UWorld Review Flashcards
What is the significance of the pol gene mutation?
Confers HIV resistance to protease inhibitors and nucleoside and non-nucleoside reverse transcriptase inhibitors.
Name three drugs that universally enhance the cytochrome P-450 pathway.
Rifampicin, phenobarbital, phenytoin
Ticlopidine (an ADP antagonist) is commonly associated with what side effect?
Neutropenia with fever and oral ulcers
Name three causes of B12 malabsorption (not including pernicious anemia).
Pancreatic insufficiency, ileal disease, and intestinal bacterial overgrowth
What is the safest anticoagulation treatment for a pregnant woman with DVT?
Heparin (Warfarin and Coumadin are teratogenic)
What is the function of 2,3-BPG in erythrocytes?
2,3-BPG binding allosterically decreases the affinity of hemoglobin for oxygen, enabling the delivery of oxygen to tissues even when PO2 is low.
What is the mechanism of action of desmopressin?
Stimulates release of factor VIII and vWF from endothelial cells. Used to treat hemophilia A.
How does lead poisoning cause anemia?
Inhibition of ALA dehydratase, the enzyme that incorporates iron in heme
What region of the lymph node is populated by T cells?
Paracortex
Extramedullary hematopoiesis is most frequently seen in what category of disease?
Chronic hemolytic anemia
What is the function of retinoblastoma (Rb) protein?
Phosphorylation of Rb renders it inactive and releases E2F transcription factor. This permits the transition from G1 to S phase of the cell cycle.
What is the name of a subcutaneous fungal infection commonly transmitted to gardeners following a thorn prick?
Sporotrichosis, a mycosis caused by Sporothrix schenckii
What is the major adverse effect associated with succinylcholine?
Hyperkalemia
What are three signs of mitochondrial encephalomyopathy?
Neuromuscular lesions, ragged red skeletal muscle fibers, lactic acidosis
What is the most common cause of osteomyelitis in children?
Staph aureus (2nd most common is group A strep)
What is the function of lecithinase (alpha toxin), a toxin produced by C perfringens?
Catalyzes the splitting of phospholipids. Causes hydrolysis of cell membranes leading to cell lysis, tissue necrosis, and edema.
What is the function of protein A made by staph aureus?
Binds the Fc region of IgG, preventing opsonization and complement-mediated destruction of the bacteria
What three drugs are commonly used for MRSA bacteremia?
Vancomycin, daptomycin, linezolid
What marker is elevated in malignant ovarian epithelial tumors?
CA-125
What are the characteristics of endocarditis caused by Strep bovis?
Subacute onset, no preexisting valve abnormality, associated with colon cancer
What infectious agent is most commonly responsible for subacute bacterial endocarditis following dental work?
Strep viridans
What is the etiology of maple syrup urine disease?
Defective breakdown of branched chain amino acids (leucine, isoleucine, valine) due to mutation in branched-chain α-ketoacid dehydrogenase.
What are the five cofactors required for pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, and branched-chain α-ketoacid dhydrogenase?
Thiamine pyrophosphate, lipoate, coenzyme A, FAD, NAD (Tender Loving Care For Nancy)
How does defective absorption of tryptophan cause the symptoms seen in Hartnup disease?
Tryptophan is a precursor required for the formation of nicotinic acid (niacin), serotonin, and melatonin. Niacin deficiency causes photosensitivity and neurological sx. Malabsorption of tryptophan causes aminoaciduria.
What are the symptoms of vitamin E deficiency?
Degeneration of spinocerebellar tracts, dorsal column of the spinal cord, and peripheral nerves. Manifests as ataxia, dysarthria, loss of proprioception and vibration sense.
When treating meningitis with empiric ceftriaxone, ampicillin should be added to cover what possible bacterial agent?
Listeria
What are the functions of HIV proteins gp120 and gp41?
gp120 binds to CD4 receptors on target human cells
gp41 is a transmembrane protein that anchors gp120 and mediates the fusion of the virus with the target cell
What is a Krukenberg tumor?
