USMLE-Rx: Week of 01/09/17 Flashcards
What electrolyte abnormality often results from acute pancreatitis?
Hypocalcemia
The mechanism is not fully understood, but it is thought that calcium may get saponified in the damaged pancreas.
In what five infectious exposures are preformed immunoglobulins given to prevent infection?
Tetanus Botulism Hepatitis B Varicella Rabies
“To Be Healed Very Rapidly”
What glucose concentration will overload the proximal convoluted tubule?
200 mg/dL
If a patient has a mostly benign hepatic neoplasm, what medication might you recommend they discontinue?
Oral contraceptives
Hepatic adenomas can be caused by oral contraceptives. Most often they are benign, but if they lead to mass-effect pain then you should recommend they stop taking OCPs. There is a small chance that this would transition to hepatocellular carcinoma.
True or false: pyloric stenosis presents with the “double-bubble” sign on abdominal plain film.
False. Duodenal atresia presents with the double-bubble sign.
What is the most common cause of death in adolescents and young adults?
Accidents
Which parts of conducting neurons have the lowest capacitance?
The myelinated parts
True or false: GLUT-2 transporters have a high affinity for glucose.
False. They have a low affinity for glucose which allows a high Km and thus the channels do not get saturated.
Which kinds of kidney stones (mineral) are most common?
Calcium oxalate
Nitroprusside can be metabolized to a product that inhibits which enzyme?
Nitroprusside is metabolized to cyanide, which inhibits mitochondrial cytochrome oxidase.
Why does cyanide poisoning lead to cherry-red lips and mucous membranes?
Oxygen is not taken up in peripheral tissues, so hemoglobin remains in the oxygenated state.
What sign is often seen on x-rays of the spine of those with ankylosing spondylitis?
The “bamboo spine,” a fusing of the vertebrae
Why does the drug that treats the HLA-B27 disorders reactivate certain dormant syndromes?
Infliximab and adalimumab –both TNF-alpha monoclonal antibodies –are used to treat psoriasis, ankylosing spondylitis, IBD, and reactive arthritis (the HLA-B27 disorders). TNF-alpha is important in granuloma formation, so inhibiting it can reactivate tuberculosis.
Remember that the primary problem in type 2 diabetes is __________________.
insulin resistance (and subsequent failure to take in glucose in peripheral tissues); eventually, beta cells will be exhausted and insulin levels will drop, but at first there will be high levels of insulin
Which thyroid carcinoma is associated with MEN 2A and 2B?
MEN 1: pancreatic islet cell tumors, parathyroid adenomas, and pituitary adenomas
MEN 2A: medullary thyroid carcinoma, pheochromocytoma, and parathyroid adenoma
MEN 2B: medullary thyroid carcinoma, pheochromocytoma, and mucous neuroma
Somatostatin is given to those suffering from what acute and painful disorder?
Pancreatitis (because it inhibits pancreatic secretions)
What is a first-line treatment for ulcerative colitis?
Mesalamine (an aspirin-like drug categorized as an 5-aminosalicylate)
What kind of drug is nizatidine?
An H2 antagonist (pay attention to the -tidine suffix)
What kind of drug is sucralfate?
An ulcer-binding agent (the sucrALfate –the AL stands for aluminum)
List the two monoclonal antibodies that bind to the IL-2 receptor.
Basiliximab and daclizumab
Imagine BASIL on a pogo stick –which looks like a T –getting a daiquiri thrown in his face.
Sirolimus, tacrolimus, and cyclosporine all inhibit IL-2 in some way, but they do so differently. Explain.
Tacrolimus and cyclosporine inhibit the secretion of IL-2, while sirolimus blocks the IL-2 receptor.
(Imagine a guy TACkling a CYCList before he can even make a SPORE. Sirolimus, meanwhile, SIlences the ability of IL-2 to have any effect.)
Which drugs are often given to elderly people for flu prophylaxis?
Oseltamivir, a neuraminidase inhibitor
You know that metoclopramide is a prokinetic D2-antagonist, but where in the GI tract does it have its effect?
