The purpose was to investigate the in vivo skin penetration of four 14C-salicylic compounds using microdialysis and to relate dermal concentrations to structural features. Furthermore, to compare two in vivo retrodialysis recovery methods for estimation of true unbound extracellular concentrations. Microdialysis probes were inserted in the dermis of hairless rats. Equimolal 14C-salicylic formul...

In vitro, the transport of [14C]riboflavin into and from the isolated choroid plexus, the anatomical locus of the blood-cerebrospinal fluid barrier, was studied. With concentrations of [14C]riboflavin of 0.7 microM (or greater) in the incubation medium, the choroid plexus accumulated [14C]riboflavin against a large concentration gradient by a process that did not depend on binding or intracellu...

The nucleoside-peptide antibiotic nikkomycin X contains the unusual heterocyclic base 4-formyl-4-imidazoline-2-on. Investigations on the biosynthesis of this base were accomplished in a resting cell system which was optimized in respect to nikkomycin production. Incorporation experiments with [2-l4C]adenine, [8 14C]adenine, [2-14C]glycine, [2-14C]uracil, [U 14C]histidine, and [2-14C]histidine r...

Streptomyces cattleya produces fluoroacetate and 4-fluorothreonine from inorganic fluoride added to the culture broth. We have shown by 19F nuclear magnetic resonance (NMR) spectrometry that fluoroacetate is accumulated first in the culture broth and that accumulation of 4-fluorothreonine is next. To show precursors of the carbon skeleton of fluoroacetate, we carried out tracer experiments with...

The desaturation-elongation of [14C]linolenic acid (n-3) in the rat small intestine was examined in homogenates of villus and crypt cells in vitro and in mesenteric lymph duct cannulated rats in vivo, using high performance liquid chromatography of fatty acid methyl esters with continuous flow measurement of 14C. Desaturation-elongation of [14C]18:3 to [14C]18:4, [14C]20:4, and [14C]20:5 (n-3) ...

The contribution of the pentose phosphate shunt to glucose metabolism in the swimbladder tissue of the American eel Anguilla rostrata has been evaluated by comparing the rate of 14CO2 and [14C]lactate production from [1-14C]glucose and [6-14C]glucose. In blood-perfused swimbladder preparations, 0.18±0.07 nmol min-1 of [6-14C]glucose and 3.19±0.57 nmol min-1 of [1-14C]glucose were ...

The radiometric method has been applied for studying the metabolism of M. lepraemurium and the conditions which might force or inhibit its metabolic activity in vitro. These organisms assimilate and oxidize (U-14C) glycerol, and (U-14C) acetate, but are unable to oxidize (U-14C) glucose, (U-14C) pyruvate, (U-14C) glycine and 14C-formate. When incubated at 30 degrees C M. lepraemurium oxidizes (...