Identification of markers for dietary intake and health status by GC-MS based metabolite profiling approaches

Markers are compounds that can be used as indicators of an exposure, a metabolic state, or any other effect. Metabolomics and metabolite profiling approaches for marker discovery will increasingly gain significance. In the context of food, diet, and health, these approaches allow among others the identification of dietary intake markers, which can complement and verify traditional dietary assessment methods in epidemiologic studies. Consequently, the investigation of associations between diet and health status in general, and also in particular diet-related diseases will be improved. Compared to classical biomarker studies, metabolomics enables a more comprehensive investigation of clinical markers for diagnosis, prognosis and monitoring of diseases, such as type 2 diabetes mellitus. Especially, early diagnosis in pre-disease states, where symptoms are not yet evident, are of particular interest. The aim of this thesis was to evaluate the application of GC-MS based metabolite profiling approaches for the identification of markers for dietary intake and health status. In this respect, volatile organic compounds and sugar compounds were analyzed to discover marker candidates in urine and plasma samples from a cross-sectional study with 300 participants, as well as from a human intervention study with diabetic, prediabetic and healthy participants. In the past, the search for markers of dietary intake mostly focused on non-volatile metabolites. To explore the potential of the volatilome, urine samples of a cross-sectional study were analyzed aiming to exemplary identify markers of coffee consumption using an untargeted HS-SPME-GC×GC-MS method. Six marker candidates were identified from a profile of 138 volatile organic compounds with the most robust represented by 3,4-dimethyl-2,5-furandione. Moreover, the correlation with the general dietary intake data highlighted the volatilome as a particularly interesting source for the detection of new dietary markers. The chromatographic separation of sugar compounds is often insufficient due to the high structural similarities. Therefore, in most studies common and well-known sugar compounds are analyzed in human body fluids. Within the scope of this thesis, a semitargeted GC-MS sugar profiling method was developed, which revealed a more complex sugar profile, both in urine and plasma, than described so far or expected. Rare sugar compounds such as psicose and trehalose were detected. However, the knowledge about their origin and presence in urine or plasma is limited to date. Moreover, the maltose concentration in urine was shown to be dependent on sex and menopause status (pre- and post-menopausal) a relationship with the vaginal microbiota is suggested here. In addition, the association of the urinary sugar profile with dietary intake data enabled the identification and confirmation of several new and also known marker candidates as for example, for consumption of avocado, dairy products and alcohol. The plasma sugar profiles of healthy, prediabetic and diabetic volunteers after an oral glucose tolerance test could be clearly distinguished, independent of glucose. Remarkably, a variety of sugar compounds showed marked postprandial differences dependent on health status. For example, trehalose showed a profile similar to the insulin-dependent profile of glucose. However, the origin and underlying biological mechanism for those sugar compounds remain to be elucidated. During the application of the one-dimensional GC-MS sugar profiling method to urine and plasma samples, it became evident that even more sugar compounds might be present, although in low concentrations, but were not detected due to limitations of the analytical method. Therefore, the one-dimensional method was transferred into a two-dimensional GC×GC-MS method. Improved sensitivity and separation finally enabled the detection of 84 instead of 55 sugar compounds in urine. The two-dimensional method was applied in an intervention study with apples, and revealed marker candidates for apple consumption for future validation. Overall, the results illustrate the benefit of a comprehensive analysis of sugar compounds in urine and plasma, including minor and rare sugar derivatives. The GC-MS based metabolite profiling approaches addressing the volatilome and the sugar profile, respectively, were demonstrated to be promising approaches for the identification of markers for dietary intake and health status. Future work should address the identification of unknown compounds, the adaptation of the GC×GC-MS sugar profiling method for quantitative purposes, and especially the validation of the identified marker candidates with respect to their suitability to more accurately assess dietary intake or diabetic state. High priority should also be given to the biochemical mechanisms and the origin of the compounds as well as their physiological or pathophysiological function in human metabolism.Marker sind Substanzen, die als Indikatoren für eine Exposition, einen