Uworld: 6-3

Front 1

6 month-old male
Recurrent otitis media
Pneumocystis pneumonia

Diagnosis

Back 1

Recurrent otitis media-->humoral (B cell) deficiency bc can't mount reaction against strep pneumo, h. flu

PCP pneumonia indicates T cell deficiency (which is why this is usually found in people with AIDS)

Thus, pt has Severe Combined Immune Deficiency--will see lymphopenia and hypogammaglobulinemia (bc no B cells!) on labs

Front 2

Candida skin test gauges a delayed hypersensitivity reaction.

What cells are required for the response?

Back 2

CD4 helper cells
CD 8 cytotoxic cells
NKCs

Failure to generate a response to this test = anergy, as in SCID

Front 3

Characteristic liver finding of Reye Syndrome.

Back 3

Microvesicular steatosis

Front 4

Patient is unable to tolerate everyday sounds.

What CN is injured?

Back 4

Facial Nerve

Stapedius is innervated by branch of CN VII; paralysis of stapedius allows stapes to oscillate more widely, producing hyperacusis (inc'd sensitivity to sound)

Ipsilateral hyperacusis is a common finding in Bell's palsy

Front 5

43 year-old man with abdominal cramps
Small bowel biopsy reveals nests of mast cells within mucosa

What is causing his abdominal cramps?

Back 5

Gastric acid is secreted by parietal cells which are stimulated by histamine, Ach, gastrin.

In systemic mastocytosis, MAST CELL PROLIFERATION occurs in BM and in other organs.

Inc'd histamine secretion will cause GASTRIC HYPERSECRETION OF ACID-->inactivates pancreatic/intestinal enzymes-->diarrhea, may also have gastric ulcerations

Will also see syncope, flushing, hypotension, tachycardia, bronchospasm, and pruritius

Front 6

The neurofibromas of neurofibromatosis are derived from ________.

Back 6

Neural crest

Front 7

Most common site of colon cancer

Back 7

Rectosigmoid colon

Front 8

51 year-old female presents with symptoms of hypothyroidism. No history of viral illness.

What is the most likely cause and what histologic changes would you see in the thyroid?

Back 8

This is Hashimoto's

You'd see mononuclear infiltration consisting of lymphocytes and plasma cells. There are several germinal centers present.

Front 9

6-mercaptopurine and 6-thioguanine inhibit de novo purine synthesis after conversion to active metabolites by __________.

What degrades these active metabolites?
What drug can be given to prevent their degradation?

Back 9

6-MC become active after interacting with HGPRT

Degradation then results from XANTHINE OXIDASE

can give a xanthine oxidase inhibitor like allopurinol

Front 10

56 year-old homeless man
Increased fatigability, exertional dyspnea
Significant lower extremity edema
Decreased sensation over ankles and feet
Cardiac dilation

What vitamin is deficient?

Back 10

This is wet beriberi: neuropathy + cardiac involvement (as opposed to dry which is neuropathy + motor impairments of distal extremities)

Due to deficiency of thiamine--vitamin B1

Front 11

15 year-old male
Presents with periodic, sudden onset, arrhythmic jerking movements
FMH positive for seizure disorder

Diagnosis
Treatment

Back 11

Pt is experiencing myoclonic seizures (may be confused with motor and phonic tics of Tourette Syndrome, which would be treated with haloperidol)

Treatment would be: valproate

Front 12

Provide drug of choice for:
Partial Seizures
Tonic-Clonic Seizures
Myoclonic Seizures
Absence Seizures

Back 12

Partial (simple or complex)--carbamazepine

Tonic-Clonic: Phenytoin, carbmazepine, valproate

Myoclonic: Valproate

Absence: Ethosuximide, followed by valproate

NOTE: VALPROATE INHIBITS Na and K+ Channels (in addition to affecting GABA and NMDA receptors)

Front 13

Which bacteria grow on:
Thayer-Martin VCN (vanco, polymixin, nystatin)

Back 13

Neisseria

Front 14

Which bacteria grow on:
Blood agar containing bile and hypertonic saline

Back 14

Enterococci
E. faecalis/faceium

Front 15

Which bacteria grow on:
Cysteine-tellurite agar

Back 15

Corynebacterium diphtheriae

Front 16

Which bacteria grow on:
Bordet-Gengou medium

Back 16

Bordetella pertussis

Front 17

Salmonella vs Shigella:
Method of causing disease (site of invasion, spread, etc.)

