Heme and Onc Flashcards
complications of lead poisoning
- neurologic (cognitive impairment, irritability)
- GI (constipation, abdominal pain)
- renal (interstitial nephritis)
- hematologic (anemia)
- lead lines on gingivae (Burton lines) and on metaphyses of long bones on x-ray
- erythrocyte basophilic stippling
- drops-wrist and foot drop
most of the cutaneous lymph from the umbilicus down, including the anus below the dentate line, drains to the ______________
superficial inguinal lymph nodes
exceptions: glans penis and posterior calf, which drain to the deep inguinal nodes
sickle cell patients have increased risk for bacteriemia due to
Streptococcus pneumoniae and Hemophilus influenza
because these patients become functionally asplenic
function of hepcidin
polypeptide synthesized by liver that acts as the central regulator of iron homeostasis
low hepcidin levels increase intestinal iron absorption and stimulate iron release by macrophages
what is the Kozak consensus sequence
occurs on eukaryotic mRNA and defined as: (gcc)gccRccAUGG, R is either adenine or guanine
sequence helps initiate translation at the methionine start codon (AUG)
appearance of RBC in beta thalassemia
hypochromic, microcytic anemia
-increased central pallor, anisopoikilocytosis (variation in size and shape), target cells, tearrop cells, nucleated red cell precursors, and basophilic stippling
unpaired alpha chains precipitate within red cells and cause membrane damage, leading to ineffective erythropoiesis and extravascular hemolysis
how come hepatitis B can integrates its DNA into the host genome but hepatitis C can’t
because hep C is an RNA virus that lacks reverse transcriptase to help it integrate its DNA into the host genome
function of von Willebrand factor
binds glycoprotein (GP) Ib receptors on platelet membrane and mediates platelet aggregation and adhesion to subendothelial collagen
also serves as a carrier for factor VII and stabilizes it
characteristics of inflammatory breast cancer
dermal lymphatic invasion by breast carcinoma
poor prognosis
peau d’orange: erythematous, itchy breast rash with skin texture changes analogous to an orange peel
what is bleeding due to heparin toxicity treated with
protamine sulfate
can’t be used for warfarin overdose
what to use for warfarin overdose
vitamin K (takes time)
fresh frozen plasma
can’t be used for heparin overdose
how does cyanide toxicity work? and how is it treated?
toxicity: bind ferric iron (Fe3+) with high affinity, inhibiting cytochrome c oxidase in mitochondria (needed for oxidative phosphorylation)–> lactic acidosis and death
treat: inhaled amyl nitrite
how does inhaled amyl nitrite treat cyanide poisoning?
it oxidizes ferrous iron (Fe2+) in hemoglobin to ferric iron (Fe3+), generating methemoglobin
methemoglobin can’t carry oxygen but has high affinity for cyanide
hemorrhagic cystitis is an adverse reaction to which two drugs
cyclophosphamide or irosfamide (nitrogen mustard-based chemotherapy) from the urinary excretion of the toxic metabolite acrolein
can be prevented by aggressive hydration, bladder irrigation, and administration of mesna (binds acrolein)
Gianzmann thrombassthenia
autosomal recessive disorder that is caused by a deficient or defective glycoprotein (GP) IIb/IIIa on platelet surfaces.
presents in childhood with mucocutaneous bleeding
peripheral smear snows no platelet clumping
mechanism of action of abciximab
blocker of GP IIb/IIIa receptor, which normally promotes platelet binding to fibrinogen
treat unstable angina and acute coronary syndrome
BRCA1 and BRCA2 are tumor suppressor genes involved in what process
repair of double-stranded DNA breaks
mutation- autosomal dominant with variable penetrance
increased risk of developing breast and ovarian cancer
characteristic of polycythemia vera
primary polycythemia
increased RBCs
intense itching after hot shower, erythromelalgia (severe, burning pain and red-blue coloration) due to episodic blood clots in vessels of extremities
decreased erythropoeitin
treat: phlebotomy, hydroxyurea, ruxolitinib (JAK1/2 inhibitor)
why do you need to check G6PD levels before administering dapsone?
to prevent hemolytic anemia in those with G6PD deficiency
Dapsone puts oxidative stress on body
where does isotype switching of immunoglobulins occur?