metabolischen Zustand oder einen Effekt herangezogen werden. Metabolomics und Metabolite profiling-Ansätze gewinnen in der Markerforschung zunehmend an Bedeutung. Metabolomics ermöglicht die Identifizierung von Markern für den Lebensmittelverzehr, die in Zukunft unter anderem in epidemiologischen Studien zur Ergänzung und Überprüfung traditioneller Ernährungserhebungsmethoden Verwendung finden werden. In der Konsequenz können Zusammenhänge zwischen Ernährung und Gesundheit im Allgemeinen, sowie ernährungsabhängigen Erkrankungen im Speziellen, besser beschrieben werden. Außerdem können mittels Metabolomics auch Marker identifiziert werden, die im klinischen Rahmen eine Diagnose, Prognose oder Überwachung von Behandlungsmaßnahmen für eine Erkrankung ermöglichen, wie z.B. bei Typ 2 Diabetes mellitus. Von besonderem Interesse sind dabei Marker, die eine frühzeitige Diagnose, das heißt vor der Manifestation von Symptomen, ermöglichen. Ziel der vorliegenden Arbeit war es, die Verwendung von GC-MS basierten Metabolite profiling-Ansätzen zur Identifizierung von Markern für den Lebensmittelverzehr und den Gesundheitsstatus zu prüfen. Einen besonderen Schwerpunkt bildeten dabei volatile organische Verbindungen und Zuckerverbindungen, die in Urin- und Plasmaproben einer Querschnittsstudie mit 300 Probanden sowie einer humanen Interventionsstudie mit Diabetikern, Prädiabetikern und Gesunden analysiert wurden. Bei der bisherigen Suche nach Markern für den Lebensmittelverzehr lag das Augenmerk vor allem auf nicht-volatilen Metaboliten. Um das Potential des Volatiloms zu eruieren, wurden Urinproben einer Querschnittsstudie mithilfe einer ungerichteten HS-SPME-GC×GC-MS Methode analysiert und darin beispielhaft nach Markern für den Kaffeekonsum gesucht. Aus dem Urinprofil mit 138 volatilen Verbindungen wurden sechs plausible Kandidaten identifiziert, von denen sich 3,4-Dimethyl-2,5-furandion als der robusteste Marker erwies. Mittels einer Korrelationsanalyse anhand von Verzehrsdaten weiterer Lebensmittel wurde darüber hinaus gezeigt, dass das Volatilom eine vielversprechende Quelle neuer Marker für den Lebensmittelverzehr ist. Zucker lassen sich aufgrund ihrer strukturellen Ähnlichkeit häufig nur unzureichend chromatographisch trennen, daher werden in humanen Matrices bisher mehrheitlich nur wenige bekannte Zuckerverbindungen erfasst. Im Rahmen dieser Arbeit wurde eine semi-gerichtete GC-MS Zuckerprofiling-Methode entwickelt, mit der gezeigt werden konnte, dass das humane Zuckerprofil im Urin und im Plasma erheblich komplexer ist, als bisher beschrieben und angenommen. Verschiedene Zuckerverbindungen, wie beispielsweise Psicose oder Trehalose, über deren Herkunft und Vorhandensein im Urin oder in Plasma fast nichts bekannt ist, wurden nachgewiesen. Im Urin zeigten sich darüber hinaus Unterschiede in der Maltosekonzentration in Abhängigkeit vom Geschlecht sowie dem prä- und postmenopausalen Status, die vermutlich im Zusammenhang mit der vaginalen Mikrobiota stehen. Die Assoziation der Zuckerprofile mit dem Lebensmittelverzehr ermöglichte zudem die Identifizierung neuer und Bestätigung bekannter Marker, beispielsweise für den Verzehr von Avocado und Milchprodukten, sowie für Alkoholkonsum. Im Plasma von Gesunden, Prädiabetikern und Diabetikern wurden nach einem oralen Glucosetoleranztest deutliche Unterschiede im Zuckerprofil festgestellt. Interessanterweise zeigten eine Reihe neuer Zuckerverbindungen markante postprandiale Unterschiede abhängig vom Gesundheitszustand. Beispielsweise zeigte Trehalose ein ähnliches Profil wie die insulinabhängige Glucose. Jedoch ist weder über den Mechanismus noch zur Herkunft dieser Zucker etwas bekannt. Bereits die bisherigen Ergebnisse des Zuckerprofilings in Urin und Plasma zeigten, dass zusätzliche Zuckerverbindungen, wenn auch in sehr geringer Konzentration, vorhanden sind. Daher wurde die eindimensionale Methode zu einer zweidimensionalen GC×GC-MS-Methode mit verbesserter Sensitivität und Trennung weiterentwickelt, was nun die Erfassung von 84 statt 55 Zuckerverbindungen in Urin ermöglicht. Erste Auswertungen der Messdaten einer Interventionsstudie mit Äpfeln zeigten, dass diese Methode die Identifizierung von potentiellen Markern für den Verzehr von Äpfeln ermöglicht. Die Ergebnisse verdeutlichen, welches Potential in der umfassenden Analyse von Zuckern, einschließlich seltener Verbindungen, steckt. GC-MS basierte Metabolite profiling-Ansätze, wie hier für das Volatilom und das Zuckerprofil gezeigt, sind geeignete Methoden für die Identifizierung von Markern des Lebensmittelverzehrs und des Gesundheitsstatus. Die Identifizierung bisher unbekannter Verbindungen, die Weiterentwicklung der Zuckeranalytik zu einer quantitativen Methode und insbesondere die Validierung der identifizierten Marker bezüglich ihrer Eignung, den Lebensmittelverzehr bzw. den diabetischen Status akkurater zu erfassen, sind zukünftige Ziele. Besonders herausfordernd ist es dabei, die mechanistischen Zusammenhänge aufzuklären, insbesondere im Hinblick auf Herkunft, Vorhandensein und Funktion der detektierten Zuckerverbindungen im menschlichen Metabolismus

