Week 4

Question 1

What is the urachus?

Answer 1

A remnant of the allantois that connects the bladder with the yolk sac during fetal development.

Failure of the urachus to obliterate at birth results in a patent urachus, which can facilitate discharge of urine from umbilicus (straw-colored).

Failure to close distal part of urachus (adjacent to umbilicus) results in urachal sinus. Presents with periumbilical tenderness and purulent umbilical discharge due to persistent and recurrent infection.

Failure of central portion of urachus to obliterate leads to urachal cyst.

Question 2

What is anticholinergic toxicity?

Answer 2

Pathogenesis: inhibition of cholinergic neurotransmission at muscarinic receptors

Presentation: fever, mucosal dryness, cutaneous flushing, nonreactive mydriasis, delirium, and urinary retention; tachycardia, decreased bowel sounds

TCAs (amitriptyline) and low potency first generation antipsychotics have strong anticholinergic properties.

Question 3

What is the result of injury to the common peroneal (fibular) nerve?

Answer 3

Function: Peronal Everts and Dorsiflexes: if injured = foot dropPED; compensate for lack of dorsiflexion with steppage gait (leg lifted high off ground); “foot slap” due to inability to gently lower forefoot upon heel strike

Superficial peroneal - motor to lateral leg, everts the foot, sensory to dorsum of foot

Deep peroneal - dorsiflexion; sensory to region between 1st and 2nd digits of the foot

Vulnerable to injuries at the neck of the fibula; prolonged immobility (hospitalization, surgery, casting)

Question 4

What is the result of injury to the tibial nerve?

Answer 4

Function: Tibial Inverts and Plantarflexes; if injured, can’t stand on TIPtoes; inability to curl toes and loss of sensation on sole

Sensory: sole of foot

Question 5

What is hereditary spherocytosis?

Answer 5

Pathogenesis: autosomal dominant; Northern European; hemolytic anemia; defective binding of the red cell cytoskeleton to the plasma membrane due to mutations in ankyrin, band 3 or spectrin proteins; acquired most often caused by autoimmune hemolytic anemia

Spherocytes are smaller, have more intensely staining cytoplasm due to membrane loss and red cell dehydration

Presentation: hemolytic anemia, jaundice, reticulocytosis, increased indirect bilirubin, splenomegaly

Complications: pigmented gallstones (increased bilirubin from lysed RBCs precipitates as calcium bilirubinate; complication of any hemolytic anemia); aplastic crises from parvovirus B19 infection

Labs: elevation in mean corpuscular hemoglobin concentration (most specific index), high lactate dehydrogenase (present in RBCs); decreased haptoglobin; normal to low mean corpuscular volume; reticulocytosis; increased osmotic fragility on acidified glycerol lysis test

Tx: splenectomy

Question 6

What are the functions of eukaryotic RNAs?

Answer 6

RNA pol 1: produces 5.8s, 18s, 28s rRNA; fxn: transcribes the 45s pre-rRNA gene, which codes for these ribosomal components

RNA pol 2: produces mRNA; fxn: translated by ribosomes to form specific proteins; fxn is restricted to the nucleolus

small nuclear RNA; fxn: involved in mRNA splicing and transcription regulation

mircoRNA; fxn: cause gene silencing via translation arrest or mRNA degradation

RNA pol 3: tRNA; fxn: adaptor molecule linking codons with specific amino acids

5s rRNA; fxn: essential component of 60s ribosomal subunit

Question 7

What are the symptoms of opioid intoxication?

Answer 7

Presentation: miosis, depressed mental status, decreased respiratory rate, decreased bowel sounds, hypotension, and bradycardia

Decreased respiratory rate is the best predictor of intoxication and is a frequent cause of mortality.

Tx: naloxone; opioid antagonist

[Cocaine intoxication: mydriasis, tachycardia, hypertension]

Question 8

What is acute tubular necrosis (ATN)?

Answer 8

Pathogenesis: due to decreased renal perfusion due to severe hypovolemia, shock, or surgery.