A metastatic tumor in the ovarian stroma that originated from a gastric carcinoma. It is made up of mucin-producing, signet-ring neoplastic cells.
What drugs have been implicated in drug-induced lupus?
Hydralazine, isoniazid, procainamide, minocycline, quinidine
What is the measure of blood solubility of an anesthetic and how does it relate to the speed of CNS effect (induction)?
Blood/gas partition coefficient.
Large blood/gas partition coefficient = high solubility in the blood = longer time to saturation = slower CNS effect induction
What are the symptoms of graft vs. host disease?
Damage to the skin (desquamation), liver (jaundice, elevated LFTs), and GI tract (diarrhea, GI bleeding, cramping, ileus).
What are the symptoms of niacin (B3) deficiency?
Pellagra: dermatitis, diarrhea, dementia. Niacin is an essential component of NAD and NADP. It can be obtained from the diet or synthesized from tryptophan.
In what setting would you see hyperosmotic volume contraction?
Hyperosmotic volume contraction = loss of free water exceeding the loss of electrolytes.
Seen in diabetes insipidus.
What neurotransmitter is implicated in the development of opioid tolerance?
Glutamate: activates NMDA receptors, leading to phosphorylation of opioid receptors and subsequent opioid tolerance
Which histones make up the nucleosome core?
H2A, H2B, H3, H4
H1 lies outside the nucleosome and facilitates the packaging of nucleosomes into compact structures.
What area of the brain maintains circadian rhythms?
The suprachiasmatic nucleus of the hypothalamus.
What are the pharmacologic characteristics of drugs that are cleared by the liver?
High lipophilicity, high volume of distribution
Lipophilic drugs also have better CNS penetration
What mutation is most commonly implicated in cystic fibrosis?
CFTR gene codes for a membrane protein. The mutation is usually a three nucleotide deletion resulting in the loss of phenylalanine at position 508. The mutation causes abnormal protein folding and failure of glycosylation.
What are the cardiac manifestation of the tetralogy of Fallot?
1) pulmonic stenosis 2) VSD
3) right ventricular hypertrophy 3) overriding aorta
What are the five T’s responsible for cyanotic heart disease?
Tetralogy of Fallot, Tricuspid atresia, Transposition of the great vessels, Truncus arteriosus, Total anomalous pulmonary venous return
What is the triad of Wernicke encephalopathy?
Confusion, ataxia, and ophthalmoplegia
Infusion of glucose w/o thiamine can precipitate Wernicke encephalopathy (damage to mamillary bodies)
What is the risk associated with taking valproate during pregnancy
Increased neural tube defects
What is the risk associated with taking lithium during pregnancy?
Ebstein’s anomaly: downward displacement of the tricuspid valve (“atrialized right ventricle”)
Why are multivitamins contraindicated with levodopa therapy?
B6 increases peripheral metabolism of levodopa and decreases its effectiveness
What is the function of leptin?
- decreases the production of neuropeptide Y, an appetite stimulant.
- stimulates production of POMC. POMC is cleaved into α-MSH, which inhibits food intake.
What disease is associated with cystic degeneration of the putamen?
Wilson’s disease
What mutation is associated with Lynch syndrome?
Mutation in a gene responsible for DNA mismatch repair
Autosomal dominant and predisposes to colon cancer
What three components are required to make nitric oxide?
Arginine, NADPH, O2
What is the most common location for intracranial schwannomas?
Cerebellopontine angle
Which two antiarrhythmics are most selective for ischemic myocardium and therefore most useful in arrhythmia following MI?
Lidocaine and amiodarone
What is the diagnostic utility of gamma-glutamyl transpeptidase?
Distinguish between liver and bone in the setting of elevated alk phos. Gamma-glutamyl transpeptidase is seen in liver but not bone disease.
What are the normal values for PO2, PCO2, and A-a gradient?
PO2 = 100, PCO2 = 40
A-a gradient = 10-15
