Heme/Onc - Stuff Missed

Question 1

Methotrexate

Answer 1

• folic acid analog that inhibits dihyrofolate reductase

- inhibits DNA synthesis by preventing syntehsis of purines and thymidylic acid

Question 2

Leucovorin

Answer 2

aka Folinic acid

• can reverse the toxicity of methotrexate in non-cancerous cells in GI mucosa and bone marrow if administered at right time
• DOES NOT REQUIRE ACTION OF DIHYDROFOLATE REDUCTASE

Question 3

Filgrastim

Answer 3

Granulocyte stimuating factor

- used to stimulate proliferation and differentiation of granulocytes with neutropenia

Question 4

Mensa

Answer 4

prevents hemorrhagic cystitis in patients receiving cyclophosphamie or ifosfamide chemotherapy
- binds to acrolein, the toxic metabolite formed from cyclophosophamide or ifofsamide

Question 5

Lead poisoning affects which enzymes in heme synthesis pathway

Answer 5

• Zn containing ALA dehydratase
• Ferrochetolase
• leads to microcytic anemia as ALA and protoporphyrin IX

Question 6

Rate limiting enzyme in heme synthesis

Answer 6

ALA synthase which coverts glycine and succinyl-cOA to ALA

** inhibited by heme and glucose

Question 7

Acute intermittent porphyria

Answer 7

• defect in uroprophyrinogen I synthase
• acute abdominal pain
• port-wine colored urine when exposed to sunlight
• polyneuropathy
• psych disturbances
• precipitated by drugs (e.g. barbs, alcohol)

Question 8

Treatment of Acute Intermittent Prophyria

Answer 8

• Glucose and heme which will stop ALA thus stop production of heme

Question 9

Porphyria Cutanea Tarda

Answer 9

• defects in uroprophyrinogen decarboxylase
• uroprophyrinogen accumulates in urine (tea colored urine)
• patients experience photosensitivity
• most common one

Question 10

Cladibrine

Answer 10

• purine analog
• treatment for hairy leukemia
• resistant to degradation of adenosine deaminase in high intracellular concentrations

Question 11

How are human tumor cells able to resistt chemotherapy?

Answer 11

MDR1 gene which codes for P-glycoprotein, an ATP- dependent efflux transmembrane protein that reduces intracellular concentrations of drugs

Question 12

High nucleotide uptake occurs during which part of cell cycle?

Answer 12

• S phase (preparin to divide)

Question 13

Grade of tumor

Answer 13

• dependent on differentiation (e.g well differentiation or poor differentiation)

Question 14

Stage of tumor

Answer 14

extent of tumor expansion

Question 15

Peau d’orange

Answer 15

• pitting edema that is yellow brown in beat

= occurs when neoplastic cells plug dermal lymphatics