germinal centers of lymph nodes and requires interaction of CD40 receptor on B-cells with the CD4- ligand CD154) expressed by activated T-cells
difference between topoisomerase I and topoisomerase II
I- makes single-stranded nicks to relieve negative supercoiling
II-induces transient breaks in both DNA strands simultaneously to relieve both positive and negative supercoiling
mechanism of action of etoposide
chemotherapeutic agent that inhibits the sealing activity of topoisomerase II
what is negative selection in T cell maturation?
eliminate T cells that bind to self MHC or self antigens with overly high affinity
occurs in thymic medullla
prevent autoimmunity
leukocyte adhesion process- step 1
1) margination: increased vascular leakage in microvasculature leads to hemoconcentration and decreased wall shear stress, improving contact of neutrophils with endothelial lining
leukocyte adhesion process-step 2
2) rolling: neutrophils roll on endothelium via loos binding of sialylated carbohydrate groups such as Sialyl Lewis X or PSGL-1 to L-selectin on neutrophils or E-selectin/P-selectin on endothelial cells
leukocyte adhesion process-step 3
3) activation: slow rolling allows leukocytes to sample chemokines secreted by inflamed tissue. this activates integrins by inducing signaling cascade that results in conformational change in integrins necessary for binding
leukocyte adhesion process-step 4
tight adhesion and crawling: neutrophils become firmly attached to endothelium via binding of CD18 beta 2 integrins (Mac-1 and LFA-1) to intercellular adhesion molecule-1 (ICAM-1) on endothelial cells
leukocyte adhesion process- step 5
transmigration: neutrophils eventually migrate out of the vasculature by squeezing between cells via integrin attachments and adherence to platelet endothelial cell adhesion molecule 1 (PECAM-1)
mechanism of action of rivaroxaban and apixaban
oral anticoagulant that directly inhibits factor Xa
used in venous venous thromboembolism and atrial fibrillation
what are cytokeratins
proteins that help form the keratin-containing intermediate filaments that make up the cytoskeleton of almost all epithelial
marker for epithelial-derived tumors
classic triad of paroxysmal nocturnal hemoglobinuria
hemolytic anemia (hemoglobinuria), pancytopenia, and thrombosis at atypical sites
due to a gene defect that leads to uncontrolled complement-mediated hemolysis
chronic hemolysis–> iron deposition in the kidney (hemosiderosis)
sickling episodes of sickle cell disease results in hemolysis, which leads to
increased indirect bilirubin and lactate dehydrogenase
decreased levels of haptoglobin
what are Reed-Sternberg cells
giant binucleated cell derived from germinal center B-lymphocytes and are the neoplastic cells of Hodgkin lymphoma
owl’s eyes
association between vitamin B12 and folate deficiency and treatment
moderate improvement in the hemoglobin level often occurs when a deficiency in vitamin B12 is treated with folate, or vice versa
treatment of vitamin B12 deficiency with folate alone can actually worsen neurologic dysfunction
characteristic laboratory abnormalities of hemolytic uremic syndrome
decreased hemoglobin and platelet count and increased bleeding time, lactate dehydrogenase, bilirubin, BUN, and creatinine
HUS –> acute kidney injury, microangiopathic hemolytic anemia, and thrombocytopenia
how does bone metastases assists in cancer diagnosis?
osteolytic (lucent): due to osteoclast stimulation, tend to represent aggressive cancer
osteoblastic (sclerotic): due to osteoblasts, indicates a more indolent course
how does chronic myelogenous leukemia (CML) differs from leukocytosis
have decreased leukocyte (neutrophil) alkaline phosphatase while that is normal or elevated in a leukemoid reaction
presentation f von Willebrand disease
lifelong history of mucosal bleeding, including gingival bleeding, epistaxis, and/or menorrhagia
normal platelet levels but porlonged bleeding time due to impaired platelet functioning
2 important functions of van Willebrand factor
- promotes platelet adhesion by binding and crosslinking platelet glycoproteins (primarily GpIb) with exposed collagen underneath damaged endothelium
- protective carrier protein for factor VIII
heinz bodies are found in which anemia type
G6PD deficiency
heinz bodies: dark, intracellular inclusion that stain with supravital stain and represent hemoglobin that has denatured/precipitated from oxidative stress
t(14;18) chromosomal translocation is associated with what gene expression abnormalities
Bcl-2 overexpression
Bcl-2 is a protooncogene becasue it has anti-apoptotic effects–> allow cells to live
associated with follicular lymphoma
acute intermittent porphyria
autosomal dominant condition caused by porphobilinogen deaminase deficiency
minority present with acute attacks characterized by abdominal pain and vomiting, peripheral neuropathy, neuropsychological symptoms, and reddish-brown urine
treat with IV glucose or heme preparations, which down-regulate ALA synthase activity
characteristic of hairy cell leukemia
indolent B-cell neoplasm
middled-aged men, bone marrow failure and infiltration into the reticuloendothelial system
massive splenomegaly
“dry tap” unsuccessful bone marrow aspiration
lymphocytes with cytoplasmic projects
how can G6PD deficiency present with hemolytic anemia?