Which produces H2S gas on triple sugar agar?

Back 17

Salmonella:
(and yersinia) penetrate bowel mucosa, gain access to lymphatics, and proliferate in LNs
Does release gas

Shigella:
Mucosal invasion, inactivation of 60S ribosomes
Doesn't release gas

Front 18

Protein M is the major virulence factor for ______.

What is its effect?

Back 18

Protein M is major virulence factor for Strep pyogenes

inhibits phagocytosis and activation of complement

Front 19

Zolpidem:
Why is it a better choice than benzodiazepines for treating insomnia?
How does it work?

Back 19

Zolpidem, like benzos, bind and enhance the inhibitory action of GABA on Gaba-A receptor)

It's preferred to benzos because is has less potential for tolerance and addiction. Much lower incidence of withdrawal syx.
No muscle relaxing effects, no anticonvulsant props.

Note: Zolpidem = AMBIEN

Front 20

Patient's PTT is unaffected by addition of activated Protein C.

Diagnosis.

Back 20

Factor V Leiden mutation--protein C normally renders Va inactive. But the mutation prevents this from happening.

Front 21

How does presentation of acute HBV differ from acute HCV?

Back 21

Acute HBV presents with serum sickness: fever, fatigue, joint pain, urticaria, malaise

Acute HCV is mild, though some may complain of malaise, nausea, or RUQ

Front 22

An inactivating mutation in this enzyme of glycolysis will not allow pancreatic beta cells to detect intracellular glucose.

Back 22

Glucokinase (hexokinase in every other cell)

This mean less insulin will be released, and pt will be prone to hyperglycemia.

This is a common mutation in people prone to gestational diabetes.

(No G6P means glucose is free to leave cell)

Front 23

ID the fungus:
Spherules packed with endospores

Back 23

Coccidoides--southwestern US

Front 24

ID the fungus:
Pigeon droppings

Back 24

Cryptococcu

Front 25

ID the fungus:
Bat/Bird droppings

Back 25

Histoplasma (Ohio River Valley)

Front 26

What clotting factor does vWF carry?

Back 26

VIII OCHO OCHO OCHO VANWILLEBRANDO

will see prolonged PTT bc of this

Front 27

Ristocetin aggregation test:
How does it work?
What is it testing?

Back 27

vWF:
Ristocetin activate GP Ib-IX receptors on PLTs and makes them available for vWF binding

When vWF is dec'd, there is poor PLT aggregation in presence of ristocetin

Front 28

This opioid drug will cause withdrawal symptoms in those that are dependent on morphine.

Back 28

Pentazocine

Front 29

BRAF mutations are associated with _______.

Back 29

Melanoma

Front 30

Prostacyclin effects

Back 30

Vasodilates
Inhibits PLT aggregation
Increases vascular permeability

Front 31

Treatment of severe hypoglycemia (inducing loss of consciousness):
In non-medical setting
In medical setting

Back 31

In non-medical setting: intramuscular GLUCAGON (increases hepatic glycogeneolysis and gluconeogenesis)

in hospital
intraVENOUS glucose (never give glucose I.M.)

