Chemical exchange saturation transfer magnetic resonance imaging for metabolic mapping of ripening tomato fruit: Quite a challenge!

Chemical Exchange Saturation Transfer Magnetic Resonance Imaging (CEST-MRI) is an established tool in animal or human MRI to indirectly visualize metabolites in vivo. We used CEST-MRI to map the major metabolites in tomato fruit at tissue level throughout ripening. Phantom experiments showed a CEST effect in the 1 and 3 ppm chemical shifts for major soluble sugars and free amino acids, respectively, and a tendency for the CEST signal to decrease from pH 4.

Impact of salting practices on sodium distribution in carrots assessed by quantitative MRI.

Currently, sodium consumption is significantly higher than the 5 g per day recommended by health organizations. This paper aimed to compare salt distribution in food according to domestic salting practices. For this study, carrots boiled in water were used as a food model.

Spatiotemporal quantification of sodium concentration in food using magnetic resonance imaging.

Quantitative Na MRI presents numerous technical challenges that limit its application in food science - especially in the context of salt reduction. This study aimed to fill this gap by developing a quantitative Na MRI protocol for following the evolution of salt concentration in food samples. By doing so, valuable information on salting processes of real food products can be obtained.

Towards portable MRI in the plant sciences.

Plant physiology and structure are constantly changing according to internal and external factors. The study of plant water dynamics can give information on these changes, as they are linked to numerous plant functions. Currently, most of the methods used to study plant water dynamics are either invasive, destructive, or not easily accessible.

Online adaptive identification of multichannel systems for audio applications.

Impulse responses (IRs) estimation of multi-input acoustic systems is a prerequisite for many audio applications. In this paper, an adaptive identification problem based on the Autostep algorithm is extended to the simultaneous estimation of room IRs for multiple input single output linear time invariant systems without any a priori information. To do so, the proposed algorithm is initially evaluated in a simulated room with several sound sources active at the same time.

Interhemispheric reactivity of the subthalamic nucleus sustains progressive dopamine neuron loss in asymmetrical parkinsonism.

Parkinson's disease (PD) is characterized by the progressive and asymmetrical degeneration of the nigrostriatal dopamine neurons and the unilateral presentation of the motor symptoms at onset, contralateral to the most impaired hemisphere. We previously developed a rat PD model that mimics these typical features, based on unilateral injection of a substrate inhibitor of excitatory amino acid transporters, L-trans-pyrrolidine-2,4-dicarboxylate (PDC), in the substantia nigra (SN). Here, we used this progressive model in a multilevel study (behavioral testing, in vivo H-magnetic resonance spectroscopy, slice electrophysiology, immunocytochemistry and in situ hybridization) to characterize the functional changes occurring in the cortico-basal ganglia-cortical network in an evolving asymmetrical neurodegeneration context and their possible contribution to the cell death progression.

Quantitative sodium magnetic resonance imaging in food: Addressing sensitivity issues using single quantum chemical shift imaging at high field.

According to various health organizations, the global consumption of salt is higher than recommended and needs to be reduced. Ideally, this would be achieved without losing the taste of the salt itself. In order to accomplish this goal, both at the industrial and domestic levels, we need to understand the mechanisms that govern the final distribution of salt in food.

Spurious phase correction in rapid metabolic imaging.

IDEAL-type magnetic resonance spectroscopic imaging (MRSI) sequences require the acquisition of several datasets using optimized sampling in the time domain to reconstruct metabolite maps. Each unitary scan consists of a selective slice (2D) or slab (3D) excitation followed by an evolution time and then the acquisition of the spatially encoded signal. It is critical that the phase variation during the evolution time for each scan is only dependent on chemical shifts.

Circadian Variation of Root Water Status in Three Herbaceous Species Assessed by Portable NMR.

Roots are at the core of plant water dynamics. Nonetheless, root morphology and functioning are not easily assessable without destructive approaches. Nuclear Magnetic Resonance (NMR), and particularly low-field NMR (LF-NMR), is an interesting noninvasive method to study water in plants, as measurements can be performed outdoors and independent of sample size.

