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

Temporal metabolomics state in pregnant rat: Analysis of amniotic fluid, placenta, and maternal plasma at embryonic and fetal time points

INTRODUCTION

During pregnancy, the dynamic metabolic demands for fetal growth require a continuous supply of essential metabolites. Understanding maternal metabolome changes during gestation is crucial for predicting disease risks in neonates.

METHODS

The study aimed to characterize the placental and amniotic fluid (AF) metabolomes during gestation in rats at gestational days GD-13 and 19 reflecting the end of the embryonic and fetal periods, respectively, and the maternal plasma, using metabolomics (LC-MS) and chemometrics. The objective was to highlight, through univariate and multivariate analyses, the complementarity of the data obtained from these different biological matrices.

RESULTS

The biological matrix had more impact on the metabolome composition than the gestational stage. The placental and AF metabolomes showed specific metabolome evolving over the two gestational stages. Analyzing the three targeted metabolomes revealed evolving pathways in arginine and proline metabolism/glutathione metabolism and phenylalanine metabolism; purine metabolism; and carbohydrate metabolism. Significantly, lipid metabolism in the placenta exhibited substantial changes with higher levels of certain phosphatidylethanolamine and sphingomyelins at GD19 while some cholesteryl esters and some glycosphingolipids levels being in higher levels at GD13.

DISCUSSION

These data highlight the metabolic gradients (mainly in placenta, also in AF, but only a few in plasma) observed through embryonic patterning and organ development during mid-to late gestation.

The Investigation of Metabonomic Pathways of Serum of Iranian Women with Recurrent Miscarriage Using 1H NMR

Purpose

Recurrent miscarriage applies to pregnancy loss expulsion of the fetus within the first 24 weeks of pregnancy. This study is aimed at comparatively investigating the sera of women with RM with those who have no record of miscarriages to identify if there were any metabolite and metabolic pathway differences using ¹H NMR spectroscopy.

Methods

Serum samples were collected from women with RM (n = 30) and those who had no records of RM (n = 30) to obtain metabolomics information. ¹H NMR spectroscopy was carried out on the samples using Carr Purcell Meiboom Gill spin echo; also, Partial Least Squares Discriminant Analysis was performed in MATLAB software using the ProMetab program to obtain the classifying chemical shifts; the metabolites were identified by using the Human Metabolome Database (HMDB) in both the experimental and control groups. The pathway analysis option of the Metaboanalyst.ca website was used to identify the changed metabolic pathways.

Results

The results of the study revealed that 14 metabolites were different in the patients with RM. Moreover, the pathway analysis showed that taurine and hypotaurine metabolism along with phenylalanine, tyrosine, and tryptophan biosynthesis was significantly different in patients with RM.

Conclusion

The present study proposes that any alteration in the above metabolic pathways might lead to metabolic dysfunctions which may result in a higher probability of RM.

Metabolomics Analysis of Amniotic Fluid in Euploid Foetuses with Thickened Nuchal Translucency by Gas Chromatography-Mass Spectrometry

Persistence of a fetal thickened nuchal translucency (NT), one of the most sensitive and specific individual markers of fetal disorders, is strongly correlated with the possibility of a genetic syndrome, congenital infections, or other malformations. Thickened NT can also be found in normal pregnancies. Several of its pathophysiological aspects still remain unexplained. Metabolomics could offer a fresh opportunity to explore maternal-foetal metabolism in an effort to explain its physiological and pathological mechanisms. For this prospective case-control pilot study, thirty-nine samples of amniotic fluids were collected, divisible into 12 euploid foetuses with an enlarged nuchal translucency (>NT) and 27 controls (C). Samples were analyzed using gas chromatography mass spectrometry. Multivariate and univariate statistical analyses were performed to find a specific metabolic pattern of >NT class. The correlation between the metabolic profile and clinical parameters was evaluated (NT showed an R2 = 0.75, foetal crown-rump length showed R2 = 0.65, pregnancy associated plasma protein-A showed R2 = 0.60). Nine metabolites significantly differing between >NT foetuses and C were detected: 2-hydroxybutyric acid, 3-hydroxybutyric, 1,5 Anydro-Sorbitol, cholesterol, erythronic acid, fructose, malic acid, threitol, and threonine, which were linked to altered pathways involved in altered energetic pathways. Through the metabolomics approach, it was possible to identify a specific metabolic fingerprint of the fetuses with >NT.

