Folate and B12 Inhibitors--Fitz Flashcards

1
Q

Folate donates ___________ to pyrimidine/purine synthesis

A

carbons, both pyrimidine and purine synthesis

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2
Q

Leucovorin is used in _________ therapy to allow normal cells with ___________ to get adequate amounts of ________

A

rescue therapy
normal reduced folate carrier
folate

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3
Q

2 carriers of folate into cells:

A

reduced folate carrier

folate transporter

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4
Q

This is the most important folate mover in physiologically normal cells

A

folate receptor

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5
Q

This is the most important folate mover in neoplastic cells

A

reduced folate carrier

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6
Q

This receptor is usually overexpressed in cancerous cells, leading to differential sensitivity of cancerous tissue to methotrexate

A

reduced folate carrier

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7
Q

This receptor is usually underexpressed in cancerous cells, making it a difficult way to get folate into a cell

A

reduced folate transporter

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8
Q

This process keeps folate in cells

A

polyglutamination

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9
Q

Why is folate supplementation in commercial products a bad idea?

A

it covers B12 deficiency by hiding megaloblastic anemia and therefore ensuing neurological disease (subacute combined degeneration of spinal cord)–but protects against other folate-deficiency diseases. what are you gonna do.

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10
Q

How do purine analogs inhibit the purine salvage pathway?

A

inhibit GPAT because of GMP buildup

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11
Q

This drug has a total lifetime cap on lifetime limit?

A

doxorubicin

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12
Q

Why is there a lifetime cap on doxorubicin?

A

chronic use can lead to CHF

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13
Q

What is the rate-limiting step in DNA synthesis?

A

thymidylate synthase

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14
Q

This antineoplastic has the most marrow therapeutic index

A

5-FU

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15
Q

This increases in B12 deficiency

A

homocysteine

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16
Q

What are the two reasons that cancer cells are differentially sensitive to MTX?

A
  1. cancer cells usually have increased reduced folate carriers
  2. cancer cells usually perform polyglutamination at higher rates (keeps in cell)
17
Q

What is the function of hydroxyurea in cancer treatment?

A

synchronizes cells, allows them to be more sensitive to radiation therapy

18
Q

Which drug is used as an abortifacaent?

A

MTX

19
Q

Does MTX cross the BBB?

A

no

in childhood leukemia, it is administered intrathecally (directly into the ventricles)

20
Q

How is MTX excreted?

A

renal