Front 32

Label

Back 32

A - RNA primers formed by DNA-dependent RNA polymerase

B - Ligase enzyme which binds fragments of lagging strand

C - DNA polymerase III

D - Single Strand BPs

E - Helicase: binds ssDNA at origin of replication, moves into replication fork, and proceeds to separate and unwind DNA

Front 33

64 year-old man
Easy fatigability
Constipation
Bone pain
Renal failure with eosinophilic casts

Diagnosis
Explain presentation

Back 33

Multiple myeloma:
Easy fatigability due to anemia
Constipation due to hypercalcemia
Bone pain due to produciton of osteoclast activating factor by myeloma cells
Renal Failure--secondary to hypercalcemia, AL amyloidosis, hyperuricemia, excess free light chains (BENCE JONES PROTEINS)

Front 34

34 year-old man in a MVA
Suffers from excessive thirst, frequent urination
Urinary osmolality after 2 hour-water restriciton is 250, but increases to 700 after ADH injection

Patient denies polyphagia

What is damaged?

Back 34

Hypothalamic nuclei!!!

Damage to posterior pituitary gland produces only transient polyuria. Diabetes insipidus usually results from damage to hypothalamic nuclei or pituitary stalk.

Front 35

32 year-old male
Hospitalized with internal bleeding following MVA
Successfully resuscitated, but develops oliguria

What happened?
What's his prognosis?

Back 35

Acute Tubular Necrosis from internal hemorrhage

In short, kidney function shuts off for a few days, slowly recovers to full function over few weeks

here are the distinct phases:

Initiation: original insult (ischemia)-->cell damage begins to evolve; GFR begins to fall and urine output decreases

During maintence (oliguric) phase, renal tubule injury established, GFR stabilizes well below normal; will see GRANULAR CASTS in tubules, along with tubules epithelial NECROSIS, denudation of its BM also

Recovery: RE-EPITHELIAZATION of tubules
Polyuria and gradual normalization of GFR-->complete restoration of renal function

MAY SEE INTERTSTITIAL SCARRING ON LIGHT MICROSCOPY

Front 36

Bacterial cause of repeated pulmonary infections in cystic fibrosis

Back 36

Pseudomonas

Front 37

Loss of anterior horns of spinal cord (__MN lesion)
+
Loss of lateral corticospinal tract (___MN lesion)

=
Diagnosis

Back 37

Anterior horns = LMN
Lateral corticospinal tract = UMN

If have both UMN and LMN lesions-->amyotropic lateral sclerosis

Front 38

Esophageal biopsy:
Diagnosis
Prognosis

Back 38

These are KERATIN PEARLS-->squamous cell carcinoma

Note that since there are keratin pearls, this tumor still retains some of its original tissue, in other words, it's well-differentiated.

Most important risk factors are EtOH and tobacco use.

Usually evolves into progressive dysphagia as tumor gradually obstructs esophageal lumen. Significant weight loss common.

Poor prognosis.

Front 39

Effect of initial and prolonged efferent renal arteriole constriction on:
GFR
FF

Back 39

GFR: Selective vasoconstriction of efferent arteriole increases hydrostatic pressure in glomerular capillaries, and therefore, increases GFR. As efferent arteriolar constriciton increases, there is inc'd oncotic pressure in glomerular capillaries, which decreases GFR.

FF which = GFR/RPF always increases with efferent constriction bc:
-GFR increases
-RPF (rate at which plasma flows through glomerulus) increases

Front 40

What does it mean when an anesthetic has a high blood/gas partitioning coefficient?

Back 40

It means it's highly soluble in the blood (blood:gas partition). Drugs with high coefficients are more soluble in blood and demonstrate slow onset of action and slow equilibrium with brain.

Front 41

Schilling test results by phase.

Back 41

1) B12 PO and radiolabeled B12 IV-->if you pee out radiolabeled B12, you have normal absorption, and that means you have a dietary deficiency

If don't pee out, move onto step 2:

2) Radioactive B12 and IF:
If pee out radioactive B12, have pernicious anemia
If don't pee out, heave malabsorption syndrome, such as panc insuff, bacterial overgrowth, or short gut syndrome

Front 42

Partial vs Complete Mole
-Karyotype
-Risk of cancer

Back 42

Partial Mole: 69 XXX or XXY, LOW RISK of malignancy

Complete Mole: 46XX or XY (of PATERNAL ORIGIN)
15-20% risk malignancy
THis is the one that looks like a bunch of grapes.
May experience pre-eclampsia, hyperthy

Front 43

Effect of chronic smoking on diffusing capacity.

