Deck XV Flashcards Preview

USMLE World Missed Questions > Deck XV > Flashcards

Flashcards in Deck XV Deck (30):

What result in the Schilling test indicates dietary deficiency of vitamin B12?

Normal urinary excretion of radiolabeled vitamin B12 suggests normal absorption and thus B12 deficiency is due to poor intake.


What Schilling test result indicates pernicious anemia?

Diminished urinary excretion of radiolabeled B12. Normal excretion after administration of intrinsic factor is diagnostic of pernicious anemia. Low excretion of B12 after intrinsic factor administration indicates malabsorption syndromes like pancreatic insufficiency, bacterial overgrowth, short gut syndrome.


What type of leukemia can be treated by all trans retinoic acid (ATRA)?

Acute promyelocytic leukemia.


What gene is fused in patients with APL?

PNL/RARa. The fusion prevents the gene from signalling for proper cellular differentiation.


Define anaplastic and describe the features of an anaplastic tumor.

Neoplastic cells that demonstrate a complete lack of differentiation. Tumors bear no resemblance to the tissue of origin and are composed of pleomorphic cells with large, hyperchromatic nuclei that grown in a disorganized fashion. Anaplastic tumors may also contain many abnormal mitoses and giant tumor cells.


What is pure red cell aplasia (PRCA)?

A rare form of marrow failure characterized by severe hypoplasia of marrow erythroid elements in the setting of normal granulopoiesis and thrombopoiesis.


What conditions are associated with pure red cell aplasia?

Thymoma (autoimmune condition), lymphocytic leukemias, parvovirus B19 infection.


What three lab findings are diagnostic of hemolytic anemia?

Elevated LDH, indirect billirubinemia, anemia.


What condition is diagnosed by a positive osmotic fragility test?



What is a complication of hemolytic anemia?

Pigmented gallstones (composed of calcium bilirubinate, bilirubin polymers, calcium salts)


In a lesion involving the jugular foramen, what are the symptoms of jugular foramen (Vernet) syndrome?

CN IX, X, XI dysfunction. Loss of taste from posterior 1/3 of tongue (IX), reduced parotid gland secretion (IX), loss of gag reflex (IX, X), dysphagia (IX, X), dysphonia/ hoarseness (CN X), soft palate drop with uvular deviation towards normal side (X), STM and trapezius paresis (XI).


What symptoms are common in a patient with von Willebrand disease?

Easy bleeding from mucosal sites including gingivae, nasal mucosa, GI tract, menorrhagia.


Name the two roles of von Willebrand Factor.

Carrier protein for factor VIII; Aids in platelet adhesion to injured blood vessels during clotting by binding platelet glycoproteins and exposed collagen on injured blood vessel walls.


Cytokeratin is used as an immunohistochemical marker of what type of tissues?

Epithelial-derived tissues.


What is encoded by the HER2/neu oncogene?

A transmembrane glycoprotein with intracellular tyrosine kinase activity. It is a member of the family of epidermal growth factor receptors.


What factor, when administered in vitro to animals produces symptoms of cachexia?



What symptoms are associated with a factor V Leiden deficiency?

Va is resistant to inactivation by protein C, an antithrombotic. This causes hypercoaguability.


Follicular lymphoma is associated with what translocation and what gene expression abnormality?

t(14,18) translocation with Bcl2 overexpression. Bcl2 is a protooncogene (anti-apoptotic effects) causing cell immortality.


What are the side effects associated with Vincristine?

Neurotoxicity- peripheral neuropathy. This is the dose limiting side effect.


What is the mechanism of action of vincristine (and other vinca alkaloids)?

Inhibition of microtubule polymerization after binding to b-tubulin. M-phase specific agents.


How do reticulocyte count, hemoglobin, and erythrocyte count levels change in a patient with a vitamin B deficiency who is started on replacement therapy?

Reticulocyte count increases dramatically upon initiation and hemoglobin and erythrocyte count levels rise more gradually.


What are the major adverse effects associated with Ganciclovir?

Neutropenia, anemia, thrombocytopenia, impaired renal function.


What is the major side effect associated with zidovudine?

Bone marrow suppression (anemia, granulocytopenia, etc,)


What are fibronectins?

Large glycoproteins produced by fibroblasts and some epithelial cells. It binds to integrins, matrix collagen, and glycosaminoglycans and serve as a mediator of normal cell adhesion and migration.


How is integrin mediated adhesion of cells to the basement membrane and extracellular matrix mediated?

Through binding of integrins to fibronects, collagen, and laminin.


What is the mechanism of action of etoposide?

Inhibition of the sealing activity of topoisomerase II. It causes chromosomal breaks to accumulate in dividing cells and ultimately causes cell death.


What is the difference between the actions of topoisomerase I vs topoisomerase II?

Topoisomerase I makes single stranded nicks to relieve negative supercoiling, topoisomerase II induces transient breaks in both DNA strands simultaneously to relieve both positive and negative supercoiling.


What two conditions is etoposide most commonly used to treat?

Testicular cancer and small cell lung cancer.


What are the two most common organisms causing bacteriemia in sickle cell patients?

Streptococcus pneumoniae followed by hemophilus influenza


What is the most common cause of osteomyelitis in a child with sickle cell anemia?

Salmonella (followed by staph. a and e. coli)