need NADPH to keep glutathione reduced to detoxifies free radicals and peroxides
so when NADPH is low in RBC–> hemolytic anemia due to RBC poor defense against oxidizing agent
need G6PD to make NADPH
difference between direct factor Xa inhibitors and direct thrombin inhibitors
factor Xa: apixaban, rivaroxaban)-increase the prothrombin and activated partial thromboplastin times but do not affect the thrombin time
thrombin (dabigatran) prolong aPTT, PT, and TT
why do patients with significant renal dysfunction have excessive bleeding
due in part to accumulation of uremic toxins int eh circulation
prolonged bleeding time with normal platelet count, prothrombin time (PT), and activated partial thromboplastin time (aPTT)
how does sickle cell anemia lead to fibrosis and atrophy f the spleen?
repetitive splenic infarctions caused by splenic microvessel occlusioin
multiple myeloma characteristics
bone marrow sample compased of greater than 30% of plasma cells
-median age of diagnosis= 70
symptoms of multiple myeloma
- normocytic and normochromic anemia due to replacement of bone marrow with malignant plasma cells
- secretion of IL-1 and IL-6 activates osteoclasts–> bone resorption –> osteopenia
- hypercalcemia
- increased susceptibility to infection
- AL amyloid due to accumulation of monoclonal immunoglobulin light chains
- renal failure due to infiltrationcof kidney by plasma cells, amyloid, Bence-Jones cases in tubules, hypercalcemia, and inflammation
auer rods stain positively for
myeloperoxidase
they are deformed azurophilic granules found in the cytoplasm of cytoplasm of the myeloblasts
found in AML M3 (acute promyeloctic leukemia)
hydroxyurea for sickle cell disease
drug that increases fetal hemoglobin synthesis
B-cell vs T-cell acute lymphoblastic leukemia
ALL= most common malignancy of childhood
B is approximately 70-80% of all cases of ALL
T present with mediastinal mass that cause respiratory symptoms, dysphagia, or superior vena cava syndrome
in what ways are selective COX2 inhibitors better than non-selective COX inhibitors
selective COX 2 inhibitors have potent anti-inflammatory effects without the side effects of bleeding and GI ulceration
do not impair platelet function because platelets predominantly express COX 1
porphyria cutanea tarda (PCT) cause and presentations
most common disorder of porphyrin (heme) synthesis
uroporphyrinogen decarboxylase deficiency
early stage: neuropsychiatric manifestations without photosensitivity
late: derangements lead to photosensitivity–> vesicle and blister formation on sun exposed area
difference between unfractionated heparin vs. low molecular weight heparin (LMWH)
only unfractionated heparin has a pentasaccharid chain long enough (>18 saccharid units) ot bind to both antithrombin and thrombin
unfractionated heparin has EQUAL activity against factor Xa and thrombin, while LMWH has greater activity against Factor Xa than thrombin
tumor lysis syndrome- what is it and how to prevent it
oncologic emergency that develop during chemotherapy because large numbers of tumor cells are destroyed in a short period, so lots of intracellular ions are released into serum along with nuclei acids (catabolized into uric acid)
prevent with hydration and use of hypouricemic agents such as allopurinol or rasburicase (convert uric acid into more soluble metabolites
how do you treat heparin-induced thrombocytopenia (HIT)
direct thrombin inhibitors (DTIs) such as argatroban
avoid all forms of heparin in these patients
why are prothrombin time and partial thromboplastin time normal in hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP) and abnormal in DIC
because the coagulation system is not activated in HUS-TTP
Li-Fraumeni syndrome- mutation and what types of cancers
autosomal dominant mutation in TP53, gene that codes for tumor suppressor protein p53
sarcoma, breast, leukemia, and adrenal cancer (SBLA mnemonic)
role of p53
arrest cells with mutant DNA in the G1/S stage of cell cycle until he damage is repaired
what is pure red cell aplasia
rare form of marrow failure characterized by severe hypoplasia of marrow erythroid elements in the setting of normal granulopoiesis and thrombopoiesis
associated with thymoma, lymphocytic leukemias, and parvovirus B19 infection
mechanism of action of enoxaparin