Back 43

Smoking decreases diffusing capacity because of alveolar destruction (and destruciton of adjoining capillary beds)

Front 44

This beta-agonist both increases cardiac contractility and decreases vascular resistance.

How?

Back 44

Isoprotenolol:
Increases cardiac contractility by acting on beta-1 receptors

At low does, selectively binds beta-2 receptors, causing RELAXATION of vascular smooth muscle

Front 45

Patient with myasthenia gravis takes neostigmine.

Given low-dose edrophonium:
-Can either elicit significant improvement or have no effect
How would either outcome change your care?

Back 45

If edrophonium (Tensilon test)--a short-acting cholinesterase inhibitor--improved syx, you'd increase dose of neostigmine

If it had no effect, she's receiving too much neostigmine and you'd stop it temporarily (note: inappropriately high doses of cholinesterase inhibitors-->excessive ACh in synaptic cleft-->NMJ becomes insensitive to ACh)

Front 46

Back 46

Spherocytes!
Hereditary spherocytosis (RBC cytoskeleton abnlts, most commolny spectrin and ankyrin abnlts)

Hemolytic anemia, jaundice, splenomegaly are classic findings

Can also find out through osmotic fragility testing

Front 47

Pralidoxime:
What is it good for?

Back 47

Will help regenerate acetylcholinesterase; used for ORGANOPHOSPHATE POISONING

Front 48

Where is alpha-1 antitrypsin formed?
Besides emphysema, what's another concern for individuals homozygous for the deficiency?

Back 48

Formed in the liver

Worry about liver dz; homozygous individuals usually demonstrate hepatomegaly, HSM, cholestasis, elevation of hepatocellular enzymes

h/o neonatal hepatitis w/cholestasis should heighten suspicion for A1AT deficiency

Front 49

9 year-old girl with positive ASO titer. Experiences joint pain/swelling after sore throat. NOw has holosytolic murmer.

She dies.

What did she die from?

Back 49

This patient has acute rheumatic fever and likely died of severe myocarditis.

Note that acute renal failure is a possibility, but that it rarely is fatal.

Front 50

What is myofibril relaxation a sign of?

Back 50

Reversible injury in cardiac myocytes--occurs within the first 30 minutes of severe ischemia

Corresponds w/intracellular ATP depletion and lactate accumulation due to anaerobic glycolysis during this period

Front 51

When does mitochondrial vacuolization occur?

Back 51

SIgn of irreversible cell injury (death)
SIgnifies that involved mitochondria permanently unable to generate ATP

Front 52

BP drops 10mmHg on inspiration

Back 52

Pulsus Paradoxus
TAMPONADE

Front 53

Inherited Pulmonary Artery Hypertension:
Genetic pathophys

Back 53

ABnormal morphogenic protein receptor type 2 (BMPR2) = first insult

Second insult (infect, drugs, ion channel defects) activates dz process, increasing endothelin (vasoconstrictor), decreasing nitric oxide (vasodilator), and decreasing prostacyclin (vasodilator, platelet inhibitor)

Result i vasoconstriction, vasc SM proliferation, fibrosis, thrombosis of pulmonary arteries and arterioles, endothelial cell growth, and elevated pulmonary pressures.

Can lead to RVH-->cor pulmonale

Front 54

Diagnosis
Cause

Back 54

Dilated superficial veins (varicose veins) and associated skin changes consistent with stasis dermatitis

Incompetent venous valves in lower extremities allow retrograde blood flow from deep to superficial. Increases the pressure in the superficial veins leading to their dilation.

Front 55

Medulloblastoma vs Pilocytic Astrocytoma:
Pathologic Differences (on slides)

Back 55

Medulloblastoma: Sheets of primitive cells with many mitotic figures ("primitive neuroectodermal tumor"--SMALL, ROUND, BLUE CELLS. Abundant mitoses. Poor prognosis.

