E. Gattavecchia

Honey bees and their products as indicators of environmental radioactive pollution

Samples of honey, pollen and honey bees have been collected in some regions of Italy after the Chernobyl accident, and subjected to gamma spectrometry in order to assess their possible use as markers of the radioactive environmental contamination. Pollen has resulted in the best indicator, since it reflects exactly the air contamination and therefore it is suitable for obtaining a map of fallout. Also bees can be used for the purpose, even if their collection is more difficult, whereas honey gives only an indication.

Determination of preservatives in cosmetic products by reversed-phase high-performance liquid chromatography. II.

We have developed a reversed-phase HPLC method that allows the complete separation of 22 preservatives, including triclosan and triclocarban, with optimization of the mobile phase composition

Interaction between reactive oxygen species and Coenzyme Q10 in an aprotic medium: A cyclic voltammetry study

The involvement of coenzyme Q (CoQ) as an antioxidant agent in several oxidative processes both in vitro and in vivo is nowadays pointed out by several biochemical and clinical studies, but the chemical mechanisms of this action are not yet unequivocally established. Electrochemistry provides very useful techniques for the analysis of the kinetics and thermodynamics, and mechanisms of chemical phenomena involving electron transfers, e.g. in the case of radical reactions. In the present study we used cyclic voltammetry to investigate the interactions between oxygen radicals and ubiquinone in aprotic medium, a condition similar to that existing in the biological membranes. The results obtained showed that ubiquinone is more easily reduced than oxygen, ruling out the possibility of an electron transfer from semiquinone to oxygen to produce superoxide radicals. On the contrary, it was demonstrated that fully reduced quinone is able to scavenge the superoxide radical, by reduction to peroxide ion, lowering actually the oxidative potential in the medium.

Thin-layer chromatographic determination of indolic tryptophan metabolites in human urine using Sep-Pak C18 extraction

Tryptophan and some of its indole metabolites were separated by thin-layer chromatography, stained with the Van Urk--Salkowski reagent, and quantitated by scanning densitometry. The application of this technique for the detection of the indoles in urine samples, employing Sep-Pak C18 cartridges for extraction, was demonstrated. The proposed method is simple and accurate. The detection limits were 2 micrograms/ml 5-hydroxytryptophan, 1.75 micrograms/ml 5-hydroxyindolyl-3-acetic acid, 1.5 micrograms/ml tryptophan, 0.8 micrograms/ml indolyl-3-acetic acid, 0.9 micrograms/ml indolyl-3-butyric acid, 1.75 micrograms/ml serotonin, and 1.25 micrograms/ml tryptamine.

Electrochemical and Pulse Radiolysis Study of Misonidazole and Its Azo and Azoxy Derivatives

Pulse radiolysis experiments were carried out on methanolic solutions of misonidazole and its azo and azoxy derivatives in order to obtain the spectra of their radical anions. The rate constants for the reaction of these compounds with es- were 2.5 X 10(10), 2.3 X 10(10) and 1.9 X 10(10) M-1 s-1 respectively. The electrochemical properties of the compounds were studied with the aim of producing their radical anions by electrolysis in aprotic medium (DMF, 0.1 M TEAP ). The potentials at cathodic peaks were -1.05, -1.10 and -1.18 V for misonidazole, azo and azoxy derivatives, respectively. The decay of the radical anion of misonidazole, which produces nitrite ions, was studied in particular, the corresponding rate constant being 2.8 X 10(-4) s-1. The possibility of using electrochemistry in the study of these transient species is discussed.

A simple and continous assay for decarboxylase activity using a carbon dioxide-selective electrode

Abstract A carbon dioxide electrode has been used for kinetic studies of decarboxylase activity. The methodology used requires only a sensitive pH meter operating in the millivolt mode with the electrode. The CO2 release may be followed continuously. Compared to other assay procedures the method outlined offers the advantages of rapidity, continuity, specificity, and sufficient precision. Techniques for the calibration of the electrode response are discussed. The applicability of this assay was appraised by determining the Km of lysine decarboxylase. The value obtained showed good agreement with that reported in literature. The procedure might be useful for the study of enzyme-inhibitor interactions.

Clinical trials with cyclophosphamide and misonidazole combination for maintaining treatment after radiation therapy of lung carcinoma

Fifteen patients with inoperable non oat cell lung carcinoma, who had already been treated with telecobalt therapy in the mediastinum-hilar region, were treated with continuing therapy with misonidazole (MISO) and cyclophosphamide (Cy). MISO was administered in single doses of 1000 mg/m2 and 500 mg/m2, orally. Cy was administered in single doses of 500 mg/m2 and 250 mg/m2, i.v. This treatment was given every 4 weeks. All patients (15/15) suffered from hyporexia, nausea and vomiting within 48 hours from administration; furthermore, 2 patients had hemoragic cystitis, 2 had peripheral neurotoxicity, 3 had fever, and 2 had serious nervous depression. Leukopenia occurred in all patients immediately after drug administration, although it was not present in any patient by the time of the next administration. This clinical trial was concluded in December 1981. The follow-up at 18 months shows 7/15 cases of relapse (3 patients dead and 1 patient alive with recurrence, 2 patients dead and 1 patient alive with metastasis without recurrence). Eight of 15 patients are alive with progression of disease from 8 to 18 months.

Determination of metronidazole, misonidazole and its metabolite in serum and urine on RP-18 high-performance thin-layer chromatographic plates

Abstract A method for the determination of radiotherapeutic concentrations of metronidazole, misonidazole and its metabolite is described. The biological fluid (serum or urine) was deproteinized with acetone containing 2-nitroimidazole as internal standard, centrifuged and the supernatant evaporated under vacuum. The residue, dissolved in acetone, was applied to an HPTLC-RP-18 layer and, after development, quantitation was achieved with a scanning densitometer. The response was linear up to 180 μg/ml for all tested compounds and the detection limit was 0.5 μg/ml. Owing to its rapidity and sensitivity the method can be considered to be equivalent to high-performance liquid chromatography.

Determination of90Sr by thin layer radiochromatography

A simple method for the determination of90Sr by using thin layer chromatography on silica gel or cellulose pretreated with calcium oxalate is proposed. In these conditions a complete separation between strontium and its daughter yttrium is obtained. Radioactivity of separated elements was measured by a linear multiscanner analyzer and the results were computer processed to obtain the activity of90Sr. The method has been applied to samples of water and milk subjected to a very simple extraction procedure. Under the experimental conditions used, the detection limit is about 25 mBq of deposited radioactivity, which corresponds to about 6 Bq/l.

Bile acid kinetics in man studied by radio thin-layer chromatography and densitometry coupling

A method based on coupling of the techniques of radioscanning a TLC plate and densitometry has been developed for the determination of pool sizes and fractional turnover rate of bile acids in man after intraduodenal administration of 14C-labelled acid. The validity of the method has been checked by comparison of the results obtained with those of an enzymatic spectrophotometric analysis, and a measurement of the radioactivity by liquid scintillation counting, after elution of the separated bile acid from a TLC plate. Advantages of the proposed method over the previous one include a reduced number of manipulations, the possibility of automation, a better reproducibility, and the possibility of elaborating the radiometric data obtained for the primary bile acid for better characterising its metabolism inside the enterohepatic circulation.