Deficits in Prenatal Serine Biosynthesis Underlie the Mitochondrial Dysfunction Associated with the Autism-Linked FMR1 Gene

Fifty-five to two hundred CGG repeats (called a premutation, or PM) in the 5′-UTR of the FMR1 gene are generally unstable, often expanding to a full mutation (>200) in one generation through maternal inheritance, leading to fragile X syndrome, a condition associated with autism and other intellectual disabilities. To uncover the early mechanisms of pathogenesis, we performed metabolomics and proteomics on amniotic fluids from PM carriers, pregnant with male fetuses, who had undergone amniocentesis for fragile X prenatal diagnosis. The prenatal metabolic footprint identified mitochondrial deficits, which were further validated by using internal and external cohorts. Deficits in the anaplerosis of the Krebs cycle were noted at the level of serine biosynthesis, which was confirmed by rescuing the mitochondrial dysfunction in the carriers’ umbilical cord fibroblasts using alpha-ketoglutarate precursors. Maternal administration of serine and its precursors has the potential to decrease the risk of developing energy shortages associated with mitochondrial dysfunction and linked comorbidities.

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

High-resolution magic angle spinning (HRMAS) MRS is a powerful method for gaining insight into the physiological and pathological processes of cellular metabolism. Given its ability to obtain high-resolution spectra of non-liquid biological samples, while preserving tissue architecture for subsequent histopathological analysis, the technique has become invaluable for biochemical and biomedical studies. Using HRMAS MRS, alterations in measured metabolites, metabolic ratios, and metabolomic profiles present the possibility to improve identification and prognostication of various diseases and decipher the metabolomic impact of drug therapies. In this review, we evaluate HRMAS MRS results on human tissue specimens from malignancies and non-localized diseases reported in the literature since the inception of the technique in 1996. We present the diverse applications of the technique in understanding pathological processes of different anatomical origins, correlations with in vivo imaging, effectiveness of therapies, and progress in the HRMAS methodology.

Congenital diaphragmatic hernia: endotracheal fluid phospholipidic profile following tracheal occlusion in an experimental model

OBJECTIVE

To compare endotracheal fluid (EF) and amniotic fluid (AF) phospholipidic profile changes following tracheal occlusion (TO) in the congenital diaphragmatic hernia (CDH) fetal lamb model, in order to support the efficacy of TO on lung maturity.

METHODS

A diaphragmatic defect was induced at 70 days' gestation, TO was carried out at day 102 and cesarean section at 136 days' gestation. EF and AF samples, collected at delivery, were evaluated using mass spectrometry (the analysis focused on palmitoyloleoyl-phosphatidylcholine [POPC, PC(18:1/16:0)], dipalmitoyl-phosphatidylcholine [DPPC, PC(16:0/16:0)] and sphingomyelins [SMs]).

RESULTS

The effects of CDH and TO were different on AF and EF. POPC levels were higher than DPPC levels in AF of healthy lambs. Following induction of the diaphragmatic malformation, an evident decrease in POPC was noted, while a substantial return to normal POPC levels and an increased DPPC peak were prompted by the TO. After CDH induction, a decrease in N-palmitoyl-D-sphingomyelin [SM(d18:1/16:0)] was revealed (P<0.01) and an increased peak in SMs in AF was prompted by the TO (P=0.05). While the most represented phosphatidylcholine (PC) species in EF of healthy lambs was DPPC, CDH induced a decrease in the DPPC peak and treatment with TO induced its partial recovery. SMs were detectable only in healthy EF samples.

CONCLUSION

The phospholipid recovery profile following TO suggests the potential role of this therapy in restoring processes involved in surfactant-mediated lung maturation, even though other interactions involved in AF turnover should be considered. Moreover, these metabolites could be used as biomarkers of fetal pulmonary development.

High-resolution magic angle spinning (1) H NMR measurement of ligand concentration in solvent-saturated chromatographic beads

A method based on (1) H high-resolution magic angle spinning NMR has been developed for measuring concentration accurately in heterogeneous materials like that of ligands in chromatography media. Ligand concentration is obtained by relating the peak integrals for a butyl ligand in the spectrum of a water-saturated chromatography medium to the integral of the added internal reference. The method is fast, with capacity of 10 min total sample preparation and analysis time per sample; precise, with a reproducibility expressed as 1.7% relative standard deviation; and accurate, as indicated by the excellent agreement of derived concentration with that obtained previously by (13) C single-pulse excitation MAS NMR. The effects of radiofrequency field inhomogeneity, spin rate, temperature increase due to spinning, and distribution and re-distribution of medium and reference solvent both inside the rotor during spinning and between bulk solvent and pore space are discussed in detail. © 2016 The Authors Magnetic Resonance in Chemistry published by John Wiley & Sons Ltd.

