title: The dynamics of brain concentrations of phenylalanine and its clinical significance in patients with phenylketonuria determined by in vivo 1H magnetic resonance spectroscopy.
abstract: Cerebral concentrations of phenylalanine (PHE) were measured by means of quantitative in vivo 1H MR spectroscopy in 8 adult patients treated early for phenylketonuria type I. A 1.5-Tesla routine magnetic resonance scanner, localization sequence with short echo time (20 ms), and a fully automated data processing scheme were used. Baseline plasma PHE concentrations were 1.04 (0.70-1.39) mmol/L PHE with concurrent brain PHE concentrations of 0.27 (0.13-0.41) mmol/kg of wet weight resulting in a plasma/brain ratio of 4.12. Plasma and brain concentrations correlated significantly (Kendall tau b = 0.91, p < 0.01). During an oral load with a single dose of 100 mg L-PHE per kg of body weight in four patients, plasma levels steeply increased. Concurrent brain PHE increase was less steep, was significantly delayed, and still continued up to 20 h postload. Despite the proven rise in plasma and brain concentrations of PHE, neuropsychologic examinations revealed no impairment of attentional and fine motor abilities from preload up to 20 h postload.
authors.affiliation: Department of Pediatric Neurology, University of Heidelberg, Federal Republic of Germany.
authors.forename: J
authors.initials: J
authors.lastname: Pietz
authors.forename: R
authors.initials: R
authors.lastname: Kreis
authors.forename: C
authors.initials: C
authors.lastname: Boesch
authors.forename: J
authors.initials: J
authors.lastname: Penzien
authors.forename: D
authors.initials: D
authors.lastname: Rating
authors.forename: N
authors.initials: N
authors.lastname: Herschkowitz
mesh_terms: D000328:Adult; D001921:Brain / Q000378:metabolism*; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010649:Phenylalanine / Q000378:metabolism*; D010661:Phenylketonurias / Q000378:metabolism*
chemical_list: D010649:Phenylalanine