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Low myo-inositol and high glutamine levels in brain are associated with neuropsychological deterioration after induced hyperammonemia

Shawcross, DL; Balata, S; Damink, SWMO; Hayes, PC; Wardlaw, J; Marshall, I; Deutz, NEP; ... Jalan, R; + view all (2004) Low myo-inositol and high glutamine levels in brain are associated with neuropsychological deterioration after induced hyperammonemia. AM J PHYSIOL-GASTR L , 287 (3) G503 - G509. 10.1152/ajpgi.00104.2004. Green open access

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Abstract

The neuropsychological effect of hyperammonemia is variable. This study tests the hypothesis that the effect of ammonia on the neuropsychological function in patients with cirrhosis is determined by the ability of the brain to buffer ammonia-induced increase in glutamine within the astrocyte by losing osmolytes like myo-inositol (mI) and not by the magnitude of the induced hyperammonemia. Fourteen cirrhotic patients with no evidence of overt hepatic encephalopathy were given a 75-g amino acid (aa) solution mimicking the hemoglobin molecule to induce hyperammonemia. Measurement of a battery of neuropsychological function tests including immediate memory, ammonia, aa, and short-echo time proton magnetic resonance spectroscopy were performed before and 4 h after administration of the as solution. Eight patients showed deterioration in the Immediate Memory Test at 4 h. Demographic factors, severity of liver disease, change in plasma ammonia, and as profiles after the as solution were similar in those that showed a deterioration compared with those who did not. In patients who showed deterioration in the memory test, the mI-to-creatine ratio (mI/Cr) was significantly lower at baseline than those that did not deteriorate. In contrast, the glutamate/glutamine-to-Cr ratio was significantly greater in the patients that deteriorated. The observation that deterioration in the memory test scores was greater in those with lower mI/Cr supports the hypothesis that the neuropsychological effects of induced hyperammonemia is determined by the capacity of the brain to handle ammonia-induced increase in glutamine.

Type: Article
Title: Low myo-inositol and high glutamine levels in brain are associated with neuropsychological deterioration after induced hyperammonemia
Open access status: An open access version is available from UCL Discovery
DOI: 10.1152/ajpgi.00104.2004
Keywords: neuropsychological function, amino acid solution, magnetic resonance spectroscopy, hepatic encephalopathy, SUBCLINICAL HEPATIC-ENCEPHALOPATHY, MAGNETIC-RESONANCE-SPECTROSCOPY, GRADE CEREBRAL EDEMA, AMINO-ACID LOAD, CIRRHOTIC-PATIENTS, MR SPECTROSCOPY, LIVER, ABNORMALITIES, HEMOGLOBIN, CHALLENGE
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine > Inst for Liver and Digestive Hlth
URI: https://discovery.ucl.ac.uk/id/eprint/298
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