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USMLE Step 1 > High Yields Week 3 > Flashcards

High Yields Week 3 Flashcards

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USMLE® Step 1 flashcards
1
Q

How does hepatitis B virus contribute to the development of hepatocellular carcinoma?

A

Integration of DNA into the genome of host hepatocytes triggers neoplastic changes

Cell proliferation, suppression of p53, chronic inflammation

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2
Q

How does left-sided heart failure contribute to pulmonary hypertension?

A

Left-sided HF causes a backflow of blood because the heart isn’t pumping it out as well
↓
Leads to increased pulmonary venous pressure and eventually pulmonary venous congestion
↓
Congestion leads to increased pulmonary arterial pressure and reactive vasoconstriction to the increased pressures

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3
Q

What is more likely to be used in a signal transduction pathway, ATP or GTP?

A

GTP - used in pathways like Ras-MAP kinase

ATP is NOT a messenger in any signal transduction pathways (ATP used in ion channels like in pancreatic beta cell K+ ion channels)

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4
Q

Injury to what nerve causes weakness of foot dorsiflexion (‘foot drop’), foot eversion and toe extension as well as sensory loss over the lateral leg and dorsilateral foot?

A

Common peroneal nerve

This nerve is particularly susceptible to injury at the lateral neck of the fibula caused by compression/trauma

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5
Q

What is the definitive treatment for idiopathic pulmonary arterial hypertension (20-40 y/o women with exercise intolerance)?

A

Bosentan

Bosentan is a competitive agonist of endothelin receptors → vasodilator action

(endothelin is a potent vasoconstrictor that also stimulates endothelial proliferation)

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6
Q

Where is the most common location for injury of the common peroneal nerve?

A

Neck of the fibula

The common peroneal nerve is the most commonly injured nerve in the leg due to its superficial location

Causes “foot drop” (loss of dorsiflexion and eversion) and loss of sensation over dorsal foot and lateral shin

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7
Q

What type of antibodies are found in 90% of patients with autoimmune thyroiditis (Hashimoto’s)?

A

Anti-thyroid peroxidase antibodies

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8
Q

What kind of drug is citalopram?

A

SSRI (selective serotonin reuptake inhibitor)

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9
Q

What treatment is used for patients with chronic asthma that cannot be managed by beta agonists alone?

A

Inhaled corticosteroids

inhibit inflammatory response in asthmatics

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10
Q

How does alpha toxin released by Clostridium perfringens cause tissue necrosis and gas gangrene?

A

Alpha toxin disrupts cell membrane function by splitting phospholipid molecules in the membrane
→ causes cell lysis and tissue necrosis

(AKA lecithinase)

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11
Q

What does CMV infection cause in a healthy, immunocompetent person?

A

Mononucleosis-like syndrome

heterophil antibody negative / Monospot negative to differentiate from EBV mononucleosis

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12
Q

What does CMV infection cause in an immunocompromised person (HIV/transplant pt)?

A

Severe retinitis (most common), pneumonia, esophagitis, colitis, hepatitis

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13
Q

What gene mutation is associated with polycythemia vera, essential thrombocythemia and primary myelofibrosis?

A

JAK2 mutation

JAK2 is a cytoplasmic tyrosine kinase associated with the erythropoietin receptor

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14
Q

What is calcitriol?

A

Active form of vitamin D (1,25-dihydroxycholecalciferol)

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15
Q

What ions move through nicotinic receptor ligand-gated ion channels?

A

Sodium and Calcium INFLUX

Potassium EFFLUX

The ligand-gated ion channels opened via nicotinic receptor binding (by ACh) are nonspecific ion channels

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16
Q

What blood vessels are affected in polyarteritis nodosa (PAN) and how are they affected?

A

PAN causes segmental, TRANSMURAL inflammation of medium to small sized arteries which can lead to ischemia, infarction and hemorrhage

Arteries in any organ can be involved EXCEPT THE LUNGS

Renal artery involvement is most prominent

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17
Q

Why is carbidopa added to levodopa treatment for Parkinson patients?

A

Carbidopa inhibits the peripheral conversion of levodopa, making more of levodopa available to the brain

This also reduces many of the peripheral side effects of levodopa (dopamine) - nausea, vomiting, tachycardia, postural hypotension

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18
Q

What nerve(s) provide sensory innervation of the tongue?

A

Anterior 2/3 - mandibular branch of trigeminal nerve (CN V3)

Posterior 1/3 - glossopharyngeal nerve (CN IX)

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19
Q

What nerve(s) provide gustatory innervation of the tongue?

