Phenylalanine: Transplacental centrations in Rhesus Monkeys.

Arbino acids are actively transported across the mammalian placenta, crncentrations in fetal blood being higher than those in the maternal circu-Elevated concentrations of phenylalanine were induced by dietarv means blood of pregnant rhesus monkeys, and the active transport mechanism vident at both normal and elevated concentrations. A normal placental may thus magnify a maternal biochemical abnormality and produce a profound disturbance in the fetus.

Phenylketonuria in rats: reversibility of behavorial deficit.

Phenylketonuria was induced in hooded rats by the conventional procedure of feeding excessive quantities of L-phenylalanine after weaning. Although this procedure reliably induced large, dose-dependent deficits in performance on a water maze, the behavioral deficits were completely eliminated after cessation of phenylalanine loading. These results cast doubt on the assumption that this animal preparation adequately simulates the irreversible intellectual impairments found in the child with late-detected phenylketonuria.

Sibship with histidinemia and an unrelated encephalopathy. Clinical and biochemical studies.

Histidinemia was found in 3 of 4 siblings in one family, while a fatal encephalopathy with mental retardation was present in two of them and in the fourth child who did not have histidinemia. Biochemical studies of the histidinemic subjects showed elevated histidine levels in urine, CSF, and brain, while in a few urine samples histidine related imidazole compounds were found. Plasma levels of other amino acids were positively correlated with plasma histidine levels. Obesity and heart abnormalities appeared to be associated with the encephalopathy, which is probably of a new type. The histidinemia appears to be unrelated to the mental retardation or the encephalopathy in this family.