LES, where it increases tone
True or false: methicillin-sensitive Staphylococcus can usually be treated with penicillin V.
False. Most methicillin-sensitive strains of Staphylococcus express beta-lactamases that will inactivate penicillin.
What kind of drug is chlordiazepoxide?
It is a long-acting benzodiazepine that is hepatically metabolized.
What are the short- and intermediate-acting benzodiazepines?
Short: the -olam suffix drugs (alprazolam, midazolam, and triazolam)
Intermediate: oxazepam and lorazepam
What is medial rectus palsy?
Palsy that prevents inward gaze
How does acetazolamide affect sodium and potassium levels?
Acetazolamide inhibits the absorption of bicarbonate in the proximal convoluted tubule. This leads to increased retention of H+, which causes excretion of potassium and sodium.
What kind of drug is bumetanide?
Loop diuretic
Hydrochlorothiazides decrease excretion of _______________.
calcium
What can lower positive predictive value?
Low prevalence
True or false: cobalamin deficiency can present with macroglossia.
True. Cobalamin deficiency can present with a “glazed” tongue with flattened villi.
Which disorder can lead to false positive results for an STD?
Antiphospholipid antibody can lead to false positive tests for syphilis. The molecule it detects is cardiolipin, found in the inner mitochondrial membrane.
True or false: congenital hypothyroidism is most often central in origin.
False. It is usually due to defective T4 synthesis and thus presents as a peripheral hypothyroidism.
By what mechanism do those with Klinefelter’s develop infertility?
It is primarily due to dysfunctional Leydig cells, which results in decreased testosterone, dysfunctional Sertoli cells, and fibrotic seminiferous tubules.
Note: their hypothalamic-pituitary axis is intact, so they will have increased levels of LH and FSH but decreased levels of testosterone.
Importantly, what category of substances does charcoal not bind?
Cations. As such, charcoal will not absorb iron, calcium, or magnesium.
What is a key property of deferoxamine that allows it to be medically helpful?
It does not bind to iron within cells, so the iron in hemoglobin, cytochrome, and myoglobin will not be absorbed.
Two cardinal symptoms of iron toxicity include __________________.
hypotension and hemorrhagic gastroenteritis
Which metals can be absorbed by dimercaprol and EDTA?
Dimercaprol: mercury, gold, and copper
EDTA: lead (lEaD = EDta)
When does Bruton’s typically present?
Around six months after birth, because that is when maternal IgG will attenuate to clinically significant levels.
People with selective IgA deficiency will have anaphylaxis in response to _______________.
receiving products containing IgA
What disorder prominent in young women can lead to cold intolerance and stress fractures?
Anorexia, because the weight loss shuts down the hypothalamic-pituitary axis which lowers levels of estrogen and causes osteoporosis. The cold intolerance is caused by decreased fat stores.
What should you do if a person suffers a stroke and requires a ventilator to live but specifically wrote an advanced directive stating that they did not want to live if a ventilator was required?
Provided they are not conscious and able to state otherwise, remove the ventilator and allow them to die.
Which chromosome might have a mutation if a patient presents with bitemporal hemianopia and low blood sugar?
11 (MEN 1)
Which disorder presents with neoplasms in cells that arose from neural crest cells?
MEN 2A
What charge does the glomerular basement membrane have?
Negative (like most connective tissue it has negatively charged proteins and carbohydrates that attract water)
Which indirect cholinomimetic treats atropine overdose?
Physostigmine.
Of all the indirect cholinomimetics, physostigmine is the only one that penetrates the CNS.
(First Aid’s mnemonic is that physostigmine “phyxes” atropine overdose. Sketchy has the PHYS ed teacher punishing the kid who spray painted Alice on the side of the gym.)
Guillain-Barré syndrome affects the ______-neurium.
endo (innermost sheath)
Describe the three layers covering peripheral nerves.
Endoneurium: innermost layer (attached in GBS)
Perineurium: middle layer (provides filtration barrier)
Epineurium: outer fascia
What effect do a class I antiarrhythmics have on ECG readings?
