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There is an increasing interest in developing innovative means to monitor animal health through precision farming. As part of this drive, we have targeted digestive health and in particular the microbiota. In this study, we investigated the effect of different dietary interventions in piglets, feeding these piglets with one of two different feeds (high protein and low protein). We then evaluated its effects by measuring the volatile organic compounds (VOC) that emanated from these faecal samples using various forms of Ion Mobility Spectrometry. Piglets were monitored for 19 days, with faecal samples collected on days 6, 12 and 19, providing a total of 69 samples. The statistical analysis attempted to separate the samples using either dietary intervention or faecal score. First, the faecal score was investigated using a value based on a visual faecal scoring system, from 0 to 3, with 0 being normal and 3 having diarrhoea. Then the VOCs were analysed in regard to dietary intervention (high vs low protein). Results indicated that our approach was able to separate the dietary intervention (area under the curve (AUC) 0.81) using VOC data. Furthermore, we were able to separate samples based on faecal score (AUC between 0.71 and 1, with six different comparisons undertaken). We believe that faeces volatiles hold potential as a future means to monitor animal health.

Hyperpolarisiertes Wasser kann NMR-Signale schnell austauschender Protonen des intrinsisch unstrukturierten Proteins Osteopontin (OPN), welches eine Rolle bei Metastasenbildung spielt, bei annahernd physiologischem pH-Wert und Temperatur verstarken. Der Transfer der Magnetisierung des hyperpolarisierten Wassers beschrankt sich auf losungsmittelexponierte Aminosauren und verstarkt deshalb nur selektiv bestimmte Signale in (1H,15N-)Korrelationsspektren. Die Bindung des Polysaccharids Heparin induziert die Entfaltung vorgeformter Strukturelemente von OPN.

The lifetimes T-LLS of long-lived states or T-LLC of long-lived coherences can be used for the accurate determination of dissociation constants of weak protein ligand complexes. The remarkable contrast between signals derived from LLS or LLC in free and bound ligands can be exploited to search for weak binders with large dissociation constants K-D > 1 mM that are important for fragment-based drug discovery but may escape detection by other screening techniques. Alternatively, the high sensitivity of the proposed method can be exploited to work with large ligand-to-protein ratios, with an evident advantage of reduced consumption of precious proteins. The detection of F-19-F-19 long-lived states in suitably designed fluorinated spy molecules allows one to perform competition binding experiments with high sensitivity while avoiding signal overlap that tends to hamper the interpretation of proton spectra of mixtures.

In gas phase, collisions that affect the rotational angular momentum lead to the return of the magnetization to its equilibrium (relaxation) in Nuclear Magnetic Resonance (NMR). To the best of our knowledge, the longitudinal relaxation rates R1 = 1/T1 of protons in H2O and HDO have never been measured in gas phase. We report R1 in gas phase in a field of 18.8 T, i.e., at a proton Larmor frequency ν0 = 800 MHz, at temperatures between 353 and 373 K and pressures between 9 and 101 kPa. By assuming that spin rotation is the dominant relaxation mechanism, we estimated the effective cross-section σJ for the transfer of angular momentum due to H2O-H2O and HDO-D2O collisions. Our results allow one to test theoretical predictions of the intermolecular potential of water in gas phase.

By monitoring the effect of deuterium decoupling on the decay of transverse 15N magnetization in D–15N spin pairs during multiple-refocusing echo sequences, we have determined fast D–D exchange rates kD and compared them with fast H–H exchange rates kH in tryptophan to determine the kinetic isotope effect as a function of pH and temperature.

In gas phase, collisions that affect the rotational angular momentum lead to the return of the magnetization to its equilibrium (relaxation) in Nuclear Magnetic Resonance (NMR). To the best of our knowledge, the longitudinal relaxation rates R1 = 1/T1 of protons in H2O and HDO have never been measured in gas phase. We report R1 in gas phase in a field of 18.8 T, i.e., at a proton Larmor frequency ν0 = 800 MHz, at temperatures between 353 and 373 K and pressures between 9 and 101 kPa. By assuming that spin rotation is the dominant relaxation mechanism, we estimated the effective cross-section σJ for the transfer of angular momentum due to H2O-H2O and HDO-D2O collisions. Our results allow one to test theoretical predictions of the intermolecular potential of water in gas phase.

International audience; Para-water is an analogue of para-hydrogen, where the two proton spins are in a quantum state that is antisymmetric under permutation, also known as singlet state. The populations of the nuclear spin states in para-water are believed to have long lifetimes just like other Long-Lived States (LLSs). This hypothesis can be verified by measuring the relaxation of an excess or a deficiency of para-water, also known as a “Triplet–Singlet Imbalance” (TSI), i.e., a difference between the average population of the three triplet states T (that are symmetric under permutation) and the population of the singlet state S. In analogy with our recent findings on ethanol and fumarate, we propose to adapt the procedure for Dissolution Dynamic Nuclear Polarization (D-DNP) to prepare such a TSI in frozen water at very low temperatures in the vicinity of 1.2 K. After rapid heating and dissolution using an aprotic solvent, the TSI should be largely preserved. To assess this hypothesis, we studied the lifetime of water as a molecular entity when diluted in various solvents. In neat liquid H2O, proton exchange rates have been characterized by spin-echo experiments on oxygen-17 in natural abundance, with and without proton decoupling. One-dimensional exchange spectroscopy (EXSY) has been used to study proton exchange rates in H2O, HDO and D2O mixtures diluted in various aprotic solvents. In the case of 50 mM H2O in dioxane-d8, the proton exchange lifetime is about 20 s. After dissolving, one can observe this TSI by monitoring intensities in oxygen-17 spectra of H2O (if necessary using isotopically enriched samples) where the AX2 system comprising a “spy” oxygen A and two protons X2 gives rise to binomial multiplets only if the TSI vanishes. Alternatively, fast chemical addition to a suitable substrate (such as an activated aldehyde or ketone) can provide AX2 systems where a carbon-13 acts as a spy nucleus. Proton signals that relax to equilibrium with two distinct time constants can be considered as a hallmark of a TSI. We optimized several experimental procedures designed to preserve and reveal dilute para-water in bulk.

The authors want to thank Dr. Jean-Nicolas Dumez for helpful discussions; Sven Sieber, Michael Schenkel, Rolf Hensel, Jacco van Beek, Ion Prisucaru, and Armin Purea for contributions to the system design and implementation; and Frank Engelke, Pietro Lendi, Klemens Kessler, Daniel Eckert, Daniel Guy Baumann, Dirk Wilhelm, Roberto Seydoux, Uwe Wagner, Cengiz Cetrefli, Tonio Gianotti, and Jorg Hinderer for contributions to the system specification. Some of the work in this article employed the SpinDynamica code for Mathematica, programmed by Malcolm H. Levitt, with contributions from Jyrki Rantaharju, Andreas Brinkmann, and Soumya Singha Roy, available at www.SpinDynamica.soton.ac.uk.; International audience; We present novel means to hyperpolarize deuterium nuclei in 13CD2 groups at cryogenic temperatures. The method is based on cross-polarization from 1H to 13C and does not require any radio-frequency fields applied to the deuterium nuclei. After rapid dissolution, a new class of long-lived spin states can be detected indirectly by 13C NMR in solution. These long-lived states result from a sextet-triplet imbalance (STI) that involves the two equivalent deuterons with spin I = 1. An STI has similar properties as a triplet-singlet imbalance that can occur in systems with two equivalent I = 12/ spins. Although the lifetimes T STI are shorter than T 1(Cz), they can exceed the life-time T 1(Dz) of deuterium Zeeman magnetization by a factor of more than 20.