USMLE-Rx: Week of 01/02/17 Flashcards
What are the possible sequelae of the disorder that presents with intermittent, colicky pain in young children?
Intussusception can lead to bowel ischemia, bloody stool, and obstruction of the colon with distended bowel loops.
Review the molecular mechanism that leads to beta cells secreting insulin.
Glucose enters beta cells through the constitutively active channel GLUT2. It is then metabolized and generates ATP. The increased ATP deactivates the ATP-sensitive potassium-influx channel. This depolarizes the cell, opening calcium channels and causing the efflux of insulin.
___________ is thought to work by decreasing hepatic gluconeogenesis and increasing the expression of GLUT4 on muscle cells.
Metformin
What antibiotics are often used to treat dental abscesses?
Amoxicillin is the first-line therapy (represented by the guy punching the other guy in Amino’s Cantina), but clindamycin is often used for those allergic to penicillins. These two are chosen because dental abscesses are usually polymicrobial, with Gram-negative and Gram-positive bacteria present.
______________ works by forming a metabolite that is toxic to DNA.
Metronidazole
Achalasia results from defective neurons in the _____________ plexus.
Auerbach (myenteric)
Esophageal candidiasis can cause ____________ in immunocompromised patients.
dysphagia to solids and liquids
The disorder caused by CTG repeats presents with what symptoms?
Myotonic dystrophy: Wide gait Cataracts Myotonia (inability to relax muscles) Cardiac conduction abnormalities
“My Ticker (cardiac); My Toupee (baldness); My Testicles (testicular atrophy); My Tone (myotonia); My caTaracTs.”
True or false: Trousseau syndrome is when you get flexion of the wrist from hypocalcemia.
False! Trousseau syndrome is migratory thrombophlebitis from pancreatic adenocarcinoma, while Trousseau sign is flexion of the wrist from hypocalcemia.
High-protein diets are recommended to those with what glycogen storage disease?
McArdle, because they have recurrent myopathy
Using half-life and volume of distribution, how can you find clearance?
Clearance = (0.7 x volume of distribution) / half-life
(Think of Sufjan Stevens with swans –because of “Seven Swans” –next to a bucket representing volume in the CLEARANCE section of Target above a glass floor with Gordon from Half-Life fighting aliens beneath it.)
_____________ is a modified, artificial triglyceride that is too bulky to be digested or absorbed.
Olestra
Severing of the ____________ nerve would result in a defect in dorsiflexion.
deep peroneal nerve
How can you differentiate craniopharyngioma from pinealoma?
Pinealomas press on the tectum and cause defective upward gaze
What muscle defect accounts for the inward rotation found in Erb’s palsy?
Teres minor (which is innervated by C5 and C6)
The main hormone that opposes the function of insulin binds to a _____________ receptor.
G-protein coupled (being glucagon)
In addition to chronic alcoholism, the “twisted rope” sign within hepatocytes is also seen in ________________.
PBC, Wilson’s, HCC, and cholestatic syndromes
A woman is diagnosed with ALL and begins treatment with cytarabine. She returns several days after treatment initiation with hyperphosphatemia and anion gap acidosis. What medication should you have given her to prevent this?
This describes part of tumor lysis syndrome, for which allopurinol can help. TLS presents after administration of cytotoxic chemotherapy to someone with lymphoma or leukemia. Typical symptoms are metabolic acidosis, hypocalcemia, hyperphosphatemia, and renal failure (from uric acid crystals in the tubules).
Any disorder with elevated PTH will present with elevated alkaline phosphatase. Why?
Because PTH stimulates osteoblasts to activate osteoclasts (via RANK-ligand), and alkaline phosphatase is a marker of osteoblast activity
Achalasia can be treated with surgical approaches such as myotomy or pneumatic dilation, but it can also be treated medically with _________________.
calcium-channel blockers, nitroglycerin, or botox
By what mechanism do calcium-channel blockers cause smooth muscle relaxation?
Decreased intracellular calcium leads to decreased calmodulin-regulated activation of myosin light-chain kinase, which decreases contraction.
The disorder that presents with delayed detachment of the umbilical cord results from a defect in a protein that has two names. What are they?
The disorder described in leukocyte adhesion deficiency, and the two proteins are CD18 and LFA1.
Describe some features of desmosomes, tight junctions, and gap junctions seen on electron microscopy.
Tight junctions: continuous line outside the cell that is composed of three bands
Desmosomes: discrete “rivet” that holds the cell together; bands extend backward directly
Gap junctions: similar to a desmosome, but without a space between
What is athetosis?
Slow, writhing movements of the hands and fingers (seen in those with Huntington’s)
If a stem says a thyroidectomy was “uneventful,” then likely _______________.
the patient still has their parathyroid gland (because normally thyroidectomies preserve the parathyroid)
What does thyroid hormone do to glucose levels?
It stimulates gluconeogenesis.