low-molecular-weight heparin that functions like heparin in that it binds and activates antithrombin III (AT III)
heparins mechanism of action
increases the effect of the naturally occurring anticoagulant antithrombin III (AT III)
unfractionated and low molecular weight heparins are commonly used for DVT prevention in inpatient settings
sideroblastic anemia- causes
results from an inability to form heme molecules in the motochondria–> leading to iron deposition inside the mitochondria (forming a ringed sideroblast)
chronic alcoholism, lead poisoning, copper deficiency, and certain meds (isoniazid, chloramphenicol, linezolid), myelodyplastic syndrome
how does lead poisoning lead to sideroblastic anemia
inhibits two key enzymes in the heme synthesis pathway:
- ferrochelatase (last enzyme in heme synthesis to help incorporate iron into protoporphyrin–> buildup of iron and protoporphyrin
- deta-ALA dehydratase: converts delta-ALA to porphobilinogen to make porphyrin –> buildup of delta-ALA
what medication is associated with sideroblastic anemia
isoniazid–> can also cause vitamin B6 deficiency–> peripheral neuropathy
how to diagnose sideroblastic anemia
bone-marrow examination with Prussian blue stain
what is hereditary spherocytosis
autosomal dominant hemolytic anemia that result from an abnormality in the RBC membrane characterized by defects in the membrane proteins such as ankyrin (most common), spectrin, or band 3
have increased MCHC due to mild dehydration of the RBC
mechanism of action of desmopressin (DDAVP)
synthetic analog of vasopressin that increases circulating factor VIII and endothelial secretion of vWF to stop bleeding
can be used to treat von Willebrand factor deficiency and mild hemophilia A
beta-thalassemia is due to what abnormal cellular process
alternate RNA splicing–> can lead to cancer, dementia, and epilepsy
how can blood transfusions lead to hypocalcemia
whole blood transfusions or packed RBCs may develop elevated plasma levels of citrate (substance added to stored blood
citrate chelates Ca2+ and magnesium and may reduce their plasma levels, causing paresthesias
methotrexate mechanism of action
folic acid antagonist used to treat ectopic pregnancy
competitively inhibits the enzyme dihydrofolate (DHF) reductase, which catalyzes the synthesis of tetrahydrofolate–> inhibition of DHF reducatase causes the intermediate DHF to accumulate intracellularly
how does radiation do to metastatic cells
induces DNA damage through DNA double-strand fractures and formation of oxygen free radicals
how does cancer cells gain resistance to chemotherapy
human multidrug resistance (MDR1) gene codes for P-glycoprotein, a transmembrane ATP-dependent efflux pump protein that can reduce the influx of drugs into the cytosol and can increase efflux form the cytosol, thereby preventing the action of chemotherapeutic agents
target of rituximab
CD20
a monoclonal antibody directed against the CD20 antigen
treatment for B-cell non-Hodgkin lymphoma, CLL, rheumatoid arthritis, and idiopathic thrombocytopenic purpura
how come tumors taht harbor KRAS mutations are resistant to treatment with anti-EGFR drugs (eg, ctuximab, panitumumab)
KRAS is an activating mutation that lead to constitutive activation of the epidermal growth factor receptor (EGFR) pathway, promoting increased cell proliferation and growth
how is tumor necrosis factor-alpha associated with muscle wasting?
thought to mediate paraneoplastic cachexia in humans by suppressing appetite and increasing basal metabolic rate
why can’t maturing erythrocytes synthesize heme
need mitochondria to produce heme
when does sickling occur?
HbS aggregates in deoxygenated state
under conditions associated with anoxia including low pH and high levels of 2,3-bisphosphoglycerate
result of vitamin K deficiency
life-threatening bleeding diathesis, such as intracranial hemorrhage and profuse bleeding from the GI tract, umbilicus, and surgical sites
Kaposi’s sarcosma is associated with
Human herpes virus type 8
presents as blue-violet or brownish skin plaques on the extremities and mucous membranes of HIV-positive patients
side effect of ganciclovir
neutropenia
risk increased with co-administration of zidovudine or trimethoprim-sulfamethoxazole
how can RBC sickle in sickle cell anemia?
