Current Metabolomics (v.1, #4)

Metabolic Evidence of Diminished Lipid Oxidation in Women With Polycystic Ovary Syndrome by Leah D. Whigham, Daniel E. Butz, Hesam Dashti, Marco Tonelli, LuAnn K. Johnson, Mark E. Cook, Warren P. Porter, Hamid R. Eghbalnia, John L. Markley, Steven R. Lindheim, Dale A. Schoeller, David H. Abbott, Fariba M. Assadi-Porter (269-278).
Polycystic ovary syndrome (PCOS), a common female endocrinopathy, is a complex metabolic syndrome ofenhanced weight gain. The goal of this pilot study was to evaluate metabolic differences between normal (n=10) andPCOS (n=10) women via breath carbon isotope ratio, urinary nitrogen and nuclear magnetic resonance (NMR)-determined serum metabolites. Breath carbon stable isotopes measured by cavity ring down spectroscopy (CRDS) indicateddiminished (p<0.030) lipid use as a metabolic substrate during overnight fasting in PCOS compared to normalwomen. Accompanying urinary analyses showed a trending correlation (p<0.057) between overnight total nitrogen andcirculating testosterone in PCOS women, alone. Serum analyzed by NMR spectroscopy following overnight, fast and at 2h following an oral glucose tolerance test showed that a transient elevation in blood glucose levels decreased circulatinglevels of lipid, glucose and amino acid metabolic intermediates (acetone, 2-oxocaporate, 2-aminobutyrate, pyruvate, formate,and sarcosine) in PCOS women, whereas the 2 h glucose challenge led to increases in the same intermediates innormal women. These pilot data suggest that PCOS-related inflexibility in fasting-related switching between lipid andcarbohydrate/protein utilization for carbon metabolism may contribute to enhanced weight gain.

The metabolomic fingerprints of a protected sea turtle species have been investigated for the first time using anuclear magnetic resonance (NMR)-based metabolomics approach. We emphasized method development of optimalplasma filtration conditions (filter type, washing techniques, extract stability) for green turtles and other organisms, whilealso using the National Institute of Standards and Technology (NIST) Standard Reference Material 1950 (SRM 1950) Metabolitesin Human Plasma for quality control. We surveyed the blood plasma metabolomic fingerprints of Hawaiiangreen sea turtles representing a wide range of physiological conditions that include varying disease states, behavioral conditions,and locales. The turtles sampled were free-swimming (n=5 from Hualalai on the west coast of the island of Hawaii),basking (n=7 from Hualalai), free-swimming tumor-free (n=3 from Kapoho, east coast of Hawaii), or freeswimmingafflicted with external tumors (n=5 from Kapoho) caused by the disease, fibropapillomatosis (FP). The metabolomicprofiles and the specific metabolites that differed among individual turtles are discussed. This optimized tooland the annotated metabolic profiles will benefit future investigations into the behavioral and disease conditions of thegreen turtle.

Carbohydrates are characterized by a truly remarkable level of structural diversity which stands in accord witha corresponding functional diversity arguably unsurpassed by any other class of biomolecule. As metabolites, structuralcomponents, mediators of molecular interaction, and modifiers of other biomolecules, carbohydrates play central roles innumerous areas of biochemistry. Detailed molecular characterization of these classes of compounds poses a number ofsignificant analytical challenges, a number of which arise from carbohydrate isomerism combined with the ability ofmonosaccharides to serve as the basis for branched oligosaccharide structures. Ion mobility spectrometry (IMS) representsa particularly appealing analytical methodology for addressing such hurdles. Because IMS provides for separation of gasphaseions according to their “shape to charge ratios,” this approach is well-suited to provide for the recognition, distinction,and resolution of isomeric carbohydrates and glycoconjugates. IMS is also readily coupled to well-established massspectrometry ionization methods and analyzers, which provide complementary information on mass to charge ratios andallow tandem mass spectrometry dissociation experiments which can supply further structural information. Here, we offera brief introduction to carbohydrate structure and diversity (including monosaccharides, oligosaccharides, and glycoconjugatesthereof), followed by an overview of relevant IMS techniques (drift tube ion mobility spectrometry; high-fieldasymmetric waveform ion mobility spectrometry; and traveling wave ion mobility spectrometry). We then provide anoverview of the literature on IMS as applied to the study of free carbohydrates (including isomer separation and generalstructural characterization) and glycoconjugates (including released glycans and intact glycoconjugates).