Hypofractionated SBRT versus conventionally fractionated EBRT for prostate cancer: comparison of PSA slope and nadir.

BackgroundPatients with early stage prostate cancer have a variety of curative radiotherapy options, including conventionally-fractionated external beam radiotherapy (CF-EBRT) and hypofractionated stereotactic body radiotherapy (SBRT). Although results of CF-EBRT are well known, the use of SBRT for prostate cancer is a more recent development, and long-term follow-up is not yet available. However, rapid post-treatment PSA decline and low PSA nadir have been linked to improved clinical outcomes. The purpose of this study was to compare the PSA kinetics between CF-EBRT and SBRT in newly diagnosed localized prostate cancer.Materials/methods75 patients with low to low-intermediate risk prostate cancer (T1-T2; GS 3 + 3, PSA < 20 or 3 + 4, PSA < 15) treated without hormones with CF-EBRT (>70.2 Gy, <76 Gy) to the prostate only, were identified from a prospectively collected cohort of patients treated at the University of California, San Francisco (1997-2012). Patients were excluded if they failed therapy by the Phoenix definition or had less than 1 year of follow-up or <3 PSAs. 43 patients who were treated with SBRT to the prostate to 38 Gy in 4 daily fractions also met the same criteria. PSA nadir and rate of change in PSA over time (slope) were calculated from the completion of RT to 1, 2 and 3 years post-RT.ResultsThe median PSA nadir and slope for CF-EBRT was 1.00, 0.72 and 0.60 ng/ml and -0.09, -0.04, -0.02 ng/ml/month, respectively, for durations of 1, 2 and 3 years post RT. Similarly, for SBRT, the median PSA nadirs and slopes were 0.70, 0.40, 0.24 ng and -0.09, -0.06, -0.05 ng/ml/month, respectively. The PSA slope for SBRT was greater than CF-EBRT (p < 0.05) at 2 and 3 years following RT, although similar during the first year. Similarly, PSA nadir was significantly lower for SBRT when compared to EBRT for years 2 and 3 (p < 0.005).ConclusionPatients treated with SBRT experienced a lower PSA nadir and greater rate of decline in PSA 2 and 3 years following completion of RT than with CF-EBRT, consistent with delivery of a higher bioequivalent dose. Although follow-up for SBRT is limited, the improved PSA kinetics over CF-EBRT are promising for improved biochemical control

Four Dimensional CFT Models with Rational Correlation Functions

Recently established rationality of correlation functions in a globally conformal invariant quantum field theory satisfying Wightman axioms is used to construct a family of soluble models in 4-dimensional Minkowski space-time. We consider in detail a model of a neutral scalar field $\phi$ of dimension 2. It depends on a positive real parameter c, an analogue of the Virasoro central charge, and admits for all (finite) c an infinite number of conserved symmetric tensor currents. The operator product algebra of $\phi$ is shown to coincide with a simpler one, generated by a bilocal scalar field $V(x_1,x_2)$ of dimension (1,1). The modes of V together with the unit operator span an infinite dimensional Lie algebra $L_V$ whose vacuum (i.e. zero energy lowest weight) representations only depend on the central charge c. Wightman positivity (i.e. unitarity of the representations of $L_V$) is proven to be equivalent to $c \in N$.Comment: 28 pages, LATEX, amsfonts, latexsym. Proposition 2.3, and Conjecture in Sec. 6 are revised. Minor errors are correcte

PEPSI deep spectra. III. A chemical analysis of the ancient planet-host star Kepler-444

