Treatment of Inborn Errors of Urea Synthesis — Activation of Alternative Pathways of Waste Nitrogen Synthesis and Excretion

Abstract Children with inborn errors of urea synthesis accumulate ammonium and other nitrogenous precursors of urea, leading to episodic coma and a high mortality rate. We used alternative pathways for the excretion of waste nitrogen as substitutes for the defective ureagenic pathways in 26 infants. These pathways involve synthesis and excretion of hippurate after sodium benzoate administration, and of citrulline and argininosuccinate after arginine supplementation. The children were treated for seven to 62 months; 22 survived. The mean plasma level of ammonium (±S.E.) was 36±2 μmol per liter, and that of benzoate was 1.5±1.0 mg per deciliter. Alternative pathways accounted for between 28 and 59 per cent of the total effective excretion of waste nitrogen. Nineteen infants had normal height, weight, and head circumference, and 13 had normal intellectual development. Activation of alternative pathways of waste nitrogen excretion can prolong survival and improve clinical outcome in children with inborn errors of urea synthesis. (N Engl J Med. 1982; 306:1387–92.

Regulation of intracellular free arachidonic acid in Aplysia nervous system

We have studied the regulation of arachidonic acid (AA) uptake, metabolism, and release in Aplysia nervous system. Following uptake of [ 3 H]AA, the distribution of radioactivity in intracellular and extracellular lipid pools was measured as a function of time in the presence or absence of exogenous AA. The greatest amount of AA was esterified into phosphatidylinositol (relative to pool size). We found that the intracellular free AA pool underwent rapid turnover, and that radioactive free AA and eicosanoids were released at a rapid rate into the extracellular medium, both in the presence and absence of exogenous AA. Most of the released radioactivity originated from phosphatidylinositol.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48020/1/232_2005_Article_BF01868464.pd