Straight proximal tubules and thick ascening limb of Henle’s loop located in outer medulla are most commonly affected portions/susceptible to hypoxia of nephron b/c they participate in active (ATP consuming) transport of ions and have high O2 demand

Labs: increased serum creatinine and BUN, normal BUN/serum creatinine ratio; muddy brown casts (pathognomonic)

Presentatin: oliguria (low urine output)

Clinical course: initiation phase (original ischemic/toxic insult; lasts about 36h; slight decrease in urine output as tubular cell damage begins); maintenance phase (tubular damage fully established - oliguria, fluid overload, electrolyte abnormalities; lasts 1-2w); recovery phase (re-epithelialization of tubules; GFR recovers quickly, tubular cells recover more slowly = transient polyuria and loss of electrolytes); majority of pts eventually experience complete restoration of renal function

Question 9

Where can the pleura be accessed in the chest wall?

Answer 9

Lungs (& visceral pleura): below mid-clavicular line - 6th rib, mid-axillary - 8th rib, paravertebral line -10th rib

Parietal pleura: above the 8th rib, 10th rib, 12th rib

Question 10

What is lactose intolerance?

Answer 10

Pathogenesis: lactase non-persistence, characterized by declining lactase expression in adulthood; secondary lactase deficiency: an acquired condition resulting from inflammation/infection (e.g., bacterial overgrowth, infectious enteritis, Crohn disease) that causes injury to mucosal brush border of small bowel where lactase is expressed

Presentation: flatulence, crampy adominal pain, watery diarrhea after dairy product consumption

Increased production of short-chain fatty acids that acidify stool (decreased stool pH), increased breath H2 content, elevated stool osmolality

Question 11

What forms the fibrous cap in an atheroma?

Answer 11

Vascular smooth muscle cells; they are stimulated to synthesize extracellular matrix proteins (e.g., collagen, elastin, and proteoglycans) that form the fibrous cap

Fibroblasts are rarely found in the tunica intima of blood vessels and are not significantly involved in atherosclerosis pathogenesis.

Question 12

What is Bloom Syndrome?

Answer 12

Autosomal recessive; caused by mutations in BLM gene, which encodes DNA helicase; helicase dysfunciton results in chromosomal instability and breakage

Presentation: growth retardation, facial anomalies (e.g., microcephaly), photosensitive rash, and immunodeficiency (e.g., recurrent infections)

Question 13

What are the differences between osteoarthritis and RA?

Answer 13

Osteoarthritis: 40yo or greater, increases with age; DIP (Heberden nodes), PIP (Bouchard nodes), 1st CMC, hips, knees, spine, none/brief (<30m) morning stiffness; no systemic sx; hard bony enlargement of joints; pain worsens with use, improves with rest

RA: 40-60yo (often younger); PIP, MCP, wrists; prolonged morning stiffness; fever, fatigue, wt loss; soft/spongy, active synovitis (warm joints); pain improves with use

Question 14

What is Selective IgA deficiency?

Answer 14

B cell disorder - don’t differentiate into IgA secreting plasma cells; antibodies against IgA

Presentation: Usually asymptomatic, airway - recurrent sinopulmonary (sinusitis, pneumonia) and GI infections (giardia), autoimmune disease, atopy, anaphylaxis during transfusions (blood products contain small amounts of IgA)

Dx: low or absent serum IgA levels; normal IgG and IgM levels

Question 15

What is polycystic kidney disease?

Answer 15

Autosomal recessive; caused by mutation in PKHD1 gene; codes for fibrocystin (present in kidney and liver)

Presentation: oligohydramnios, which leads to Potter sequence (flattened facies, limb deformities, pulmonary hypoplasia) due to compression of fetus

Less severe: hepatomegaly, portal HTN

Dx: bilatral enlarged, echogenic kidneys on US

Tx: dialysis or renal transplant

Question 16

What is the main blood supply to the femoral head?

Answer 16

Derives mainly from the ascending cervical and retinacular branches of the medial circumflex artery.

Question 17

What is the optimal site for a femoral nerve block?

Answer 17

The inguinal crease at the lateral border of the femoral artery; anesthetizes the skin and muscles of the anterior thigh, femur, and knee, as well as the saphenous nerve to decrease sensation in medial leg below the knee

Question 18

What is normal pressure hydrocephalus?

