Nutrition

Question 1

Cofactor for methionine synthase

Answer 1

B12

Question 2

Sources of B12

Answer 2

Animal products

Question 3

When does vitamin B12 deficiency develops

Answer 3

After 4 to 5 years of absent intake

Question 4

Subacute combined degeneration is due to deficiency of what vitamin

Answer 4

B12

Question 5

Vitamin B1 (thiamine) is a cofactor for what type of enzymes

Answer 5

Dehydrogenases

1. Pyruvate dehydrogenase (glycolysis-TCA cycle)
2. alpha-ketoglutarate dehydrogenase (TCA cycle)
3. Branched-chain ketoacid dehydrogenase (metabolism of valine, leucine, and isoleucine)
4. Transketolase (HMP shunt)

Question 6

Diseases caused by vitamin B1 deficiency

Answer 6

1. Wernicke-Korsakoff syndrome: triad of ataxia, nystagmus, and ophthalmoplegia (Wernicke) with confabulation (korsakoff)
2. Dry beri-beri: polineuritis, SYMMETRICAL muscle wasting
3. Wet beri-beri: high-output cardiac failure (dilated cardiomyopathy), edema

Question 7

Part of the CNS damaged by vitamin B1 deficiency

Answer 7

1. MAMMILLARY BODIES

2. Medial dorsal nucleus of the thalamus

Question 8

Laboratory diagnosis of vitamin B1 deficiency

Answer 8

Increase in RBC transketolase activity following vitamin B1 administration

Question 9

Niacin is synthesized from which aminoacid

Answer 9

Tryptophan

Question 10

Pathogenesis of Hartnup disease

Answer 10

Deficiency of neutral aminoacid (tryptophan) transporters in proximal renal tubular cells and on enterocytes, leading to neutral aminoaciduria and decreased absorption from the gut

*Can lead to pellagra-like symptoms

Question 11

4 D’s of pellagra

Answer 11

1. Diarrhea
2. Dermatitis (C3/C4 circumferential “broad collar” rash - Casal necklace, and hyperpigmentation of sun-exposed limbs)
3. Dementia
4. Death

Question 12

Pyridoxine (vitamin B6) is a cofactor for…

Answer 12

1. Aminotransferase reactions (ALT and AST)
2. Delta aminolevulinate synthase (rate-limiting enzyme in heme synthesis)
3. Glycogen phosphorylase
4. Synthesis of cystathionine

Question 13

Most common cause of pyridoxine deficiency

Answer 13

Isoniazid

Question 14

Clinical manifestations of pyridoxine deficiency

Answer 14

1. SIDEROBLASTIC ANEMIA
2. PERIPHERAL NEUROPATHY
3. Cheilosis/stomatitis
4. Convulsions

Question 15

Function of biotin (vitamin B7)

Answer 15

Cofactor for carboxylation enzymes (adding of a 1-carbon group)

1. Pyruvate carboxylase (pyruvate to oxaloacetate)
2. Acetyl-CoA carboxylase (acetyl-CoA to malonyl-CoA)
3. Propionyl-CoA carboxylase (propionyl-CoA to methylmalonyl-CoA)

Question 16

Folate stores in the body can cover its need for how long

Answer 16

3 to 4 months

Question 17

Most important clinical manifestations of folic acid deficiency

Answer 17

1. Macrocytic megaloblastic anemia (with hypersegmented neutrophils)
2. Homocysteinemia
3. Neural tube defects (pregnant women)

Question 18

Common signs and symptoms to all B-complex deficiencies

Answer 18

• Dermatitis
• Glossitis
• Diarrhea

Question 19

Diseases that can be treated with vitamin A

Answer 19

• Measles

* Acute promyelocytic leukemia (all-trans retinoic acid)