The choice of amniotic fluid in metabolomics for the monitoring of fetus health

Amniotic fluid (AF) is a biological fluid in which metabolite transport is regulated by the placenta, the permeable skin, fetal lung egress and gastric fluid. During pregnancy, the composition of AF changes from similar to the interstitial fluid of the mother, to a more complex system, influenced by the fetus's urine. Since AF reflects the mother's and the fetus's health status at the same time, it may be an important diagnostic tool for a wider spectrum of clinical conditions. Indeed, the metabolic characterization of AF in relation to pathological occurrences may lead to the discovery of new biomarkers for a better clinical practice. For this reason, metabolomics may be the most suitable strategy for this task. In this review, research works on metabolomic AF analysis are discussed according to the morbidity of interest, being preterm birth/labor, gestational age and diabetes and fetal malformations, along with a number of other important studies.

High-Resolution (1)H NMR Spectroscopy Discriminates Amniotic Fluid of Fetuses with Congenital Diaphragmatic Hernia from Healthy Controls

Lung hypoplasia in congenital diaphragmatic hernia (CDH) is a life-threatening birth defect. Severe cases can be offered tracheal occlusion to boost prenatal lung development, although defining those to benefit remains challenging. Metabonomics of (1)H NMR spectra collected from amniotic fluid (AF) can identify general changes in diseased versus healthy fetuses. AF embodies lung secretions and hence might contain pulmonary next to general markers of disease in CDH fetuses. AF from 81 healthy and 22 CDH fetuses was collected. NMR spectroscopy was performed at 400 MHz to compare AF from fetuses with CDH against controls. Several advanced feature extraction methods based on statistical tests that explore spectral variability, similarity, and dissimilarity were applied and compared. This resulted in the identification of 30 spectral regions, which accounted for 80% variability between CDH and controls. Combination with automated classification discriminates AF from CDH versus healthy fetuses with up to 92% accuracy. Within the identified spectral regions, isoleucine, leucine, valine, pyruvate, GABA, glutamate, glutamine, citrate, creatine, creatinine, taurine, and glucose were the most concentrated metabolites. As the metabolite pattern of AF changes with fetal development, we have excluded metabolites with a high age-related variability and repeated the analysis with 12 spectral regions, which has resulted in similar classification accuracy. From this analysis, it was possible to distinguish between AF from CDH fetuses versus healthy controls independent of gestational age.

Comprehensive multiphase NMR: a promising technology to study plants in their native state

Nuclear magnetic resonance (NMR) spectroscopy is arguably one the most powerful tools to study the interactions and molecular structure within plants. Traditionally, however, NMR has developed as two separate fields, one dealing with liquids and the other dealing with solids. Plants in their native state contain components that are soluble, swollen, and true solids. Here, a new form of NMR spectroscopy, developed in 2012, termed comprehensive multiphase (CMP)-NMR is applied for plant analysis. The technology composes all aspects of solution, gel, and solid-state NMR into a single NMR probe such that all components in all phases in native unaltered samples can be studied and differentiated in situ. The technology is evaluated using wild-type Arabidopsis thaliana and the cellulose-deficient mutant ectopic lignification1 (eli1) as examples. Using CMP-NMR to study intact samples eliminated the bias introduced by extraction methods and enabled the acquisition of a more complete structural and metabolic profile; thus, CMP-NMR revealed molecular differences between wild type (WT) and eli1 that could be overlooked by conventional methods. Methanol, fatty acids and/or lipids, glutamine, phenylalanine, starch, and nucleic acids were more abundant in eli1 than in WT. Pentaglycine was present in A. thaliana seedlings and more abundant in eli1 than in WT.

Determination of fetal lung maturity using magnetic resonance imaging signal intensity measurements

PURPOSE

The objective of this study was to determine if magnetic resonance signal intensity measurements can be used to predict gestational age and hence fetal lung maturity.

METHODS

This institutional review board-approved study was a retrospective review of 394 fetal magnetic resonance imaging cases from a single institution for the years 2001 to 2011. For each case, T1- and T2-weighted sequences were selected for data collection. A single reviewer obtained 10 regions of interest (when possible) from each scan (fetal lung, fetal liver, fetal muscle, fetal spleen, and maternal urine, for both T1- and T2-weighted sequences). The medical record was searched for relevant information including best estimate of gestational age, Apgar scores, karyotype, and fetal diagnosis. A variety of organ-to-organ ratios and direct organ signal intensity measurements were assessed for correlation with gestational age.

