commonly damaged in **_straddle_** injuries. **Posterior urethra**: located above the bulb of the penis; divided into the **prostatic and membranous** segments **Membranous** segment is **unsupported** and is **weakest** point of posterior urethra. Injury associated w/ **_pelvic fractures_**. Presentation of urethral injury: inability to void w/ full bladder sensation, high-**riding** boggy **prostrate**, blood at **urethral** **meatus**; indicative of urethral injury particulary in presence of pelvic fracture **Contraindication**: placement of **Foley** **catheter**

Question 68

What is tracheoesophageal fistula with esophageal atresia?

Answer 68

Pathogenesis: results from f**ailure of the primitive foregut** to appropriately divide into **separate** trachea and esophageal structures Presentation: shortly after birth; excessive **secretions** (**drooling** due to inability to swallow saliva) and **choking**/**cyanosis** during feeds (due to reflux of breastmilk/formula and aspiration into trachea/lungs) Dx: x-ray shows positioning of nasogastric tube in atretic esophageal pouch after attempt to pass tube into stomach (**inabiity** to pass NEG tube into stomach); **_stomach_ _bubble_** due to **air** **flow** from trachea through fistula to distal esophagus

Question 69

What is linkage disequilibrium?

Answer 69

Two genetic loci are in linkage disequilibrium when their respective alleles are inherited together in the same gamete (haplotype) **more** or **less** often than expected by chance alone given their corresponding allele frequencies. Often the result of physical **proximity** of genes on same chromosome, but it does not always imply physical linkage between the allelic loci.

Question 70

What is microsomal monooxygenase?

Answer 70

A **cyp450 enzyme** present in hepatic **microsomes** and the **ER** of other tissues. It **metabolizes** steroids, alcohol, toxins, and other foreign substances by making them **soluble** and easier to excrete. Most chemical carcinogens enter the body in an **inactive** state (i.e., as pro-carcinogens). Unfortunately, the metabolic processing also **converts** pro-carcinogens into **carcinogens** capable of causing mutation in human DNA.

Question 71

What is **bortezomib**?

Answer 71

MOA: A **proteosome** **inhibitor**; a boronic acid containing dipeptide. Indication: **multiple** **myeloma**

Question 72

What is pseudocholinesterase deficiency?

Answer 72

Inherited blood plasma enzyme abnormality in which body's production of **butyryl** **cholinesterase** (**pseudocholinesterase**) is **impaired**. Can't break down drugs used in **anesthesia** Presentation: sensitivity to certain anesthetic drugs, including muscle relaxants (**succinylcholine** and **mivacurium**)