A

Anterior 2/3 - facial nerve (CN VII)

Posterior 1/3 - glossopharyngeal nerve (CN IX)

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20
Q

A 45 yo male presents with fever, headache, abdominal pain, 1-week history of watery diarrhea that has recently become bloody and several faint, erythematous maculopapular lesionson the chest and abdomen. The patient revealed he recently traveled to Latin America. Disease/Dx?

A

Salmonella Typhi infection (typhoid fever)

Gram negative rod that can survive in macrophages

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21
Q

Which antiarrhythmic drug that prolongs the cardiac action potential has the lowest risk of causing torsade de pointes?

A

Amiodarone (Class III antiarrhythmic - potassium)

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22
Q

What precipitates DIC in pregnancy?

A

Tissue factor from the placenta

The most common trigger of DIC in pregnancy is release of tissue factor (thromboplastin) from an injured placenta into maternal circulation

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23
Q

How do enhancers and silencers effect gene transcription and where are they located on the gene?

A

Enhancers and silencers interact with transcription factors and RNA polymerase II to increase and decrease the rate of transcription, respectively

Enhancers/silencers may be located upstream, downstream or within the gene being transcribed

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24
Q

What is the underlying etiology for a patient with stress incontinence?

A

Pelvic floor laxity and urethral sphincter dysfunction

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25
Q

What is the underlying etiology for a patient with urge incontinence?

A

Detrusor overactivity / uninhibited bladder contraction

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26
Q

What is the underlying etiology for a patient with overflow incontinence?

A

Impaired detrusor activity / contractility

Bladder outlet obstruction

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27
Q

What electrolyte abnormality is associated with Legionella pneumonia?

A

Hyponatremia (↓ Na+)

other findings include high fever, dry cough, confusion, diarrhea

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28
Q

What type of motor and sensory loss is seen in radial nerve injury?

A

Motor - weakness of forearm, hand and finger/wrist EXTENSION

Sensory - loss of sensation over the POSTERIOR arm, forearm, dorsolateral hand, dorsal thumb

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29
Q

What does the lepromin skin test evaluate?

A

Lepromin skin test is similar to a PPD for tuberculosis

Positive test (development of nodule on skin) indicates a strong Th1 CD4+ response to M. leprae
→ good response to infection and defined as *tuberculoid leprosy*
Negative test (no nodule on skin) indicates a weak Th1 CD4+ (cell-mediated immune response) to M. leprae
→ poor response to infection and defined as *lepromatous leprosy* (bad prognosis)
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30
Q

A 53 yo male presents with shortness of breath for the past several months. Several of his coworkers are also experiencing similar symptoms. CXR reveals nodular densities and calcification of hilar lymph nodes. Biopsy of the nodes show birefringent particles surrounded by fibrous tissue under polarized light. Disease/Dx?

A

Silicosis caused by inhalation of silica particles

Will appear as birefringent particles surrounded by fibrous tissue under polarized light

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31
Q

Pica is the compulsive consumption of a nonfood and/or non-staple food such as dirt, cornstarch, or ice. What populations is pica most common in?

A

Pregnant women and school children

can be associated with iron or zinc deficiency

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32
Q

What two classes of drugs are used to treat motion sickness?

A

Antimuscarinics (scopolamine)

1st gen antihistamines (meclizine, dimenhydrinate)

Anticholinergic side effects are obviously common with these medications

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33
Q

What type of drug is pramipexole?

A

Dopamine agonist (nonergot)

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34
Q

Defective Fas-FasL interactions can contribute to what category of diseases?

A

Autoimmune diseases

(autoreactive T lymphocytes can’t be killed)

Mutations involving the Fas receptor or Fas ligand can prevent apoptosis of autoreactive lymphocytes, thereby increasing the risk of autoimmune disorders (like SLE)

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35
Q

An injury of the musculocutaneous nerve from trauma such as a shoulder dislocation or over-used baseball pitching arm would result in what motor and sensory abnormalities?

A

Motor - weakness/loss of forearm flexors and coracobrachialis responsible for flexing the arm at the elbow

Sensory - loss of sensation over the lateral forearm

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36
Q

What is the underlying defect in the disease Osteogenesis Imperfecta Type 1?

A

Defective synthesis of type 1 collagen (autosomal dominant)

This causes:

  • brittle bones (no collagen for proper bone matrix formation)
  • small teeth
  • BLUE SCLERA (whites of the eyes are blue)
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37
Q

What is released/activated in the body in physiologic reaction to a state of hypoglycemia?