RESULTS

Three hundred thirty-five cases met inclusion criteria with gestational ages ranging from 17 to 39 weeks (mean, 28.6 weeks). A significant relationship between magnetic resonance signal intensity ratios and gestational age was demonstrated on the T2 lung-to-liver, T2 lung-to-spleen, T2 lung-to-muscle, T1 lung-to-liver, and T1 lung-to-spleen ratios (P < 0.05). T2 lung-to-liver and T2 lung-to-muscle demonstrated the strongest relationship with gestational age (best correlation r = 0.483, P < 0.001). T1 lung-to-liver and T1 lung-to-spleen demonstrated inverse relationships with gestational age (r = -0.174 [P = 0.03] and r = -0.236 [P = 0.02], respectively).

CONCLUSIONS

A significant correlation between multiple signal intensity ratios and gestational age is demonstrated. However, the large variances preclude a clinically useful relationship.

Metabolomic profile of amniotic fluid to evaluate lung maturity: the diaphragmatic hernia lamb model

Background

Tracheal occlusion (TO) stimulates lung growth in fetuses affected with congenital diaphragmatic hernia (CDH) although the processes involved in lung maturation still remain unknown. The objective of this study was to evaluate the metabolomic profile of amniotic fluid (AF) following TO in fetal lamb model in order to obtain an indirect view of mechanisms involved in pulmonary reversal hypoplasia and biochemical maturity in response to fetal TO.

Methods

Liquid Chromatography Mass Spectrometry was performed on lamb AF samples at: age I (70 days’ gestation); age II (102 days’ gestation); age III (136 days’ gestation). CDH was induced at age I and TO at age II.

Results

Betaine, choline, creatinine were found significantly increased during gestation in the control group. The CDH group showed choline (p =0.007) and creatinine (p =0.004) decreases during pregnancy. In the TO group choline and creatinine profiles were restored.

Conclusions

Alveolar tissue and fetal global growth ameliorated after TO. Metabolomics provided useful information on biochemical details during lung maturation. Metabolomic profiling would help to identify the best time to perform TO, in order to increase survival of CDH affected patients.

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

The performance of three quantitative NMR methods was compared in terms of short-term and long-term precision and accuracy, robustness, linear range, and general applicability. The Internal Reference method employs a reference material co-dissolved with sample; the External Reference method employs a reference material contained in a separate solution; and the third method, known as Electronic REference To access In vivo Concentrations (ERETIC), employs an externally calibrated digital reference peak. The Internal Reference method results were the most precise and remained stable within 0.1% for at least 4 weeks. The results from the External Reference and ERETIC methods were practically equivalent to each other during this time. These methods exhibited small differences relative to the standard set by the Internal Reference method and slightly lower precision, establishing them as practical alternatives to the Internal Reference method. In contrast to the Internal Reference method, the External Reference and ERETIC methods possess several advantages that address peak overlap, flexibility of calibration, and duration of applicability. The study was designed such that each spectrum contained the information needed to compare the three methods while all other variables were kept constant. Applicability of pulse width compensation is addressed. ERETIC software compensation and minor adjustments to 90° pulse width were concluded to be unnecessary for this system. Although each of the methods was applied here to specifically calculate and compare chemical purity values, this evaluation applies generally to absolute quantitation by NMR.

Fetal blood flow velocimetry by phase-contrast MRI using a new triggering method and comparison with Doppler ultrasound in a sheep model: a pilot study

OBJECT

We present the first study demonstrating the feasibility of antenatal blood flow velocimetry performing ECG triggered phase-contrast (PC)-MRI in the fetal aorta by using a newly developed Doppler ultrasound trigger.

MATERIALS AND METHODS

Five pregnant sheep carrying singleton fetuses (gestational age 121 days) were anesthetized to undergo fetal 2D PC-MRI in the fetal descending aorta (1.5 T) using a newly developed MR-compatible Doppler ultrasound trigger for fetal cardiac triggering. Inter-operator variability was assessed for PC-MR measurements and reproducibility was tested by repeated scans in one fetus. Inter-modality comparison was performed by Doppler ultrasound velocimetry.

