Biochem metabolism Flashcards Preview

FA: random > Biochem metabolism > Flashcards

Flashcards in Biochem metabolism Deck (129)
Loading flashcards...
91

How does benzoate or phenyl butyrate treat hyperammonemia?

both bind amino acid & lead to excretion

92

How does lactulose treat hyperammonemia?

it is a sugar that is not absorbed so gets to colon & bacteria there have a feast thus making the colon acidic causing binding of the NH4+ for excretion

93

What is the MC urea cycle disorder? How is it inherited? When does it present?

ornithine transcarbamoylase deficiency is XLR presenting in first few days of life but can present later

94

What are the labs of OTC deficiency?

excess carbamoyl phosphate in mitochondria spills out & is converted to orotic acid (part of pyrimidine synthesis)

increased orotic acid in blood & urine, decreased BUN, Sx of hyperammonemia (tremor, vomit, somnolence, cerebral edema)

95

Differentiate OTC deficiency vs orotic aciduria

OTC deficiency is NOT associated w/ megaloblastic anemia

96

What are the derivates of phenylalanine?

(via BH4) tyrosine to make Dopa (vit B6) DA, (vit C) NE, (SAM) Epi

97

derivates of tryptophan

(vit B6) niacin to NAD+/NADP+
(BH4) serotonin to melatonin

98

derivates of histidine

(vit B6) histamine

99

derivates of glycine

(via B6) porphyrin to heme

100

derivates of arginine

creatine;
urea;
(BH4) nitric oxide

101

derivates of glutamate

(via B6) GABA;
glutathione

102

What amino acid derives melanin? How?

phenylalanine (BH4) to tyrosine to (BH4) Dopa which is converted to melanin

103

What amino acid derives thyroxine?

Phenylalanine via BH4 to tyrosine to thyroxine

104

derivates of methionine

SAM

105

What are the respective breakdown products of catecholamines? how are they broken down?

MAO & COMT breaks down

DA to HVA
NE to VMA
Epi to metanephrine

106

What is the etiology of PKU? What will be found in urine?

AR decrease in phenylalanine hydroxylase (adds OH) or decrease in BH4 (malignant PKU)

phenylketones in urine (phenylacetate, phenyllactate, phenylpyruvate)

107

When does PKU typically present & earliest signs?

2-3 days after birth bc uses mother's enzyme during fetal life

musty odor due to aromatic AA metabolism

108

Findings of child with PKU

mental & growth retardation;
seizures;
fair skin;
eczema;
musty odor

109

Treatment of PKU

decrease Phe in diet (NO aspartame ~ nutrasweet)

Increase tyrosine (essential AA now)

Must be done w/in first 3 wks

110

Maternal PKU can occur how? what are the findings in the child?

lack of proper diet during pregnancy

microcephaly; growth & mental retardation; congenital heart defects

111

Pt notices urine turns black in the air & presents to ortho w/ debilitating joint pain. What is the disease caused by?

Alkaptonuria (ochronosis) =>
AR congenital deficiency of homogentisic acid oxidase in degradation of tyrosine to fumarate

112

What are the findings of alkaptonuria?

dark connective tissue;
brown pigmented sclera;
urine turns black w/ air exposure;
May have debilitating arthralgias

113

What are the debilitating arthralgias of alkaptonuria from?

homogentisic acid being toxic to cartilage

114

What are the 2 causes of albinism?

congenital deficiency of:

tyrosinase (inability to synthesize melanin) => AR

Defective tyrosine transporters (decrease amounts of tyrosine & melanin)

115

During embryology, what also may cause albinism?

lack of migration of neural crest cells

116

Describe the inheritance pattern of albinism

variable inheritance due to locus heterogeneity

ocular albinism is XLR

117

What are the 3 forms of homocystinuria? How are they inherited & what is result?

ALL are AR resulting in excess homocysteine & cysteine is now essential amino acid

Cystathionine synthase deficiency

Decreased affinity of cystathioinine synthase for pyridoxal phosphate

Homocysteine methyltransferase deficiency

118

How is Cystathionine synthase deficiency treated?

decreased methionine;
increase cysteine, B12 & folate, B6 in diet

119

How is Decreased affinity of cystathioinine synthase for pyridoxal phosphate treated?

increased a lot of vitamin B6 in diet

120

How is Homocysteine methyltransferase deficiency treated?

requires B12 so give it