High resolution proton NMR spectroscopy of human amniotic fluid

Abstract

Human amniotic fluid (HAF) is a dynamic system whose characteristics depend on continuous interchanges between fetal and maternal circulations. HAF reflects not only the environment of the fetus but may also provide information about fetal development or pathology. The concentration of HAF constituents varies with gestational age and pathological states. The number of the compounds currently implicated in fetal developmental pathology are relatively few. Currently used assay methods are not adequate to totally explain or predict the complex biochemistry of the fetus. The purpose of this work was to investigate HAF with NMR spectroscopy. In the present study HAF was obtained from 47 women undergoing routine amniocentesis. Cells were separated for karyological analysis and the supernatant was acid-extracted, lyophilized and re-suspended in D20 resulting in a concentration increase over native fluid. 1H NMR spectra were obtained at 360 MHz and 60 MHz. Eighteen compounds including several amino acids, were identified using parallel reference and standard addition protocols. NMR spectroscopy detected compounds of known clinical importance including glucose, leucine, isoleucine, lactate and creatinine. In conclusion, we have demonstrated that a number of physiologically relevant compounds are readily observable in HAF using 1H NMR spectroscopy. This technique can currently provide valuable information regarding HAF composition and has the potential of being used in vivo in the future.

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

“…A reference database was created containing quantitative 1D spectra of the most common metabolites in amniotic fluid and urine as well as metabolites associated with fetal maturity [ 4 , 17 , 24 ]. All chemicals were purchased from Sigma–Aldrich (Sigma, Aldrich, Fluka and Supelco, St Louis, MO).…”

“…High-resolution magnetic resonance spectroscopy (MRS) of human amniotic fluid has the potential to become a valuable technique for the evaluation of fetal health and development [ 1 – 3 ]. Although numerous clinical assays utilize amniotic fluid to evaluate chromosomal abnormalities, metabolic errors, and fetal lung maturity [ 4 ], none currently uses MRS to exploit the complex metabolic information contained within amniotic fluid. Many of these clinical assays require time-consuming laboratory procedures and provide only a limited amount of information.…”

“…Several metabolites associated with fetal developmental abnormalities have previously been identified by MRS. 31 P MRS studies of human amniotic fluid detected various phospholipid analytes related to fetal respiratory distress syndrome (RDS) [ 5 – 7 ]. Subsequent 1 H MRS investigations identified several organic acids, amino acids, sugars, choline-containing compounds and developmental catabolites [ 1 , 4 , 8 , 9 ]. Other studies employing a variety of methods searched for biomarkers of renal function [ 1 ], diabetes [ 8 , 10 ], pre-eclampsia [ 8 , 11 ], perinatal infection [ 12 ], spina bifida [ 8 , 13 ], trisomy 21 [ 8 , 14 ], cystic fibrosis [ 14 ] and fetal lung maturity [ 2 , 3 , 15 , 16 ].…”

Use of Near-Infrared Spectroscopic Analysis of Second Trimester Amniotic Fluid to Assess Preterm Births

“…The two study groups were similar with respect to both maternal age and maternal BMI. The AF samples were obtained following genetic testing and stored at −80°C; there is minimal source of biochemical error resulting from repeated freezing and thawing of amniotic fluid [18, 19]. …”

Artificial amniotic fluid for nuclear magnetic resonance spectroscopy studies

“…MRS builds on NMR by enabling the acquisition of tissue spectra without the need of removing tissue from the subject, by using clinical magnetic resonance imaging (MRI) hardware. Advances in MRS have allowed for the analysis of cells and tissue in vivo, permitting non‐invasive means of diagnosing disease and identifying genetic anomalies in gestation 12–16 . Applying this technology to the metabolomic analysis of AF could replace invasive amniocentesis throughout gestation, and provide novel means of prenatal screening 13,14,17,18 .…”