Evaluation of thumbnail clipping as a specimen for retrospectively assessing average production of testosterone.

BACKGROUND: The chronic abnormal production of testosterone (T) is associated with many disorders in men. Fingernail clippings might be more suited for the diagnosis and medium-to-long term therapeutic monitoring for the T-related chronic disorders than the blood-derived specimens. The objective of this study was to characterize a thumbnail clipping as the specimen for assessing the several months-old T status. METHODS: Thumbnail clippings from various subjects were analyzed by liquid chromatography/electrospray ionization-tandem mass spectrometry to evaluate the gender difference, and changes caused by aging and androgen deprivation therapy (ADT) in the thumbnail T concentration. RESULTS: There was an evident gender difference in the thumbnail T concentrations [male; 2.55 ± 0.85 ng/g and female; 0.48 ± 0.29 ng/g, mean ± SD (n = 25 each), Welch t-test]. The thumbnail T concentrations significantly decreased with age in men (n = 268, Scheffé F-test), which was similar to those of the free or bioavailable T in serum/plasma. The thumbnail T concentrations sharply decreased by a 6-months ADT (especially the effect of the luteinizing hormone-releasing hormone agonist/antagonist) for patients with prostate cancer (n = 10). CONCLUSIONS: The thumbnail clipping can be a specimen to retrospectively assess the average T production.

An LC/MS/MS method for quantifying testosterone and dehydroepiandrosterone sulfate in four different serum samples during a single run.

Simultaneous measurements of the circulating testosterone (TS) and dehydroepiandrosterone sulfate (DHEAS) are deemed to be helpful for the assessment of men's health. Liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) is the most reliable methodology for this purpose; however, it has room for improvement in analysis throughput. In this study, a quadruplicate of the Girard reagents was used to develop an LC/ESI-MS/MS method capable of quantifying TS and DHEAS in four different serum samples in a single run. The four serum samples were separately pretreated, derivatized with one of four Girard reagents, and then combined. The LC/ESI-MS/MS analysis of the combined sample provided the androgen concentrations of four serum samples in parallel. The method had practical measuring ranges, in which good precision and accuracy, as well as negligible matrix effects were verified. The speed-up capability of the developed method was evaluated through the analysis of ten batches of serum samples (total 40 samples); the method saved a 60% post-pretreatment analysis time compared to the non-derivatization method for 40 samples.

A self-regenerable soot sensor with a proton-conductive thin electrolyte and a nanostructured platinum sensing electrode.

In recent years, exhaust sensors have become increasingly attractive for use in energy and environmental technologies. Important issues regarding practical applications of these sensors, especially for soot measurements, include the further development of ion-conductive electrolytes and active electrode catalysts for meeting performance and durability requirements. Herein, we design a proton conductor with a high breakdown voltage and a sensing electrode with high sensitivity to electrochemical carbon oxidation, enabling continuous soot monitoring with self-regeneration of the sensor. A Si0.97Al0.03HxP2O7-δ layer with an excellent balance between proton conductivity and voltage endurance was grown on the surface of a Si0.97Al0.03O2-δ substrate by reacting it with liquid H3PO4 at 600 °C. Specific reactivity of the electrochemically formed active oxygen toward soot was accomplished by adding a Pt-impregnated Sn0.9In0.1HxP2O7-δ catalyst into a Pt sensing electrode. To make the best use of these optimized materials, a unipolar electrochemical device was fabricated by configuring the sensing and counter electrodes on the same surface of the electrolyte layer. The resulting amperometric mode sensor successfully produced a current signal that corresponded to the quantity of soot.