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17 Cards in this Set
- Front
- Back
What is the result of total deficiency of urea cycle enzymes
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Death in utero, anyone living has only a partial deficiency
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Why is the loss of a urea cycle enzyme toxic?
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Creates hyperammonemia--It backs up all the way to ammonia which has toxic effects.
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What is the classic presentation of urea enzyme defect in infants?
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irritability, hypotonia (low muscle tone), lethargy, vomiting, ataxia (no coordinated muscle movement), delayed growth
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When can a urea cycle defect in adults or older children be seen?
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After a precipitating event such as feast
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What is the prognosis of untreated urea cycle defect?
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spasticity, mental retardation, coma, death
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Does product concentration change in deficiency?
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Increased pressure due to substrate concentration makes each enzyme more efficient causing little change in product concentration
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CPSD- what is it, diagnosis
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1) Enzyme def STEP 1 CPS I
2) ONLY hyperammonemia diagnose by eliminating all the other possibilities |
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OTCD- what is it, diagnosis
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1) Enzyme def STEP 2 OTC
2) hyperammonemia, oratate back up in blood (carbamoyl phosphate leaks into cytoplasm CPS II causes pyrimidine cycle form, oratate produced) |
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ASD- what is it diagnosis
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1) Enzyme def STEP 3, AS
2) elevated citrulline in blood, urine |
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ALD- what is it, diagnosis
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1) Enzyme def STEP 4, AL def
2) elevated argininosuccinate in blood and urine |
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AD, what is it? diagnosis?
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1) arginase deficiency
2) elevated arginine in blood/urine |
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What is the effect of dialysis?
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treat inborn defects by reducing blood ammonia levels
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What does intravenous sodium benzoate phenylacetate do?
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Treatment for inborn defect, these compounds bind random aa and excrete them
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What defects are treated via arginine supplementation, how?
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ASD and ALD. Both citrulline and arginosuccinate can be excreted by the kidney so you can rid of ammonia, however in order to regenerate ornithine, you must supply additional arginine
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When would supplying arginine not treat ASD ALD?
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If there was also arginase deficiency
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What is the affect of levulose?
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Acidifies gut so ammonia binds to acid moeities to treat inborn defects
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What is the effect of antibiotics
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kills some gut bacteria therefore minimizing ammonia production by these bacteria to treat inborn defect
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