Simultaneous proteoglycans and hypoxia mapping of chondrosarcoma environment by frequency selective CEST MRI.

Purpose: To evaluate the relevance of CEST frequency selectivity in simultaneous in vivo imaging of both of chondrosarcoma's phenotypic features, that are, its high proteoglycan concentration and its hypoxic core.

Methods: Swarm rat chondrosarcomas were implanted subcutaneously in NMRI nude mice. When tumors were measurable (12-16 days postoperative), mice were submitted to GAG, guanidyl, and APT CEST imaging.

Effects of Long-Term Endogenous Corticosteroid Exposure on Brain Volume and Glial Cells in the AdKO Mouse.

Chronic exposure to high circulating levels of glucocorticoids has detrimental effects on health, including metabolic abnormalities, as exemplified in Cushing's syndrome (CS). Magnetic resonance imaging (MRI) studies have found volumetric changes in gray and white matter of the brain in CS patients during the course of active disease, but also in remission. In order to explore this further, we performed MRI-based brain volumetric analyses in the AdKO mouse model for CS, which presents its key traits.

Low field, time domain NMR in the agriculture and agrifood sectors: An overview of applications in plants, foods and biofuels.

In this contribution, a selective overview of low field, time-domain NMR (TD-NMR) applications in the agriculture and agrifood sectors is presented. The first applications of commercial TD-NMR instruments were in food and agriculture domains. Many of these earlier methods have now been recognized as standard methods by several international agencies.

MRSI vs CEST MRI to understand tomato metabolism in ripening fruit: is there a better contrast?

Besides structural information, magnetic resonance imaging (MRI) is crucial to reveal the presence and gradients of metabolites in organs constituted of several tissues. In plant science, such knowledge is key to better understand fruit development and metabolism. Routine methods based on fixation for cytological studies or dissection for metabolite measurements induce biases and plant sample destruction.

Parsimonious discretization for characterizing multi-exponential decay in magnetic resonance.

We address the problem of analyzing noise-corrupted magnetic resonance transverse decay signals as a superposition of underlying independently decaying monoexponentials of positive amplitude. First, we indicate the manner in which this is an ill-conditioned inverse problem, rendering the analysis unstable with respect to noise. Second, we define an approach to this analysis, stabilized solely by the nonnegativity constraint without regularization.

Antioxidant and Cardioprotective Effects of EPA on Early Low-Severity Sepsis through UCP3 and SIRT3 Upholding of the Mitochondrial Redox Potential.

Sepsis still causes death, often through cardiac failure and mitochondrial dysfunction. Dietary 3 polyunsaturated fatty acids are known to protect against cardiac dysfunction and sepsis lethality. This study set out to determine whether early low-severity sepsis alters the cardiac mitochondrial function in animals fed a Western-type diet and whether dietary eicosapentaenoic acid (EPA) administration protects the myocardium against the deleterious effects of sepsis and if so to seek possible mechanisms for its effects.

Glyoxalase activity in human erythrocytes and mouse lymphoma, liver and brain probed with hyperpolarized C-methylglyoxal.

Methylglyoxal is a faulty metabolite. It is a ubiquitous by-product of glucose and amino acid metabolism that spontaneously reacts with proximal amino groups in proteins and nucleic acids, leading to impairment of their function. The glyoxalase pathway evolved early in phylogeny to bring about rapid catabolism of methylglyoxal, and an understanding of the role of methylglyoxal and the glyoxalases in many diseases is beginning to emerge.

Uncertainties of calculated Cramér-Rao lower bounds: implications for quantitative MRS.

Purpose: To investigate the uncertainties on relative Cramér-Rao lower bound (rCRB) estimates and demonstrate their biasing effects in MRS quantification.