By blocking sodium channels, they slow the action potential upstroke, thus prolonging ventricular depolarization and widening the QRS complex.
(Remember the solo singer’s slanted microphone cord.)
If someone has supraventricular tachycardia – evidenced by rapid heart rate with normal rhythm and lack of symptoms –the first-line treatment works by what mechanism?
Adenosine works by activating A1 channels that decrease calcium entry and causing more potassium exit, thus hyperpolarizing the AV node and briefly stopping the heart.
(Remember the A1 dancers in the sketching video with the falling ice cream and the banana flying off the podium.)
True or false: Job syndrome results from failure to produce interferon gamma.
False. Job syndrome results from failure to produce IL-17 (a potent stimulator of neutrophils) and thus interferon gamma is given to treat the condition.
The microtubule disorder that causes progressive decline in B cells and T cells has what inheritance pattern?
Wiskott-Aldrich syndrome presents with eczema, thrombocytopenic purpura, and recurrent infections; it has an XLR inheritance pattern.
What endothelial receptor does LFA-1 bind to?
ICAM-1 (this makes sense because ICAM stands for intercellular adhesion molecule)
True or false: Peyer patches are located throughout the small and large intestines.
False. Peyer patches are only located in the ileum. Thus, IBD patients post-ileectomy are at increased risk of GI infections.
By what two mechanisms does digoxin help treat congestive heart failure?
It increases contractility and decreases heart rate by stimulating vagal tone.
(Remember the “Las Vegas” theme of the digoxin video.)
________________ is a treatment for acute heart failure that works by inhibiting phosphodiesterase and thus dilating arterioles and increasing contractility.
Milrinone
(Think of the Sketchy video with the donkey advertising his “one in a MILiON” campaign with dilated red ears and the slogan “don’t PHOSter disINterest.”)
Vincristine has what adverse effect?
Neurotoxicity (just think about how VIN diesel’s NEUROns must have been damaged at some point)
Liver disease presents with what RBC pathologies?
Target cells and acanthocytes
________________ can transition to squamous cell carcinoma.
Actinic keratosis (“It’s scc ACTINg as a benign lesion.”)
Describe the presentation and treatment of neurogenic bladder.
Often caused by diabetes, neurogenic bladder presents with urinary retention and nocturia. It can be treated with a muscarinic agonist such as bethanechol.
(Remember the bladder-shaped hose that Beth the construction worker is holding.)
A patient with 17-alpha hydroxylase will have overexpression of a hormone produced in which layer of the adrenal cortex?
The zona glomerulosa
Those with 17-alpha hydroxylase deficiency cannot make cortisol or androgens. However, intermediates in the aldosterone synthesis pathway have glucocorticoid activity, so they can often survive into adolescence without developing adrenal crisis.
Which parts of the spine are affected in pernicious anemia?
Dorsal columns
Lateral corticospinal tracts
Spinocerebellar tracts
What electrolyte abnormality is seen in those with DiGeorge?
Hypocalcemia (due to hypoparathyroidism)
The product made by glucose-6 phosphate dehydrogenase has what three cellular functions?
Electron-carrier for anabolic reactions that synthesize cholesterol and lipids
Regenerator of glutathione
Generating the respiratory burst of neutrophils
Mannitol has what significant side effect?
Pulmonary edema
Which diuretic can cause ototoxicity?
Furosemide
What three diuretics lack sulfa?
Mannitol
Spironolactone
Ethacrynic acid
Are afferent fibers from the carotid sinus stimulatory or inhibitory?
Inhibitory
The vessels are under sympathetic control, and the afferent fibers are stretch-sensitive neurons that fire in response to increased pressure. Thus, when they fire, they need to decrease sympathetic input.
RhoGAM is an antibody to _______________.
anti-Rh factor; it works by eliminating the maternal antibodies before they can be activated
Bilateral Schwannomas are a classic finding of a disorder in which chromosome?
22 (being neurofibramatosis 2)
Think: NF2 presents on 22 with 2 Schwannomas.