HbS contains a mutation that replaces glutamic acid with valine at the 6th amino acid position of the beta globin chain
promotes hydrophobic interaction among Hb molecules –> HbS polymerization and erythrocyte sickling
association between chronic hemolysis and gallstone formation
chronic hemolysis increase the amount of unconjugated bilirubin in bile, which promotes calcium bilirubinate precipitation and leads to black pigment stone
pigmented gallstones are a complication of any hemolytic anemia
how does warfarin-induced skin necrosis occur
inhibition of vitamin K-dependent gamma-carboxylation of clotting factors-> procoagulant effect
-> interrupt blood flow to skin and lead to skin necrosis, particularly in patients with protein C or S deficiency
what is the Haldane effect? what is the Bohr effect?
Haldane: in the lungs, the binding of oxygen to hemoglobin drives the release of H+ and CO2 from hemoglobin
Bohr: in peripheral tissues, high concentrations of CO2 and H+ facilitate oxygen unloading from hemoglobin
histology of Burkitt lymphoma
diffuse midium-sized lymphocytes and a high proliferation index represented by the high Di-67 fraction (approaching 100%)
“starry sky” appearance due to presence of benign macrophages
plummer-vinson syndrome characteristics
dysphagia (esophageal web formation), iron deficiency anemia, koilonychia (spoon-shaped nailed) and shiny red tongue
symptoms resolve with iron supplementation
mechanism of action of trastuzumab
monoclonal antibody used in management of patient with HER2-positive breast cancer
binds to portion of the extracellular domain of HER2 and prevents activation of a transmembrane tyrosine kinase
what cause bruises to turn green
heme oxygenase converts heme to biliverdin, a pigment that causes the greenish color to develop in bruises several days after an injury
how come you have to reduce the doses of 6-mercaptopurine if patients are also receiving xanthine oxidase inhibitor allopurinol?
because xanthine oxidase (XO) and thiopurin methyltransferase in the liver inactivate 6-mercaptopurine (cytotoxic purine analogs that inhibit de novo purine synthesis)
and since allopurinol is an XO inhibitor, it can increase concentration of 6-mercaptopurine
how does c-Myc function?
functions as a transcription activator controlling cell proliferation, differentiation, and apoptosis
retinoblastoma (Rb) tumor suppressor gene
encodes Rb protein to regulates cell cycle
active (hypophosphorylated) prevents damaged cells from passing G1 to S checkpoint
inactive (hyperphosphorylated) Rb protein allows the damaged cell to enter mitosis
abnormal phosphorylation leads to Rb inactivation
with the exception of chronic myelogenous leukemia, the chronic myeloproliferative disorders (especially polycythemia vera) frequently harbor a mutation in the
nonreceptor cytoplasmic tyrosine kinase, Janus kinase 2 (JAK2)–> mutation leads to tyrosine phosphorylation activity and in the cytokine-independent activation of signal transducers and activators of transcription (STAT) proteins (JAK-STAT signaling pathway)
how does the mutations lead to beta-thalassemia
mutation–> defective transcription, processing, and translation of beta-globin mRNA—> deficiency of the beta-globin chains
clinical features that suggest malignant cause of back pain
worse at night, not relieved with rest or analgesics, advanced age, and systemic symptoms
common cancers that metastasize to bone: prostate, breast, kidney, thyroid, and lung
hematologic side effects of chloramphenicol (suppresses bacterial protein synthesis by binding to the ribosomal 50S subunit and inhibit the peptidyl transferase enzyme
dose-related anemia, leukopenia, and/or thrombocytopenia that are reversible by withdrawing the medication
also cause dose-independent (idiosyncratic) aplastic anemia) which is severe and fatal without treatment (bone marrow transplant) and it is irreversible
what does haptoglobin do?
serum protein that binds to free hemoglobin and promotes its uptake by the reticuloendothelial system
decrease when significant quantities of hemoglobin are released into circulation like in intravascular hemolysis
protein mutated in hereditary hemochromatosis
HFE protein-normally interacts with transferrin receptor to sense iron stores level. if mutated, then falsely detect low iron levels and make the body accumulate more iron
inactivation of HFE–> decreased hepcidin (helps destroy ferroportin) synthesis by hepatocytes and increased DMT1 expression (divalent metal transporter so iron would be absorbed more in the intestinal lumen) by enterocytes