Question 20

Food sources of vitamin A

Answer 20

Liver and leafy vegetables

Question 21

Vitamin A derivative used to treat severe cystic acne

Answer 21

Isotretinoin

Question 22

Signs and symptoms of vitamin A deficiency

Answer 22

• Nyctalopia (earliest manifestation)
• Xerosis cutis
• Keratomalacia (metaplasia to stratified keratinizing squamous epithelium)
• Bitot spots
• Immunosuppression

Question 23

Water soluble vitamin that is teratogenic

Answer 23

Vitamin A

Question 24

Signs and symptoms of B2 deficiency

Answer 24

• Cheilosis
• Corneal vascularization
• Magenta-colored tongue

Question 25

Vitamin that can be derived from the aminoacid tryptophan

Answer 25

B3 *Its synthesis requires B2 and B6

Question 26

Pharmacologic use of niacin

Answer 26

Dyslipidemia *Lowers VLDL and raises levels of HDL

Question 27

Common causes of niacin deficiency

Answer 27

1. Harnup disease 2. Malignant carcinoid syndrome (increased tryptophan metabolism) 3. Isoniazid (decreased B6)

Question 28

Drug that can be taken to prevent facial flushing caused by niacin

Answer 28

Aspirin *In this case, facial flushing is caused by prostaglandins, not by histamine

Question 29

Ingestion of what type of food can lead to biotin deficiency

Answer 29

Raw egg whites (they contain avidin, which binds to biotin)

Question 30

Regions of the spinal cord affected by subacute combined degeneration (vitamin B12 deficiency)

Answer 30

* Dorsal columns * Lateral corticospinal tracts * Spinocerebelar tracts

Question 31

Vitamin C facilitates absorption of which element

Answer 31

Iron, by reducing it to its Fe2+ state

Question 32

Neurotransmitter synthesis enzyme that requires vitamin C as a cofactor

Answer 32

Dopamine beta hydroxylase *Converts dopamine to NE

Question 33

Signs and symptoms of scurvy

Answer 33

* Swollen gums * Brusing * Petechiae * Hemarthrosis * Anemia * Poor wound healing * Perifollicular and subperiosteal hemorrhages * Corkscrew hair

Question 34

Enzyme in charge of activating vitamin K to its reduced form

Answer 34

Epoxide reductase

Question 35

Gamma carboxylation of glutamic acid resiudes on blood clotting proteins needs which lipid-soluble vitamin

Answer 35

Vitamin K

Question 36

Clotting factors that need vitamin K for their synthesis

Answer 36

Factors 2, 7, 9, 10, and proteins C and S

Question 37

Molecule deficiency that leads to Kwashiorkor

Answer 37

Protein deficiency

Question 38

Signs and symptoms of Kwashiorkor

Answer 38

"Kwashiorkor results from protein-deficient MEALS" * Malnutrition * Edema * Anemia * Liver (fatty) * Skin lesions (hyperkeratosis/hyperpigmentation)

Question 39

Define the "flag sign"

Answer 39

Seen in Kwashiorkor, when hair color is restored with periods of adequate dietary intake

Question 40

Pathogenesis of marasmus

Answer 40

Malnutririon not causing edema, diet is deficient in calories but no nutrients are entirely absent *Marasmus results in muscle wasting

Question 41

Limiting reagent of alcohol metabolism

Answer 41

NAD+

Question 42

Functions of vitamin D in GI tract, kidney, and bone

Answer 42

* GI: induces synthesis of calcium binding proteins and increases phosphate absorption * Kidney: stimulates absorption of calcium and secretion of phosphate * Bone: activates osteoclasts and induces bone resorption

Question 43

Allosteric activator of pyruvate kinase

Answer 43

Fructose-1,6-biphosphate

Question 44

Enzyme inhibited by warfarin

Answer 44

Vitamin K epoxide reductase

Question 45

Function of vitamin K epoxide reductase

Answer 45

It transforms vitamin K to its active form after it has been used by the gamma glutamyl carboxylase to carboxylate clotting factors