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M Salmona

Publications and source records attributed to M Salmona.

At least 181 records · Page 10Linked to original sources
PubMed1981

Nuclear metabolism. II. Further studies on epoxide hydrolase activity.

Apparent Km- and Vmax-values of nuclear styrene 7,8-oxide hydrolase were determined at different protein concentrations. In the protein concentrations range used no significant differences in the apparent Km-values were observed. The influence of the incubation with different modifiers (i.e. SKF-525A, metyrapone, 1,2-epoxy-3,3,3 trichloropropane, cyclohexene oxide) at two different concentrations on this enzyme activity was also determined. Cyclohexene oxide and 1,2-epoxy-3,3,3-trichloropropane, two well known inhibitors of the microsomal epoxide hydrolase(s) caused a marked inhibition, metyrapone had a strong activating effect whereas SKF-525A had no effect. In vivo pretreatment with phenobarbital significantly induced the nuclear epoxide hydrolase whereas beta-naphthoflavone caused a lower degree of induction. This pattern is quantitatively different but qualitatively very similar to the microsomal one. Moreover a toxifying to detoxifying enzymatic activity balance is attempted for the metabolization of the alkenic double bond of styrene, taking into account the ratio between the styrene monooxygenase (toxifying enzyme) and the styrene, 7,8-oxide hydrolase (detoxifying enzyme) after the above mentioned pretreatments, both in the microsomal and nuclear fractions.

Animals↗
PubMed1981

Induction of mixed-function oxidase by chronic treatment with 2,3,7,8-tetrachloro-dibenzo-p-dioxin in female rats.

The effect of a 45-week treatment with different doses of 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) (0.01, 0.10 and 1.00 microgram/kg/week) was evaluated in female rat liver by determining cytochrome P-450 and b5 content and the activities of the enzymes cytochrome c reductase, aryl hydrocarbon hydroxylase (AHH) and 7-ethoxycoumarin O-deethylase (7-ECD); TCDD content in the liver was also measured. Cytochrome b5 and cytochrome c reductase were unaffected at any of the dose levels and cytochrome P-450 was significantly induced only at the highest TCDD dose, but marked induction of AHH and 7-ECD was apparent when the animals were treated with 0.01 microgram/kg/week; a clear dose-response relationship was present in the induction at the 2 lower doses (0.01 and 0.10 microgram/kg/week). The amount of TCDD found in liver tissue (1050, 4740 and 30 700 ppt, respectively, for 0.01, 0.10 an 1.00 microgram/kg/week) indicated a relatively higher accumulation of this compound at lower doses.

Animals↗
PubMed1981

Plasma kinetics and urinary elimination of saccharin in man.

The plasma kinetics and urinary elimination of saccharin were studied in 3 groups each of 5 healthy male volunteers given the sweetener as three different single oral doses (50, 150 and 333 mg/60 kg body weight). Saccharin concentrations were determined by gas liquid chromatography-stable isotope dilution mass fragmentography. The compound was rapidly absorbed through the gastrointestinal tract, reaching plasma peak concentrations between 30 and 60 min after intake. Plasma saccharin elimination was also fast, with a monoexponential pattern of decay. At the 3 doses studied saccharin was excreted in urine within a few hours, about 60% of the dose being excreted unchanged at 6 h and 76% at 24 h.

Humans↗
PubMed1980

Non-linear kinetics of microsomal styrene monooxygenase after phenobarbital pre-treatment.

Pretreatment of rats with phenobarbital, but not with 3-methylcholanthrene, induces liver microsomal styrene monooxygenase. Under these conditions the kinetic profile is not linear and can be divided into 2 distinct curves. Evidence is presented indicating that the combined treatment with phenobarbital and CoCl2 destroy the affinity enzyme, suggesting that the native cytochrome is less sensitive to the action of CoCl2.

Animals↗
PubMed1980

Is nuclear styrene monooxygenase activity a microsomal artifact?

Microsomal contamination in nuclear preparations could represent one of the main sources of bias in the evaluation of the real metabolic capacity of the nuclear envelope. In this paper we present a quantitative study of the level of nuclear styrene monooxygenase enzymatic activity after artificially increasing the native microsomes to nuclei ratio. In one experimental conditions no significant elevation of the nuclear monooxygenase was observed. These data indicate that, if any microsomal contamination is present, it cannot account for more than 30% of the total enzymatic activity found in nuclear preparations.

Animals↗
PubMed1980

Nuclear metabolism. I. Determination of styrene monooxygenase activity in rat liver nuclei.

Styrene monooxygenase activity was measured in intact nuclear preparations from rat liver by means of a gas chromatographic method. Styrene epoxide formation is NADPH-dependent although it is enhanced when NADH is added with NADPH. This activity is inhibited by microsomal monooxygenase inhibitors SKF 525A and metyrapone and by microsomal epoxide hydrase inhibitors 1,2-epoxy-3,3,3-trichloropropene oxide and cyclohexene oxide. The percentage of inhibition is quantitatively different for the four compounds. Known inducers of liver microsomal monooxygenase show different patterns of induction on nuclear preparations. Phenobarbital induces nuclear monooxygenase activity more than the respective microsomal activity, whereas the contrary holds true for beta-naphthoflavone.

