Derivatization in liquid chromatography/mass spectrometric analysis of neurosteroids.

Liquid chromatography/mass spectrometry (LC/MS) is now considered to be the most promising analytical method for the determination of biological substances, especially nonvolatile or highly polar substances. However, some compounds do not show enough sensitivity in LC/MS and soft-ionization methods commonly used in LC/MS, such as electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI), sometimes do not give satisfactory structural information. This report presents an overview of the derivatization methods in the LC/MS analysis of neurosteroids or neuroactive neurosteroids, which are synthesized and accumulated in the nervous system.

Characterization of a novel missense mutation E637K in the pore-S6 loop of HERG in a patient with long QT syndrome.

Objective: In a 32-year-old woman with marked QT prolongation (QTc=0.61 s) and repeated episodes of syncope, we identified a single pertinent base substitution (G to A at 1909) in HERG by genetic analysis. This novel missense mutation is predicted to cause an amino acid substitution of lysine for glutamic acid at position 637 (E637K) in the pore-S6 loop.

Regulation of tumor angiogenesis by oxygen-regulated protein 150, an inducible endoplasmic reticulum chaperone.

Expression of angiogenic factors such as vascular endothelial growth factor (VEGF) under conditions of cell stress involves both transcriptional and translational events, as well as an important role for inducible endoplasmic reticulum (ER) chaperones. Coexpression of VEGF and 150-kDa oxygen-regulated protein (ORP), a novel ER chaperone, in human glioblastoma suggested a link between angiogenesis and ORP150. C6 glioma cells stably transfected with ORP150 antisense displayed selectively reduced ORP150 expression.

A sensitive postcolumn derivatization/UV detection system for HPLC determination of antitumor divalent and quadrivalent platinum complexes.

A sensitive postcolumn derivatization/UV detection system has been developed for HPLC analysis of antitumor divalent and quadrivalent platinum complexes. It is based on the derivatization of platinum complexes by reaction with sodium bisulfite to corresponding product(s) which has enhanced absorptivity at 280-300 nm. Platinum complexes examined in this study were cisplatin, carboplatin and oxaliplatin (divalent platinum complexes) and oxoplatin and tetraplatin (quadrivalent ones).

Follicular dynamics prior to and during superovulation in heifers.

The present ultrasonographic study examined the relationship between certain follicular parameters and the superovulatory response in gonadotropin-stimulated heifers. Thirty heifers received a total of 35 mg FSH twice daily for 4 d and 0.75 mg cloprostenol were given to induce luteolysis and estrus at 72 h after the initial FSH injection.

Preovulatory evaluation of the superovulatory response in donor cattle.

Dairy cows and heifers (n = 134) were induced to superovulate with exogenous gonadotrophins. In 103 animals, peripheral plasma concentrations of progesterone (P4) and luteinizing hormone (LH) were measured during the preovulatory period. On the basis of these measurements, normal and deviating profiles of P4 and LH were defined.

Premature ovulations in superovulated cattle.

The incidence and consequences of premature ovulations in superovulated cattle were studied. These ovulations, presumably induced by the luteinizing hormone content of the gonadotrophin preparation used, were found in 17 of 133 (13%) stimulated cows and heifers used as oocyte donors. In general this group of donors exhibited deviating periovulatory patterns of plasma hormone profiles (progesterone, estradiol17beta and LH), estrus behaviour, follicular steroidogenesis of progesterone and estradiol-17beta, and oocyte meiosis.