Use Of Nuclear Magnetic Resonance Spectroscopy Research Articles

Characterizing the Semiconductor Nanocrystal Surface through Chemical Reactivity.

ConspectusMany desirable and undesirable properties of semiconductor nanocrystals (NCs) can be traced to the NC surface due to the large surface-to-volume ratio. Therefore, precise control of the NC surface is imperative to achieve NCs with the desired qualities. Ligand-specific reactivity and surface heterogeneity make it difficult to accurately control and tune the NC surface. Without a molecular-level appreciation of the NC surface chemistry, modulating the NC surface is impossible and the risk of introducing deleterious surface defects is imminent. To gain a more comprehensive understanding of the surface reactivity, we have utilized a variety of spectroscopic techniques and analytical methods in concert.This Account describes our use of robust characterization techniques and ligand exchange reactions in effort to establish a molecular-level understanding of NC surface reactivity. The utility of NCs in target applications such as catalysis and charge transfer hangs on precise tunability of NC ligands. Modulating the NC surface requires the necessary tools to monitor chemical reactions. One commonly utilized analytical method to achieve targeted surface compositions is 1H nuclear magnetic resonance (NMR) spectroscopy. Here we describe our use of 1H NMR spectroscopy to monitor chemical reactions at CdSe and PbS NC surfaces to identify ligand specific reactivity. However, seemingly straightforward ligand exchange reactions can vary widely depending on the NC materials and anchoring group. Some non-native X-type ligands will irreversibly displace native ligands. Other ligands exist in equilibrium with native ligands. Depending on the application, it is important to understand the nature of exchange reactions. This level of understanding can be obtained by extracting exchange ratios, exchange equilibrium, and reaction mechanism information from 1H NMR spectroscopy to establish precise NC reactivity.Reactivity that occurs through multiple, parallel ligand exchange mechanisms can involve both the liberation of metal-based Z-type ligands in addition to reactivity of X-type ligands. In these reactions, 1H NMR spectroscopy fails to discern between an X-type oleate or a Z-type Pb(oleate)2 because only the alkene resonance of the organic constituent is probed by this method. Multiple, parallel reaction pathways occur when thiol ligands are introduced to oleate-capped PbS NCs. This necessitated the use of synergistic characterization methods including 1H NMR spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and inductively coupled plasma mass spectrometry (ICP-MS) to characterize both surface-bound and liberated ligands.Similar analytical methods have been employed to probe the NC topology, which is an important, but often overlooked, component to NC reactivity given the facet-specific reactivity of PbS NCs. Through the tandem use of NMR spectroscopy and ICP-MS, we have monitored the liberation of Pb(oleate)2 as an L-type ligand is titrated to the NC to determine the quantity and equilibrium of Z-type ligands. By studying a variety of NC sizes, we correlated the number of liberated ligands with the size-dependent topology of PbS NCs.Lastly, we incorporate redox-active chemical probes into our toolbox to study NC surface defects. We describe how the site-specific reactivity and relative energetics of redox-active surface-based defects are elucidated using redox probes and show that this reactivity is highly dependent on the surface composition. This Account is designed to encourage readers to consider the necessary characterization techniques needed establish a molecular-level understanding of NC surfaces in their own work.

Comparisons of Ribonuclease HI Homologs and Mutants Uncover a Multistate Model for Substrate Recognition.

Ribonuclease HI (RNHI) nonspecifically cleaves the RNA strand of RNA:DNA hybrid duplexes in a myriad of biological processes. Several RNHI homologs contain an extended domain, termed the handle region, which is critical to substrate binding. Nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations have suggested a kinetic model in which the handle region can exist in open (substrate-binding competent) or closed (substrate-binding incompetent) states in homologs containing arginine or lysine at position 88 (using sequence numbering of E. coli RNHI), while the handle region populates states intermediate between the open and closed conformers in homologs with asparagine at residue 88 [Stafford, K. A., et al., PLoS Comput. Biol. 2013, 9, 1-10]. NMR parameters characterizing handle region dynamics are highly correlated with enzymatic activity for RNHI homologs with two-state (open/closed) handle regions [Martin, J. A., et al., Biochemistry 2020, 59, 3201-3205]. The work presented herein shows that homologs containing asparagine 88 display distinct structural features compared with their counterparts containing arginine or lysine 88. Comparisons of RNHI homologs and site-directed mutants with asparagine 88 support a kinetic model for handle region dynamics that includes 12 unique transitions between eight conformations. Overall, these findings present an example of the structure-function relationships of enzymes and spotlight the use of NMR spectroscopy and MD simulations in uncovering fine details of conformational preferences.

