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A Iannone

Publications and source records attributed to A Iannone.

At least 19 recordsLinked to original sources
PubMed2001

N-acetylcysteine inhibits in vivo nitric oxide production by inducible nitric oxide synthase.

This in vivo study evaluates the effect of N-acetylcysteine (NAC) administration on nitric oxide (NO) production by the inducible form of nitric oxide synthase (iNOS). NO production was induced in the rat by the ip administration of 2 mg/100 g lipopolysaccharide (LPS). This treatment caused: (1) a decrease in body temperature within 90 min, followed by a slow return to normal levels; (2) an increase in plasma levels of urea, nitrite/nitrate, and citrulline; (3) the appearance in blood of nitrosyl-hemoglobin (NO-Hb) and in liver of dinitrosyl-iron-dithiolate complexes (DNIC); and (4) increased expression of iNOS mRNA in peripheral blood mononuclear cells (PBMC). Rat treatment with 15 mg/100 g NAC ip, 30 min before LPS, resulted in a significant decrease in blood NO-Hb levels, plasma nitrite/nitrate and citrulline concentrations, and liver DNIC complexes. PBMC also showed a decreased expression of iNOS mRNA. NAC pretreatment did not modify the increased levels of plasma urea or the hypothermic effect induced by the endotoxin. The administration of NAC following LPS intoxication (15 min prior to sacrifice) did not affect NO-Hb levels. These results demonstrate that NAC administration can modulate the massive NO production induced by LPS. This can be attributed mostly to the inhibitory effect of NAC on one of the events leading to iNOS protein expression. This hypothesis is also supported by the lack of effect of late NAC administration.

Acetylcysteine↗
PubMed2001

Maximal endothelial tissue plasminogen activator release is not impaired in patients with acute coronary syndromes before heparin treatment.

Procoagulant and fibrinolytic disturbances are described in patients with acute coronary syndromes (ACS), but whether defective maximal tissue plasminogen activator (t-PA) release from the endothelium is also present is still controversial. Previous studies did not take into consideration the contribution of heparin, which strongly affects fibrinolysis. Accordingly, in this study, we measured maximal t-PA release in patients with ACS before, during, and after heparin treatment. Maximal t-PA release was measured by the venous occlusion test in 38 hospitalized patients with confirmed ACS (18 acute myocardial infarctions and 20 unstable anginas) before starting heparin, during heparin treatment, and 4 and 12 h after discontinuation. Plasma plasminogen activator inhibitor type 1 (PAI-1), D-dimer and prothrombin fragment F1 + 2 were also measured. Eighteen age-matched subjects with no evidence of coronary disease were used as controls. At admission, patients showed significantly higher plasma levels of t-PA, PAI-1, and F1 + 2 than controls. Before heparin, maximal t-PA release was similar in patients and controls. Heparin treatment was associated with a significant increase of plasma t-PA, while it did not affect maximal t-PA release. Coagulative and fibrinolytic disturbances are present in patients with ACS, but these do not include maximal t-PA release. Among our patients, maximal t-PA release appears stable over time and is not affected by heparin treatment.

Aged↗
PubMed2000

Factors determining the formation of complexes between alpha-cyclodextrin and alkylated substances in aqueous solutions: a calorimetric study at 25 degrees C.

The formation of complexes of alpha-cyclodextrin with cycloalkanediols, monoalkylamines and 1-alkanols has been studied calorimetrically at 25 degrees C in water, in phosphoric acid, pH 1.3, and in phosphate buffer, pH 5.5, respectively. When a complex is formed, calorimetry enables the calculation of both the enthalpy and the association constant, from which the free energy and the entropy of the process can be obtained. A model is proposed to explain the unusual trend of the association parameters for substances having alkyl chains longer than six-seven carbon atoms. The main role played by the different functional groups, and the forces involved in the association process, are discussed in the light of the signs and values of the thermodynamic parameters obtained. The effect of the variation of the aqueous medium on the hydration of the interacting substances and the consequent changes in the association parameters have been investigated. To this end, the thermodynamic parameters for the formation of the complexes between the cyclodextrin and 1-pentanol were determined at increasing concentrations of phosphate buffer. There is an increase in the association constant due to a positive entropy contribution originating from the relaxation of water molecules from the hydrophobic hydration cosphere of the alkanol to an increasingly disordered bulk. Deaquation of the interacting substances is the main factor determining the stability of the inclusion complex.

