Urinary N-methylpyridinium and trigonelline as candidate dietary biomarkers of coffee consumption

Scope : In order to validate the in vivo function of putatively healthy molecules in foods, human intervention studies are required. As the subject's compliance concerning intake or abstinence of a given food is considered mandatory to be monitored by biomarkers, the objective was to identify analytical markers for coffee consumption. Methods and results : Urine samples collected from coffee drinkers were compared with those of non‐coffee drinkers using hydrophilic liquid interaction chromatography (HILIC)/time‐of‐flight mass spectrometry‐based metabolite profiling. Two urinary molecules, found to be contributing most to the dissimilarities between both groups, were identified as N‐methylpyridinium (NMP) and trigonelline and their suitability as coffee‐specific biomarkers was validated by means of a coffee intervention study. After the volunteers (five females and four males) consumed a single dose of coffee, morning urine was collected for 10 days while staying abstinent from any coffee. HILIC‐MS/MS‐stable isotope dilution analysis (SIDA) revealed elevated urinary concentrations of trigonelline and NMP for up to 48 (p=0.001) and 72 h (p=0.002), respectively, after coffee consumption when compared with non‐coffee drinkers. Conclusion : Analysis of urinary NMP allows to check for coffee consumption within a period of 3 days and is proposed as a dietary biomarker which might be used as an analytical probe to control compliance in human intervention studies on coffee.     

Comparison of residence time estimation methods for radioimmunotherapy dosimetry and treatment planning--Monte Carlo simulation studies

Estimating the residence times in tumor and normal organs is an essential part of treatment planning for radioimmunotherapy (RIT). This estimation is usually done using a conjugate view whole body scan time series and planar processing. This method has logistical and cost advantages compared to 3-D imaging methods such as Single photon emission computed tomography (SPECT), but, because it does not provide information about the 3-D distribution of activity, it is difficult to fully compensate for effects such as attenuation and background and overlapping activity. Incomplete compensation for these effects reduces the accuracy of the residence time estimates. In this work we compare residence times estimates obtained using planar methods to those from methods based on quantitative SPECT (QSPECT) reconstructions. We have previously developed QSPECT methods that provide compensation for attenuation, scatter, collimator-detector response, and partial volume effects. In this study we compared the use of residence time estimation methods using QSPECT to planar methods. The evaluation was done using the realistic NCAT phantom with organ time activities that model (111)In ibritumomab tiuxetan. Projection data were obtained using Monte Carlo simulations (MCS) that realistically model the image formation process including penetration and scatter in the collimator-detector system. These projection data were used to evaluate the accuracy of residence time estimation using a time series of QSPECT studies, a single QSPECT study combined with planar scans and the planar scans alone. The errors in the residence time estimates were 3.8%, 15%, and 2%-107% for the QSPECT, hybrid planar/QSPECT, and planar methods, respectively. The quantitative accuracy was worst for pure planar processing and best for pure QSPECT processing. Hybrid planar/QSPECT methods, where a single QSPECT study was combined with a series of planar scans, provided a large and statistically significant improvement in quantitative accuracy for most organs compared to the planar scans alone, even without sophisticated attention to background subtraction or thickness corrections in planar processing. These results indicate that hybrid planar/QSPECT methods are generally superior to pure planar methods and may be an acceptable alternative to performing a time series of QSPECT studies.     

Zur Festigkeitsberechnung von Kegelböden

Zusammenfassung Es wird ein N?herungsverfahren zum Berechnen der Spannungsverteilung bei ringf?rmig gestützten Kegelb?den angegeben. Die mittels Dehnungsme?streifen l?ngs der Mantellinie eines kegelf?rmigen Modellbeh?lters gemessene Spannungsverteilung stimmte gut mit den theoretischen Ergebnissen überein, wenn man bei diesen die durch die Versuchsdurchführung bedingten besonderen Verh?ltnisse berücksichtigte. Mitteilung aus der Staallichen Materialprüfungsanstall an der Technischen Hochschule Stuttgarl Gekürzte Fassung der gleichnamigen Dissertation des Verfasers. Technische Hochschule Stuttgart 1954.     

Hydroperoxide formation in model collagens and collagen type I

Protein hydroperoxides represent a relatively new concept in understanding biological oxidation chemistry. Here, we show with post-column-chemiluminescence that this sometimes remarkably stable and yet reactive species can be formed in collagen models and collagen type I when submitted to oxidative stress as exemplified by the Fenton reaction. These findings are supported by mass spectrometry and iodometry. Using (Proline-hydroxyproline-glycine)(10) (POG)(10), those hydroperoxides are stable for hours at room temperature and can give rise to free radicals in the presence of ferrous sulphate, as evidenced by EPR spin trapping with DMPO. Possible implications for biological systems are discussed with emphasis on collagen in the extracellular matrix in skin as a major type of connective tissue.     

