Urinary glutamine/glutamate ratio as a potential biomarker of pediatric chronic intestinal pseudo-obstruction

New ratio as a useful marker for early diagnosis of proximal urea cycle disorders

BACKGROUND AND AIMS

Proximal urea cycle disorders (PUCDs) are not included in most newborn screening programs due to the lack of adequate markers to monitor. Failure to alter citrulline and glutamine levels, the prognostic markers commonly used, can results in high false negative. Therefore, new biomarkers, prognostic of PUCDs, are strongly desirable.

MATERIALS AND METHODS

We used tandem mass spectrometry to analyze blood spot from PUCDs patients during their follow up in our referral center focusing on glutamine to glutamate (Gln/Glu) ratio. We reanalyzed the same specimens of three patients after two months and the specimen of a new patient with suspicious of PUCD disorder.

RESULTS

Specimens of our patients shown a significant elevation of the ratio Gln/Glu compared to that of a healthy population (p < 0.05) as well as the specimens analyzed after two months, while the glutamine concentration dropped. New patient, showing high value of the ratio, was molecularly confirmed as PUCD patient. We further analyzed the blood spots from a neonatal population in order to fix a cut-off value and include it in a newborn screening panel.

CONCLUSION

Our preliminary results suggest that the Gln/Glu ratio could be a very useful diagnostic marker, more stable over time than glutamine, which could improve the performance in early PUCDs identification.

Glutamate sensing in biofluids: recent advances and research challenges of electrochemical sensors

Electrochemical sensing guidelines for glutamate in biofluids, associated with different diseases, providing knowledge translation among science, engineering, and medical professionals.

Plasma profile and urine excretion of amino acids in children with celiac disease on gluten-free diet after oligofructose-enriched inulin intervention: results of a randomised placebo-controlled pilot study

The circulating amino acid (AAs) concentrations are indicators of dietary protein intake and metabolic status. In celiac disease (CD), the AA imbalance is frequently observed. Prebiotics are found to alleviate nutrient deficiencies. Therefore, the aim of this study was to analyse the impact of oligrofructose-enriched inulin (Synergy 1), administered for 3 months as a gluten-free diet (GFD) supplement to children with CD, on the plasma and urine concentrations of AAs. CD children (N = 34) were randomised into two groups, receiving Synergy 1 (10 g/day) or placebo (maltodextrin) for 3 months. The AA profile and concentration was determined in plasma and urine before and after the dietary intervention by gas chromatography. 22 and 28 AAs were determined in plasma and urine samples, respectively. After the intervention, the plasma concentrations of several AAs (Ala, Pro, Asn, Glu, Tyr, Lys, His, Orn) increased significantly in both experimental groups, while Gln increased only in the Synergy 1 group. The urinary excretion of Asn, Lys and Aaa increased significantly in the Synergy 1 group, and the excretion of Asp and Met decreased (p < 0.05) in the placebo group. The Gln:Glu ratio in urine increased in both groups after the intervention. An increased urinary excretion of AAs observed in Synergy 1 group with a simultaneous increase in the content of circulating AAs could be attributed to higher absorption or intensified metabolism of AAs, and on the other hand further healing of the intestinal mucosa being the result of continuous treatment with GFD. Moreover, the observed changes in Glu concentration suggest that oligofructose-enriched inulin could improve the intestinal condition and permeability. To conclude, a prebiotic-supplemented GFD influences beneficially the overall AAs metabolism in CD children; however, further prospective cohort studies are needed to confirm the results obtained.