LEC 45 Water Soluble Vitamins I

Question 1

What is the main generic function of B vitamins?

Answer 1

they act as coenzymes for enzymes

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Question 2

What are some of the causes of water soluble vitamin deficiency?

Answer 2

• not stored
• decreased intake
• decreased absorption
• increased urinary losses
• increased requirement (pregnancy, infancy, hyperthyroidism)
• decreased precursor (substrate) - Inborn error of metabolism

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Question 3

Which two water soluble vitamins do not typically have a toxicity?

Answer 3

Biotin or Vitamin C

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Question 4

Which B vitamin has a sulfur within its structure?

Answer 4

Thiamin (B1)

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Question 5

Describe the reaction that converts Thiamin to Thiamin Pyrophosphate (TPP).

enzyme?

Answer 5

Thiamin-ATP Phosphoryltransferase catalyzes this reaction

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Question 6

Which important enzymes need TPP?

in metabolic pathways we have studies thusfar

Answer 6

• RBC transketolase (PPP)
• Pyruvate Dehydrogenase
• α-ketoglutarate dehydrogenase

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Question 7

How does Thiamin Deficiency present?

Answer 7

Early: anorexia, nausea, constipation
Later: depression, peripheral neuropathy, ataxia, opthaloplegia, dementia (Wernicke’s encephalopathy)

Can result in Wernicke-Korsakoff or Beri-Beri

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Question 8

What is the difference in wet and dry beriberi?

Answer 8

Wet: affects CV system (fast HR, SOB, leg swelling)

Dry: affects nervous system (numbness of hands/feet, confusion, trouble moving legs, pain)

Slides 16 & 17 (internet for clarification)

Question 9

What are the biochemically active moieties of Vitamin B2?

Answer 9

the two nitrogens w/ the green arrows

this is where the compound is reduced (H’s added to form FADH2)

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Question 10

What important enzyme from TCA and ETC uses FAD to produce FADH2

Answer 10

Succinate Dehydrogenase (Succinate-Coenzyme Q reductase)

catalyzes conversion of succinate to fumarate

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Question 11

What are some enzymes that utilize FAD (B2)?

Answer 11

• Fatty acyl-CoA dehydrogenase (β-ox of FAs)
• PDH
• Succinate Dehydrogenase
• RBC glutathione reductase

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Question 12

Riboflavin is widely distributed in which food products?

Answer 12

• Flesh of warm blooded animals & fish
• Dairy products
• Seeds
• Green leafy vegetables

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Question 13

Angular stomatitis is associated with which B vitamin deficiency?

Answer 13

Riboflavin (B2) deficiency

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Question 14

Pellegra is associated with a deficiency in which B vitamin?

Answer 14

Niacin (B3)

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Question 15

What are the symptoms of Pellegra?

Answer 15

• Dermatitis
• GI symptoms (vomiting, diarrhea)
• CNS findings: Dementia (depression, insomnia, headaches, dizziness, limb rigidity, paresis, & fatal encephalopathy)
• Death

4 D’s

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Question 16

Aside from pellegra, niacin deficiency can also result in what?

Answer 16

Casal’s Necklace & Hyperpigmentation of Hands

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Question 17

How is nicotinamide synthesized in the body?

what 2 compounds can it be made from?

Answer 17

Nicotinic Acid or Tryptophan

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Question 18

What about corn and pellegra?

Answer 18

• europeans & americans but not central & southern americans were getting pellegra from not treating thier corn with an alkaline solution (they were exclusively eating corn)
• niacin is bound to hemicellulose and the solution is necessary to free it to be used by our bodies

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Question 19

B6 dependent enzymes are needed to synthesize many things. Name some.

Answer 19

• AST/ALT enzymes to produce Asp and Ala
• many neurotransmitters such as serotonin, Epi, NE, and GABA

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Question 20

What is the Tryptophan Load test used for?

Answer 20

to test for B6 deficiency

if Xanthurenic acid is produced, then pt is B6 deficient

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Question 21

What is pyridoxine responsive anemia?

Answer 21

• microcytic anemia unresponsive to Fe caused by B6 deficiency which causes aminolevulinic acid sythnase to not work properly
• atypical nucleated RBCs

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Question 22

What are some symptoms of B6 deficiency?

Answer 22

• Cheilosis/stomatitis
• Glossitis
• Impaired cellular immunity
• Fatty liver
• Peripheral Neuropathy

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Question 23

What is usually a cause of B6 deficiency in young women?

Answer 23

Oral contraceptives’ lowered activity of kynurinase increasing xanthenuric acid response to tryptophan load

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Question 24

What is the recommended dosage info for B6?

Answer 24

2 mg

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