Metabolism III

Question 1

hyperammonemia

Answer 1

excess NH4+ - deplete a-KG
-inhibition of TCA cycle

tx - limit protein in diet
lactulose - acidify GI tract
rifamaxin - decreased colonic ammoniagenic bacteria
benzoate - bind AAs

Question 2

N-acetylglutamate

Answer 2

cofactor for CPS-1
-deficient - same as CPS-1 deficiency

get hyperammonemia

Question 3

CPS-1 deficiency

Answer 3

hyperammonemia
neonate poorly regulate temp/respiration
poor feeding 
developmental delay
intellect disability

Question 4

MC urea cycle disorder

Answer 4

OTC deficiency

-X-linked recessive

Question 5

OTC deficiency

Answer 5

ornithine transcarbamylase

excess carbamoyl phosphate > orotic acid

see orotic aciduria, decreased BUN, hyperammonemia

Question 6

orotic aciduria

Answer 6

megaloblastic anemia

Question 7

AA for dopamine, NE, E

Answer 7

phenylalanine

converted to tyrosine > dopa

Question 8

melatonin AA source

Answer 8

tryptophan

require BH4 and B6

Question 9

AA source of NAD+

Answer 9

tryptophan

require B6

Question 10

AA source heme

Answer 10

glycine

require B6

Question 11

AA source GABA

Answer 11

glutamate

require B6

Question 12

AA source nitric oxide

Answer 12

arginine

Question 13

AA source creatinine

Answer 13

arginine

Question 14

AA source urea

Answer 14

arginine

Question 15

tyrosinase deficient

Answer 15

albinism

converts DOPA > melanin

Question 16

deficient phenylalanine hydroxylase

Answer 16

PKU

converts phenylalanine > tyrosine

Question 17

deficient tetrahydrobiopterin

Answer 17

BH4

PKU - cofactor for phenylalanine hydroxylase

Question 18

deficient homogentisate oxidase

Answer 18

alkaptonuria

black pigment

converts homogentisic acid > maleyacetoacetic acid

Question 19

carbidopa

Answer 19

inhibit DOPA decarboxylase

Question 20

cortisol

Answer 20

stimulate phenelethanolamine-N-methyltransferase

convert NE > E

Question 21

phenylketonuria

Answer 21

PKU

deficient phenylalanine hydroxylase
or deficient tetrahydrobiopterin (BH4) - cofactor

auto recessive

musty body odor

excess phenylketones in urine

Question 22

phenylketones

Answer 22

phenylacetate, phenyllactate, phenylpyruvate

-in urine of pt with PKU

Question 23

aspartame

Answer 23

artificial sweetener

contains phenylalanine

should be avoided PKU

Question 24

tx PKU

Answer 24

restrict phenylalanine in diet

also - supplement tyrosine (bypass enzyme deficiency)

Question 25

maple syrup urine disease

Answer 25

deficient a-ketoacid DH cannot break down branched chain AAs -leucine, isoleucine, valine urine smells of burnt sugar auto recessive

Question 26

restricted AAs in maple syrup urine disease

Answer 26

no branched chain AAs -leucine, isoleucine, valine also - thiamine supplementation

Question 27

alkaptonuria

Answer 27

deficiency homogentisate oxidase -pigment forming homogentisic acid accumulate auto recessive dark CT, brown sclera, urine black after exposure to air

Question 28

homocystinuria

Answer 28

auto recessive 3 types: 1 -cystathione synthase deficiency -tx decreased methionine, increased cysteine, B12, folate 2 -decreased affinity cystathione synthase for pyridoxal P -tx vit B6 and cysteine 3 -homocysteine methyltransferase deficiency -tx methionine in diet

Question 29

clinical homocystinuria

Answer 29

``` elevated homocysteine in urine intellect disability osteoporosis marfanoid habitus kyphosis lens subluxation thrombosis atherosclerosis ```

Question 30

cystinuria

Answer 30

auto rec defect renal PCT -and intestinal AA transporter of cysteine, ornithine, lysine, arginine (COLA)

Question 31

COLA

Answer 31

defective transport in cystinuria cysteine ornithine lysine arginine

Question 32

hexagonal kidney stones

Answer 32

cystinuria

Question 33

tx cystinuria

Answer 33

urine alkalinization - potassium citrate, acetazolamide chelating agent - penicillamine

Question 34

diagnosis of cystinuria

Answer 34

urinary cyanide-nitroprusside test

Question 35

cystine

Answer 35

2 cysteine - connected by disulfide bond

Question 36

glucagon regulation of glycogen

Answer 36

activate adenylate cyclase > increased cAMP > increased protein kinase A > activation glycogen phosphorylase kinase > increased activity glycogen phosphorylase > breakdown glycogen to glucose

Question 37

epinephrine regulation of glycogen - beta receptors

Answer 37

activate adenylate cyclase > increased cAMP > increased protein kinase A > activation glycogen phosphorylase kinase > increased activity glycogen phosphorylase > breakdown glycogen to glucose

Question 38

epinephrine regulation of glycogen - alpha receptors

Answer 38

release of Ca from endoplasmic reticulum > activation glycogen phosphorylase kinase > increased activity glycogen phosphorylase > breakdown glycogen to glucose

Question 39

insulin regulation of glycogen

Answer 39

tyrosine kinase receptor dimerize > active protein phosphatase > activate glycogen synthase > more glucose to glycogen

Question 40

glycogen branches

Answer 40

a-1,6

Question 41

glycogen linkages

Answer 41

1-1,4

Question 42

glycogenolysis

Answer 42

glycogen > glucose 1-P > glucose 6-P > ATP

Question 43

glycogen phosphorylase

Answer 43

liberates glucose 1-P from glycogen

Question 44

debranching enzyme

Answer 44

4-a-D glucanotransferase - when 4 glucose on branch - transfer 3 to the long chain a-1,6 glucosidase - when 1 glucose on branch (after 4-a-D) - breaks it off to release glucose 1-P