Review of the use of NMR spectroscopy to investigate structure, reactivity, and dynamics of lead soap formation in paintings.

Heavy metal carboxylate or soap formation is a widespread deterioration problem affecting oil paintings and other works of art bearing oil-based media. Lead soaps are prevalent in traditional oil paintings because lead white was the white pigment most frequently chosen by old masters for the paints and in some cases for the ground preparations, until the development of other white pigments from approximately the middle of the 18th century on, and because of the wide use of lead-tin yellow. In the latter part of the 19th century, lead white began to be replaced by zinc white. The factors that influence soap formation have been the focus of intense study starting in the late 1990s. Since 2014, nuclear magnetic resonance (NMR) studies have contributed a unique perspective on the issue by providing chemical, structural, and dynamic information about the species involved in the process, as well as the effects of environmental conditions such as relative humidity and temperature on the kinetics of the reaction(s). In this review, we explore recent insights into soap formation gained through solid-state NMR and single-sided NMR techniques.

Nontargeted Analysis of a Non-Aqueous-Phase Liquid From a Chemical Manufacturing Site Using Nuclear Magnetic Resonance Spectroscopy.

Non-aqueous-phase liquids (NAPLs), composed primarily of organic solvents and other immiscible liquids, can be found in the subsurface at many industrial sites. The chemical composition of NAPLs is often complex and, in many instances, difficult to fully characterize using conventional analytical techniques based on targeted compound analysis. Incomplete characterization of NAPLs leaves gaps in the understanding of the chemical profile at an impacted site. Previous work has shown that nuclear magnetic resonance (NMR) spectroscopy may be able to assist in the improved characterization of complex NAPL samples. In general, NMR spectroscopy provides an unbiased approach for the analysis of organic compounds because different classes of compounds are all treated and analyzed using the same methods. In addition, NMR spectroscopy provides unique structural information that can be used to elucidate unknowns. The present study describes the use of NMR spectroscopy as a nontargeted tool to characterize the composition of NAPLs collected from an impacted site. It is shown that NMR spectroscopy can be a complementary tool to be used in site assessments to help provide improved understanding of NAPL chemistry, leading to the development of improved conceptual site models and improved strategies for remedial and managerial activities at impacted sites. Environ Toxicol Chem 2019;00:1-9. © 2019 SETAC.

β-Cyclodextrin as a Metal-anionic Porphyrin Complexation Accelerator in Aqueous Media.

The rate of the complexation reaction between anionic porphyrins and 11 metal ions was found to be accelerated by the presence of β-cyclodextrin (β-CD) in aqueous media at room temperature without the need for additional heating or sonication. The porphyrin complexation reaction with metal ions under aqueous conditions can be difficult due to the strong hydration energy between the metal ions and water. In this study, the specific role of β-CD as an accelerator was determined and found to enhance the typically slow reaction of the porphyrin with metal ions. A significant acceleration effect was exhibited when the model anionic porphyrin, 5,10,15,20-tetraphenyl-21H,23H-porphine-tetrasulfonic acid, and Pb(II) ions were combined in the presence of β-CD. Other than for Hg ion, the addition of β-CD decreased the metalation reaction time from 30 to 2 min. The order in the degree of acceleration was Pb >> Zn, Cd > Cu > Fe, Pd > Sn >> Ag, Co, Mn. Using Pb(II) as the model ion, it was determined that the complexation rate constant was enhanced by a factor of 2.4, while the dissociation rate constant was diminished by a factor of 135 in the presence of added β-CD relative to that in its absence. Overall, the complex was much more stable (formation equilibrium constant 324-fold greater in the β-CD medium. The formation of a ternary complex (cf. bicapped complex; (β-CD)2-porphyrin-metal ion) was demonstrated through the use of nuclear magnetic-resonance spectroscopy and mass spectrometry. This acceleration effect is expected to be applicable systems in which porphyrin ligands are employed for determining of metal ions in chemical analysis and separation science.

