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Biomedical subjects

F Tursi

Publications and source records attributed to F Tursi.

18 recordsLinked to original sources
PubMed1995

Mechanism of ITF 296-induced vasorelaxation compared to nitroglycerin and isosorbide dinitrate: relationship between relaxation of rabbit aorta and tissue cGMP.

The vasorelaxant properties of ITF 296, a new mononitrate ester, were studied in endothelium-denuded rabbit aortic rings and were compared to nitroglycerin (NTG) and isosorbide dinitrate (ISDN). In norepinephrine-contracted arteries, ITF 296, NTG, and ISDN elicited maximal and concentration-dependent vasodilation with pD2 values of 7.07, 7.95, and 7.2, respectively. The concentration-relaxation curves of ITF 296 were shifted markedly to the right (p < 0.01) in the presence of 10 microM methylene blue (MB) and 3 microM oxyhemoglobin (HbO2), whereas a significant shift to the left (p < 0.01) was observed in the presence of 10 microM M&B-22948 (a specific cGMP phosphodiesterase inhibitor). When KCl (60 mM) was used as contracting agent, a weak relaxation was observed with ITF 296, suggesting the absence of activity on the voltage-dependent Ca2+ channels. A time-dependent increase in cGMP content and a positive correlation between cGMP and vasodilation were observed in norepinephrine-contracted arteries after exposure to a single submaximal concentration of ITF 296 (1 microM). Similar results were obtained with NTG and ISDN, although NTG was found to be more active than ITF 296 or ISDN. The presence of either MB or HbO2 almost completely abolished the increase in cGMP induced by ITF 296, whereas a further increase in cGMP was observed in the presence of isobutylmethylxanthine. No changes in cAMP levels were observed after exposure of the tissues to a concentration of ITF 296 that induced significant elevation in the cGMP content. In the presence of L-cysteine, ITF 296 stimulated semipurified rat lung guanylate cyclase at higher concentrations than those of NTG or ISDN, probably because of its lower rate of nitric oxide (NO) release. These results suggest that, in common with the reference compounds NTG and ISDN, ITF 296-induced vasorelaxation in rabbit aortic rings is mediated by an NO-cGMP mechanism.

Animals↗
PubMed1994

Heparin-like compounds prepared by chemical modification of capsular polysaccharide from E. coli K5.

O-Sulfation of sulfaminoheparosan SAH, a glycosaminoglucuronan with the structure-->4)-beta-D-GlcA(1-->4)-beta-D-GlcNSO3(-)-(1-->, obtained by N-deacetylation and N-sulfation of the capsular polysaccharide from E. coli K5, was investigated in order to characterize the sulfation pattern eliciting heparin-like activities. SAH was reacted (as the tributylammonium salt in N,N-dimethylformamide) with pyridine-sulfur trioxide under systematically different experimental conditions. The structure of O-sulfated products (SAHS), as determined by mono- and two-dimensional 1H and 13C NMR, varied with variation of reaction parameters. Sulfation of SAH preferentially occurred at O-6 of the GlcNSO3- residues. Further sulfation occurred either at O-3 or at O-2 of the GlcA residues, depending on the experimental conditions. Products with significantly high affinity for antithrombin and antifactor Xa activity were obtained under well-defined conditions. These products contained the trisulfated aminosugar GlcNSO3-3,6SO3-, which is a marker component of the pentasaccharide sequence through which heparin binds to antithrombin.

Carbohydrate Conformation↗
PubMed1988

Immunoassay procedures to detect exposure to aflatoxin B1 and benzo(a)pyrene in animals and man at the DNA level.

Immunological methods were used to examine human liver for the presence of aflatoxin-DNA adducts and human lung for benzo(a)pyrene diol-epoxide DNA (BPDE-DNA) adducts. Eight liver samples obtained from Czechoslovakian patients with primary hepatocellular carcinoma were studied, seven of which had detectable anti-aflatoxin inhibitory material. Values ranged between 0.63 and 3.51 picomoles aflatoxin per mg DNA. In a separate, independent study performed in another laboratory the one sample with no aflatoxin bound to DNA also had no free aflatoxin present in the liver. In the case of the human lung DNA samples, 12 samples were examined, the samples having been removed during thoracic surgery, and five had detectable anti-BPDE-DNA antibody activity. The positive samples were all from smokers and had inhibitory values ranging from 4 to 12 femtomoles per mg DNA. Samples were prepared by immunoconcentration prior to analysis. These preliminary results support the view that immunological methods can be used to examine human tissue DNA for carcinogen adducts.

