Heme/Onc - Stuff Missed Flashcards Preview

USMLE Step 1 > Heme/Onc - Stuff Missed > Flashcards

Flashcards in Heme/Onc - Stuff Missed Deck (15):
1

Methotrexate

- folic acid analog that inhibits dihyrofolate reductase
- inhibits DNA synthesis by preventing syntehsis of purines and thymidylic acid

2

Leucovorin

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

3

Filgrastim

Granulocyte stimuating factor
- used to stimulate proliferation and differentiation of granulocytes with neutropenia

4

Mensa

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

5

Lead poisoning affects which enzymes in heme synthesis pathway

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

6

Rate limiting enzyme in heme synthesis

ALA synthase which coverts glycine and succinyl-cOA to ALA
** inhibited by heme and glucose

7

Acute intermittent porphyria

- 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)

8

Treatment of Acute Intermittent Prophyria

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

9

Porphyria Cutanea Tarda

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

10

Cladibrine

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

11

How are human tumor cells able to resistt chemotherapy?

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

12

High nucleotide uptake occurs during which part of cell cycle?

- S phase (preparin to divide)

13

Grade of tumor

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

14

Stage of tumor

extent of tumor expansion

15

Peau d'orange

- pitting edema that is yellow brown in beat
= occurs when neoplastic cells plug dermal lymphatics