The impact of charcoal and soil mixtures on decomposition and soil microbial communities in boreal forest

Fire is a natural disturbance that operates as a major ecological driver in many ecosystems worldwide, and it produces charcoal which is incorporated into soil in significant quantities. Charcoal can serve as a long-term carbon (C) sink, but it is not inert, and could potentially impact native soil organic matter and decomposer micro-organisms. However, studies have shown contrasting results for how charcoal impacts the belowground subsystem, and the mechanisms involved are poorly understood, especially in pyrogenic ecosystems. We performed a laboratory experiment in which six contrasting boreal forest soil types and nine charcoal types (each from different woody plant species) were incubated for 9.5 months, both by themselves and in 50:50 mixtures for all possible soil–charcoal combinations. At harvest we measured mass loss, and for several charcoal-soil combinations, we measured microbial properties, and composition of C compounds using 13C CP-MAS nuclear magnetic resonance (NMR) spectroscopy. Overall, mixtures of charcoal and soil lost more mass than expected based on when the components were incubated separately. The magnitude of increased soil mass loss in mixtures did not differ among charcoal types, but varied among soil types, because greater mass loss occurred when soil from a site dominated with herbaceous vegetation was used, relative to other soil types. The use of NMR spectroscopy showed that enhanced mass loss in mixtures was due mainly to mass loss of soil organic matter rather than charcoal. However, mixing of charcoal and soil did not influence key decomposer microbial groups compared with expected values derived from when components were incubated alone, irrespective of charcoal and soil type. This study shows that when charcoal is incorporated into boreal forest soil (e.g., after wildfire), there is enhanced loss of total C (arising primarily from mass loss of soil organic matter), with this effect being relatively consistent across contrasting charcoal and soil types. This effect, in combination with recently documented impacts of charcoal on aboveground processes, reveals important but largely overlooked legacy effects of charcoal on forest processes that contribute to ecosystem C balance and ecosystem functioning.

Nucleophilic Substitution Reactions Using Phosphine Nucleophiles: An Introduction to Phosphorus-31 NMR

Nuclear magnetic resonance (NMR) spectroscopy is commonly used in modern synthetic chemistry to monitor the conversion of reactants to products. Since instruction in the use of NMR spectroscopy typically does not occur until after the introduction of nucleophilic substitution reactions, organic chemistry students are not able to take advantage of this technique to measure and quantify important concepts such as relative electrophile and nucleophile reactivity. A phosphorus-31 (31P) NMR spectroscopy experiment is reported that allows undergraduate students to monitor product formation for a number of different alkyl halide electrophiles and phosphorus nucleophiles. In this experiment, students are able to use reactant-to-product ratios obtained by simple 31P NMR spectroscopy to explore the relative reactivities of these compounds. This exercise serves as an introduction to both NMR spectroscopy and the specific advantages of heteronuclear NMR spectroscopy.

Invited Presentation: NMR and Diffraction Studies of Electrode Reactions: The Effect of Structure, Rate and Electrode Formulations on Reaction Mechanisms

A full understanding of the operation of a battery requires that we utilize methods that allow devices or materials to be probed while they are operating (i.e., in-situ). This allows, for example, the transformations of the various cell components to be followed under realistic conditions without having to disassemble and take apart the cell. To this end, the application of new in and ex-situ Nuclear Magnetic Resonance (NMR) and X-ray diffraction (XRD) approaches to correlate structure and dynamics with function in lithium-ion batteries will be described. The in-situ approach allows processes to be captured, which are very difficult to detect directly by ex-situ methods. For example, we can detect side reactions involving the electrolyte and electrode materials and non-equilibrium processes that can occur during extremely fast charging and discharging. Ex-situ NMR investigations allow more detailed structural studies to be performed to correlate local and long-range structure with performance in battery materials.In this talk, I will describe the use of NMR spectroscopy and X-ray diffraction to probe local structure changes in lithium ion batteries focusing on our work on olivines, spinels and lithium air cathodes. In the olivine work, we show how the use of fast charging allows us to capture metastable/non-equilibrium states. Mapping of the electrodes allows the distribution of the reaction front across the electrode to be followed. Second, the development of new NMR approaches to investigate paramagnetic battery materials, both in and ex situ, will be discussed, the approach making use of both theory and experiment. Although it is difficult to achieve high-resolution spectra from these paramagnetic materials (see for example the Li1.08-xMn1.92O4 resonance in Figure 1) in the in situ experiments, measurements of the relaxation time allow access to the dynamics of the lithium ions in real time as a function of state of charge. Figure 1: 7Li in situ NMR of Li1.08Mn1.92O4 during galvanostatic cycling (electrochemistry shown on the left). The red arrows indicate the evolution of the resonance from the tetrahedral sites in Li1.08-xMn1.92O4. Short recycle delays are used so as to suppress the resonance from the electrolyte. Note the apparent increase in intensity at the end of the 4.0 V process/beginning of 4.2 V process on charge and the end of the 4.2 V process on discharge. The behaviour originates from a change in spin-spin relaxation behaviour and indicates a slowing down of the cation/electron mobility. This phenomena has been explored as a function of temperature and spinel stoichiometry.

