An innovative LC-MS/MS-based method for determining CYP 17 and CYP 19 activity in the adipose tissue of pre- and postmenopausal and ovariectomized women using 13C-labeled steroid substrates.

Context: Does adipose tissue produce steroid hormones like an endocrine organ?

Object: To clarify whether adipose tissue produces sex steroid hormone like an endocrine organ, we estimated several key steroid hormone levels, as well as CYP17 and CYP19 activity, in ovariectomized, pre- and postmenopausal women by liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Subjects And Methods: The subjects were 19 premenopausal (n = 12), postmenopausal (n = 4), and ovariectomized women (n = 3) aged 27-68 years. Serum, visceral adipose and sc adipose samples were taken from these subjects and stored at -70°C.

Development of highly sensitive quantification method for testosterone and dihydrotestosterone in human serum and prostate tissue by liquid chromatography-electrospray ionization tandem mass spectrometry.

We developed highly sensitive detection of testosterone (T) and 5alpha-dihydrotestosterone (DHT) by liquid chromatography-electrospray ionization tandem mass spectrometry using high proton affinitive derivatization of 17beta-hydroxyl group of T and DHT with picolinic acid, mobile phase consisting of MeCN-MeOH-H(2)O-formic acid and conventional octadecylsilica (ODS) column. Purification of the derivatives was carried out using solid-phase extraction with ODS cartridge. By this method, T and DHT were determined simultaneously with limits of quantification (LOQs) of 1 pg/0.

Studies on neurosteroids XXIII. Analysis of tetrahydrocorticosterone isomers in the brain of rats exposed to immobilization using LC-MS.

The identification and quantification of tetrahydrocorticosterone isomers (THBs; 3alpha,5alpha-, 3beta,5alpha-, 3alpha,5beta- and 3beta,5beta-THB) in rat brains using liquid chromatography (LC)-mass spectrometry (MS) are described. For the identification, the THBs were converted to the atmospheric pressure chemical ionization (APCI)-active derivatives, i.e.

Anion chromatography using on-line recycled eluents.

Non-suppressed anion chromatography, using on-line recycled eluents, was investigated. Cations and anions from samples were excluded from the eluents using a mixture of strongly acidic cation-exchange resins and strongly basic anion exchange resins in the eluent reservoir. This exclusion was performed after determination of the anions in the non-suppressed anion chromatography, and the eluents were then recycled on-line.