Detection of dehydroepiandrosterone misuse by means of gas chromatography- combustion-isotope ratio mass spectrometry

According to World Anti-Doping Agency (WADA) rules (WADA Technical Document-TD2004EAAS) urine samples containing dehydroepiandrosterone (DHEA) concentrations greater than 100 ng ML(-1) shall be submitted to isotope ratio mass spectrometry (IRMS) analysis. The threshold concentration is based on the equivalent to the glucuronide, and the DHEA concentrations have to be adjusted for a specific gravity value of 1.020. In 2006, 11,012 doping control urine samples from national and international federations were analyzed in the Cologne doping control laboratory, 100 (0.9%) of them yielding concentrations of DHEA greater than 100 ng mL(-1). Sixty-eight percent of the specimens showed specific gravity values higher than 1.020, 52% originated from soccer players, 95% were taken in competition, 85% were male urines, 99% of the IRMS results did not indicate an application of testosterone or related prohormones. Only one urine sample was reported as an adverse analytical finding having 319 ng mL(-1) DHEA (screening result), more than 10,000 ng mL(-1) androsterone and depleted carbon isotope ratio values for the testosterone metabolites androsterone and etiocholanolone. Statistical evaluation showed significantly different DHEA concentrations between specimens taken in- and out-of- competition, whereas females showed smaller DHEA values than males for both types of control. Also a strong influence of the DHEA excretion on different sport disciplines was detectable. The highest DHEA values were detected for game sports (soccer, basketball, handball, ice hockey), followed by boxing and wrestling. In 2007, 6622 doping control urine samples were analyzed for 3alpha,5-cyclo-5alpha-androstan-6beta-ol-17-one (3alpha,5-cyclo), a DHEA metabolite which was described as a useful gas chromatography-mass spectrometry (GC-MS) screening marker for DHEA abuse. Nineteen urine specimens showed concentrations higher than the suggested threshold of 140 ng mL(-1), six urine samples yielded additionally DHEA concentrations higher than 100 ng mL(-1), none of them showing positive IRMS findings. These results should be taken into consideration in future discussions about threshold values for endogenous steroids in doping control.     

Er：Yb：YCOB晶体制备及其激光二极管抽运激光特性

研究了Er：Yb：YCa4O(BO3)3(简称Er：Yb：YCOB)的多晶制备和单晶生长，用提拉法生长出光学质量优良的Er：Yb：YCOB单晶，测量了其吸收光谱和荧光光谱，分析了其能级和泵浦原理，并进行了以激光二极管为抽运源的激光试验，实现了Er：Yb：YCOB晶体的在1．55μn附近110mW的激光输出，且斜效率达18．9％。     

Analysis of endogenous steroids in urine by means of multi-immunoaffinity chromatography and isotope ratio mass spectrometry for sports drug testing

Analytical and Bioanalytical Chemistry - Detecting the administration of naturally occurring but synthetically derived steroids (e.g., testosterone) in routine doping controls is particularly...     

Silica microparticles as a solid support for gadolinium phosphonate magnetic resonance imaging contrast agents

Particle-based magnetic resonance imaging (MRI) contrast agents have been the focus of recent studies, primarily due to the possibility of preparing multimodal particles capable of simultaneously targeting, imaging, and treating specific biological tissues in vivo. In addition, particle-based MRI contrast agents often have greater sensitivity than commercially available, soluble agents due to decreased molecular tumbling rates following surface immobilization, leading to increased relaxivities. Mesoporous silica particles are particularly attractive substrates due to their large internal surface areas. In this study, we immobilized a unique phosphonate-containing ligand onto mesoporous silica particles with a range of pore diameters, pore volumes, and surface areas, and Gd(III) ions were then chelated to the particles. Per-Gd(III) ionic relaxivities ranged from ～2 to 10 mM(-1) s(-1) (37 °C, 60 MHz), compared to 3.0-3.5 mM(-1) s(-1) for commercial agents. The large surface areas allowed many Gd(III) ions to be chelated, leading to per-particle relaxivities of 3.3 × 10(7) mM(-1) s(-1), which is the largest value measured for a biologically suitable particle.     