Alkylation↗
PubMed2000

Antioxidative efficacy of parallel and combined supplementation with coenzyme Q10 and d-alpha-tocopherol in mildly hypercholesterolemic subjects: a randomized placebo-controlled clinical study.

It has been claimed that coenzyme Q10 (Q10) would be an effective plasma antioxidant since it can regenerate plasma vitamin E. To test separate effects and interaction between Q10 and vitamin E in the change of plasma concentrations and in the antioxidative efficiency, we carried out a double-masked, double-blind clinical trial in 40 subjects with mild hypercholesterolemia undergoing statin treatment. Subjects were randomly allocated to parallel groups to receive either Q10 (200 mg daily), d-alpha-tocopherol (700 mg daily), both antioxidants or placebo for 3 months. In addition we investigated the pharmacokinetics of Q10 in a separate one-week substudy. In the group that received both antioxidants, the increase in plasma Q10 concentration was attenuated. Only vitamin E supplementation increased significantly the oxidation resistance of isolated LDL. Simultaneous Q10 supplementation did not increase this antioxidative effect of vitamin E. Q10 supplementation increased and vitamin E decreased significantly the proportion of ubiquinol of total Q10, an indication of plasma redox status in vivo. The supplementations used did not affect the redox status of plasma ascorbic acid. In conclusion, only vitamin E has antioxidative efficiency at high radical flux ex vivo. Attenuation of the proportion of plasma ubiquinol of total Q10 in the vitamin E group may represent in vivo evidence of the Q10-based regeneration of the tocopheryl radicals. In addition, Q10 might attenuate plasma lipid peroxidation in vivo, since there was an increased proportion of plasma ubiquinol of total Q10.

Aged↗
PubMed1999

1-Benzopyran-4-one antioxidants as aldose reductase inhibitors.

Starting from the inhibitory activity of the flavonoid Quercetin, a series of 4H-1-benzopyran-4-one derivatives was synthesized and tested for inhibition of aldose reductase, an enzyme involved in the appearance of diabetic complications. Some of the compounds obtained display inhibitory activity similar to that of Sorbinil but are more selective than Quercetin and Sorbinil with respect to the closely related enzyme, aldehyde reductase, and also possess antioxidant activity. Remarkably, these compounds possess higher pKa values than carboxylic acids, a characteristic which could make the pharmacokinetics of these compounds very interesting. Molecular modeling investigations on the structures of inhibitors bound at the active site of aldose reductase were performed in order to suggest how these new inhibitors might bind to the enzyme and also to interpret structure-activity relationships.

Aldehyde Reductase↗
PubMed1999

Prooxidant activity of ferrioxamine in isolated rat hepatocytes and linoleic acid micelles.

The complex iron-desferrioxamine (ferrioxamine) is considered chemically unreactive, and not able to participate in redox cycle reactions. Desferrioxamine-dependent toxicity is, however, described in both human and animal studies. The aim of this work was to test the possibility that chelated iron, under certain circumstances, could enter redox reactions, giving an explanation of desferrioxamine side effects. Carefully prepared ferrioxamine, to obtain a 1:1 desferrioxamine:iron ratio, was added to isolated rat hepatocytes and to linoleic acid micelles. A strong prooxidant and cytotoxic effect was observed in the cells, also potentiating tert-butyl hydroperoxide-induced lipid peroxidation. In micelles, the prooxidant effect was observed only in the presence of ascorbate, which is oxidized during the process, giving rise to ascorbyl radical. Ferrioxamine, under the experimental conditions used, did not release iron, indicating that the prooxidant effect was due to iron redox cycling. The addition of desferrioxamine prevented both ferrioxamine- and tert-butyl hydroperoxide-induced lipid peroxidation and cytotoxicity. Concurrently, a nitroxide radical was detected, an indication of the radical scavenger activity of the hydroxamic moiety. No radical species was observed when ferrioxamine was added to the same system. The prooxidant effect of ferrioxamine gives a possible explanation of the reported human and animal desferrioxamine toxicity. When, in compartmentalized regions, the ratio of desferrioxamine:metal reaches 1:1, ferrioxamine is formed. In the absence of metal-free desferrioxamine, ferrioxamine can participate in redox cycling reactions, initiating lipid peroxidation and cytotoxicity.