Tuberculosis (TB), caused by Mycobacterium tuberculosis is a highly infectious disease, responsible for 1.4million deaths annually. Unfortunately, the latest reports of treatment outcomes for patients using the current anti-TBdrugs are disappointing, considering the high treatment failure rates. This has been ascribed to a number of factors, including,amongst others: (1) variable individual metabolism (including xenobiotic metabolism, drug malabsorption and drugdruginteractions), (2) drug resistance by the infectious organism and (3) non-adherence to the treatment program, especiallydue to the associated drug side-effects. Despite this however, only two new drugs have been approved by the FDAsince 1962. Thus, it is clear that new strategies are needed for the better elucidation of in vivo anti-TB drug mechanismsand their associated side-effects, and the mechanisms by which the infectious organism develops drug resistance. To thisend, the relatively new research approach termed 'metabolomics', shows promising results through its capacity for identifyingnew drug markers, or metabolic pathways related to these contributing factors. Metabolomics refers to the unbiasedidentification and quantification of all metabolites (products of bio-molecular processes) present in a biological system,using highly selective and sensitive analytical methods. The application of metabolomics, for biomarker discovery, isbased on the principle that an external stimulus, such as TB disease or infection, an anti-TB drug, or a mutation resultingin drug resistance, may disrupt normal metabolism, altering the overall physiological status of an organism or host, andthese metabolic changes are specific to the perturbation investigated and not due to overall inflammation or disease process.Analyses of these altered metabolic pathways, may subsequently shed new light on the mechanisms associated withthe causes of treatment failure, and ultimately lead to new treatment strategies which may most likely be aimed at targetingspecific metabolic pathways in M. tuberculosis, and/or the genes/proteins associated with these.

Advances in Metabonomics on Infectious Diseases by Hongde Li, Huiru Tang, Yulan Wang (318-334).
Metabonomics is a powerful holistic approach for biomarker discovery and an effective tool for pinpointingendpoint metabolic effects of external stimuli, such as pathogens. Therefore, metabonomics is a promising method to enhanceour understanding of infection mechanism, and holds potential for discovery of novel targets for diagnostics, drugsand vaccines. Due to advances in metabonomics technology, emerging research on infectious diseases in the past decadehas been reported. In this review, we emphasise the importance of host metabolic responses to infectious pathogens, includingviruses, bacteria and parasites, in the understanding mechanism of infection and potential for diagnostic capability.Researches carried on cell, animal and human models are included. Finally, we conclude with a section on researchneeds for improved analytical techniques and integrative systems biological approach for in-depth understanding mechanismsof infection.

Current Metabolomic Methodologies & their Application to Thermal Stress by Sonia Gandhi, Subash Khushu, Rajendra P. Tripathi (335-352).
The field of metabolomics continues to grow rapidly over the last decade and has proven to be a powerfultechnique in predicting and explaining complex phenotypes in various biological systems. As one of the 'omic'technology, metabolomics has exciting applications in varied fields including medical science, synthetic biology,medicine and predictive modelling of plant, animal and microbial systems. Integrated application with genomics,transcriptomics and proteomics provide greater understanding of global system biology. Metabolomics is often considereda powerful tool to provide an instantaneous snapshot of the physiology of a cell. It is increasingly being used tocharacterize the interaction of organism with their environment. Although thermal conditions influence the developmentof living organism in a wide variety of ways, this topic has been recently ignored in humans. This review reintroducesthermal conditions as a topic of importance by presenting an example of how thermal conditions influence variousmetabolic pathways. The first section highlights the advances in metabolomics technologies followed by the effects andrecent studies of organism function and metabolic responses to thermal stress, including investigations of heat and coldstress are reviewed. This review forms the basis for future studies to detect early biomarkers for thermal stress in humansand identifying population at risk. Furthermore, it can be used to develop methods to provide protection to the bodyagainst environmental insult, thereby, reducing the adverse response to thermal stress.