Spectrofluorometric determination of the antibiotic lasalocid in blood

A spectrofluorometric assay was developed for the determination of the antibiotic lasalocid in dog blood, based on the intrinsic fluorescence of the compound in ethyl acetate. The assay can measure "total" levels of drug and any metabolites present. The specificity of the assay was verified by TLC separation of the dog blood extract, which indicated the presence of only intact drug. The overall recovery (+/- SD) of lasalocid was 62.0 +/- 3.6% in the concentration range of 1.0-10 mug of compound/ml of dog blood. The sensitivity of the assay is 0.5 mug/ml. The assay was applied to the determination of blood levels of lasalocid in the dog following the intravenous administration of a 5-mg/kg dose.

Control of the mRNA for hepatic tryptophan oxygenase during hormonal and substrate induction

Glucocorticoid hormones increase the level of hepatic tryptophan oxygenase (EC 1.13.11.11; L-tryptophan:oxygen 2,3-oxidoreductase (decyclizing) by increasing its rate of synthesis. Studies were performed to determine whether this induction is mediated by controlling the level of the mRNA for tryptophan oxygenase of by changing the translational efficiency of a fixed level of mRNA. Activity of tryptophan oxygenase mRNA was quantitated in a Krebs ascites cell-free, protein-synthesizing system, supplemented with tRNA and rabbit reticulocyte initiation factors. De novo synthesis of the protomeric unit(s) of the enzyme was a linear function of the amount of mRNA added. Time course and dose-response studies in which the enzyme level and mRNA activity in livers from rats injected with inducing doses of hydrocortisone were compared indicate that the induction of this enzyme is accompanied by a proportional increase in the level of its mRNA. This was true for mRNA isolated from total liver as well as from cytoplasmic polysomes. Induction of the enzyme by its substrate, tryptophan, however, was not accompanied by a parallel increase in mRNA activity.

Neurohumors in acupuncture

In acupuncture an increase of some substance at the reactive site seems to be required in order to have a biochemical response. Among the substances to be considered are the neurohormones. Experimentally, the sympathetic and parasympathetic neurohormones are shown to be involved in analgesia and in the transmission of nerve impulses.

Metachromatic leucodystrophy: isolation and chemical analysis of metachromatic granules

The abnormal, cytoplasmic metachromatic granules found in the brain of metachromatic leucodystrophy were isolated in high purity. They show metachromasia by von Hirsch-Peiffer's cresyl violet method. Electron microscopy revealed very slight contaminations by other components, such as mitochondria, myelin, and ribosomes. Chemical analysis of two separately obtained collections has shown that the molar ratio of cholesterol to galactolipids to phosphatides is 1 : 1 : 1. Most of the galactolipids are sulfatides.