Aflatoxin B1↗
PubMed1986

Aflatoxin B1 binding to plasma albumin and liver DNA upon chronic administration to rats.

The hepatocarcinogen aflatoxin B1 (AFB1) was administered to male Wistar rats by oral intubation in either single or repeated doses and the binding to plasma protein and liver DNA determined. Twenty-four hours after a single dose (3.5-200 micrograms/kg AFB1) a constant ratio was found between levels of aflatoxin bound to plasma protein and that bound to liver DNA. In total 0.98-2.15% of the administered dose was bound to the plasma protein at this time point. In the chronic study rats received two doses of 0.5 microgram AFB1/day and groups of animals were killed on days 2, 3, 7, 14, 21 and 24. Binding of aflatoxin to plasma protein accumulated to a level 3-fold higher than that seen after a single dose. Levels of binding reached a plateau between days 7 and 14 of treatment and then remained stable until the end of the experiment. Binding to DNA also accumulated, 2.5-fold and in parallel to plasma protein, binding reached a plateau between days 7 and 14 of treatment. In both the chronic and acute studies fractionation of the plasma proteins by Sephadex G-200 chromatography showed that all detectable bound aflatoxin was associated with a single peak corresponding to albumin. Thus, a constant ratio was observed, after chronic or single exposure, between the concentration of plasma albumin-bound aflatoxin and that bound to DNA of the liver, the target organ for carcinogenesis by AFB1. In order to investigate the proposed role of AFB1 in the aetiology of primary hepatocellular carcinoma in man it would be of great value to have a method for assessing long-term human exposure at an individual level. The relevance of the observations presented in this paper are discussed in the light of such a requirement.

Aflatoxin B1↗
PubMed1985

Chromosome damage induced by vinyl acetate through in vitro formation of acetaldehyde in human lymphocytes and Chinese hamster ovary cells.

A 48-h treatment with vinyl acetate (0.05-1 mM) induced a drastic increase in sister chromatid exchanges (SCEs) and (in first division cells) structural chromosome aberrations in cultured human lymphocytes. The effects were more pronounced in cultures of isolated lymphocytes than in whole-blood cultures. A distinct dose-dependent induction of SCEs similarly occurred in Chinese hamster ovary cells after a 24-h vinyl acetate treatment (0.125-1 mM). A pulse treatment of Chinese hamster ovary cells for 4 h also yielded a clear increase in SCEs, but at higher concentrations (0.3-5 mM). The presence of rat liver S9 mix enhanced the SCE-inducing effect of vinyl acetate in Chinese hamster ovary cells. Gas chromatographic analysis of human whole-blood lymphocyte cultures treated for 10 s-20 min with vinyl acetate (5.4 mM) revealed a rapid degradation of vinyl acetate and formation of acetaldehyde. During the 20-min observation period, no degradation of vinyl acetate or formation of acetaldehyde were observed in complete culture medium without blood, which suggested that the reaction was enzymatic. Acetaldehyde induced SCEs in human whole-blood lymphocyte cultures at concentrations (0.125-2 mM) comparable to those used for vinyl acetate. The results indicate that vinyl acetate induces chromosome damage in cell cultures through enzyme-mediated hydrolysis to acetaldehyde.

Acetaldehyde↗
PubMed1984

Kinetics of caffeine metabolism in control and 3-methylcholanthrene induced rat liver microsomes.

The kinetics of formation of primary metabolites of caffeine (paraxanthine, theophylline, theobromine and 1,3,7-trimethyluric acid) was studied in control (CO) and 3-methylcholanthrene-induced (MC) rat liver microsomes. Vmax was similar but Km was 16 times lower for total caffeine metabolism in CO and MC microsomes, respectively. Similar behavior was observed in the formation of each metabolite. Single metabolites showed different degrees of induction at non-saturating concentrations of caffeine. Kinetics was non-linear in CO microsomes.

Animals↗
PubMed1984

An enzyme-linked immunosorbent procedure for assaying aflatoxin B1.

