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17 Cards in this Set

  • Front
  • Back
How does folic acid act in one-carbon transfers in purine/pyrimidine synthesis?
- carries the units as tetrahydroflorate (TH4)
How is Vitamin B12 deficiency and the Folate Trap related?
- Without Vitamin B12 as the cofactor in the remethylation of Homocysteine to Methionine,
- FH4 cannot be remade from N5-methyl FH4
What accumulates in a Folate Trap?
---intermediate in breakdown of histidine to glutamate
---FH4 breaks FIGLU into several products
---without FH4, FIGLU is excreted
How does folate deficiency cause homocysteinemia?
-Lack of folate (FH4) so unable to remethylate Methionine from Homocysteine
- Buildup of Homocysteine
What was the purpose of folate fortification of flour?
- prevent neural tube defects, macrocytic anemia, homocysteinuria
- lowers dementia
Folate and Macrocytosis in Neural Tube Defects
- spinal cord cells enlarge and prevent spinal column from fusing over them during embryogenesis (neurons increase in size)
Folate and Macrocytosis in Atherosclerosis
- Arterial cells want to swell outwards, but tunica adventitia is thick and sturdy
- Cells swell inwards instead, decreasing size of lumen, increase turbulence, cellular damage, platelet adhesion
Folate and Macrocytosis in Cervical Dysplasia
- Macrocytic cervical cells convey normal signs of cervical cancer such as an increase of cytoplasm, size of cell, shape of cell
Folate and Macrocytosis in Macrocytic Anemia
- Neutrophil nuclei are hypersegmented
- RBC have nuclei remnats (Howell-Jolly bodies)
- Anisocytes (cells vary in size)
- Schistocytes (cells are shredded b/c unable to pass through capillary)
What causes neutrophils to be hypersegmented?
- Folate deficiency means that DNA is not made, and histones are not made either
- no proteins available to wrap DNA up properly
What are nuclei remnants in RBCs called?
- Howell-Jolly bodies
What causes Howell-Jolly bodies?
- Inefficient production of cells, so nuclei are not properly disposed
What intermediate increases in Folate trap?
- N5-methyl FH4
What happens in short-gut syndrome?
- not enough intestine to absorb Vitamin B12
- excrete methylmalonic acid
What 2 reactions require Vitamin B12 as a cofactor?
- Homocysteine---> Methionine
- Methinoyl CoA---> Succinyl CoA
What is MCV and how does it relate to Folate deficiency?
- Mean corpusical volume (volume of individual cells)
- Folate= Macrocytosis= Increase in MCV
What part of Folate does Sulfa drugs mimic?
- Para- aminobenzoate (PABA)