Animals↗
PubMed1998

Antioxidant activity of carotenoids: an electron-spin resonance study on beta-carotene and lutein interaction with free radicals generated in a chemical system.

beta-Carotene is thought to be a chain-breaking antioxidant, even though we have no information about the mechanism of its antioxidant activity. Using electron-spin resonance (ESR) spectroscopy coupled to the spin-trapping technique, we have studied the effect of beta-carotene and lutein on the radical adducts of the spin-trap PBN (N-t-butyl-alpha-phenylnitrone) generated by the metal-ion breakdown of different tert-butyl hydroperoxide (tBOOH) concentrations in methylene chloride. The peroxyl radical, along with an oxidation product of PBN (the PBNOx), trapped at room temperature from the breakdown of high concentration of tBOOH (1 M), were quenched by beta-carotene or lutein, in competition with the spin-trapping agent. However, carotenoids were not able to quench the alkoxyl and methyl radicals generated in the reaction carried out in the presence of low tBOOH concentration (1 mM). The reaction between carotenoids and the peroxyl radical was also carried out in the absence of the spin trap, at 77 K: Under these different experimental conditions, we did not detect any radical species deriving from carotenoids. In the same system, a further evidence of the peroxyl radical quenching by beta-carotene and lutein was obtained. The antioxidant activity of vitamin E was also tested, for comparison with the carotenoids. In the presence of alpha-tocopherol, peroxyl and alkoxyl radicals were quenched, and the tocopheroxyl radical was detected. Our data provide the first direct evidence that carotenoids quench peroxyl radicals. Under our experimental conditions, we did not detect any carotenoid radical species that could derive from the interaction with the peroxyl radical. The radical-trapping activity of beta-carotene and lutein demonstrated in this chemical reaction contributes to our understanding carotenoid antioxidant action in biological systems.

Antioxidants↗
PubMed1998

Spatial and temporal dynamics of hepatic stellate cell activation during oxidant-stress-induced fibrogenesis.

In vitro and in vivo studies indicate that oxidant stress is implicated in liver fibrogenesis. However, it is still unknown whether, in vivo, oxidant stress directly affects the hepatic cells responsible for fibrogenesis, ie, the hepatic stellate cells (HSCs). This study was aimed at answering this question by assessing the temporal and spatial relationships between oxidant stress and activation of HSCs in an in vivo model of oxidant-stress-associated fibrogenesis. To this purpose, rats were treated with carbon tetrachloride (CCl4) and livers subjected to in situ perfusion with nitroblue tetrazolium, which, in the presence of superoxide ions, is reduced to an insoluble blue-colored formazan derivative and is readily detectable in the tissue by light microscopy. Moreover, various combinations of in situ hybridization and immunocytochemical analyses were performed. An acute dose of CCl4 caused a transient production of superoxide radicals at 24 hours into pericentral necrotic areas, whereas HSC appearance and expression of collagen mRNA were detectable only at 48 and 72 hours. After chronic CCl4 intoxication, higher levels of oxygen radical production in necrotic areas were detectable along with dramatic and sustained activation of HSCs. However, maximal HSC activation was still delayed as compared with superoxide production. Expression of heme oxygenase, a gene responsive to a variety of oxidant stress mediators, was strongly enhanced by chronic CCl4 administration but remained unchanged in HSCs, both in situ and after isolation of pure HSC fractions from control and CCl4-treated animals. In conclusion, during postnecrotic fibrogenesis, oxidant stress anticipates HSC activation. HSCs do not directly face an oxidant stress while engaged in active fibrogenesis.

Animals↗
PubMed1996

'Free' iron, as detected by electron paramagnetic resonance spectroscopy, increases unequally in different tissues during dietary iron overload in the rat.

'Free' iron concentration, as determined by electron paramagnetic resonance (EPR) spectroscopy, and lipid peroxidation (LPO), as determined by thiobarbituric acid test, were assessed in the lung, heart, liver, spleen, brain and kidney of rats subjected to experimental iron overload. Two tests, Desferal- and NO-available iron, were used to measure 'free' iron and gave comparable results. The most pronounced accumulation of 'free' iron was observed in liver, kidney and spleen. Differences between control and iron loaded animals increased during the initial 90 days of treatment. Between 90 and 180 days 'free' iron concentration reached a steady state level, or even decreased, as in the case of liver. Lipid peroxidation level, measured in the organs of both treated and matched controls, did not give any significant difference during the initial 90 days of treatment. A significant augmentation was observed in liver, kidney, spleen and heart at 180 days. The results of the present research show that, under conditions of moderate siderosis, the occurrence of LPO is partially related to the level of 'free' iron.