RESULTS

Fetal cardiac triggering was possible in all examinations. PC-MR velocimetry revealed a mean inter-operator variability of 3 ± 5%. Average peak systolic flow velocities of 62.5 ± 4.4 cm/s were in good agreement with Doppler ultrasound measurements of 62.0 ± 9.2 cm/s (p (Lord's U test) ≫ 0.05).

CONCLUSION

Fetal PC-MR velocimetry was successfully performed using the newly developed MR-compatible Doppler ultrasound trigger for intrauterine fetal cardiac triggering, demonstrating high inter-operator and inter-modality agreement. This new method has the high potential for alternative assessment of hemodynamic decompensation of the fetal circulation.

Amniotic fluid: the use of high-dimensional biology to understand fetal well-being

Our aim was to review the use of high-dimensional biology techniques, specifically transcriptomics, proteomics, and metabolomics, in amniotic fluid to elucidate the mechanisms behind preterm birth or assessment of fetal development. We performed a comprehensive MEDLINE literature search on the use of transcriptomic, proteomic, and metabolomic technologies for amniotic fluid analysis. All abstracts were reviewed for pertinence to preterm birth or fetal maturation in human subjects. Nineteen articles qualified for inclusion. Most articles described the discovery of biomarker candidates, but few larger, multicenter replication or validation studies have been done. We conclude that the use of high-dimensional systems biology techniques to analyze amniotic fluid has significant potential to elucidate the mechanisms of preterm birth and fetal maturation. However, further multicenter collaborative efforts are needed to replicate and validate candidate biomarkers before they can become useful tools for clinical practice. Ideally, amniotic fluid biomarkers should be translated to a noninvasive test performed in maternal serum or urine.

Correlation of 2nd trimester amniotic fluid amino acid profile with gestational age and estimated fetal weight

OBJECTIVES

Our aim was to identify and quantitate free amino acids in human amniotic fluid (AF) specimens collected during 2nd trimester amniocentesis and determine the correlation between amino acid concentrations, gestational age, and estimated fetal weight.

METHODS

Seventy-eight AF samples were retrieved between 18 and 22 weeks of gestation. Fetal weight estimation was based on fetal biometric measurements.

RESULTS

Twenty-one amino acids were quantified. The concentration of glutamine exhibited the greatest correlation with gestational age (r = 0.477, p < 0.01). Additionally, significant negative correlations were recorded between gestational age and levels of alanine, proline, lysine, valine, taurine, leucine, glutamic acid, tyrosine, phenylalanine, isoleucine, ornithine, methionine, and tryptophane (p < 0.05). After adjusting for maternal age, fetal gender, intervals between consecutive pregnancies, pre-pregnancy body mass index, and smoking during pregnancy the strength of the correlation for proline and lysine decreased. A stepwise multiple linear regression model including gestational age as a first level predictor of fetal weight indicated that lysine and cysteine concentrations were additional predictors.

CONCLUSIONS

Our results suggest that AF amino acids are crucial for fetal growth. Our purpose was not to establish an immediate diagnostic application. However, further exploration is likely to be fruitful, especially in high-risk pregnancies.

Calculation of gestational age in late second and third trimesters by ex vivo magnetic resonance spectroscopy of amniotic fluid

OBJECTIVE

The purpose of this study was to develop a reliable model for the calculation of gestational age (GA) in second and third trimesters with the use of amniotic fluid (AF) metabolite profiles that were determined by magnetic resonance spectroscopy.

STUDY DESIGN

High-resolution (11.7 T) ex vivo magnetic resonance spectroscopy was performed on 95 AF samples (mean, 31.7 weeks; range, 15.6-39.9 weeks). GA was determined by last menstrual period or first-trimester ultrasound scanning. Concentrations of 21 AF metabolites were measured with automated techniques. Metabolite concentrations, inverses, natural logs, and squares were entered as predictive variables in a stepwise linear regression model.

RESULTS

The following formula was derived: GA = 64.922 - (14.456 x alanine) + (4.965 x natural log [creatinine]) - (0.931 x glucose) - (5.202 x valine). This model fit the data with an R(2) value of 0.926. Average error among all samples was +/-1.75 weeks (SD, +/-1.43 weeks), for the second trimester was +/-2.21 weeks (SD, +/-1.78 weeks), and for the third trimester was +/-1.59 weeks (SD, +/-1.26 weeks).

CONCLUSION

Statistical modeling accurately predicted GA with amniotic fluid metabolite profiles that were obtained by magnetic resonance spectroscopy, which may represent a significant improvement over conventional ultrasound dating in the third trimester. Future studies should compare these techniques directly.