A polyclonal rabbit antibody preparation against aflatoxin B1 (AFB1), produced by immunization with a bovine serum albumin-AFB1 conjugate, has been used to develop an enzyme-linked immunosorbent assay (ELISA). AFB1-ovalbumin, obtained by reacting either AFB1-8,9-dichloride or -8,9-dibromide with ovalbumin, was used to coat each well of a polyvinyl microtitre dish. Rabbit antibody, diluted 1:100 000, was added to each well and left to attach for 90 min, then the excess was washed off with phosphate-buffered saline/Tween. Anti-rabbit IgG coupled to peroxidase was then added, left for 90 min and the excess washed away. Residual peroxidase activity was assayed using tetramethylbenzidine as substrate; the reaction was quenched at the end of the 15-min incubation period with 2 N sulfuric acid. Inhibitor studies to assay AFB1 and related compounds in urine involved prior incubation of the diluted anti-AFB1 antibody with inhibitor for 60 min at 37 degrees C, prior to dispensing into the multi-well plates. Inhibitor studies with AFB1 showed inhibition over a concentration range of 10(-1) to 10(-5) micrograms/ml. The minimum detectable concentration was approximately 10(-5) micrograms/ml (0.032 pmol/ml). Anti-AFB1 antibody was also inhibited by iro-AFB1-DNA, one of the forms of AFB1-DNA, as well as by AFB1-guanine. Undiluted urine from normal subjects inhibited antibody binding to plates; this inhibition could be prevented by either dilution or extraction procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Aflatoxin B1↗
PubMed1983

Styrene oxidation to styrene oxide in human erythrocytes is catalyzed by oxyhemoglobin.

Oxygenated human erythrocytes catalyzed the oxidation of styrene to styrene oxide. This reaction was inhibited by CO but not by superoxide dismutase, catalase and scavengers of hydroxyl radicals. In partially deoxygenated erythrocytes styrene oxidation showed a linear relationship with the molar fraction of oxyhemoglobin. These data indicate that oxyhemoglobin and not free oxygen radicals are involved in styrene oxidation.

Carbon Monoxide↗
PubMed1983

Styrene oxidation to styrene oxide by hydroxyl radicals produced during reaction of xanthine with xanthine oxidase in the presence of Fe3+.

Styrene was oxidized to styrene oxide during reaction of xanthine (X) with xanthine oxidase (XO) in the presence of Fe3+. This reaction showed a dose-dependent requirement of iron and was inhibited by superoxide dismutase (SOD) and catalase, indicating that both the superoxide anion and H2O2 were essential. Styrene oxide production was inhibited by hydroxyl radical scavengers indicating that this reactive oxygen intermediate could be the proximal oxidant involved in styrene oxidation to styrene oxide.

Chemical Phenomena↗
PubMed1983

Styrene oxidation to styrene oxide coupled with arachidonic acid oxidation by soybean lipoxygenase.

Styrene was co-oxidated to styrene oxide during soybean lipoxygenase catalyzed formation of arachidonic acid lipid peroxides. Styrene oxidation showed linear dependence on the amount of enzyme and on arachidonic acid concentration, and saturation kinetics with styrene concentration. Styrene oxide formation was dependent on the lipid substrate used and was inhibited by antioxidants. Lipid peroxides appear to be able to support styrene oxidation when produced from rat liver microsomes.

Animals↗
PubMed1982

C-band heterochromatin polymorphism of human chromosomes 1, 9, 16, Y.

Results are presented of a C-band investigation of the chromosomes 1, 9, 16, Y of two unselected populations from Central Italy and of 30 normal families. A high incidence of polymorphism was observed in these populations. Moreover, though the majority of the observed variants were inherited from parents to child in a Mendelian way, 3/30 children presented differences from the parental pattern. The results are discussed together with the data of other reports.

Adult↗
PubMed1982

Polymorphism of human chromosomes 1, 9, 16, Y: variations, segregation and mosaicism.

A study was carried out on C-banded chromosomes 1, 9, 16, Y from an unselected population and from 30 normal families. We found: a) great variability in length and position of the C-bands; b) somatic mosaicism involving C-bands; c) variants in children that were not present in parental patterns. The possible role of crossing-over in generating the last two phenomena is discussed.

Adult↗
PubMed1981

Styrene oxidation to styrene oxide in human blood erythrocytes and lymphocytes.

Human erythrocytes and lymphocytes catalyzed styrene oxidation to styrene oxide. The erythrocyte catalyzed reaction was inhibited by CO, occurred in the absence of NADPH and NADH and was undetectable in the absence of O2 and with erythrocyte membranes. Lymphocyte catalyzed styrene oxide formation required the addition of cofactors and these cells showed 6 times the activity of erythrocytes with a 4 times lower styrene concentration. Although lymphocytes appear to be more active than red blood cells in styrene oxidation, their contribution to styrene metabolism in whole blood seems extremely small.

Epoxy Compounds↗