A

Counter-regulatory agents:

  • Glucagon
  • Activated sympathetic nervous system
  • Cortisol
  • Growth hormone
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38
Q

Why do non-selective B-blockers (propanolol, timolol, nadolol) need to be used with caution in patients with diabetes mellitus?

A

Non-selective B-blockers:

  • exacerbate hypoglycemia (block gluconeogenesis and glycogenolysis)
  • mask the adrenergic symptoms of hypoglycemia (tremulousness, palpitations, anxiety)
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39
Q

What trinucleotide repeat is seen in Fragile X syndrome?

A

CGG repeat in the FMR1 gene of the X chromosome

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40
Q

What is the most important inflammatory mediator of sepsis / septic shock (systemic inflammatory response)?

A

TNF-a (tumor necrosis factor alpha)

TNF-a is an acute phase cytokine produced by activated macrophages

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41
Q

What are the basic cranial nerves responsible for the afferent and efferent signals of the pupillary light reflex?

A

Afferent (to the midbrain) carried by CN II
-when light is shined in the eye, CN II carries the signal to the Edinger-Westphal nucleus

Efferent (to the iris) carried by CN III (oculomotor)
-signal is carried back to the iris via CN III parasympathetic fibers innervating sphincter contraction → constricted pupils

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42
Q

What will be greater in conductive hearing loss, bone or air?

A

Bone conduction > Air conduction in CONDUCTIVE hearing loss

This suggests impaired transmission of air vibrations to the inner ear

(tested via Rinne test)

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43
Q

What will be greater in sensorineural hearing loss, bone or air?

A

Air conduction > Bone conduction in SENSORINEURAL hearing loss

This is permanent hearing loss involving the inner ear (cochlea or auditory nerve)

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44
Q

An intracranial tumor is removed from a 27 yo patient that histologically displays a biphasic pattern of cellularity and has S-100 positivity. What is the likely tumor type?

A

Schwannoma

S-100 indicates neural crest cell origin (which would also be seen in melanoma)

The most common type of schwannoma is an acoustic neuroma which compress CN VIII (hearing loss, tinnitus, loss of balance)

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45
Q

Which two hormones in the body utilize tyrosine kinase-associated receptors with the JAK/STAT signaling pathway?

A

Growth hormone and Prolactin

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46
Q

How is EBV diagnosed?

A

Monospot test (+) - heterophile antibodies detected by agglutination of sheep or horse RBCs by human serum

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47
Q

A 45 yo woman present to clinic with a red rash on her chest that has been present for approximately 1 month. The rash is itchy and feels firm and course. There is induration (firmness) and swelling over the right breast and right axillary lymphadenopathy. Disease/Dx?

A

Inflammatory breast cancer

Caused by invasion and obstruction of lymphatic drainage by breast carcinoma

Rough skin rash is key finding (‘orange peel skin’ known call peau d’orange)

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48
Q

Which acetylcholinesterase inhibitor (indirect cholinergic agonist) can exert its effect peripherally and in the CNS?

A

Physostigmine

Physostigmine is a tertiary amine, capable of crossing the BBB (neostigmine and edrophonium cannot)

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49
Q

What is the mechanism of action of nystatin, an antifungal drug?

A

Binds to ergosterol molecules in fungal cell membranes, creating pores and causing cell lysis

(Nystatin has the same mechanism of Amphotericin B)

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50
Q

In the alveolar capillaries of the lungs, what drives the release H+ and CO2 from hemoglobin?

A

High pO2 and the resulting binding of oxygen to hemoglobin (Haldane effect)

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51
Q

In the peripheral capillaries, what facilitates the release of oxygen unloading from hemoglobin?

A

High concentrations of CO2 and H+ facilitate the release of oxygen from hemoglobin to the peripheral tissues (increased acidity/decreased pH, right shift - known as Bohr effect)

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52
Q

Where are anal fissures most likely to occur?

A

Posterior midline BELOW the pectinate/dentate line

“tear in the anal mucosa below the Pectinate line. Pain while Pooping; blood on toilet Paper. located Posteriorly since this area is Poorly Perfused”

(P’s of anal fissure from FA)

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53
Q

What is the mechanism of action of octreotide?

A

Somatostatin analog → activates somatostatin receptors (which inhibit secretion of many hormones, mostly GI)

Used to treat carcinoid syndrome and pancreatic VIPomas

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54
Q

What type of tumor/tissue origin is evidenced by presence of the marker chromogranin?

A

Neuroendocrine tumors

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55
Q

What is the mechanism of action of Azole drugs?