Answer 18

Due to decreased CSF resorption by arachnoid granulation of arachnoid mater (communicating hydrocephalus); may be idiopathic or secondary to prior brain trauma or SAH (scar arachnoid granulations)

Presentation: ventriculomegaly with normal ICP; gait abnormalities (white matter tracts affected) - leads to magnetic gate, UMN signs (spasticity, hyperreflexia); cognitive disturbances; urinary incontinence; “wet, wobbly, wacky”

Ventriculomegaly out of proportion to or w/o corresponding sulci enlargement is classic neuroradiographic finding;

Dx: improvement of sx in response to CSF removal

Question 19

What are the development milestones for a toddler (1-3y)?

Answer 19

Child Rearing Working

Cruises (takes first steps by 12mo), Climbs stairs (by 18mo); Cubes stacked - number = age x3; Cutlery - feeds self w/ fork and spoon; Kicks ball (by 24mo)

Recreation: parallel play (by 24-36mo); Rapproachment: moves away from and returns to mom (by 24mo); Realization: core gender identity formed by 36mo

Words: 200 words by age 2 (2 zeros); 2-word sentences

Question 20

What is Osler-Weber-Rendu Syndrome (HHT)?

Answer 20

Also known as hereditary hemorrhagic telangiectasia; characterized by autosomal dominant inheritance of congenital telangiectasias to the skin and mucous membranes

Presentation: telangiectasias in mucous membranes of lips, oronasopharynx, respiratory tract, GI tract, urinary tract

Ruptures of these telangiectasias may cause epistaxis, GI bleeding, and hematuria

Question 21

What is holoprosencephaly?

Answer 21

A developmental field defect, which is when an initial embryonic disturbance leads to multiple malformations by disrupting the development of adjacent tissues and structures w/in a particular region.

Etiology: genetic (trisomy 13, sonic hedgehog gene mutations); environmental: maternal etoh use

Presentation: incomplete division of the forebrain (prosencephalon);

Mild - closely set eyes (hypotelorism), cleft lip/palate

Severe - single midline eye (cyclopia), primitive nasal structure (proboscis), midfacial clefts

Question 22

What is a homeobox or hox gene?

Answer 22

A high conserved DNA sequence that is 180 nucleotides in length. Gene containing homeobox sequence is a homeobox or hox gene.

Codes for transcription factors; involved in expression of genes involved in segmental organization of the embryo along the cranio-caudal axis

Mutations lead to skeletal malformations and improperly positioned limbs and appendages.

Question 23

What is meconium ileus?

Answer 23

Specfic finding for Cystic Fibrosis; Distal small bowel obstruction due to abnormally dehydrated meconium in a patient wiht CF. Persistent, treatment-resistant infectious pneumonias, bronchiectasis, and cor pulmonale account for most deaths due to CF.

Presenation: abdominal distention, bilious emesis, green inspissated mass in distal ileum; secretion of abnormally viscous mucus into small bowel

“Squirt sign” is negative (no explosive expulsion of feces)

Question 24

What is aortic regurgitation?

Answer 24

Causes a decrescendo diastolic murmur w/ maximal intensity occuring just after closure of aortic valve, when pressure gradient between aorta and LV is highest. Best heard with patient leaning forward.

Pressure tracing for AR is characterized by loss of dicrotic notch, steep diastolic decline in aortic pressure and high-peaking systolic pressures.

Question 25

What is a well known complication of nephrotic syndrome?

Answer 25

**Renal vein thrombosis**; Nephrotic syndrome is a **hypercoaguable** state. **Sudden**-onset varicocele with **abdominal** or **flank** **pain**, **hematuria** suggest **renal vein thrombosis** causing impaired left gonadal venous drainage Loss of **antithrombin III** is responsible for **thrombotic** and **thromboembolic** complications of nephrotic syndrome; elevated **lactate** **dehydrogenase**

Question 26

What is lateral epicondylitis?