Pilocytic Astrocytoma: Rosenthal fibers, not blue at all. More pink.

Note that these both occur in the cerebellum and can result in ataxia.

Front 56

The QRS complex corresponds to phase ____ of of the ventricular myocyte action potential.

Back 56

Phase 0--when Na+ rushes in

Front 57

34 year-old female
Proteinuria
Facial rash
Chest pain that increases with inspiration
Radiates to trapezius ridge, partially relieved by sitting up

Diagnosis
Pathophys

Back 57

She has lupus: virtually all pts w/lupus have renal involvement

Inflammation of serous membranes is another common manifestation of lupus--it can cause pleuritis and pericarditis

Pericarditis is very common in pts w/SLE

Pain increases on inspiraiton (pleuritic) and relieved by sitting up and leaning forward (postural)

Auscultation reveals a scratchy sound called a pericardial friction rub best heard when pt sitting upright and leaning forward

Front 58

What chemical signals pyruvate to become glucose?

i.e., acts as allosteric activator

Back 58

Acetyl CoA

Front 59

Advanced HIV
Diffuse cortical atrophy
Enlargement of ventricles

Diagnosis

Back 59

Hydrocephalus ex vacuo: in diseases associated with cerebral atrophy (AD, Pick disease, etc), ventricular enlargement occurs secondary to brain atrophy.

Such compensatory ventricular expansion is called "hydrocephalus ex vacuo"

Although distended ventriculi produce CT scan similar to true hydrocephalus, CSF pressure IS NOT INCREASED. Cortical atrophy is a common sequelae of advanced HIV infection.

Front 60

What two ACh structures in the brain are affected by AD?

Back 60

Basal nucleus of Meynert
Hippocampus

Front 61

Histologic findings of renal artery stenosis caused by:
Malignant HTN
Diabetes

Back 61

Malignant HTN: homogenous, onion-like, concentric thickening of walls of arterioles (results from laminated SMC and reduplicated basement membranes)

Diabetes: hyaline arteriosclerosis--arteriolar walls will be homogenously thickened and stain pink with hematoxylin-eosin. Hyaline usually result of excessive excessive ECM production by smooth muscle cells.

Front 62

Immune thrombocytopenia purpura:
Pathophys
Presentation

Back 62

Autoimmune platelet destruction

Presents with ecchymoses, petechiae, mucosal bleeding, thrombocytopenia, but not signs of pancytopenia, marrow failure, or splenomegaly

Front 63

Muddy brown casts

Back 63

Acute TUBULAR necrosis

Front 64

Acute tubular necrosis often due to ischemia (as in the setting of blood loss):
What regions of the kidney are most susceptible to ischemia?

Back 64

Proximal tubules and thick ascending limp of Henle are locaed in outer medulla, an area that even under normal conditions has low blood supply.

In addition, proximal tubules and ascending limb participate in active transport of ions (ATP-consuming).

When oxygen delivery to kidney is compromised, these portions of the nephron suffer first.

Proximal tubules, Ascending Limb

Front 65

What is renal papillary necrosis associated with?

Back 65

DM
Sickle CELL DISEASE

Front 66

Cancer risks of long-term asbestos exposure (most common and second most common)

Back 66

Most common is bronchogenic carcinoma (greatly increased risk--90-fold increase in fact--if smoker)

Second-most common is mesothelioma (smoking does not increase risk of mesothelioma)

Front 67

What is the inciting event of appendicitis?

Back 67

Obstruciton of lumen

Fecaliths (hard poop), foreign bodies, or tumors may cause obstruction

Retained mucus causes appendicular wall to distent, impairs venous outflow; resulting hypoxia causes ischemia and associated bacterial invasion

Inflammation and edema of appendicular wall occur, causing further distention. Necrosis may follow.

Inflammatory fluid and bacterial contents spill into peritoneal cavity, causing peritonitis.