Rethinking COSY and TOCSY acquisition

Nolis, Pau & Teodor Parella. 2019. Practical aspects of the simultaneous collection of COSY and TOCSY spectra. Magnetic Resonance in Chemistry. DOI: 10.1002/mrc.4835

The practical aspects of some NMR experiments designed for the simultaneous acquisition of 2D COSY and 2D TOCSY spectra are presented and discussed. Several techniques involving afterglow‐based, CTP‐based and NOAH‐based strategies for the collection of different FIDs within the same scan are evaluated and compared. These methods offer a faster recording of these spectra in small‐molecule NMR when sensitivity is not a limiting factor, with a reduction in spectrometer time about 45%‐60% when compared to the conventional sequential acquisition of the parent experiments. It is also shown how the optimized design of an extended three‐FID approach yields one COSY and two TOCSY spectra simultaneously by combining CTP and NOAH principles in the same experiment, affording substantial sensitivity enhancements per time unit.

New methodology to obtain High Resolution aliased HSQC

Nolis, Pau, Kumar Motiram-Corral, Míriam Pérez-Trujillo & Teodor Parella. 2019. Simultaneous acquisition of two 2D HSQC spectra with different 13C spectral widths. Journal of Magnetic Resonance. DOI: 10.1016/j.jmr.2019.01.004

ABSTRACT: A time-efficient NMR strategy that involves the interleaved acquisition of two 2D HSQC spectra having different spectral widths in the indirect 13C dimension is presented. We show how the two equivalent coherence transfer pathways involved in sensitivity-enhanced HSQC experiments are managed selectively and detected separately in different FID periods within the same scan. The feasibility of this new SADA-HSQC (Spectral Aliasing in Dually Acquired HSQC) technique is demonstrated by recording simultaneously two complementary datasets, conventional and highly-resolved spectral-aliased 2D HSQC spectra, in a single NMR experiment. Combining the information from both datasets, accurate chemical shift determination and excellent signal dispersion is achieved in a unique measurement using only few t1 increments.

Prenatal cerebral and cardiac metabolic changes in a rabbit model of fetal growth restriction

Simões, Rui V., Miquel E. Cabañas, Carla Loreiro, Miriam Illa, Fatima Crispi & Eduard Gratacós. 2018. Assessment of prenatal cerebral and cardiac metabolic changes in a rabbit model of fetal growth restriction based on 13C-labelled substrate infusions and ex vivo multinuclear HRMAS. PLOS ONE 13(12). e0208784. DOI: 10.1371/journal.pone.0208784

Background: We have used a previously reported rabbit model of fetal growth restriction (FGR), reproducing perinatal neurodevelopmental and cardiovascular impairments, to investigate the main relative changes in cerebral and cardiac metabolism of term FGR fetuses during nutrient infusion.

Methods: FGR was induced in 9 pregnant New Zealand rabbits at 25 days of gestation: one horn used as FGR, by partial ligation of uteroplacental vessels, and the contralateral as control (appropriate for gestation age, AGA). At 30 days of gestation, fasted mothers under anesthesia were infused i.v. with 1-13C-glucose (4 mothers), 2-13C-acetate (3 mothers), or not infused (2 mothers). Fetal brain and heart samples were quickly harvested and frozen down. Brain cortex and heart apex regions from 30 fetuses were studied ex vivo by HRMAS at 4°C, acquiring multinuclear 1D and 2D spectra. The data were processed, quantified by peak deconvolution or integration, and normalized to sample weight.

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Job offer for the INSPiRE-MED project

We are recruiting an Early Stage Researcher to work on the implementation of high-resolution MRSI methods in a pre-clinical scanner as part of the INSPiRE-MED European project.

We seek a highly motivated and qualified individual as Early Stage Researcher for a three-year applied research project. The successful candidate will contribute to the development of advanced biomedical research tools in the field of Magnetic Resonance Spectroscopy and Imaging, and its application to the clinical day-to-day practice.

Project description: This position is one of the 15 ESR positions of the INSPiRE-MED European Training Network, which focuses on the development of Magnetic Resonance Spectroscopy (MRS) and MR Spectroscopic Imaging (MRSI) combined with Positron Emission Tomography (PET), enhanced by machine learning techniques.

The main aim of the PhD project (ESR4) will be the implementation of innovative high spatial resolution MRSI methods in a pre-clinical scanner. The ultimate goal will be the validation of optimal methods for improving imaging biomarker development of brain tumour in longitudinal studies of therapy response in mouse glioblastoma models. The project will involve evaluation of the methodology performance limits, repeatability and reproducibility compared to stock Bruker Biospec MRSI sequences and the assessment of speed-up MRSI methods in a 7-Tesla pre-clinical scanner.

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INSPiRE-MED project awarded to GABRMN & SeRMN

Integrating Magnetic Resonance Spectroscopy and Multimodal Imaging for Research and Education in MEDicine (INSPiRE-MED) is an European research project awarded in the call H2020-MSCA-ITN-2018, of the MSCA-ITN-ETN – European Training Networks, to a consortium of partners including the GABRMN and SeRMN at UAB. The project is coordinated by Prof. Dominique Sappey-Marinier, of the Université Lyon-1 Claude-Bernard, Lyon, France. The scientist-in-charge at UAB will be Prof. Carles Arús (GABRMN), and Silvia Lope-Piedrafita (SeRMN) and Miquel Cabañas (SeRMN) will participate as senior scientists in the project.