Answer 26

Lateral epicondylitis (tennis elbow) is caused by overuse of extensor carpi radialis brevis and extensor digitorum, which are involved in wrist extension. Classically seen in tennis players (backhand). Characterized by angiofibroblastic tendinosis at its origin on the lateral epicondyle. [Analogous disorder involving the wrist flexors at their attachment on medial epicondyle is medial epicondylitis (golfer's elbow).

Question 27

Damage to what nerve can result in erectile dysunction?

Answer 27

**Prostatic plexus**; it lies within the fascia of the prostate and innervates the corpus cavernosa of the penis, which facilitates penile erection. As a result, prostatectomy or injury to the prostatic plexus can cause erectile dysfunction.

Question 28

What is graft versus host disease?

Answer 28

Graft **attacks** the host; Can occur following transplantation of organs rich in **lymphocytes** (e.g., liver). T lymphocytes (not B cells) found in immunocompent donor organ become sensitized against the MHC antigens of the immunocompromised recipient and attack host's tissues. Presentation: diffuse **maculopapular** rash (skin), jaundice (liver), diarrhea (GI), hepatosplenomegaly

Question 29

What is unique about organisms in the Mycoplasma genus?

Answer 29

They lack a cell wall; all organisms in the Mycoplasma genus, including Ureaplasma urealyticum, lack peptidoglycan cell walls and are therefore resistant to agents that target the cell wall such as penicillins, cephalosporins, carbapenems, and vancomycin. **Glycosyltransferase** is a crucial component of **peptidoglycan** synthesis; it adds glycan molecules to the growing peptidoglycan chain (composed of N-acetylglucosamine and N-acetylmuramic acid). Mycoplasma infections can be treated with **antiribosomal** agents (e.g., tetracyclines and macrolides)

Question 30

What is Burkitt Lymphoma?

Answer 30

The **Epstein**-**Barr** virus genome is identified in approx. 50% of systemic B-cell lymphomas and almost all primary CNS lymphomas occurring in the setting of HIV infection. Balanced t(8;14) translocation, which causes overexpression of c-myc. Classic for Burkitt Lymphoma: diffuse medium-sized lymphocytes and a high **proliferation** **index** represented by **high Ki-67** approaching 100%.

Question 31

What is buspirone?

Answer 31

A **nonbenzodiazepine anxiolytic** used to treat **general anxiety disorder.** It has a **slow onset of action** (delayed for up to 2w). It is not effective in treating panic disorder. MOA: acts a partial a**gonist of the 5HT1A receptor**; has no muscle relaxant or anticonvulsant properties; carries **no** **risk** of tolerance, dependence, or withdrawal

Question 32

What is the difference between colitis-associated and sporadic colorectal cancer?

Answer 32

**Colitis associated**: **younger** (40-55); **flat (nonpolypoid) lesions** are the origins of dysplasia; **proximal**\>distal (particularly with Crohn disease); **multifocal** tumors; histology - **mucinous** and/or **signet** ring cells, **poorly** differentiated/**high** **grade** histology (more **aggressive**); mutations - **EARLY _p53_, LATE APC** gene mutations **Sporadic**: **older** (\>60); **polypoid** lesions are origins of **dysplasia**; **distal**\>proximal; **singular** tumors; histology - **rarely** mucinous, **well** differentiated; mutations - **EARLY APC gene, LATE p53**

Question 33

What is the MOA of bile acid binding resins (cholestyramine, colestipol, colesevelam)?

Answer 33

They bind bile acids in the GI tract, inhibiting enterohepatic circulation. This leads to diversion of hepatic cholesterol to **synthesis** of new bile acids, increased uptake of LDL cholesterol from circulation, and reduced blood LDL levels. SEs: GI upset and impaired absorption of **nutrients** (vit. ADEK) and drugs; increased hepatic production of **triglycerides** and increased release of **triglyceride** heavy VLDLs leading to **hypertriglyceridemia**

Question 34

What is borderline personality disorder?

Answer 34

Characterized by persistent pattern of **unstable** relationships, mood liability, and impulsivity (substance abuse, unsafe sex); self-mutilating behavior; exhibit **suicidal** ideation or behavior in context of interpersonal crisis where they feel rejected or abandoned

Question 35

What is suppurative parotitis?