Theory And Methods: Simulations were performed to calculate the distribution of the computed rCRB (noted rCRB*) for several rCRB levels. One hundred thousand simulations per rCRB value were performed on simulated NMR signals containing either 1 signal (singlet) or 2 partially overlapping signals.

mGlu5 receptor antagonist blocks bromocriptine-induced conditioned place preference in bilateral mesolimbic-lesioned rat.

Dopamine dysregulation syndrome (DDS) has been attributed to both dopamine replacement therapies (DRT) and the mesencephalic dopaminergic lesion. The DRT reinforcement effect is due to its action on the reward system, particularly on the nucleus accumbens (NAc). This nucleus receives two major projections, a glutamatergic from the prefrontal cortex and a dopaminergic from the posterior ventral tegmental area (pVTA).

Pulsed Field Gradient NMR with Sigmoid Shape Gradient Sampling To Produce More Detailed Diffusion Ordered Spectroscopy Maps of Real Complex Mixtures: Examples with Medicine Analysis.

NMR diffusion measurements are based on signal attenuation. In the case of complex mixtures for which some molecules are diffusing quickly while others are significantly slower, it is challenging to obtain a diffusion ordered spectroscopy (DOSY)-type 2D map giving reliable information on all molecules. In this paper, we propose a new gradient sampling approach based on a sigmoid shape allowing the acquisition of a significant number of points for both the fast and slow diffusing molecules.

Evaluation of a benchtop cryogen-free low-field ¹H NMR spectrometer for the analysis of sexual enhancement and weight loss dietary supplements adulterated with pharmaceutical substances.

Nuclear magnetic resonance (NMR) spectroscopy is a unique tool for detection, structural characterization, and quantification of compounds in complex mixtures. However, due to cost constraints, NMR is rarely used in routine quality control (QC) analysis. The recent release of benchtop cryogen-free low-field NMR spectrometers represents a technological break in the NMR field.

Hyperpolarized [1,(13)C]pyruvate in lysed human erythrocytes: effects of co-substrate supply on reaction time courses.

Hyperpolarized [1,(13)C]pyruvate was injected rapidly into haemolysates in which hydrolysis of nicotinamide adenine dinucleotide (phosphate) (NAD(P))/NAD(P)H had been inhibited with nicotinamide. Haemolysates provide a stable glycolytic system in which membrane permeability is not a flux-controlling step, and they enable the concentration of NADH to be adjusted experimentally while keeping the rest of the sample with the same composition as that of the cytoplasm of the cell (albeit diluted twofold at the time of injection of the [1,(13)C]pyruvate). We showed that the maximum amplitude of the (13)C NMR signal from the [1,(13)C]L-lactate, produced from [1,(13)C]pyruvate, and the time at which it occurred was dependent on NADH concentration, as predicted by enzyme-kinetic analysis.

FmRα analysis: Rapid and direct estimation of relaxation and kinetic parameters from dynamic nuclear polarization time courses.

Purpose: To introduce a direct method for estimating relaxation and kinetic parameter values from rapid dissolution dynamic nuclear polarization (RD-DNP) NMR time courses.

Theory And Methods: The analysis relied on a kinetic model that is often used to analyze data in these studies-a unidirectional (bio)chemical reaction with rate constant k1 , coupled to longitudinal relaxation of the magnetization of substrate and product that is characterized by the time constant T1 . The latter value was estimated from the width of the product curve (peak) at the height α relative to the maximum height.

Structure and antimicrobial activity of platypus 'intermediate' defensin-like peptide.

The three-dimensional structure of a chemically synthesized peptide that we have called 'intermediate' defensin-like peptide (Int-DLP), from the platypus genome, was determined by nuclear magnetic resonance (NMR) spectroscopy; and its antimicrobial activity was investigated. The overall structural fold of Int-DLP was similar to that of the DLPs and β-defensins, however the presence of a third antiparallel β-strand makes its structure more similar to the β-defensins than the DLPs. Int-DLP displayed potent antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa.