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E Lissi

Publications and source records attributed to E Lissi.

35 records · Page 2Linked to original sources
PubMed1998

[Duchenne muscular dystrophy. Effects of vitamin E administration on urinary luminescence].

BACKGROUND: Urinary luminescence is increased in patients with Duchenne muscular dystrophy, probably due to the higher oxidative stress present in this disease. AIM: To assess the effects of vitamin E supplementation on urinary luminescence in children with Duchenne muscular dystrophy. PATIENTS AND METHODS: Eighteen children with muscular dystrophy aged 12.2 years old and nine control children aged 10 years old, received 400 IU/day of vitamin E during one month. Prior to supplementation and twice a week thereafter, spot urine samples were obtained to measure urinary luminescence in a scintillation counter. RESULTS: There was a wide variability in urinary luminescence within and between children. Mean values decreased after vitamin E supplementation in six of nine controls and in 12 of 18 children with muscular dystrophy. CONCLUSIONS: Vitamin E supplementation significantly decreases urinary luminescence in healthy children and in patients with Duchenne muscular dystrophy. Therefore, it could be useful for the treatment of this disease.

Adolescent↗
PubMed1996

Nitric oxide diffusion in membranes determined by fluorescence quenching.

Quenching of pyrene derivative fluorescence by nitric oxide was used to evaluate the apparent diffusion coefficients of nitric oxide in artificial and biological membranes. The apparent second-order quenching constants of nitric oxide were obtained from Stern-Volmer plots using methyl- and undecylpyrene derivatives incorporated into liposomes and erythrocyte plasma membranes in order to assess the ability of nitric oxide to interact with molecules located at different positions in the membrane. Diffusion coefficients were estimated from the determined second-order quenching constants and compared to that of oxygen obtained under the same conditions. Oxygen and nitric oxide presented similar diffusional behavior in agreement with their similarity in structures, with the differences observed attributable to the higher lipophilicity of oxygen compared to nitric oxide. In solution, both showed the same quenching efficiency while in liposomes and erythrocyte ghosts oxygen diffusion was twice that of nitric oxide (k(O2)/k(NO) = 2). Nitric oxide diffusion coefficients determined at 20 degrees C ranged from 1.3 x 10(-5) cm2 s-1 in liposomes to 0.4 x 10(-5) cm2 s-1 in surface erythrocyte plasma membranes. Both nitric oxide and oxygen had larger quenching constants for the undecyl derivative compared to the methylpyrene compound incorporated into erythrocyte plasma membranes, indicating an increased solubility of both gases toward the center of the membrane.

Animals↗
PubMed1996

Effect of Additives on the $ \hbox{I}_{2} + \hbox{I}^{-} \leftrightarrow \hbox{I}^{-}_{3} $ Reaction in Micellar Solutions of Sodium Dodecylsulfate: Partitioning and Solubilization Site of Iodine.

The partition constants (K(p)) of iodine between sodium dodecylsulfate micelles and the external media have been measured in the presence of water-soluble (sodium sulfate) and micelle-soluble (n-hexane and n-hexanol) additives. A spectrophotometric method based in the analysis of the alterations provoked by the presence of the surfactant plus the additives upon the reversible reaction taking place between iodine and iodide to give tri-iodide ions was employed (Abuin, E., and Lissi, E., J. Chem. Ed. 69, 340 (1992)). The effect of the additives upon the n-octanol/water partitioning (K(o/w)) of iodine was also determined. The results obtained for K(p) and its relationship with the K(o/w) values are indicative of a preferential localization of iodine at the surface of the micelles.

Journal Article↗
PubMed1996

Total antioxidant capacity of human seminal plasma.

Although the importance of seminal plasma in the protection of spermatozoa against reactive oxygen species is well known, only a few studies have investigated its antioxidative properties and the possible relationship between infertility and plasmatic antioxidant defences. The aim of the present study was to assess the status of the total non-enzymatic antioxidant defences of human seminal plasma. Semen samples were obtained from 101 patients consulting for infertility and 15 fertile donors. A total reactive antioxidant potential (TRAP) in seminal plasma was determined by luminol-chemiluminescence. The relationship of seminal TRAP values to lipid peroxidation was also evaluated. Our results show that semen samples from fertile controls show total antioxidant capacity at higher frequency and value than equivalent samples from suspected subfertile men. This fact as well as the inverse relationship observed between antioxidant capacity and lipid peroxidation potential strongly suggest that impaired antioxidant defences may play a role in infertile disorders.

Antioxidants↗
PubMed1995

Evaluation of total antioxidant potential (TRAP) and total antioxidant reactivity from luminol-enhanced chemiluminescence measurements.

