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We present a general scheme for metabolite quantification from a two-dimensional (2D) [sup.1]H-[sup.13]C heteronuclear single quantum correlation (HSQC) nuclear magnetic resonance (NMR) experiment of body fluids observed in natural abundance. The scheme of quantification from 2D HSQC spectra consists of measurement of relaxation parameters of proton resonances, such as [T.sub.1] and [T.sub.2] of the metabolites and [sup.1]H-[sup.13]C heteronuclear J-coupling for accurate quantification. The measured cross-peak volume from 2D HSQC NMR spectra is multiplied by a calculated correction factor (which depends upon two-dimensional NMR experimental parameters and relaxation parameters) to measure accurate quantification of the metabolite. The correction factor is theoretically derived from the solution of the Bloch equation and product operator formalism. The accuracy of the scheme is tested on a solution containing a mixture of amino acids of known concentration. For human urine samples, the accuracy of the method for measuring the concentration of various metabolites was tested with spike-in experiments. The scheme is general in nature and can be applied to any other body fluid samples for metabonomic studies. We also test the measured cross-peak volume of various metabolites from 2D [sup.1]H-[sup.13]C HSQC NMR spectra of human urine samples for clustering analysis with scatter plots, making the scheme complete for metabolic profiling. 10.1021/ac902405z

Despite advancements in ventilator technologies, lung supportive and rescue therapies, the outcome and prognostication in acute respiratory distress syndrome (ARDS) remains incremental and ambiguous. Metabolomics is a potential insightful measure to the diagnostic approaches practiced in critical disease settings. In our study patients diagnosed with mild and moderate/severe ARDS clinically governed by hypoxemic P/F ratio between 100–300 but with indistinct molecular phenotype were discriminated employing nuclear magnetic resonance (NMR) based metabolomics of mini bronchoalveolar lavage fluid (mBALF). Resulting biomarker prototype comprising six metabolites was substantiated highlighting ARDS susceptibility/recovery. Both the groups (mild and moderate/severe ARDS) showed distinct biochemical profile based on 83.3% classification by discriminant function analysis and cross validated accuracy of 91% using partial least squares discriminant analysis as major classifier. The predictive performance of narrowed down six metabolites were found analogous with chemometrics. The proposed biomarker model consisting of six metabolites proline, lysine/arginine, taurine, threonine and glutamate were found characteristic of ARDS sub-stages with aberrant metabolism observed mainly in arginine, proline metabolism, lysine synthesis and so forth correlating to diseased metabotype. Thus NMR based metabolomics has provided new insight into ARDS sub-stages and conclusively a precise biomarker model proposed, reflecting underlying metabolic dysfunction aiding prior clinical decision making. [ABSTRACT FROM AUTHOR]

Ultra fastmagic angle spinning (MAS) has been a potent method to significantly average out homogeneous/inhomogeneous line broadening in solid-state nuclear magnetic resonance (ssNMR) spectroscopy. It has given a new direction to ssNMR spectroscopy with its different applications. We present here the first and foremost application of ultra fast MAS (∼60kHz) for ssNMR spectroscopy of intact bone. Thismethodology helps to comprehend and elucidate the organic content in the intact bonematrix with resolution and sensitivity enhancement. At thisMAS speed, amino protons fromorganic part of intact bone start to appear in 1HNMR spectra. The experimental protocol of ultra-high speed MAS for intact bone has been entailed with an additional insight achieved at 60kHz. [ABSTRACT FROM AUTHOR]

Boneis one of the most intriguing biomaterials found in natureconsisting of bundles of collagen helixes, hydroxyapatite, and water,forming an exceptionally tough, yet lightweight material. We presenthere an experimental tool to map water-dependent subtle changes intriple helical assembly of collagen protein in its absolute nativeenvironment. Collagen being the most abundant animal protein has beensubject of several structural studies in last few decades, mostlyon an extracted, overexpressed, and synthesized form of collagen protein.Our method is based on a 1H detected solid-state nuclearmagnetic resonance (ssNMR) experiment performed on native collagenprotein inside intact bone matrix. Recent development in 1H homonuclear decoupling sequences has made it possible to observespecific atomic resolution in a large complex system. The method consistsof observing a natural-abundance two-dimensional (2D) 1H/13C heteronuclear correlation (HETCOR) and1H double quantum–single quantum (DQ-SQ) correlation ssNMRexperiment. The 2D NMR experiment maps three-dimensional assemblyof native collagen protein and shows that extracted form of collagenprotein is significantly different from protein in the native state.The method also captures native collagen subtle changes (of the orderof ∼1.0 Å) due to dehydration and H/D exchange, givingan experimental tool to map small changes. The method has the potentialto be of wide applicability to other collagen containing biomaterials. [ABSTRACT FROM AUTHOR]

This work developed a 2-dimensional (2D) 1H-13C heteronuclear single quantum coherence (HSQC) approach to directly quantify metabolites in chemical mixtures without using a calibration curve. Using non-linear sampling (NLS) and forward maximum (FM) entropy reconstruction, this method is fast enough to be used for routine quantitative metabonomics. Here, the use of this method to analyse complex human serum samples was demonstrated. This method resulted in 24-fold reduction in the nuclear magnetic resonance (NMR) data collection time compared to previously existing methods. [ABSTRACT FROM AUTHOR]