We have recently obtained strong evidence for a nutritional requirement for taurine in children and possibly in adults undergoing long term total parenteral nutrition (TPN). These children and adults develop low plasma taurine concentrations and the children have an abnormal electroretinogram (ERG). When taurine was added to TPN solutions in three children, the ERG became normal in each case. In this application, it is proposed to study taurine nutrition and metabolism in a large group of children and adults undergoing long term TPN at home with and without taurine. Taurine is present in many foods, and its rate of turnover appears low; the manifestations of taurine deficiency may take months to become apparent, and it is probable that taurine will be added to parenteral amino acid solutions and enteral diets in the not distant future. Therefore, we believe that this proposal may present a unique opportunity to study taurine nutrition and metabolism in humans.
The specific aims are to assess whether there is a nutritional need for taurine in children and adults undergoing long term TPN. The sizes, exchange rates, and rates of synthesis (if any) and degradation of taurine will be examined in children and adults undergoing long term TPN with and without taurine and in healthy adults. The daily exogenous requirements for taurine in children and adults undergoing long term TPN will also be investigated. Two protocols will be utilized. Adult patients who have bee receiving long term TPN at the onset of the study and all children will be continued on this treatment until they have received TPN without taurine for a minimum of one year; taurine will then be added to the TPN regimen for one year. Taurine concentrations will be assessed periodically in plasma, platelets, leukocytes, red cells, urine, and, in selected patients, in other tissues. ERGs, other tests of visual function, and nutritional status, including growth and development, will be monitored. In selected patients, kinetic analysis of taurine metabolism will be carried out using tracer (13C)taurine, bile composition will be assessed, and quantitative studies of central nervous system function will be performed. In the second protocol, adult patients who begin long term TPN immediately before or after the commencement of this project will be randomly assigned to receive long term TPN either with no taurine or with one of two different daily doses of taurine. Taurine concentrations in plasma, platelets, leukocytes, red cells, urine, and other tissues and nutritional status and visual function will be monitored as in the first protocol.