Recent advances in protein NMR spectroscopy and their implications in protein therapeutics research

Nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography are the two main methods for protein three-dimensional structure determination at atomic resolution. According to the protein structures deposited in the Protein Data Bank, X-ray crystallography has become the dominant method for structure determination, particularly for large proteins and complexes. However, with the developments of isotope labeling, increase of magnetic field strength, common use of a cryogenic probe, and ingenious pulse sequence design, the applications of NMR spectroscopy have expanded in biological research, especially in characterizing protein dynamics, sparsely populated transient structures, weak protein interactions, and proteins in living cells at atomic resolution, which is difficult if not impossible by other biophysical methods. Although great advances have been made in protein NMR spectroscopy, its applications in protein therapeutics, which represents the fastest growing segment of the pharmaceutical industry, are still limited. Here we review the recent advances in the use of NMR spectroscopy in studies of large proteins or complexes, posttranslation modifications, weak interactions, and aggregation, and in-cell NMR spectroscopy. The potential applications of NMR spectroscopy in protein therapeutic assays are discussed.

Fragment-based drug discovery using NMR spectroscopy.

Nuclear magnetic resonance (NMR) spectroscopy has evolved into a powerful tool for fragment-based drug discovery over the last two decades. While NMR has been traditionally used to elucidate the three-dimensional structures and dynamics of biomacromolecules and their interactions, it can also be a very valuable tool for the reliable identification of small molecules that bind to proteins and for hit-to-lead optimization. Here, we describe the use of NMR spectroscopy as a method for fragment-based drug discovery and how to most effectively utilize this approach for discovering novel therapeutics based on our experience.

WeNMR: Structural Biology on the Grid

The WeNMR ( http://www.wenmr.eu ) project is a European Union funded international effort to streamline and automate analysis of Nuclear Magnetic Resonance (NMR) and Small Angle X-Ray scattering (SAXS) imaging data for atomic and near-atomic resolution molecular structures. Conventional calculation of structure requires the use of various software packages, considerable user expertise and ample computational resources. To facilitate the use of NMR spectroscopy and SAXS in life sciences the WeNMR consortium has established standard computational workflows and services through easy-to-use web interfaces, while still retaining sufficient flexibility to handle more specific requests. Thus far, a number of programs often used in structural biology have been made available through application portals. The implementation of these services, in particular the distribution of calculations to a Grid computing infrastructure, involves a novel mechanism for submission and handling of jobs that is independent of the type of job being run. With over 450 registered users (September 2012), WeNMR is currently the largest Virtual Organization (VO) in life sciences. With its large and worldwide user community, WeNMR has become the first Virtual Research Community officially recognized by the European Grid Infrastructure (EGI).

