Observations on the uptake of 35sulfur by the hypothalamo-hypophysial system of the White-crowned sparrow (Zonotrichia leucophrys gambelii) following intraventricular injection of 35S DL-cysteine

Summary By use of a stereotaxic instrument it has been consistently possible to introduce ³⁵S DL-cysteine into the third ventricle of the White-crowned Sparrow, Zonotrichia leucophrys gambelii. Such injections are followed within six hours by a reproducible pattern of accumulation of the isotope in the hypothalamic nuclei around the third ventricle. The nucleus supraopticus, the nucleus paraventricularis magnocellularis, the lamina terminalis, and the area ependymalis vasculosa consistently showed the greatest accumulation of the isotope. In the supraoptic and paraventricular nuclei, conspicuous accumulation of the isotope was consistently observed in association with cells containing aldehyde-fuchsin positive material. The supraoptico-hypophysial tract, the pars nervosa, and the palisade layer of the zona externa of the median eminence showed pronounced accumulations of the isotope. These accumulations were, to a great extent, associated with aldehyde-fuchsin positive neurosecretory material.Dedicatet to Professor Dr. W. Bargmann in honor of his 60th birthday.This investigation was conducted under Contract No. DA 18-108-AMC-127 (A) US Army Chemical Center Procurement Agency, Edgewood, Maryland, with Professor Farner as principal investigator.     

Determination of dioxopiperazine metabolites of quinapril in biological fluids by gas chromatography—mass spectrometry

The dioxopiperazine metabolites of quinapril in plasma and urine were extracted with hexane—dichloroethane (1:1) under acidic conditions. Following derivatization with pentafluorobenzyl bromide and purification of the desired reaction products using a column packed with silica gel, the metabolites were analysed separately by capillary column gas chromatography—electron-impact mass spectrometry with selected-ion monitoring. The limits of quantitation for the metabolites were 0.2 ng/ml in plasma and 1 ng/ml in urine. The limits of detection were 0.1 ng/ml in plasma and 0.5 ng/ml in urine, at a signal-to-noise ratio of > 3 and > 5, respectively. The proposed method is applicable to pharmacokinetic studies.