Refined Energy Correction for Calibration of Submerged Radial Gates

The energy-momentum (E-M) method for calibrating submerged radial gates was refined using a large laboratory data set collected at the Bureau of Reclamation hydraulics laboratory in the 1970s. The original E-M method was accurate in free flow, and when the gate significantly controls submerged flow, but for large gate openings with low head loss through the gate, discharge prediction errors were sometimes large (approaching 70%). Several empirical factors were investigated with the laboratory data, including the combined upstream energy loss and velocity distribution factor and the submerged flow energy correction. The utility of the existing upstream energy loss and velocity distribution factor relation was extended to larger Reynolds numbers. The relation between the relative energy correction and the relative submergence of the vena contracta was shown to be sensitive to the relative jet thickness. A refined energy correction model was developed, which significantly improved the accuracy of submerged flow discharge predictions. Although the focus of this work was radial gates, the energy correction concept and these refinements potentially have application to all submerged sluice gates.     

Coating composition and the formation of protective oxide layers at high temperatures

The interaction between the oxide scale and the composition and structure of a coating is described theoretically. It is assumed that the coating material comprises two phases: (1) a matrix phase containing the oxide-forming element M; (2) inclusions, which are rich in the material M, whose oxide (MO_v) should be formed selectively on the surface of the coating (M is aluminium, chromium or silicon). These inclusions act as a reservoir phase which supplies metal for the oxide formation on the surface.A criterion for the minimum concentration of the element M for selective oxidation in the matrix of such a two-phase material is estimated whereby the possible formation of internal oxides is taken into account. It is shown theoretically that the critical concentration for selective oxidation can be decreased strongly by the existence of a reservoir phase. According to the models demonstrated, different directions of research on coating development can be defined, e.g. (1) minimization of the oxide layer parabolic growth constants, (2) maximization of the diffusion constants of the element M in the coating and (3) optimization of the mechanical properties of the oxide layer. For a coating without precipitates the selective oxidation after spalling is estimated.     

Analysis of whole bacterial cells by flow field-flow fractionation and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The purpose of this study is to develop a novel bacterial analysis method by coupling the flow field-flow fractionation (flow FFF) separation technique with detection by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The composition of carrier liquid used for flow FFF was selected based on retention of bacterial cells and compatibility with the MALDI process. The coupling of flow FFF and MALDI-TOF MS was demonstrated for P. putida and E. coli. Fractions of the whole cells were collected after separation by FFF and further analyzed by MALDI-MS. Each fraction, collected over different time intervals, corresponded to different sizes and possibly different growth stages of bacteria. The bacterial analysis by flow FFF/MALDI-TOF MS was completed within 1 h with only preliminary optimization of the process.     

Preparation of chameleon coatings for space and ambient environments

Tribological coatings of yttria-stabilized zirconia (YSZ), Au, diamond like carbon (DLC) and MoS₂ were synthesized using magnetron assisted pulsed laser deposition. The coatings were synthesized in four-component and three-component combinations that included YSZ/Au/DLC/MoS₂, YSZ/Au/MoS₂, and YSZ/Au/DLC. A range of coating compositions was studied to explore coating optimization for low friction in varying environments (dry, humid and high temperature). For four-component YSZ/Au/DLC/MoS₂ coatings, the optimal compositions for friction adaptation between dry nitrogen and humid air included relatively high concentrations of the soft phase, Au (> 20 at.%), and low amounts of the hard phases, DLC and YSZ. Ex situ Raman spectroscopy analysis indicates that friction adaptation involves a combination of both lubricating species, MoS₂ and carbon, where transitions of DLC to graphitic-carbon and amorphous MoS₂ to its hexagonal phase occur after cycling between both room temperature humid air and dry nitrogen. In large carbon concentrations (> 30 at.%), the DLC component was found to be detrimental for friction in dry nitrogen and humid air, but promoted a longer coating wear life at 500 °C. The three-component coating of YSZ/Au/MoS₂ performed well in both dry nitrogen and humid air, suggesting a synergism between Au and MoS₂, where carbon was not necessary for lubrication in humid air.     

Improvements in routine internal monitoring--an overview of the IDEA project

This study evaluates the decorporation efficacy of a pulmonary administration of a new Ca-DTPA (diethylenetriaminepentaacetic acid) dry powder (18 micromol kg(-1) of body mass) after pulmonary contamination of rats with different Pu compounds. After inhalation of PuO2, a delayed intratracheal administration of DTPA cannot reduce significantly the retention of Pu in the lungs but limits its transfer in liver and skeleton. After pulmonary contamination by Pu nitrate, early insufflation of the DTPA powder appears twice as more efficient than an i.v injection of DTPA (30 micromol kg(-1)) to reduce Pu retention in the lungs and is as effective as i.v. injection to limit the extrapulmonary deposit. In contrast, a delayed administration of DTPA cannot reduce the lung or extrapulmonary retention. In conclusion, the improvement of aerodynamic properties of DTPA powder leads to an increase of DTPA amount deposited in the lungs and enhances the body decorporation.