NMR Studies on Membrane Protein OEP16

Membrane protein structure is continuing to be a topic of interest in the scientific community. However, high resolution structural data of these proteins is difficult to obtain. In this study we attempt to use Nuclear Magnetic Resonance (NMR) to begin investigating the finer structural aspects of membrane protein OEP16. Latest structural information suggest a multimer consisting strongly of alpha helices. The amino acid transporter located on the outer membrane of chloroplast organelles, Outer Envelope Protein 16kDa (OPE16) was expressed recombinantly in E. coli BL21 (DE3) cells for use in NMR spectroscopy. Uniform isotopic labeling with 13C and 15N together with 80% perdeuteration allowed for ∼90% of the polypeptide/protein backbone assignments to be carried out using the three dimensional experiments HNCO, HN(CA) CO, HNCA, HN(CO)CA, HNCACB, and CBCA(CO)NH using a 600 MHz spectrometer equipped with a cryoprobe. Chemical shift indices were analyzed for secondary structure through TALOS and PECAN algorithms. Together with NOE connectivities these will enable bond-angle restraints to be introduced for calculating a structural model of the protein. In addition we expressed OEP16 with 15N uniform isotope labeling for relaxation measurements of protein structural dynamics. In order to separate the flexible regions from the rigid regions of the protein, TOCSY-HSQC, HSQC-TOCSY, and NOESY-HSQC experiments were performed on 15N-OEP16 to aid in the assignment of side chains and obtain spatial restraints for use in the determination of three dimensional structure. Results of NMR analysis are compared to results of characterizing the protein by dynamic light scattering (DLS) and circular dichroism (CD) spectroscopy. The findings described in this study provide the first steps in the structure determination of OEP16 and will ultimately contribute to the now limited library of membrane protein structures.

Is nuclear magnetic resonance lipoprotein subclass related to diabetic retinopathy? The multi-ethnic study of atherosclerosis (MESA)

To examine the associations between nuclear magnetic resonance (NMR) defined lipoproteins and diabetic retinopathy (DR) in a population-based sample of adults with type 2 diabetes. In all, 921 persons with diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA) were included. DR was assessed from retinal photographs. Lipoproteins were measured by NMR spectroscopy. After controlling for age, race/ethnicity, study centre and diabetes and vascular risk factors, no consistent patterns of associations between NMR-defined lipoprotein particle concentrations and subclass with DR were evident. The lack of association between NMR-defined lipoproteins and DR does not support clinical use of NMR spectroscopy for management of patients with DR.

NMR Spectroscopy and Its Value: A Primer

Nuclear magnetic resonance (NMR) spectroscopy is widely used by chemists. Furthermore, the use of NMR spectroscopy to solve structures of macromolecules or to examine protein–ligand interactions is popular. Yet, few students entering graduate education in biological sciences have been introduced to this method or its utility. Over the last six years, I have had the task of introducing NMR spectroscopy to first-year graduate students with a largely biological bent. During the last four years, I have used a new strategy in teaching this topic. Starting with some seemingly frivolous examples of NMR utilization, I introduce basic ideas and concepts in NMR spectroscopy in the first lecture and then present more serious biophysical and biotechnological applications in the second lecture. Students are then asked to solve a few simple problems to reinforce concepts and then to summarize an original research article from a list of journals, published within a 4-month period, to initiate them into reading research articles employing NMR methods. This strategy to introduce NMR spectroscopy to beginning graduate students would also be suitable for upper-level undergraduate students.

HPLC Separation and NMR Structural Elucidation of sn-1,2-, 2,3-, and 1,3-Diacylglycerols from Olive Oil as Naphthylethylurethane Derivatives

In this study, sn-1,2-, sn-2,3-, and sn-1,3-diacylglycerols were isolated from olive oil, and their urethane derivatives (urethanes) were prepared. Normal-phase high-performance liquid chromatography (NP-HPLC) separation of the urethane isomers was performed and the separate classes were studied by nuclear magnetic resonance (NMR). The use of 1H NMR and homo- and heteronuclear 2D techniques provided a great amount of information in a very short time, particularly when a high-field NMR instrument (700 MHz) was used. Particularly diagnostic for this kind of compound was the glyceridic moiety that presents typical chemical shifts both for carbon and hydrogen. These studies show the usefulness of NMR spectroscopy to recognize clearly the sn-1,3- and, moreover, sn-1,2- with respect to sn-2,3-diacylglycerols, although very minor differences occur between them.