The effect of antioxidants and biological fluids on the intensity of luminol induced chemiluminescence by radicals derived from the thermolysis of 2,2'-azo-bis(2-amidinopropane) has been employed to monitor TRAP and TOTAL ANTIOXIDANT REACTIVITY (TAR) levels. The latter parameter, which considers not only the quantity of oxidants but also their reactivity, is considered a potentially more useful index of the antioxidant status of a biological fluid. The results obtained employing human blood plasma and human urine show that the detected antioxidant capacity of both fluids is mainly related to the uric acid concentration of the samples.

Amidines↗
PubMed1994

On the use of the quenching of luminol luminescence to evaluate SOD activity.

Addition of horseradish peroxidase to a luminol solution (pH = 9.4) produces a burst of light followed by a steady luminescence that lasts for several minutes. This steady-state luminescence is readily quenched by SOD, with a Q1/2 concentration (the additive concentration needed to decrease by one-half the emitted luminescence intensity) of c.a. 4 ng/ml (14 mU/ml). The luminescence intensity decrease can then be employed to evaluate SOD activity in SOD-containing samples. However, the light intensity can also be quenched by additives, such as Trolox, that are able to trap luminol-derived intermediates. It is proposed that double quenching experiments must be performed in order to be able to relate the observed effect of an additive to its SOD-like activity.

Antioxidants↗
PubMed1994

Antioxidant activity of depsides and depsidones.

The antioxidant activity of lichenic metabolites, depsides and depsidones, was assessed by their effects as inhibitors of rat brain homogenate auto-oxidation and beta-carotene oxidation. The results obtained in both systems indicate that lichenic metabolites afford a moderate protection in the microM concentration range. The largest effect was measured employing 1'-chloropannarin in the brain homogenate auto-oxidation, where a 66% protection was afforded at 1.7 microM. This protection is very similar to that elicited by addition of the reference antioxidant propylgallate (70% protection at 1.3 microM).

Animals↗
PubMed1993

Photoreactions of riboflavin with spermine and their role in tryptophan photoconsumption induced by riboflavin.

The influence of spermine (Spr) on riboflavin (Rb) and riboflavin-tryptophan (Rb-Trp) solutions irradiated at 450 nm under aerobic and anaerobic conditions was studied. In both systems, it is shown that Spr interacts with 3Rb probably giving spermine-derived and flavin-derived radicals. In the presence of oxygen, modified Rb is regenerated with the simultaneous production of the active oxygen species O2.- and/or HO2.. The addition of Spr to the Rb-Trp system under aerobic conditions leads to a small protection of Trp consumption, although oxygen consumption is increased. This small protection arises as a consequence of competitive interaction of Trp and Spr with 3Rb. The competition of Spr and oxygen for 3Rb could also explain the autocatalytic oxygen consumption observed in the presence of the amine. Under anaerobic conditions Spr produces a larger protection of Trp consumption, which is compatible with the larger Rb triplet lifetime expected under these conditions.

Animals↗
PubMed1992

Luminol luminescence induced by 2,2'-Azo-bis(2-amidinopropane) thermolysis.

2,2'-Azo-bis(2-amidinopropane) thermolysis induces luminol luminescence. The luminescence intensity is quenched by SOD, catalase, Trolox and human blood serum. However, the time course of the light intensity profile is different for the different additives. In particular, the quenching efficiency of Trolox and human blood serum decreases with time after addition. Double quenching experiments show that SOD and Trolox are not competitive quenchers, while a simple competition can be established between Trolox and human blood serum in trapping a common intermediate. From the kinetic analysis of the data it is concluded that, at least at low additive concentrations, Trolox scavenges a luminol derived radical. Higher concentrations of Trolox or human blood serum produce induction times that are proportional to the additives concentrations. The possibility of employing luminol luminescence in the evaluation of TRAP levels and the capacity of biological samples to scavenge free radicals is discussed.

Amidines↗
PubMed1991

Effects of pH and ionic micelles on the riboflavin-sensitized photoprocesses of tryptophan in aqueous solution.

The effects of pH and ionic micelles on the rates of product formation following irradiation of riboflavin in the presence of tryptophan were investigated by absorption and fluorescence spectroscopy. Under anaerobic conditions, formation of riboflavin-tryptophan adducts was inhibited in acid solutions and by the addition of anionic (sodium dodecylsulphate) and cationic (cetyltrimethylammonium bromide) micelles. The oxidation of tryptophan photoinduced by riboflavin was considerable faster in basic solutions.

Cetrimonium↗
PubMed1991

Free radical scavenging activity of carnosine.

The capacity of carnosine to decrease free radical-induced damage was evaluated using the oxidation of brain homogenates, the 2,2'-azobis-2-amidino propane-induced oxidation of erythrocyte ghost membranes, the radiation induced inactivation of horseradish peroxidase and the 2,2'-azobis-2-amidino propane-induced inactivation of lysozyme. Carnosine addition up to 17 mM did not produce any significant protection in either lipid peroxidation system, as assayed by the oxygen uptake rate. Carnosine addition reduces the intensity of the visible luminescence emitted, apparently due to a dark decomposition of the luminescent intermediates. Carnosine addition protects horseradish peroxidase and lysozyme from free radical mediated inactivation. The mean carnosine concentrations required to inhibit the inactivation rates by 50% were 0.13 mM and 0.6 mM for horseradish peroxidase and lysozyme, respectively.