Animals↗
PubMed1980

Monosodium glutamate kinetic studies in human volunteers.

(a) A kinetic study of plasma glutamic acid (GA) was made after monosodium glutamate (MSG) administration to human volunteers. MSG was given at doses of 30,60 and 120 mg/kg in a bouillon and of 60 mg/kg in tomato juice. In another experiment a normal meal was consumed without added MSG. (2) Plasma area under the curve (AUC) was found to be lower in females than in males. (3) Plasma AUC was lower when MSG was taken in tomato juice than when consumed in bouillon. (4) Consumption of the normal meal did not result in any significant increase in plasma GA.

Adult↗
PubMed1980

Effect of oral monosodium glutamate on glutamic acid levels in the nucleus arcuatus of the hypothalamus and on serum osmolality of adult and infant mice.

Monosodium glutamate (MSG) given by gavage to 7-day-old mice at 2 g/kg body weight (b.wt.) as a 20% solution w/v resulted in a 27% increase in the glutamic acid (GA) content in the nucleus arcuatus of the hypothalamus (NAH). When MSG was administered by gavage to adult mice at 4 g/kg b.wt. as a 20% solution w/v, GA levels in NAH remained unchanged. Serum osmolality, measured after oral MSG, was elevated in infant mice but was unaffected in adults.

Animals↗
PubMed1980

Plasma glutamic acid levels in premature newborn.

24 premature, newborn infants were investigated for plasma glutamic acid (GA) levels before and after a normal milk feed, to ascertain if the ingestion of GA present in the milk could result in an increase of its plasma level. No increases were detected in plasma between 5 and 90 min after the feed. These results may be important in respect to the problem of the possible toxicity of monosodium glutamate (MSG) added to baby foods.

Animals↗
PubMed1980

In vitro effects of saccharin on cell-mediated host defence mechanisms.

In vitro exposure to saccharin (0.1-2 mg/ml) did not affect the tumoricidal activity of macrophages and natural killer (NK) cells from mice and rats. In contrast saccharin at doses of 0.5-2 mg/ml significantly and consistently depressed the blastogenic response of rat lymph node cells to phytohemagglutinin (PHA). Similarly mouse splenocytes showed impaired responsiveness to PHA and bacterial lipopolysaccharides n the presence of 2 mg/ml saccharin. Compared with murine lymphoid cells, human peripheral blood lymphocytes were relatively resistant to the immunodepressive activity of saccharin, a low but significant, depression (21%) of the response to PHA being observed only at the highest concentration (2 mg/ml) in 1 of 3 normal healthy donors tested.

Animals↗
PubMed1980

Effects of chronic treatment with di-(2-ethylhexyl) phthalate on rat liver microsomal activities.

The effects of chronic di-(2-ethylhexyl)phthalate (DEHP) on liver microsomal activity were studied in rats. Daily doses of 50 and 500 mg/kg for 4 weeks did not affect O-demethylation, aromatic hydroxylation, N-demethylation, C3-hydroxylation, styrene monooxygenase, glutamic-oxalacetic and glutamic-pyruvic transaminases (GOT, GPT). Inhibition of glutathione-S-transferase A and C and induction of epoxide hydrase, glutathione-S-transferase B and nitroreductase activity were instead observed. Protein, cytochrome P-450 and reduced glutathione levels in liver did not appear to be affected by DEHP pretreatment.

Animals↗
PubMed1979

Quantitative thin-layer chromatographic measurement of n-trifluoroacetyladriamycin-14-valerate (AD 32) and trifluoroacetyladriamycin (AD 41) in blood and tissues.

A thin-layer chromatographic method has been developed for the detection and measurement of N-trifluoroacetyladriamycin-14-valerate (AD 32) and its major metabolite trifluoroacetyladriamycin (AD 41). The procedure gives satisfactory linearity over a large range of concentrations. The coefficient of variability is about 10% over the entire range of usable concentrations, giving good reproducibility; sensitivity is 25 ng for both AD 32 and AD 41. Analysis is specific for AD 32 and AD 41 since adriamycin or more polar metabolites can be differentiated. Recovery is high (85-90%) and the method is simple and economical to use. Pharmacokinetics of AD 32 and AD 41 are reported in blood and some tissues of mice bearing Lewis Lung carcinoma.

Animals↗
PubMed1979

Esterase activity of rat muscle.

The esterasic capacity of a series of skeletal muscles in response to three hemisuccinate ester drugs was investigated in rats and compared to that on alpha-naphthylacetate as a reference esterase substrate. Marked variations between different muscles and between given muscles of animals of different sex were observed, indicative of a complex heterogeneity in muscular expression of esterase activity.

Animals↗
PubMed1979

Isolation and structure determination of enzymatically formed styrene oxide glutathione conjugates.

When styrene oxide was incubated with glutathione in the presence of rat liver cytosolic fraction, two conjugates were formed. Structural investigation by mass spectrometry (MS), proton magnetic resonance (PMR) analysis and chemical fragmentation showed the presence of two positional isomers, namely S-(1-phenyl-2-hydroxyethyl)glutathione and S-(2-phenyl-2-hydroxyethyl)glutathione in a ratio of approx. 60 : 40.

Animals↗