Animals↗
PubMed1995

Activation of alkylhydrazines to free radical intermediates by ethanol-inducible cytochrome P-4502E1 (CYP2E1).

Electron spin resonance (EPR) spectroscopy analysis using the spin trapping agent 4-pyridyl-1-oxide-t-butyl nitrone (4-POBN) was used to measure the formation of free radical intermediates during NADPH-dependent oxidation of 1-methyl-, 1-ethyl-, and 1-isopropylhydrazine in rat liver microsomes and in reconstituted enzyme systems. The experiments in microsomes revealed that the specific activation of the hydrazines, as measured by the EPR signal intensities, was about two-fold higher, when expressed per nmol of P-450, in microsomes from rats treated with ethanol (EtOH) as compared to membranes isolated from either phenobarbital (PB)-, beta-naphthoflavone (beta-NF)-treated or control rats. Furthermore, kinetic experiments revealed that EtOH-microsomes had an apparent affinity for 1-ethylhydrazine about one order of magnitude higher than PB-microsomes. In reconstituted vesicular systems composed of phospholipids, NADPH cytochrome P-450 reductase and P-450, the intensities of EPR signals produced by the formation of the methyl-, ethyl- and isopropyl-free radicals, were 3- to 5-fold more intense in membrane vesicles containing ethanol-inducible CYP2E1 than phenobarbital-inducible CYP2B1. By contrast, CYP1A2, CYP2B4 and CYP2C4 were inefficient catalysts of radical formation. Desferrioxamine, catalase and superoxide dismutase did not influence the extent of ethyl radicals formed in EtOH-microsomes, indicating that hydroxyl radicals are not involved in the CYP2E1-dependent activation of 1-ethylhydrazine. Addition of cytochrome b5, an efficient donor of the second electron to P-450 and hence an inhibitor of the formation of the oxy-cytochrome P-450 complex, increased to be consistent with the results, did not influence the amount of ethyl radicals trapped. In liver microsomes from untreated rats selective substrates of CYP2E1, such as diethyl-dithiocarbamate and p-nitrophenol, as well as anti-CYP2E1-IgG, inhibited the free radical formation from 1-ethylhydrazine by about 60%. The anti-CYP2E1 IgG used significantly inhibited ethyl radical production also in human liver microsomes incubated with 1-ethylhydrazine and 4-POBN. Taken together, these results indicate that CYP2E1, as compared to other rat liver cytochromes P-450, is an efficient catalyst of transformation of alkylhydrazines to free radical intermediates, a finding that might be of importance in the development of the toxicity of these compounds.

Animals↗
PubMed1993

Free radical production during metabolism of organic hydroperoxides by normal human keratinocytes.

Evidence of a relationship between tumor production induced by various organic (hydro)peroxides and free radical formation has been shown in cultured murine keratinocytes and human skin-tumor cell line. In the present study the bioactivation of cumene hydroperoxide, t-butyl-hydroperoxide, and benzoyl peroxide via one-electron oxidation or reduction was compared in freshly isolated and in cultured normal human keratinocytes. The formation of methyl free radicals during the metabolism of cumene and t-butyl-hydroperoxide was shown by the electron spin resonance-spin trapping technique. Radical formation increased under hypoxic conditions. An intracellular activation site was demonstrated by the use of two spin-trapping agents, the hydrophilic, membrane-impermeable, 3,5-dibromo-4-nitrosobenzenesulfonic acid and the lipophilic, membrane-permeable alpha-(4-pyridyl-1-oxide)-N-t-butylnitrone. At 30 min incubation and 25 mM concentration, hydroperoxides exhibited cytotoxicity, as indicated by trypan blue exclusion and lactate dehydrogenase release assay; free radicals were concurrently trapped. Hydroperoxides at a lower concentration (1 mM) did not significantly affect cell viability. However, free radical production was still detected using a membrane-permeable spin trap. The incubation of keratinocytes with benzoyl peroxide did not show any peroxide-dependent radical adduct. No significant differences in bioactivation capability were demonstrated between freshly isolated and cultured human keratinocytes. The results indicate that cultured human keratinocytes can be used as a model system for the study of the metabolic activation to free radical intermediates of toxic and carcinogenic compounds in the epidermis.

