Hyperphenylalaninaemia in children with falciparum malaria.

Abstract

Brain monoamine levels may underlie aspects of the cerebral component of falciparum malaria. Since circulating amino acids are the precursors for brain monoamine synthesis, we measured them in malaria patients and controls. Malaria elicited significantly elevated plasma levels of phenylalanine, particularly in comatose patients, with the Tyr/Phe (%) ratio reduced from 83.3 in controls to 39.5 in infected children, suggesting an impaired phenylalanine hydroxylase enzyme system in malaria infection. Malaria significantly increased the apparent K(m) for Trp, Tyr and His, with no effect on K(m)(app) for Phe. Using the kinetic parameters of NAA transport at the human blood-brain barrier, malaria significantly altered brain uptake of Phe (+96%), Trp (-28%) and His (+31%), with no effect on Tyr (-8%), compared with control findings. Our data suggest impaired cerebral synthesis of serotonin, dopamine and norepinephrine, and enhanced production of histamine, in children with severe falciparum malaria.

• Authors: C O Enwonwu, B M Afolabi, L A Salako, E O Idigbe, H al-Hassan, R A Rabiu
• Journal: QJM : monthly journal of the Association of Physicians (QJM) Vol. 92 Issue 9 Pg. 495-503 (Sep 1999) ISSN: 1460-2725 [Print] England
• PMID: 10627868 (Publication Type: Journal Article, Multicenter Study, Research Support, Non-U.S. Gov't)

Chemical References

• Amino Acids
• Phenylalanine Hydroxylase

Topics

• Adolescent
• Amino Acids (blood)
• Analysis of Variance
• Brain (metabolism)
• Child
• Child, Preschool
• Chromatography, High Pressure Liquid
• Coma (blood, parasitology)
• Female
• Humans
• Infant
• Malaria, Falciparum (blood)
• Male
• Phenylalanine Hydroxylase (metabolism)
• Phenylketonurias (metabolism, parasitology)