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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
2
|
| pubmed:dateCreated |
1998-3-3
|
| pubmed:abstractText |
In vivo proton magnetic resonance spectroscopy was used to investigate intracerebral phenylalanine (Phe) concentrations in nine patients with classical phenylketonuria (PKU). The study included serial examinations (n = 31; plasma Phe levels: 0.47-2.24 mmol/l) of patients either receiving a Phe-restricted diet (200 mg Phe per day; four patients) or a diet rich in Phe (1000 mg Phe per day; three patients). No spectrum showed metabolic abnormalities besides elevated Phe. Difference spectroscopy yielded intracerebral Phe concentrations between 0.20 and 0.76 mmol/l. Regional variations between parieto-occipital periventricular brain, frontal brain, and cerebellum were not statistically significant. Data could be fitted assuming saturable Phe transport into the brain, based on a symmetric Michaelis-Menten model (characterized by an apparent Michaelis transport constant, K(t,app), and a maximum transport velocity, Tmax) and constant Phe consumption in the brain cells (described by a velocity Vmax). Non-linear least-squares fitting of the combined data from all patients yielded K(t,app) = 0.16 +/- 0.11 mmol/l and (Tmax / Vmax) = 9.0 +/- 4.1. Carrier saturation and competitive inhibition of the influx of other large neutral amino acids can be expected at plasma Phe levels usually found in PKU patients.
|
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical | |
| pubmed:status |
MEDLINE
|
| pubmed:month |
Dec
|
| pubmed:issn |
0006-8993
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:day |
19
|
| pubmed:volume |
778
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
329-37
|
| pubmed:dateRevised |
2004-11-17
|
| pubmed:meshHeading |
pubmed-meshheading:9459550-Adolescent,
pubmed-meshheading:9459550-Adult,
pubmed-meshheading:9459550-Blood-Brain Barrier,
pubmed-meshheading:9459550-Brain Chemistry,
pubmed-meshheading:9459550-Child,
pubmed-meshheading:9459550-Female,
pubmed-meshheading:9459550-Humans,
pubmed-meshheading:9459550-Kinetics,
pubmed-meshheading:9459550-Magnetic Resonance Spectroscopy,
pubmed-meshheading:9459550-Male,
pubmed-meshheading:9459550-Phenylalanine,
pubmed-meshheading:9459550-Phenylketonurias
|
| pubmed:year |
1997
|
| pubmed:articleTitle |
Kinetics of phenylalanine transport at the human blood-brain barrier investigated in vivo.
|
| pubmed:affiliation |
Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC 27710, USA. hem@orion.mc.duke.edu
|
| pubmed:publicationType |
Journal Article
|