Starting 1st of January 2019, the INSPiRE-MED Initial Training Network will investigate the theoretical and practical aspects of in vivo Magnetic Resonance Spectroscopy (MRS) and Spectroscopic Imaging (MRSI) with applications in oncology and neurology.

The network will host 15 Early Stage Researchers in the field of biomedical imaging, particularly in the field of Magnetic Resonance Spectroscopy (MRS) and MR Spectroscopic Imaging (MRSI) combined with Positron Emission Tomography (PET) and enhanced by machine learning techniques. The research training is supervised by a consortium of 12 academic partners with an established collaborative track record in R&D and 9 industrial partners from the broad and competitive preclinical and clinical imaging sector.

The main research topic to be carried at UAB —in close collaboration with other project members— will be the implementation of innovative high spatial resolution MRSI methods in a pre-clinical scanner. The ultimate goal will be the validation of optimal methods for improving imaging biomarker development of brain tumour in longitudinal studies of therapy response in mouse glioblastoma models.

Continue reading INSPiRE-MED project awarded to GABRMN & SeRMN

Beneficial effects of Uric Acid Treatment After Stroke in Hypertensive Rats

Jiménez-Xarrié, Elena, Belén Pérez, Ana Paula Dantas, Lídia Puertas-Umbert, Joan Martí-Fabregas, Ángel Chamorro, Anna Maria Planas, Elisabet Vila, Francesc Jiménez-Altayó. 2018. Uric Acid Treatment After Stroke Prevents Long-Term Middle Cerebral Artery Remodelling and Attenuates Brain Damage in Spontaneously Hypertensive Rats. Translational Stroke Research. DOI: 10.1007/s12975-018-0661-8

Hypertension is the most important modifiable risk factor for stroke and is associated with poorer post-stroke outcomes. The antioxidant uric acid is protective in experimental normotensive ischaemic stroke. However, it is unknown whether this treatment exerts long-term protection in hypertension. The authors aimed to evaluate the impact of transient intraluminal middle cerebral artery (MCA) occlusion (90min)/reperfusion (1–15 days) on brain and vascular damage progression in adult and spontaneously hypertensive rats (SHR) treated with uric acid. Ischaemic brain damage was assessed longitudinally with magnetic resonance imaging at the Nuclear Magnetic Resonance Service of the Universitat Autònoma de Barcelona.

In SHR rats, more severe brain damage and poorer neurofunctional outcomes were coupled to higher cortical cerebral blood flow at the onset of reperfusion, a transient increase in oxidative stress and long-lasting stroke-induced MCA hypertrophic remodelling. Thus, stroke promotes larger brain and vascular damage in hypertensive rats that persists for long-time. Uric acid administered during early reperfusion attenuated short- and long-term brain injuries in both normotensive and hypertensive rats, an effect that was associated with abolishment of the acute oxidative stress response and prevention of stroke-induced long lasting MCA remodelling in hypertension. These results suggest that uric acid might be an effective strategy to improve stroke outcomes in hypertensive subjects.

New time-efficient approach in TOCSY and HSQC experiments

Nolis, Pau, Kumar Motiram‐Corral, Míriam Pérez‐Trujillo & Teodor Parella. 2018. Interleaved Dual NMR Acquisition of Equivalent Transfer Pathways in TOCSY and HSQC Experiments. ChemPhysChem 20(3). 356–360. DOI: 10.1002/cphc.201801034

A dual NMR data acquisition strategy to handle and detect two active equivalent transfer pathways is presented and discussed. We illustrate the power of this time-efficient approach by collecting two different 2D spectra simultaneously in a single experiment: (i) TOCSY or HSQC-TOCSY spectra with different mixing times, (ii) F2-13C-coupled and decoupled HSQC spectra, (iii) conventional and pureshift HSQC spectra, and (iv) complementary HSQC and HSQC-TOCSY spectra.

Saving time using different NMR concepts

Nolis, Pau, Kumar Motiram-Corral, Míriam Pérez-Trujillo & Teodor Parella. 2019. Broadband homodecoupled time-shared 1H-13C and 1H-15N HSQC experiments. Journal of Magnetic Resonance 298. 23–30. DOI: 10.1016/j.jmr.2018.11.00

The concepts of pure-shift NMR and time-shared NMR are merged in a single NMR experiment. A 13C/15N time-shared version of the real-time BIRD-based broadband homodecoupled HSQC experiment is described. This time-efficient approach affords simultaneously 1H-13C and 1H-15N pure-shift HSQC spectra in a single acquisition, while achieving substantial gains in both sensitivity and spectral resolution. We also present a related 13C/15N-F2-coupled homodecoupled version of the CLIP-HSQC experiment for the simultaneous measurement of 1JCH and 1JNH from the simplified doublets observed along the direct dimension. Finally, a novel J-resolved HSQC experiment has been designed for the simple and automated determination of both 1JCH/1JNH from a 2D J-resolved spectrum.

4 experiments in 1 shot

Motiram-Corral, Kumar, Míriam Pérez-Trujillo, Pau Nolis & Teodor Parella. 2018. Implementing one-shot multiple-FID acquisition into homonuclear and heteronuclear NMR experiments. Chemical Communications 54(96). 13507–13510. DOI: 10.1039/c8cc08065h

Multiple-FID acquisition (MFA) within the same scan is applied to acquire simultaneously multiple 2D spectra from a single NMR experiment. A discussion on the incorporation of the MFA strategy in several homonuclear and heteronuclear 2D pulse sequences is presented. As a proof of concept, a set of novel COSY, TOCSY and HMBC experiments are reported as a time-efficient solution in small-molecule NMR spectroscopy.

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