A

Azoles inhibit the synthesis of ergosterol, an essential component of the fungal cell membrane

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56
Q

Which hormones share alpha subunits?

A

TSH, LH, FSH, hCG

57
Q

What do apoptotic bodies look like histologically?

A

Shrunken, eosinophilic cells

58
Q

What is cytochrome C associated with?

A

Apoptosis via the intrinsic pathway (also an enzyme of the ETC in the mitochondria)

Increased mitochondrial membrane permeability in a cell undergoing apoptotic processes ultimate results in the leakage of cytochrome C into the cytoplasm which results in caspase-mediated apoptosis

59
Q

What is serum sickness?

A

Type-III hypersensitivity-mediated reaction (immune complex deposits)

Antibodies to foreign protein (usually drugs) results in formation of immune complexes which are deposited in membranes/vasculature where they fix complement causing:

  • fever
  • pruritic rash
  • joint pain (arthralgias)
  • proteinuria
  • vasculitis
60
Q

What is the mechanism of action of the drugs cromolyn and nedocromil (same drug class)?

A

Cromolyn inhibits mass cell degranulation, preventing the release of preformed chemical inflammatory mediators

Used for 2nd line treatment for asthma (1st line is glucocorticoids)

61
Q

The glomerular basement membrane and epithelial foot processes in the glomeruli filter molecules based on size and charge. What type of charge (positive or negative) is filtered out by the GBM/foot processes?

A

Negative charge

Negatively charged molecules (such as albumin) are repelled and do not filter through the GBM into the renal tubules

62
Q

What is nephrotic syndrome from minimal change disease treated with?

A

Corticosteroids

63
Q

Why does isoniazid have varying metabolism and half-life between different people?

A

Genetically ‘fast’ vs. ‘slow’ acetylators
-pharmacogenetic variations that exist in the general population

Isoniazid is metabolized by acetylation

Slow acetylators are at risk of isoniazid toxicity

Fast acetylators require higher doses to achieve a therapeutic effect

64
Q

The use of medications to raise HDL levels improves cardiovascular outcomes. True/False?

A

False

Use of medications to raise HDL levels does NOT improve cardiovascular outcomes

65
Q

What serum calcium abnormality is present in patients with sarcoidosis and why does this occur?

A

Hypercalcemia

Non-caseating granuloma formation is due to activation and activity of macrophages

Hypercalcemia is caused by 1-a-hydroxylase activity in activated macrophages which converts Vitamin D to its active form → increases intestinal calcium absorption

66
Q

What is the first line treatment for essential tremor (intention tremor)?

A

Nonspecific B-blocker (propranolol)

67
Q

What muscle component monitors and maintains muscle FORCE?

A

Golgi tendon organ

Detects muscle tension against resistance (like when weightlifting) and can result in sudden relaxation of the muscle if there is too much pressure

68
Q

What muscle component monitors and maintains muscle STRETCH?

A

Intrafusal muscle fibers (muscle spindles)

The muscle spindle system senses muscle stretch and can contract the muscle if there is a damaging stretch

This reflex/system is tested when testing deep tendon reflexes

69
Q

What are neurophysins?

A

Carrier proteins for oxytocin and vasopressin (ADH)

Oxytocin and vasopressin are carried by neurophysins from their site of production in the cell bodies of the paraventricular and supraoptic nuclei (respectively) to their site of release in the axon terminals of the POSTERIOR PITUITARY

70
Q

An infant is born to a 27-year old immigrant with congenital cataracts, sensory-neural deafness and patent ductus arteriosus. Disease/Dx?

A

Congenital rubella syndrome

Can be prevented by vaccinating the mother at least 1 month before conception with live rubella virus vaccine (MMR vaccine)

71
Q

What anatomical structure in the skull do cranial nerves IX, X and XI run through?

A

Jugular foramen (so does the jugular vein)

72
Q

What is the series of mutations involved in the ‘adenoma to carcinoma’ sequence of adenomatous colon polyps to malignant colon adenocarcinoma?

A

APC → K-RAS → p53/DCC

73
Q

What is tryptase?

A

An enzyme released by mast cells that can be used as a serum marker of mast cell activity

Useful for making a clinical diagnosis of anaphylaxis

74
Q

BRAF mutations can be seen in many types of cancer; however, which type of cancer is a BRAF mutation most common in?

A

Melanoma

BRAF is a protein kinase involved in activation of signaling pathways for melanocyte proliferation

BRAF mutation seen in 40-60% of melanoma patients and indicates an aggressive tumor

75
Q

What is a classic clinical finding associated with an uncal herniation (transtentorial heniation of the uncus)?

A

Fixed dilated pupil

Uncal hernations compress CN III (oculomotor) and damage the parasympathetic fibers running to the iris (responsible for contracting the eye, hence dilatation)

76
Q

What are common complications seen in infants associated with congenital CMV infection (vertical transmission of CMV)?

A 
Chorioretinitis 
Sensorineural deafness (#1 cause of virus induced hearing loss)
Seizures 
Mental retardation
Microcephaly
77
Q

What neurotransmitter is decreased in Huntington disease?

A

↓ GABA

78
Q

What hormones does somatostatin reduce the secretion of?

A 
Growth hormone
Insulin
Glucagon
Cholecystokinin
Secretin
Gastrin

(somatoSTOPin)

79
Q

Tamoxifen and raloxifene are selective estrogen receptor modulators with varying agonist/antagonist activity based on the tissue type. What are their respective effects in bone, breast and uterus?

A

Raloxifene
+ bone
- breast
- endometrium

Tamoxifen
+ bone
- breast
+ endometrium (bad)

80
Q

Which opioid medication can precipitate opioid withdrawal in opioid-tolerant patients with chronic pain?

A

Buprenorphine

Buprenorphine is a PARTIAL opioid receptor agonist that binds with high affinity but has low activity (which can displace other opioids and precipitate withdrawal)

81
Q

A 35 y/o man being treated for depression presents with severe confusion and hallucinations, hypotension, tachycardia, dry mouth, facial flushing and QRS prolongation on ECG. What is the diagnosis and how should it be treated?

A

Tricyclic antidepressant overdose

Treat with sodium bicarbonate (NaHCO3)

NaHCO3 raises serum pH and inactivates the tricyclic antidepressant drug

82
Q

What is the mechanism of action of Baclofen and what does it treat?

A

GABA-B receptor agonist

Baclofen is used to treat spasticity in patients with multiple sclerosis or brain/spinal cord disease and injury.

Activating GABA receptors (inhibitory neurotransmitter) decreases the excitability of spinal reflexes, decreasing spasticity

83
Q

What type of collagen is present in the glomerular basement membrane?

A

Type IV collagen

Goodpasture syndrome is an autoimmune disease that targets this type IV collagen with anti-GBM antibodies

84
Q

What metabolic serum abnormality puts patients at risk for recurring acute pancreatitis?

A

Hypertriglyceridemia (↑ triglycerides)

Hypercalcemia

85
Q

What is Jervell and Lange-Nielsen syndrome?

A

Congenital long-QT syndrome (most common congenital long-QT syndrome)

Accompanied by congenital neurosensory deafness

Can lead to syncopal episodes and sudden cardiac death (due to torsades de pointes, a ventricular tachyarrhythmia)

86
Q

What is the effect of the valsalva maneuver, handgrip maneuver and squatting on cardiac output?

A

Valsalva - ↓ preload (↓ CO)

Handgrip - ↑ afterload (↓ CO)

Squatting - ↑ preload (↑ CO)

87
Q

How does pulmonary edema effect lung compliance?

A

Decreases lung compliance → causes dyspnea and hypoxia

Fluid accumulation in the lung interstitium results in decreased lung compliance which results in an inability to adequately distend the lungs during inspiration

88
Q

What metabolic pathway are glucokinase/hexokinase involved in?

A

Glycolysis - 1st step glucose → glucose-6-phosphate

Glucokinase is in liver and pancreatic beta cells

Hexokinase is found in all other tissues

89
Q

A gastrointestinal endoscopic procedure reveals the presence of an ulcer that is very likely to be malignant based on its location. What part of the GI tract is the ulcer in?

A

Duodenum

In contrast, esophageal, gastric and colorectal ulcers can all potentially be malignant and cancerous

90
Q

In cranial nerve III (oculomotor), what nerve fibers run in the center of the nerve and what nerve fibers run on the periphery of the nerve?

A

Center of nerve - muscle component, moves eyelids/eye (ischemic lesion → down and out eye with pupillary control intact)

Peripheral of nerve - parasympathetic output to iris, innervating accommodation and pupillary light reflex (compression lesion → fixed dilated pupil with ocular movement intact)

91
Q

What is Kussmaul sign and when is it seen?

A

Kussmaul sign is a paradoxical RISE in jugular venous pressure during inspiration

This occurs due to a volume-restricted right ventricle that is unable to accommodate increased venous return during inspiration

So this may occur anytime the heart struggles to move fluid through the right heart such as RHF, right ventricular infarction or constrictive pericarditis

92
Q

In a person with central diabetes insipidus, injury to what part of the brain would result in:

  • transient central DI?
  • permanent central DI?
A

Injury to posterior pituitary → transient central DI
-b/c ADH is simply stored and released from the posterior pituitary

Injury to hypothalamus → permanent central DI
-b/c ADH is synthesized in the hypothalamus and then sent to the posterior pituitary

93
Q

What is the function of the retinoblastoma protein?

A

Retinoblastoma protein regulates the G1 → S phase transition of the cell cycle

Active Rb protein serves as a “brake” that stops the cell from dividing (typically until DNA damage is repaired)

Hyperphosphorylated Rb = inactive (brakes off)

Hypophosphorylated Rb = active (brakes on)

94
Q

What condition is associated with bilateral renal angiomyolipomas (benign tumors composed of blood vessels, smooth muscle and fat)?

A

Tuberous sclerosis

Autosomal dominant condition characterized by:

  • seizures and cognitive disability
  • brain hamartomas
  • ash-leaf skin patches
  • facial angiofibromas
  • cardiac rhabdomyomas
95
Q

What is Bell’s palsy?

A

An idiopathic, unilateral paresis of the facial nerve (CN VII)

Lesion of the facial nerve (CN VII) can cause:

  • loss of motor output to facial muscles
  • loss of parasympathetic innervation to lacrimal and salivary glands (loss of tears and spit)
  • loss of taste to anterior 2/3 of tongue
  • increased sensitivity to sound
96
Q

What effect do beta blockers have on the kidney?

A

Beta blockers inhibit renin secretion (via B1 receptors on the juxtaglomerular cells)

The effect on lowering hypertension via this mechanism is modest

97
Q

What are the best short-acting insulins for post-prandial (after eating) use?

A

Lispro
Aspart
Glulisine

Onset of action is in 15 minutes and peaks around 45-75 minutes

98
Q

What are the best long-acting insulins for an all day, basal level of insulin?

A

Glargine
Detemir

These insulins typically last ~24 hours and are usually used once a day and supplemented with short-acting insulins (lispro, aspart)

99
Q

What is the mechanism of action of phenoxybenzamine?

A

IRREVERSIBLE a1 and a2 receptor antagonist

Phenoxybenzamine is used to treat pheochromocytoma because even the very high concentrations of norepinephrine cannot overcome it effects as an IRREVERSIBLE antagonist of a1/a2

100
Q

What is an oxidase positive, non-lactose fermenting, Gram-negative rod that is commonly associated with UTI in patients with indwelling bladder catheters and nosocomial UTI?

A

Pseudomonas aeruginosa

Tx with aminoglycosides and fluoroquinolones

101
Q

What metabolic effects do thiazide diuretics cause?

A

Hyponatremia
Hypokalemia
Metabolic alkalosis

HyperGLUC

  • hyperGlycemia
  • hyperLipidemia (↑ LDL/triglycerides)
  • hyperUricemia
  • hyperCalcemia
102
Q

What are common symptoms of multiple myeloma?

A

Multiple myeloma is caused by a cancerous growth of monoclonal plasma cells (B cells) in the bone marrow

Symptoms associated with it are:

  • Normocytic anemia
  • “punched out” lytic bone lesions on x-ray
  • hypercalcemia due to ↑ bone resorption
  • increased susceptibility to infection due to lack of normal immunoglobulins
  • primary AMYLOIDOSIS
  • renal failure
103
Q

What medication should not be used in patients with hereditary angioedema, an autosomal dominant disorder with C1 esterase inhibitor deficiency?

A

ACE inhibitors (captopril, lisinopril)

C1 esterase inhibitor normally inactivates kallikrein, a catalyst for bradykinin formation

Patients with C1 esterase inhibitor deficiency have naturally elevated levels of bradykinan which is exacerbated by ACE inhibitors (↑ bradykinan) → leads to increased vasodilation and vascular permeability and thus worsening angioedema

104
Q

What is sorbitol and what is the end product of sorbitol metabolism in cells of the seminal vesicles, ovaries, Schwann cells and lens?

A

Sorbitol is a glucose metabolite that provides a method of trapping glucose within a cell

Sorbitol is converted to FRUCTOSE which can be used as energy by the cell

Chronic hyperglycemia can cause sorbitol accumulation within a cell leading to osmotic damage (cataracts, retinopathy, neuropathy)

105
Q

What major metabolic processes occur at some point within the mitochondria?

