Preparation and characterization of subcellular fractions from the head kidney of the Northern pike (esox lucius), with particular emphasis of xenobiotic-metabolizing enzymes
The present study was designed to prepare and characterize subcellular fractions from the head kidney of the Northern pike (Esox lucius), with special emphasis on the preparation of a microsomal fraction suitable for studying xenobiotic metabolism. The purity of the different fractions obtained by differential centrifugation as well as the recovery of different cell components was determined using both enzyme markers and morphological criteria. Finally, the subcellular distributions of several drug-metabolizing enzymes (NADPH-cytochrome c reductase, NADH-ferricyanide reductase, glutathione transferase, epoxide hydrolase) were determined. With the exception of NADPH-cytochrome c reductase, the subcellular distributions obtained here for drug-metabolizing and marker enzymes closely resembled those reported for rat liver. NADPH-cytochrome c reductase was apparently partially solubilized here from microsomal vesicles by an endogenous protease, which reduced its usefulness as a marker enzyme and raises questions concerning the measurement of activities catalyzed by the cytochrome P-450 system in these subfractions. In other respects the microsomal fraction prepared here from the pike head kidney seems well-suited for studies of drug metabolism.
Enrichment of gaseous compounds from diluted gasoline exhausts: A comparison between adsorption and cryogenic condensation
A comparison between an adsorption system and a condensation system for the enrichment of gaseous emissions in gasoline vehicle exhausts is presented. Chemical analyses involve extraction with acetone, fractionation into five fractions, based on different polarity, followed by gas chromatography. The results show that low molecular weight polynuclear aromatic hydrocarbons (PAH) (
DYNAMIC SHAPE FACTORS OF SPHERE AGGREGATES IN AN ELECTRIC-FIELD AND THEIR DEPENDENCE ON THE KNUDSEN NUMBER
Preparation and characterization of subcellular fractions from the intestinal mucosa of the Northern pike (Esox lucius), with special emphasis on enzymes involved in xenobiotic metabolism
The present study was designed to prepare and characterize subcellular fractions from the intestinal mucosa of the Northern pike (Esox lucius), with special emphasis on the preparation of a microsomal fraction suitable for studying xenobiotic metabolism. The purity of the different fractions obtained by differential centrifugation, as well as the recovery of different organelles, was determined using both enzyme markers and morphological examination with the electron microscope. The subcellular distributions of several enzymes involved in drug metabolism (NADPH-cytochrome c reductase, NADH-ferricyanide reductase, epoxide hydrolase activity towards both cis- and trans-stilbene oxide as substrates, and glutathione transferase) were also examined. The subcellular distributions obtained here for drug-metabolizing and marker enzymes closely resembled those reported for rat and pike liver. The microsomal fraction obtained contained about 50% of the total endoplasmic reticulum. This fraction was relatively free of nuclei, mitochondria, Golgi, peroxisomes and cytosol, but relatively heavily contaminated with lysosomes and fragments of the plasma membrane. Within the limitations discussed, the subfractions prepared here are suitable for further characterization of drug-metabolizing systems in the intestinal mucosa of the Northern pike, as well as for other studies with this tissue.
The solubility of tri-n-octylamine in water and phosphoric acid solutions
The solubility of tri-n-octylamine (TOA) in water and phosphoric acid is reported. Equilibration is achieved by circulating the solutioin through PVC pieces saturated with the absorbed amine in a glass tube. The dissolved TOA is determined by capillary gas chromatography which can detect amine concentrations down to 10 μg l−1. The solubility of TOA in water is 0.039 mg l−1 and in 5.5 M phosphoric acid 0.82 mg l−1; these values are much lower than those reported in the literature.
Trace analysis of amines and isocyanates using glass capillary gas chromatography and selective detection V. Direct determination of isocyanates using nitrogen-selective and electron-capture detection
The possibilities of direct determination of isocyanates by glass capillary gas chromatography using nitrogen-selective or electron-capture detection was studied in some detail. It was found that only the former method was generally applicable, allowing the quantitative assay of trace isocyanates down to the low picogram range. A comparison with other methods for isocyanate determination, previously developed at these laboratories, was made.
Capillary gas chromatographic method for the determination of complex mixture of isocyanates and amines
A capillary gas chromatographic method using nitrogen-selective detection was developed for the analysis of complex mixtures of isocyanates and amines in air. The isocyanate group was converted directly in the air sampling step into urethane by reaction with ethanol using potassium hydroxide as a catalyst. The amine group was converted into an amide using pentafluoropropionic anhydride in an extractive derivatization procedure. The complex pattern of air pollutants after thermal degradation of a polyurethane polymer, based on toluene diisocyanate (TDI) and 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA), was investigated. Substantial amounts of amines, isocyanates and aminoisocyanates, molecules containing both an amine and an isocyanate group, were found. Consideration must be given to these findings when using current methods for isocyanate and amine determination. The detection limits for isocyanates, amines and aminoisocyanates, essentially depending on the nitrogen content of the molecule, were about equal and in the order of 40–80 fmol.
Trace analysis of amines and isocyanates using glass capillary gas chromatography and selective detection. IV. Determination of free aromatic amines using nitrogen-selective detection
A method for trace analysis of free aromatic amines of special interest in relation to the rubber industry is presented. It involves separation of the amines by high temperature glass capillary gas chromatography on an OV-73 stationary phase, using on-column injection and nitrogen-selective detection. The necessary inertness of the column was achieved by deactivation with octamethylcyclotetrasiloxane. Linear calibration plots were obtained over the range 50–1600 pg and detection limits in the range 10–20 pg.