Answer 35

Parotid gland secretes amylase; acute bacterial parotitis occurs more commonly in elderly post op pts who are **intubated** or **dehydrated** Risk factors: deceased salivary flow, **dehydration** post surgical intubation; micro - s. **aureus**, **anaerobes** Presentation: firm erythematous pre/post auricular swelling, trismus, dysphagia; systemic findings: fever, chills Dx: imaging (US/CT) - ductal inflammation/obstructive frank **abscess**; labs - elevated serum **amylase** w/o pancreatitis, **normal** **lipase** levels

Question 36

How does Trendelenburg gait occur through IM injection?

Answer 36

Iatrogenic injury during intramuscular injection to **superomedial gluteal region**, risk of injury to **superior** **gluteal** **nerve**; injections into superiomedial, inferomedial, and inferolateral regions of buttock risk injury to sciatic nerve; Prevent by choosing **superolateral** **quadrant**, althought **anterolateral** **gluteal** region is **preferred**.

Question 37

What is adenocarcinoma in situ?

Answer 37

A major **subtype of lung adenocarcinoma**. The tumor arises from alveolar epithelium and is located at the periphery of the lung; considered a **pre-invasive** lesion characterized by **growth along intact alveolar septa w/o vascular or stroma invasion** Presentation: cough, shortness of breath, hemoptysis; copious amounts of watery sputum (**bronchorrhea**) Histology: well-differentiated, dysplastic **columnar** cells w/ or w/o **intracellular mucin**; undergoes **aerogenous** **spread** (along airways) and can progress to **invasive** **disease** if not resected

Question 38

What are organophosphates?

Answer 38

**Cholinesterase inhibitors** that are used as pesticides in agriculture; **irreversible**; lead to **Ach** **excess** Presentation: Diarrhea, Urination, Miosis, **Bronchospasm**, Bradycardia, Emesis, Lacrimation, Sweating, Salivation (DUMBBELSS) Tx: **atropine** (treats **peripheral** and **CNS** effects; **doesn't** treat paralysis) and pralidoxime (PAM; treats **peripheral** effects - **muscarinic** and **nicotonic**), a drug that **reactivates** acetylcholinestrase by binding organophosphates and **decoupling** them from the enzyme

Question 39

What is **leflunomide**?

Answer 39

MOA: reversibly inhibits **dihydroorotate** **dehydrogenase**, preventing **pyrimidine** synthesis; **suppresses** T cell proliferation Indications: **RA**, **psoriatic** **arthritis** SEs: diarrhea, hypertension, hepatotoxicity, teratogenicity

Question 40

What is danazol?

Answer 40

Moa: Synthetic **androgen** that acts as **partial** **agonist** at **androgen** **receptors** Indications: **endometriosis**, **hereditary** **angioedema** SEs: weight gain, edema, acne, hirsutism, **masculinization**, decreased HDL levels, hepatotoxicity, **pseudotumor** **cerebri**

Question 41

What is tamsulosin?

Answer 41

**MOA: alpha 1** **antagonist** Indication: used to treat **BPH** by inhibiting smooth muscle contraction; selective for alpha 1A, 1D receptors (found on **prostate**) vs. vascular alpha 1B receptors

Question 42

What causes abnormal uterine bleeds?

Answer 42

Structural causes: **polyp**, **adenomyosis**, **leiomyoma** (fibroids), **malignancy**/hyperplasia Non-structural causes: **coagulopathy**, **ovulatory**, **endometrial**, **iatrogenic**, not yet classified

Question 43

What are eculizumab, natalizumab, ustekinumab?

Answer 43

E**C**ulizumab: targets **C5 complement protein;** used in **paroxysmal** **nocturnal** **hemoglobinuria** Natalizumab: targets **alpha4 integrin**; used in **multiple sclerosis**, **crohn** **disease**; WBC adhesion, **risk of PML** in pts w/ **JC virus** Ustekinumab: targets **IL12/IL23**; used in **psoriasis**, **psoriatic** **arthritis**