Restricted joint movement is a symptom of a disorder of what organelle?
The Golgi apparatus (I-cell disease)
True or false: infection with Ascaris lumbricoides increases risk of gallbladder adenocarcinoma.
False. It increases the risk of cholangiocarcinoma.
Inhaled anesthetics that have a high ___________ are less soluble.
oil:blood partition coefficient
What is a typical presentation of alpha-1,4-glucosidase deficiency?
Cardiomegaly and hepatomegaly with death in infancy
Pompe disease
Hemorrhoids above the ___________ are painless.
pectinate line
What two types of tissue are commonly recapitulated by the vitelline duct?
Gastric and pancreatic
To perform a PCR, you need to include primers that _________________.
will bind to the piece of DNA that you want to amplify; so if a question asks you what strand will allow for amplification of the DNA segment, pick the sequence complementary to the gene
Which HLA types predispose to diabetes?
HLA-DR3 and HLA-DR4
Compare and contrast the two types of fructosuria.
Essential fructosuria: defect in fructokinase that leads to complete inability to metabolize fructose; as such, fructose exits in the urine
Fructose intolerance: defect in aldolase B that leads to fructose-1 phosphate getting trapped inside cells and leading to liver damage
The nutrient deficient in those with Wernicke encephalopathy is a cofactor for which enzymes?
Pyruvate dehydrogenase
Alpha-ketoglutarate dehydrogenase
Transketolase
Branched-chain ketoacid dehydrogenase
Biotin is a cofactor for which mitochondrial enzyme?
Pyruvate carboxylase (along with ATP and acetyl co-a)
What is the F in the FATED mnemonic for Job syndrome?
Facies
How does having only one lung affect wedge pressure?
It increases it because of hypoxia-induced vasoconstriction.
True or false: those with alkaptonuria have chronically dark urine.
False. It turns dark when it becomes alkaline.
What kind of receptor does angiotensin II bind?
Gq
(Think about it: angiotensin II causes vasoconstriction of smooth muscle in the efferent arteriole. To cause vasoconstriction in smooth muscle, you need to increase intracellular calcium!)
What lab values might you see in someone with ischemic bowel?
Lactic acidosis (same with any ischemic damage)
Why do serum hydrolase levels rise in a child with I-cell disease?
Because without mannose phosphorylation, the proteins destined for the lysosome become exocytosed.
Celecoxib causes a decrease in _____________ that leads to platelet aggregation.
prostacyclin
_______________ stimulates the macula densa to release renin.
Low sodium in the DCT
H. pylori is more common in ____________ ulcers.
duodenal (in fact, 100% of duodenal ulcers have H. pylori, so if a patient reports that his/her GI pain decreases with eating then they will need triple therapy)
From which vessel do fat soluble vitamins first enter the blood?
From the thoracic duct! Fat gets absorbed as chyle in lacteals that lead to lymphatics.
Malignant hypertension is characterized by which sign of serious underlying damage?
Papilledema
What drug can you give to prevent cyanide poisoning in someone being treated for malignant hypertension?
Nitroprusside can cause cyanide poisoning and sodium thiosulfate acts as an antidote.
What is associated with DR2?
The two-word disorders: Goodpasture syndrome, multiple sclerosis
Heparin can cause what renal-cardio disorder?
Hypoaldosteronism (remember in the hunter Sketch that the mine has a big K symbolizing the hyperkalemia that results from hypoaldosteronism)
The autosomal dominant disorder that presents with juvenile cataracts increases the risk of what three neoplasms?
Vestibular Schwannomas
Meningiomas
Ependymomas
How do beta-2 antagonists worsen a complication of diabetes treatment?
Two ways:
- Non-selective blockers inhibit glycogenolysis in the liver (which is mediated by B2), thereby increasing risk of hypoglycemia
- B1 blockers inhibit the tachycardia that would occur with hypoglycemia, thereby masking the symptoms
Remember that you can calculate PPV from sensitivity and specificity if the stem gives you ______________.
pretest probability (i.e., prevalence in the sample)