Variable phase dark-field contrast--a variant illumination technique for improved visualizations of transparent specimens

Variable phase dark-field contrast has been developed as an illumination technique in light microscopy, which promises significant improvements and a higher variability in imaging of several transparent specimens. In this method, a phase contrast image is optically superimposed on a dark-field image so that a partial image based on the principal zeroth-order maximum (phase contrast) interferes with an image that is based on the secondary maxima (dark field). The background brightness and character of the resulting image can be continuously modulated from a phase-contrast-dominated to a dark-field-dominated character. The condenser aperture diaphragm can be used for modulations of the image's appearance. Specimens can either be illuminated concentrically or obliquely (eccentrically) when parts of the illuminating light beams are covered and blocked. Moreover, a bright-field-like partial image can be added. In this way, the illumination can be optimally adjusted to the specific properties of the specimen. The techniques described can lead to improved visual information especially in biological specimens consisting of phase structures and additional light-absorbing or -reflecting components. Moreover, the specimen's three-dimensionality can be accentuated with improved clarity because the illuminating light beams associated with phase contrast and dark field run to the specimen at different angles of incidence.     

Optical activity of trigonal coordination compounds

The optical activity of trigonal coordination compounds is investigated using the crystal field theory. The ionic model is shown to account for the circular dichroism of Co(en)₃ ⁺³. The absolute configuration of Cr(C₂O₄)₃ ^-3 is assigned on the basis of the ionic model.     

A continuous wave SrMoO4 Raman laser

We demonstrate a cw, laser diode-pumped Nd:GdVO4/SrMoO4 crystalline Raman laser. First Stokes laser output at 1173.5?nm of 2.18?W was achieved with a diode-to-first Stokes efficiency of 8.7%. With intracavity frequency doubling in LiB3O5, 3.1?W of cw yellow emission at 586.8?nm was obtained with a 12.4% diode-to-yellow efficiency. The experimental results show that SrMoO4 is an excellent stimulated Raman scattering gain material for high-power cw near-IR Stokes and yellow lasers.     

Effect of changes in the deuterium content of drinking water on the hydrogen isotope ratio of urinary steroids in the context of sports drug testing

The hydrogen isotope ratio (HIR) of body water and, therefore, of all endogenously synthesized compounds in humans, is mainly affected by the HIR of ingested drinking water. As a consequence, the entire organism and all of its synthesized substrates will reflect alterations in the isotope ratio of drinking water, which depends on the duration of exposure. To investigate the effect of this change on endogenous urinary steroids relevant to doping-control analysis the hydrogen isotope composition of potable water was suddenly enriched from -50 to 200 ‰ and maintained at this level for two weeks for two individuals. The steroids under investigation were 5β-pregnane-3α,20α-diol, 5α-androst-16-en-3α-ol, 3α-hydroxy-5α-androstan-17-one (ANDRO), 3α-hydroxy-5β-androstan-17-one (ETIO), 5α-androstane-3α,17β-diol, and 5β-androstane-3α,17β-diol (excreted as glucuronides) and ETIO, ANDRO and 3β-hydroxyandrost-5-en-17-one (excreted as sulfates). The HIR of body water was estimated by determination of the HIR of total native urine, to trace the induced changes. The hydrogen in steroids is partly derived from the total amount of body water and cholesterol-enrichment could be calculated by use of these data. Although the sum of changes in the isotopic composition of body water was 150 ‰, shifts of approximately 30 ‰ were observed for urinary steroids. Parallel enrichment in their HIR was observed for most of the steroids, and none of the differences between the HIR of individual steroids was elevated beyond recently established thresholds. This finding is important to sports drug testing because it supports the intended use of this novel and complementary methodology even in cases where athletes have drunk water of different HIR, a plausible and, presumably, inevitable scenario while traveling.