We obtained an LBT/PEPSI spectrum with very high resolution and high signal-to-noise ratio (S/N) of the K0V host Kepler-444, which is known to host 5 sub-Earth size rocky planets. The spectrum has a resolution of R=250,000, a continuous wavelength coverage from 4230 to 9120A, and S/N between 150 and 550:1 (blue to red). We performed a detailed chemical analysis to determine the photospheric abundances of 18 chemical elements, in order to use the abundances to place constraints on the bulk composition of the five rocky planets. Our spectral analysis employs the equivalent width method for most of our spectral lines, but we used spectral synthesis to fit a small number of lines that require special care. In both cases, we derived our abundances using the MOOG spectral analysis package and Kurucz model atmospheres. We find no correlation between elemental abundance and condensation temperature among the refractory elements. In addition, using our spectroscopic stellar parameters and isochrone fitting, we find an age of 10+/-1.5 Gyr, which is consistent with the asteroseismic age of 11+/-1 Gyr. Finally, from the photospheric abundances of Mg, Si, and Fe, we estimate that the typical Fe-core mass fraction for the rocky planets in the Kepler-444 system is approximately 24 per cent. If our estimate of the Fe-core mass fraction is confirmed by more detailed modeling of the disk chemistry and simulations of planet formation and evolution in the Kepler-444 system, then this would suggest that rocky planets in more metal-poor and alpha-enhanced systems may tend to be less dense than their counterparts of comparable size in more metal-rich systems.Comment: in press, 11 pages, 3 figures, data available from pepsi.aip.d

Self-consistent nonperturbative anomalous dimensions

A self-consistent treatment of two and three point functions in models with trilinear interactions forces them to have opposite anomalous dimensions. We indicate how the anomalous dimension can be extracted nonperturbatively by solving and suitably truncating the topologies of the full set of Dyson-Schwinger equations. The first step requires a sensible ansatz for the full vertex part which conforms to first order perturbation theory at least. We model this vertex to obtain typical transcendental equations between anomalous dimension and coupling constant $g$ which coincide with know results to order $g^4$.Comment: 15 pages LaTeX, no figures. Requires iopart.cl

Exploring The Understanding And Application Of Motivational Interviewing In Applied Sport Psychology.

The purpose of this study was to explore how sport and exercise psychologists working in sport understand and use motivational interviewing (MI). Eleven practitioners participated in semi-structured interviews, and inductive thematic analysis identified themes linked to explicit use of MI, such as building engagement and exploring ambivalence to change; the value of MI, such as enhancing the relationship, rolling with resistance and integrating with other approaches; and barriers to the implementation of MI in sport psychology, such as a limited evidence-base in sport. Findings also indicated considerable implicit use of MI by participants, including taking an athlete-centred approach, supporting athlete autonomy, reflective listening, demonstrating accurate empathy, and taking a non-prescriptive, guiding role. This counselling style appears to have several tenets to enhance current practice in sport psychology, not least the enhancement of therapeutic alliance

Oscillatory Spin Polarization and Magneto-Optic Kerr Effect in Fe3O4 Thin Films on GaAs(001)

The spin dependent properties of epitaxial Fe3O4 thin films on GaAs(001) are studied by the ferromagnetic proximity polarization (FPP) effect and magneto-optic Kerr effect (MOKE). Both FPP and MOKE show oscillations with respect to Fe3O4 film thickness, and the oscillations are large enough to induce repeated sign reversals. We attribute the oscillatory behavior to spin-polarized quantum well states forming in the Fe3O4 film. Quantum confinement of the t2g states near the Fermi level provides an explanation for the similar thickness dependences of the FPP and MOKE oscillations.Comment: to appear in Phys. Rev. Let

Two-Time Physics with gravitational and gauge field backgrounds

It is shown that all possible gravitational, gauge and other interactions experienced by particles in ordinary d-dimensions (one-time) can be described in the language of two-time physics in a spacetime with d+2 dimensions. This is obtained by generalizing the worldline formulation of two-time physics by including background fields. A given two-time model, with a fixed set of background fields, can be gauged fixed from d+2 dimensions to (d-1) +1 dimensions to produce diverse one-time dynamical models, all of which are dually related to each other under the underlying gauge symmetry of the unified two-time theory. To satisfy the gauge symmetry of the two-time theory the background fields must obey certain coupled differential equations that are generally covariant and gauge invariant in the target d+2 dimensional spacetime. The gravitational background obeys a null homothety condition while the gauge field obeys a differential equation that generalizes a similar equation derived by Dirac in 1936. Explicit solutions to these coupled equations show that the usual gravitational, gauge, and other interactions in d dimensions may be viewed as embedded in the higher d+2 dimensional space, thus displaying higher spacetime symmetries that otherwise remain hidden.Comment: Latex, 19 pages, references adde