Quantitative metabolic profiles of 2nd and 3rd trimester human amniotic fluid using 1H HR-MAS spectroscopy

Abstract

ObjectTo establish and compare normative metabolite concentrations in 2nd and 3rd trimester human amniotic fluid samples in an effort to reveal metabolic biomarkers of fetal health and development.Materials and methodsTwenty-one metabolite concentrations were compared between 2nd (15–27 weeks gestation, N = 23) and 3rd (29–39 weeks gestation, N = 27) trimester amniotic fluid samples using 1H high resolution magic angle spinning (HR-MAS) spectroscopy. Data were acquired using the electronic reference to access in vivo concentrations method and quantified using a modified semi-parametric quantum estimation algorithm modified for high-resolution ex vivo data.ResultsSixteen of 21 metabolite concentrations differed significantly between 2nd and 3rd trimester groups. Betaine (0.00846±0.00206 mmol/kg vs. 0.0133±0.0058 mmol/kg, P <0.002) and creatinine (0.0124±0.0058 mmol/kg vs. 0.247±0.011 mmol/kg, P <0.001) concentrations increased significantly, while glucose (5.96±1.66 mmol/kg vs. 2.41±1.69 mmol/kg, P <0.001), citrate (0.740±0.217 mmol/kg vs. 0.399±0.137 mmol/kg, P <0.001), pyruvate (0.0659±0.0103 mmol/kg vs. 0.0299±0.286 mmol/kg, P <0.001), and numerous amino acid (e.g. alanine, glutamate, isoleucine, leucine, lysine, and valine) concentrations decreased significantly with advancing gestation. A stepwise multiple linear regression model applied to 50 samples showed that gestational age can be accurately predicted using combinations of alanine, glucose and creatinine concentrations.ConclusionThese results provide key normative data for 2nd and 3rd trimester amniotic fluid metabolite concentrations and provide the foundation for future development of magnetic resonance spectroscopy (MRS) biomarkers to evaluate fetal health and development.

A comparison of quantitative nuclear magnetic resonance methods: internal, external, and electronic referencing

“…The need for a comparison of external referencing with and without PULCON has been previously proposed . Our comparison indicates that the PULCON compensation for small pulse width adjustments, when applied to non‐ionic solutions with sample concentrations up to about 100 mg/ml, is detrimental.…”

Amniotic Fluid and the Fetal Mucosal Immune System

“…Many studies suggest that AF composition is more highly regulated than AF volume. Metabolite profiles for second and third trimester amniotic fluid samples, using high-resolution 1 H NMR spectroscopy, showed significant differences with gestational age (Groenen et al, 2004;Cohn et al, 2009;Graca et al, 2010). The concentrations of creatinine and betaine increased while concentrations of creatine, glucose, and various amino acids decreased with the advancing gestational age, providing excellent metabolomic evidence of fetal maturation and having the potential to improve the evaluation of fetal health and development.…”

Applications of high‐resolution magic angle spinning MRS in biomedical studies II—Human diseases

“…HRMAS MRS metabolic profiles of AF were generated for second and third gestation trimesters . Using a targeted approach and measuring metabolite concentration through the electronic reference to access in vivo concentrations (ERETIC) method, HRMAS MRS results presented increases in creatinine and decreases in Glc, Cit, pyruvate, Cr, Ala, Glu, Lys, and Val with advancing GA ( p < 0.001).…”

“…Using a targeted approach and measuring metabolite concentration through the electronic reference to access in vivo concentrations (ERETIC) method, HRMAS MRS results presented increases in creatinine and decreases in Glc, Cit, pyruvate, Cr, Ala, Glu, Lys, and Val with advancing GA ( p < 0.001). A linear GA prediction model ( R 2 = 0.926) that incorporated Ala, Cr, Glc, and Val was proposed. Interestingly, a better estimate was obtained for third trimester pregnancies, possibly due to the larger sample size (71 versus 24 samples) or superior performance of the model in late gestation.…”