Benzene Derivatives↗
PubMed1993

Tert-butylhydroperoxide bioactivation to methyl radical in rat liver mitochondria and submitochondrial particles.

Electron paramagnetic resonance spectroscopy (EPR) coupled to the spin trapping technique was used to detect carbon-centered radicals in rat liver mitochondria and submitochondrial particles exposed to t-butyl-hydroperoxide (TBH), using the spin trapping agent 3,5-dibromo-4-nitroso-benzenesulfonic acid (DBNBS). The signal recorded was unambiguously assigned to the methyl radical adduct. DBNBS was added to isolated rat liver mitochondria energized with succinate, and the methyl radical adduct was observed. The addition of NADH, NADPH, inhibitors of the respiratory chain, and of monoaminoxidase (MAO) inhibitors did not cause any relevant modification in the yield of radical adduct formation. Boiling and the addition of a non-ionic detergent inhibited the formation of the radical adduct, while experiments carried out under hypoxic conditions generated a significant increase in methyl radical formation. Further experiments were carried out on sub-mitochondrial particles (SMP) giving rise to, basically, the same results. From the above results, we are proposing that haem prosthetic groups are the likely source of TBH bioactivation in mitochondria.

Animals↗
PubMed1992

In vitro and in vivo evidence for the formation of methyl radical from procarbazine: a spin-trapping study.

Electron spin resonance (ESR) analysis combined with the use of 4-pyridyl-1-oxide-t-butyl nitrone (4-POBN) and dibromonitroso benzenesulfonic acid (DBNBS) as spin-trapping agents was used to characterize free radical generation during the metabolism of the anticancer agent procarbazine [N-isopropyl-a-(2-methylhydrazino)-p-toluamide hydrochloride]. The formation of free radical species, identified as methyl radicals, was observed during oxidation of procarbazine in rat liver microsomes and isolated hepatocytes in vitro, as well as in several organs following administration of the drug in vivo. A cytochrome P450-mediated reaction, involving P450IA and IIB isoenzymes, was responsible for the activation process. The metabolic pathway leading to free radical formation was characterized using various procarbazine metabolites and revealed strict analogies with previously published data on methane production from procarbazine. These results supported the identification of the trapped species as methyl free radical and suggested that C-oxidation of azoprocarbazine is the main source of radical intermediates derived from this anticancer drug.

Animals↗
PubMed1992

Detection and quantitation in rat tissues of the superparamagnetic magnetic resonance contrast agent dextran magnetite as demonstrated by electron spin resonance spectroscopy.

RATIONALE AND OBJECTIVES: The compound studies in this article is a superparamagnetic macromolecular complex of magnetite cores coated with hydrophilic dextran, which is under active investigation as a contrast agent for magnetic resonance imaging (MRI) in liver and spleen. The biodistribution of paramagnetic compounds is problematic and is usually studied by histochemical reactions or by radiolabeling the compound under study. The purpose of this article is to show how electron spin resonance (ESR) spectroscopy detects dextran magnetite (DM) particles in tissues. METHODS: DM injected intravenously in the experimental animal was detected in some reticulo-endothelial organs by ESR. The spectroscopic study was validated using electron microscopy and electron-probe microanalysis. RESULTS: DM exhibits an ESR spectrum; ESR delineated the distribution of DM distribution in liver, spleen, bone marrow, and blood as a function of time. The blood clearance was biphasic, dependent on the size of particles. CONCLUSIONS: ESR spectroscopy is a highly sensitive and reproducible method of studying DM distribution.

Animals↗
PubMed1991

Blood clearance of dextran magnetite particles determined by a noninvasive in vivo ESR method.

Dextran magnetite (DM) is a potential MR contrast agent with superparamagnetic properties. Its fast clearance from the blood and selective uptake by tissue macrophages provide advantages for imaging tumors in the liver and spleen. DM consists of a suspension of solid particles with a wide distribution of sizes. In this study we have used ESR spectroscopy to determine the blood clearance of DM injected iv in mice. The spectra are obtained on living animals by inserting the tail of a mice into the waveguide cavity of the ESR spectrometer and recording the ESR spectrum continuously. This procedure allows the direct measurement of the plasma clearance of DM from individual animals, without blood sampling. We applied this method to study the clearance of suspensions of DM particles with different average sizes.

Animals↗