Exam 2, B6

Question 1

vitamin B6 name

Answer 1

pyridoxine

Question 2

pyridoxine structure

Answer 2

hexose but with more things attached

Question 3

Paul Gyorgy

Answer 3

cured dermatitis in rats, discovered lactobacillus bifidus growth factor activity in human milk

Question 4

what is the B6 form in supplements

Answer 4

pyridoxine (alcohol form)

Question 5

what is the main B6 form, the most active

Answer 5

pyridoxal (aldehyde form)

Question 6

Esmond Snell

Answer 6

discovered 2 forms of B6

Question 7

what is necessary for absorption of pyridoxine

Answer 7

Zinc because alkaline phosphatases are dependent of it to breakdown B6

Question 8

pyridoxine coenzyme

Answer 8

PLP

Question 9

how is PLP found in the body

Answer 9

-most bound to albumin
-10% stored in liver, 80% bound to glycogen to protect it

Question 10

main function of pyridoxine

Answer 10

protein, fat and carb metabolism but especially amino acid metabolism

Question 11

what types of reactions are involved in AA metabolism?

Answer 11

deamination, decarboxylation, cleavage, transamination, transulfhydration, transelenation

Question 12

what happens in transulfhydration

Answer 12

breakdown of homocysteine (increased in CVD, alzheimer’s and parkinson’s)

Question 13

why does a pyridoxine deficiency cause hypochromic, microcytic anemia?

Answer 13

PLP is the first step in heme synthesis, so no B6 = low color and small cell

Question 14

what accounts for 1/2 of B6 usage in the body

Answer 14

glycogen degradation for glucose homeostasis

Question 15

what other deficiencies can cause hypochromic microcytic anemia

Answer 15

folate, copper

Question 16

what deficiencies cause Macrocytic anemia

Answer 16

B12, folic aid

Question 17

B6 relationship to B3

Answer 17

niacin (B3) is synthesized from tryptophan and nucleic acid production thanks to B6
*basically, synthesis of NAD requires B6

Question 18

what is PLP non-coenzyme role

Answer 18

gene expression

Question 19

deficiency of vitamin B6 symptoms

Answer 19

-seborrheic dermatitis
-weakness, fatigue
-mental disability, retardation, convulsive seizures
-antibody impairment at risk (low grade inflammation)

Question 20

photo: rat with irritated eye

Answer 20

dermatitis: B6 deficiency

Question 21

photo: chicken with inflamed edema of eyelids

Answer 21

dermatitis: B6 deficiency

Question 22

photo: pig on the floor

Answer 22

epileptic-like seizures: B6 deficiency

Question 23

best indicator of B6 stores

Answer 23

plasma PLP

Question 24

toxicity of B6 + TUIL

Answer 24

-2 to 6 grams for 2-40 months
-100 mg/day
-cause sensory neuropathy: unsteady gait, impaired tendon reflexes and motor control + lesions of skin

Question 25

RDI for B6

Answer 25

1.3 mg/ day

Question 26

why does supplementing cause toxicity*

Answer 26

supplements are in form of pyridoxine (alcohol form) which competes for enzyme pyridoxal phosphate, so it would inhibit the conversion to active forms. also excess B6 (and B12) could lead to neuropathy

Question 27

main source of B6

Answer 27

tuna, cooked