Metabolite profiling identifies a branched chain amino acid signature in acute cardioembolic stroke.

BACKGROUND AND PURPOSE: There is limited information about changes in metabolism during acute ischemic stroke. The identification of changes in circulating plasma metabolites during cerebral infarction may provide insight into disease pathogenesis and identify novel biomarkers. METHODS: We performed filament occlusion of the middle cerebral artery of Wistar rats and collected plasma and cerebrospinal fluid 2 hours after the onset of ischemia. Plasma samples from control and patients with acute stroke were also analyzed. All samples were examined using liquid chromatography followed by tandem mass spectrometry. Positively charged metabolites, including amino acids, nucleotides, and neurotransmitters, were quantified using electrospray ionization followed by scheduled multiple reaction monitoring. RESULTS: The concentrations of several metabolites were altered in the setting of cerebral ischemia. We detected a reduction in the branched chain amino acids (valine, leucine, isoleucine) in rat plasma, rat cerebrospinal fluid, and human plasma compared with respective controls (16%, 23%, and 17%, respectively; P<0.01 for each). In patients, lower branched chain amino acids levels also correlated with poor neurological outcome (modified Rankin Scale, 0-2 versus 3-6; P=0.002). CONCLUSIONS: Branched chain amino acids are reduced in ischemic stroke, and the degree of reduction correlates with worse neurological outcome. Whether branched chain amino acids are in a causal pathway or are an epiphenomenon of ischemic stroke remains to be determined.

Cerebrospinal fluid concentrations of large neutral and basic amino acids in Macaca mulatta: diurnal variations and responses to chronic changes in dietary protein intake.

In rats, dietary protein intake influences brain concentrations of tryptophan, tyrosine, and other large neutral amino acids (LNAAs) and the neurotransmitters to which they are linked. Few experiments have examined these dietary protein-amino acid relationships in nonhuman primates, in relation to time of day or dietary protein content. We therefore examined the effect in monkeys of changes in chronic protein intake on 24-hour plasma and cerebrospinal fluid (CSF) concentrations of LNAAs (tyrosine, phenylalanine, branched-chain amino acids) and basic amino acids. Juvenile male monkeys (Macaca mulatta) consumed for sequential 4-week periods diets differing in protein content (approximately 23% --> approximately 16% --> approximately 10% --> approximately 6% protein [percentage of energy]). The daily ration was presented as a morning meal of fruit and an afternoon meal of fruit and a commercial diet to mimic feeding patterns in the wild. During week 4 on each diet, blood and CSF were sampled repeatedly over a 48-hour period via indwelling catheters. Plasma and CSF LNAA concentrations varied markedly with time of day and dietary protein content, showing up to 4-fold variations. Diurnal variations in plasma and CSF basic amino acids were smaller in magnitude and generally not strongly linked to dietary protein content. A measure of the competitive transport of LNAAs across the blood-brain barrier, calculated using plasma concentrations of the LNAAs and their blood-brain barrier kinetic constants, predicted the observed CSF concentration of each LNAA examined remarkably well, except for phenylalanine. Based on observations in rats, the variations in the CSF concentrations of the LNAAs in monkeys may be large enough to influence metabolic and signaling pathways in brain to which they have been linked.

A double-blind randomized clinical trial in amyotrophic lateral sclerosis using lamotrigine: effects on CSF glutamate, aspartate, branched-chain amino acid levels and clinical parameters.

OBJECTIVES: A study was conducted to examine the effect of lamotrigine (LTG) in amyotrophic lateral sclerosis (ALS). MATERIAL AND METHODS: Patients were entered in a double-blind, placebo-controlled, crossover study. None of the patients were treated with riluzole, which was not approved for treatment of ALS in Sweden when the study started. After randomization, each patient was treated with placebo or LTG 300 mg daily, followed by a washout period and a second treatment period. RESULTS: Thirty patients completed the study and were included in the analysis of the primary outcome, which was measured with clinical scales. The cerebrospinal fluid (CSF) levels of glutamate, aspartate, branched-chain amino acids and LTG were also measured. Changes for glutamate, valine and LTG were found during the progression of the disease. The clinical parameters and the levels of CSF amino acids were similar for the two treatment groups. CONCLUSION: No clinical effect of LTG on ALS progression could be found.

Maple syrup urine disease in calves: a clinical, pathological and biochemical study.

The clinical, pathological and biochemical findings of a study of 30 Poll Hereford, Hereford, Poll Hereford cross or Hereford cross calves affected with branched chain ketoacid dehydrogenase (BCKAD) complex deficiency or maple syrup urine disease (MSUD) are presented. In breeding studies, 6 of 21 calves from obligate heterozygote matings were affected with MSUD, suggesting the disease is inherited in an autosomal recessive manner. Calves were clinically affected from birth, but there were variations in the subsequent course of progressive deterioration of central nervous system function. Concentrations of the branched chain amino acids and keto acids were elevated in pre-suckle plasma and cerebellar water content was higher in affected calves. Activity of BCKAD complex was minimal in fibroblasts cultured from an affected calf. Spongiform encephalopathy and elevated ratios of the branched to straight chain amino acids in formalin fixed cerebral tissue were found in a stillborn foetus and a 3-month-old Hereford calf. These findings suggest the disease occurs prenatally and that a delayed form may exist.