Beryllofluoride Binding Mimics Phosphorylation of Aspartate in Response Regulators

Beryllofluoride Binding Mimics Phosphorylation of Aspartate in Response Regulators

HR MAS 1H NMR spectroscopy analysis of marine microalgal whole cells

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 256:57-62 (2003) - doi:10.3354/meps256057 HR MAS 1H NMR spectroscopy analysis of marine microalgal whole cells Matilde S. Chauton1,*, Odd Inge Optun2, Tone F. Bathen2, Zsolt Volent3, Ingrid S. Gribbestad2, Geir Johnsen1 1Norwegian University of Science and Technology, Trondhjem Biological Station, 7491 Trondheim, Norway 2Sintef Unimed MR-centre, 7465 Trondheim, Norway 3Sintef Fisheries and Aquaculture, 7465 Trondheim, Norway *Email: matilde.chauton@vm.ntnu.no ABSTRACT: To study the use of nuclear magnetic resonance (NMR) spectroscopy as a method of classification, we performed high-resolution magic angle spinning proton (HR MAS 1H) NMR spectroscopy analysis of whole-cell samples of Dunaliella sp. (Chlorophyceae), Amphidinium carterae (Dinophyceae), Phaeodactylum tricornutum and Thalassiosira pseudonana (Bacillariophyceae). Emphasising the potential use of NMR spectroscopy as a routine analysis of microalgae we chose a straightforward procedure for culturing and harvesting, without extraction or radioactive labelling. We obtained well-resolved HR MAS 1H NMR spectra from the 4 algae, despite the fact that our samples contained whole cells and some residual sea water. Selected parts of 5 replicate spectra from each microalga were used as input in 2 multivariate pattern-recognition strategies (principal component analysis and fuzzy clustering), both analyses showing clear grouping of the different species. Two spectra from a previous sample run (cultures grown under the same conditions) were also included, and both were correctly classified. We therefore consider HR MAS 1H NMR spectroscopy to be a potential method of classification for microalgae, with statistical data processing indicating replicability and robustness of the method. KEY WORDS: HR MAS 1H NMR spectroscopy · Microalgae · Whole cell sample · Classification · Principal component analysis · Fuzzy clustering Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 256. Online publication date: July 17, 2003 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2003 Inter-Research.

The novel use of NMR spectroscopy with in situ laser irradiation to study azo photoisomerisation

Cis–trans photoisomerisation of four azo dyes has been studied by 1 H nuclear magnetic resonance (NMR) spectroscopy, with in situ laser irradiation of the sample. The laser radiation was coupled into the sample within the NMR magnet via an optical fibre. This enabled the first 1 H NMR measurements to be made of the transient cis isomers of 4-(4-nitrophenylazo)aniline (CI Disperse Orange 3) and 4-[ N-ethyl- N-(2-hydroxyethyl)amino]-4′-nitroazobenzene (CI Disperse Red 1). Typical NMR methods, including 1 H 1D, 1 H – 1 H 2D COSY and 1 H – 1 H 2D EXSY/NOESY, were used to assign 1 H resonances of the trans and cis isomers. Ab initio calculations were used to predict the chemical shifts of cis- and trans-azobenzene, in good agreement with the experimental results, and to rationalise the chemical shift changes observed on isomerisation.

NMR in Environmental Science

NMR in Environmental Science

Investigation of skeletal muscle denervation and reinnervation using magnetic resonance spectroscopy

Objective: To determine changes in skeletal muscle metabolism after nerve transection and repair and to correlate metabolic changes with functional recovery. Study Design and Setting: Male Wistar rats were divided into 6 experimental groups plus a control group. The posterior tibial nerve was transected and reapproximated. At varying times after surgery (1, 2, 4, 6, or 8 weeks) animals were sacrificed, the gastrocnemius muscle was harvested, and proton nuclear magnetic resonance (NMR) spectroscopy was performed. Functional recovery was measured using the sciatic function index. Results: Animals undergoing nerve repair all showed functional recovery whereas the nonrepaired nerve group did not. Concentration of glucose and lactate increased after denervation and then returned toward normal. Choline concentration decreased and then returned toward normal. In animals not undergoing nerve repair, the metabolic abnormalities persisted and showed no sign of recovery over the 8-week observation period. Conclusions: 1H NMR spectroscopy is a potentially useful tool to study changes in skeletal muscle metabolism after motor nerve injury. Significance: NMR spectroscopy is rapidly developing into a clinically useful tool. High-field magnets have improved resolution and data acquisition. Basic experiments, such as those described here, will help guide the use of NMR spectroscopy in clinical medicine and will also lead to a better understanding of basic mechanisms of nerve injury and repair. (Otolaryngol Head Neck Surg 2001;125:617-22.)