UWorld- Heme/Onc Flashcards
taken 3/10/14
what kind of heparin (unfractionated, low molecular weight like enoxaparin or dalteparin, fondaparinux) is most effective at inactivating thrombin
unfractionated heparin; it has a long enough polysaccharide chain to form a ternary complex with antithrombin and thrombin to inactivate thrombin
what kind of drugs are argatroban and bivalirudin and what effect do they have on PT, aPTT and thrombin time (TT)
direct thrombin inhibitors (derived from hirudin from leeches);
they increase thrombin time, but have little effect on PT or aPTT
if a patient has a t(15;17) translocation what treatment would you provide?
what’s the disease?
treat with all-trans-retinoic acid (ATRA)
this patient has APML (which involves a defective retinoic acid receptor)
a patient for whom Heinz bodies are seen on blood smear and who tends to experience jaundice and dark urine after taking antimalarials and sulfonamides has inherited his/her disease via what inheritance pattern
G6PD deficiency is X-linked
nitrite poisoning will cause what to happen to PO2, % Hb sat, and O2 content
methemoglobinemia, caused by nitrite, which oxidize Fe2+ to ferric oxide (Fe3+) leads to:
- normal PO2 (amt. of O2 dissolved in the plasma is unchanged)
- decreased Hb saturation
- decreased O2 content
A patient with sore throat, malaise, persistent fever, cervical LAD, myalgias and splenomegaly has atypical cells on blood smear that have an eccentrically placed nucleus, ample cytoplasm and edges that seem to take the shape of the cells around them. What are these atypical cells?
What is the likely disease?
atypical CD8+ cytotoxic lymphocytes
EBV
A patient is on warfarin therapy after an acute cardiac incident. She says she’s taking her medications, but her PT is subtherapeutic. What other drugs might this patient be taking?
CYP450 inducers increase warfarin metabolism (removal)
ethosuximide, barbituates, phenytoin, chronic alcohol and smoking, St. John’s wort, glucocorticoids, carbamazepine, rifampin, griseofulvin
what kind of heparin is enoxaparin and how does it work
enoxaparin is a low molecular weight heparin that binds antithrombin to activate it, leading to inactivation of Factor Xa (preventing cleavage of prothrombin to thrombin)
A 5 year old had abdominal pain, diarrhea and fever. A few days later he presents with pallor and oliguria. Which lab findings would be decreased? Increased?
This patient probably has HUS.
increased: bleeding time, retic, LDH, BUN, Cr
decreased: platelets, Hgb, Hct, RBC count
note: PT and PTT are normal b/c no coag factor involvement
what are Nef and Tat? explain what they do.
Nef and Tat are HIV genes; Nef decreases MHC I expression on infected cell surfaces; Tat plays a role in viral replication
a patient with recurrent respiratory and GI infections is found to have low serum immunoglobulin;
what substructure in the lymph node is he/she likely lacking and what disease does this patient likely have
lacking germinal centers;
this patient has Bruton X-linked agammaglobulinemia which causes defective B cell maturation
what values are best for diagnosing/ confirming suspicion of hereditary spherocytosis
osmotic fragility test will indicate fragility of the membrane, characteristic of HS
also, mean corpuscular hemoglobin concentration will be increased due to membrane loss and dehydration of the cell
where is major basic protein found and what does it do
found in eosinophilic granules and protects against parasites
myeloperoxidase stains for what liquid cancer
AML
what is argatroban; name the drug type and others of its class
argatroban, along with hirudin and lepirudin, are direct thrombin inhibitors (they inhibit thrombin, but don’t affect factor Xa and they are used for anticoagulation as an alternative to heparin for patients with HIT)
explain the relative locations of HbA, HbH, HbC and HbS on hemoglobin electrophoresis
HbH moves farthest (tetramers of normal beta globin); then HbA (negative a.a. residues); then HbS (a valine aka neutral a.a. substitution); HbC moves the shortest distance (a lysine aka positive a.a. substitution)
what are the 5 steps of leukocyte accumulation in the tissues
- margination: vascular leakage allows leukocytes to contact endothelium
- rolling: selectins mediate loose binding to endothelium
- activation: while rolling neutrophils sample chemokines that activate integrins
- tight adhesion and crawling: integrins bound to ICAM promote tighter adhesion
- transmigration: in the periphery integrins and PECAM-1 promote extravasation into interstitium
what is the preferred route of iron administration
oral iron supplementation (parenteral iron is only given to patients who cannot take orally or need iron fast)
are most cases of B12 deficiency treated with oral or parenteral administration
parenteral: most cases of vit B12 deficiency are due to malabsorption so oral supplementation would be inadequate
the three symptoms eczema, thrombocytopenia and combine B and T cell deficiency (manifested as repeated infections) suggest what disease
Wiskott-Aldrich syndrome
why is vitamin K deficiency seen in preterm infants and what disease does it cause
preterm infants may have vitamin K deficiency due to immature liver, low vit K content in breast milk and meager intestinal microbiota;
vit K deficiency can cause hemorrhagic disease of the newborn due to low factors 2, 7, 9, and 10
name the chromosomes where the following genes are found:
bcl-2, c-myc, Ig heavy chain, kappa light chain, lambda light chain
bcl-2 = chromosome 18 c-myc = chromosome 8 Immunoglobulin heavy chain = chromosome 14 kappa light chain = chromosome 2 lambda light chain = chromosome 22