A 
TCA cycle (Kreb cycle)
Gluconeogenesis
Lipogenesis
B-oxidation of fatty acids
Ketogenesis
Urea cycle
106
Q

A 37 y/o hospitalized patient receiving parenteral nutrition via a central venous catheter is found to have sepsis (fever, tachycardia, hypotension). Blood cultures are positive for yeast. What agent is causing this septic infection?

A

Candida albicans

Candida can colonize the catheter leading to candidemia

Central venous catheter + receipt of parenteral nutrition = risk factor for candidemia

107
Q

What abnormalities would be seen in a spinal cord injury at the ventral white commissure?

A

BILATERAL loss of pain and temperature sensation that is limited to the affected levels

Distal sensation is preserved (b/c this is simply the decussation of pain/temp fibers at that spinal level, not a lesion of the ascending fibers)

108
Q

A 78 y/o man presents with easy fatigability, constipation, back pain, elevated serum protein and azotemia (↑ creatinine, urea in blood). Disease/Dx?

A

Multiple myeloma

Fatigability - due to anemia
Constipation - due to hypercalcemia (↑ bone resorption)
Bone pain - bone lysis induced by myeloma cells
Elevated serum protein - due to monoclonal immunoglobulins
Renal failure/Azotemia - excess free light chains (Bence Jones protein) filtered into the kidney

109
Q

A 32 yo woman presents with complaints of sudden episodes of severe, right-sided facial pain that feels like “stabbing pain”. This occurs every time she eats or brushes her teeth. What drug should be used for treatment?

A

Carbamazepine

This patient his trigeminal neuralgia (CN V) and the 1st line therapy is carbamazepine

Carbamazepine acts by reducing the ability of sodium channels to recover from inactivation, reducing neuronal firing

110
Q

What 5 receptor types are involved in the vomiting reflex of the area postrema in the CNS?

A 
M1 muscarinic
D2 dopaminergic 
H1 histaminic
5-HT3 serotonergic
NK1 neurokinin
111
Q

What is pulsus paradoxus and when is it seen?

A

Pulsus paradoxus is an exaggerated drop in systolic blood pressure during inspiration

It is most commonly seen in cardiac tamponade

TLDR - weak pulses during inspiration in a person with cardiac tamponade

112
Q

What cleaves fibrinogen to form fibrin (for use in fibrin clots) in the coagulation cascade?

A

Thrombin

113
Q

What is the origin of the gonadal arteries (arterial supply to the testes)?

A

Abdominal aorta

testicular veins return to IVC (right vein) and left renal vein (left vein)

114
Q

What is the mechanism of action of buspirone and what is it used for?

A

Buspirone is a 5-HT1a receptor agonist

Treatment for generalized anxiety disorder

No addiction, sedation or tolerance, takes 1-2 weeks to take effect

115
Q

What is the fate of HCO3- after being filtered by the glomerulus in the kidney?

A

The vast majority of filtered HCO3- is reabsorbed in the proximal convoluted tubule

116
Q

When stained with Congo red and viewed under polarized light, brain tissue from a biopsy exhibits apple-green birefringence. What is the most likely diagnosis?

A

Alzheimer disease

B-amyloid proteins are abnormally folded proteins into a B-sheet structure that accumulate forming senile plaques in the grey matter of the brain

Amyloid proteins, no matter where in the body, will show up as “apple-green” or “yellow-green” under polarized light

117
Q

What are anti-mitochondrial antibodies associated with?

A

Primary biliary cirrhosis

autoimmune destruction of bile ducts, ↑ alk phos

118
Q

What is the unique function of prokaryotic (bacterial) DNA polymerase I?

A

5’ to 3’ DNA exonuclease activity to remove RNA primers

5’ to 3’ DNA synthesis (I, II and III all do this)
3’ to 5’ exonuclease ‘proofreading’ activity (I, II, and III all do this)

119
Q

What type of disease typically presents with myopathy, nervous system dysfunction, lactic acidosis and ragged red fibers on muscle biopsy?

A

Mitochondrial dysfunction disorders

Inherited in via MATERNAL inheritance only

Signs/symptoms due to inability to efficiently produce ATP, effecting high metabolic demand tissues first (brain, muscle)

120
Q

A bacteria exhibits decreased activity of bacterial catalase-peroxidase. What drug does this convey resistance to?

A

Isoniazid

Mycobacterial catalase-peroxidase is required for the initial enzymatic conversion of INH to its active metabolite within the mycobacterial cells

121
Q

What is the sodium-channel-binding strength of Class 1 antiarrhythmics from strongest to weakest?

