A baby boy aged 6 weeks, showed symptoms of pronounced hyperammonemia, which included vomiting, fever, irritability, and screaming episodes interspersed with periods of lethargy. The baby had low levels of blood urea, elevated serum transaminase, and generalized hyperaminoacidemia and aminoaciduria. The levels of citrulline, argininosuccinate and arginine were relatively low in both blood and urine.
Enzyme assays of liver tissue showed that the levels of mitochondrial carbamoyl synthetase (CPS) was approx. 20% of normal; the enzyme was active only in the presence of relatively high concentrations of N-acetylglutamate. All other urea cycle enzyme levels were relatively normal. The baby was treated with a supplement containing arginine, pyridoxine and α-keto analogs of essential amino acids (those that cannot be synthesized by humans). As part of the therapy, dietary protein was also restricted
Please explain
1) Why were blood levels of ammonia high in this baby?
2) Explain why infants with CPS deficiency normally show relatively low blood levels of citrulline, argininosuccinate, arginine and urea?
3) Why is the administration of an arginine supplement recommended for this infant?
4) Why was dietary protein restricted?
A baby boy aged 6 weeks, showed symptoms of pronounced hyperammonemia, which included vomiting, fever, irritability, and screaming episodes interspersed with periods of lethargy. The baby had low levels of blood urea, elevated serum transaminase, and generalized hyperaminoacidemia and aminoaciduria. The levels of citrulline, argininosuccinate and arginine were relatively low in both blood and urine.
Enzyme assays of liver tissue showed that the levels of mitochondrial carbamoyl synthetase (CPS) was approx. 20% of normal; the enzyme was active only in the presence of relatively high concentrations of N-acetylglutamate. All other urea cycle enzyme levels were relatively normal. The baby was treated with a supplement containing arginine, pyridoxine and α-keto analogs of essential amino acids (those that cannot be synthesized by humans). As part of the therapy, dietary protein was also restricted
Please explain
1) Why were blood levels of ammonia high in this baby?
2) Explain why infants with CPS deficiency normally show relatively low blood levels of citrulline, argininosuccinate, arginine and urea?
3) Why is the administration of an arginine supplement recommended for this infant?
4) Why was dietary protein restricted?