A

1C > 1A > 1B

The higher the binding strength, the greater the use dependence and the slower the dissociation (unbinding) from the sodium channel

122
Q

What is the Reid Index?

A

Measures the duration and severity of chronic bronchitis (in COPD)

Measures the ratio of the thickness of mucous gland layer in the bronchial wall to the thickness of the entire bronchial wall (sans bronchial cartilage)

Elevations of the ratio > 40% = bad

123
Q

A 16 y/o girl presents with primary amenorrhea , normal secondary sexual characteristics and complains of cyclical abdominal and pelvic pain. She has a boyfriend but has never had sex. Disease/Dx?

A

Imperforate hymen

Blood cannot drain from the uterus during menses and results in a massive buildup of blood within the vagina and uterus

124
Q

What drugs are used in patients with systolic heart failure (left ventricular systolic dysfunction) to improve their long-term survival?

A 
Beta blockers (-lols)
ACE inhibitors (-prils)
Aldosterone antagonists (spironolactone)
125
Q

What serum markers would indicate a 21-hydroxylase deficiency (congenital adrenal hyperplasia)?

A 
↓ cortisol
↓ aldosterone
↑ ACTH (no inhibition)
↑ 17-hydroxyprogesterone
(↑ androgen production)

21-hydroxylase deficiency is the most common cause of CAH

126
Q

A common side effect of statin use is myopathy. What other lipid-lowering agents, when paired with statins, can exacerbate myopathy?

A

Fibrates (gemfibrozil) and niacin

127
Q

What part of the nervous system is affected by a late complication of syphilis (neurosyphilis)?

A

Tabes dorsalis
→ degeneration of the dorsal columns and dorsal roots of the spinal cord

Loss of proproception and vibration senses carried in the dorsal columns leads to ataxia; Argyll Robertson pupils may also be seen (pupils that accommodate but don’t react to light)

128
Q

Gastric acid secretion (H+) from the parietal cells in the stomach is stimulated by what hormones/neurotransmitters?

A

Gastrin
Acetylcholine (muscarinic M3)
Histamine (H2

129
Q

What does pulmonary capillary wedge pressure measure?

A

Left atrial pressure (indirectly)

130
Q

What type of medication can be used to treat drug-induced parkinsonism from antipsychotic therapy?

A

Cholinergic antagonists (benzotropine)

131
Q

How does mechanical ventilation-mediated hyperventilation (low pCO2) treat high ICP in a patient with traumatic brain injury and cerebral edema?

A

pCO2 is a potent vasodilator of cerebral vasculature

By lowering the pCO2 via hyperventilation, blood vessels in the brain vasoconstrict and reduce cerebral blood flow → ↓ ICP

132
Q

What is riboflavin (vitamin B2) a precursor for?

A

FAD

FAD is used in the succinate dehydrogenase reaction of the TCA cycle

133
Q

Portal hypertension (typically arising from cirrhosis) can result in formation of esophageal varices, hemorrhoids and caput medusae due to backflow and dilatation through what portosystemic collateral veins?

A

Left gastric v. → Esophageal v. → Esophageal varices

Superior rectal v. → Middle/Inferior rectal v. → Hemorrhoids

Paraumbilical v. → Superficial/Inferior epigastric v. → Caput medusae

134
Q

A 8 yo boy from Yemen presents with a fever, maculopapular rash that began on his face and spread rapidly downward to his trunk and extremities as well as tender lymphadenopathy behind the ears. Disease/Dx?

A

Rubella (German measles)

Caused by Togavirus infection

Differentiated from paramyxovirus measles and other viruses giving kids red rashes is by the POSTAURICULAR LYMPHADENOPATHY

135
Q

What is the mechanism of action of phentolamine?

A

a1/a2 blocker (adrenergic antagonist)

136
Q

What drug can be given to decrease the facial flushing side effect of niacin treatment (for lipid-lowering)?

A

NSAIDs (aspirin)

Facial flushing due to niacin administration is mediated by prostaglandins

137
Q

What is the mechanism of action of entacapone and tolcapone used for Parkinson disease?

A

COMT inhibitors which decrease the breakdown of dopamine, increasing levodopa availability to the brain

Tolcapone - acts centrally and peripherally

Entacapone - acts peripherally only (doesn’t cross BBB)

138
Q

What segments of the spinal cord does the phrenic nerve arise from?

A

C3-C5

The phrenic nerve innervates the ipsilateral hemidiaphragm

USMLE Step 1 (7 decks)

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