Amidines↗
PubMed1986

Effects of antioxidants and haemoglobin status on the t-butyl hydroperoxide-induced oxygen uptake by red blood cells.

Oxygen uptake by erythrocytes exposed to t-butyl hydroperoxide (t-BHP) exhibited an induction period. The rate of oxygen consumption can be reduced by antioxidants and blood plasma. The induction time was not appreciably modified by the antioxidants tested, however, plasma increased it by a factor of two. The in vivo pretreatment with diethyl maleate (0.6 g kg-1) produced increased rates of oxygen uptake without changes in the induction period, while vitamin E (12.5 mg kg-1) elicited lower oxygen consumption rates and longer induction times, compared to those observed in cells from control rats upon addition of the hydroperoxide. These results suggest that the antioxidants tested on the t-BHP lipid peroxidation in erythrocyte suspensions act as inhibitors and/or retarders of the process. Furthermore, lipid peroxidation induced in these conditions seems to depend upon the haemoglobin status of the cells as oxygen uptake, malondialdehyde production and chemiluminescence were significantly higher in methaemoglobin-containing cells than in those containing oxyhaemoglobin.

Animals↗
PubMed1986

Interactions of neutral molecules with ionic micelles.

The interactions of neutral molecules with ionic micelles are analyzed. The cell and mass action models are presented in order to provide a semi-quantitative description of the solubilization process. Both approaches are discussed from a thermodynamic and kinetic point of view and the different definitions of solute incorporation constants are also discussed and compared. An extensive compilation of standard free energies of transfer from water to micelles is provided and the basis of the employed methods to obtain them is presented. Several aspects of the solubilization process such as its dynamics, the effect of additives, the probe microenvironment and its dependence with the solute mean occupation number are reviewed and critically discussed. The effect of solute incorporation upon the micelle shape and size is also briefly reviewed.

Colloids↗
PubMed1984

Visible chemiluminescence induced by t-butyl hydroperoxide in red blood cell suspensions.

Red blood cells from Wistar rats were exposed to milimolar concentrations of t-butyl hydroperoxide. Extensive hemoglobin oxidation (methemoglobin formation), t-butyl hydroperoxide cleavage (t-butanol formation) and peroxidation (measured by oxygen consumption and thiobarbituric acid reactive substances) was observed. Significant chemiluminescence was emitted by the system. Hemoglobin oxidation and t-butanol production were independent of oxygen pressure and free radical scavengers, however, luminescence was enhanced as oxygen pressure increased and it was reduced by addition of free radical scavengers. The spectral distribution of the light emitted suggests that the luminescence detected is not due to singlet oxygen dimol emission. The results are in agreement with a lipid peroxidative mechanism initiated by t-butoxy radicals produced in the interaction of hemoglobin and t-butyl hydroperoxide.

Animals↗
PubMedDate not supplied

Rat urinary chemiluminescence: effect of ethanol and/or hexachlorobenzene uptake.

Hexachlorobenzene (HCB) administration to rats induces porphyria cutanea tarda, characterized by high levels of urinary porphyrins (> 40 micrograms/day) and accumulation of highly carboxylated porphyrins in liver (> 15 micrograms/g of tissue). Ethanol administration, under the conditions employed, was not porphyrinogenic and was able to diminish some of the responses elicited by HCB. Furthermore, ethanol and/or HCB administration leads to organ disturbances that involve oxidative stress. We have measured the changes in urinary chemiluminescence (CL) levels, as part of a systematic evaluation of the metabolic alterations in rats chronically treated with ethanol and/or HCB. The results, that constitute the first set of urinary CL data obtained from an animal model system, indicate that the measurement of the spontaneous urinary CL can constitute a fast, simple and sensitive method to evaluate disturbances associated with oxidative stress.

Animals↗
PubMedDate not supplied

Lysozyme photo-oxidation by singlet oxygen: properties of the partially inactivated enzyme.

This work studies the behaviour of partially inactivated lysozyme formed by the effect of singlet oxygen, which was obtained through the irradiation of the native enzyme solution with polychromatic visible light using Methylene Blue as a sensitizer. The polyacrylamide gel analysis of the partially inactivated lysozyme solution shows the presence of different protein fractions. One of them, which corresponds to 53% of the original enzyme, has the same migration as the native enzyme. The others are a mixture of fractions (47%) that show slower migration to the cathode. When this experiment is carried out in the presence of sodium dodecyl sulfate, only one fraction is obtained, which rules out the presence of covalently aggregated forms of lysozyme. The partially inactivated lysozyme has lost 74% of the fluorescence emission of the tryptophan (Trp) residues. By using the anionic quencher iodide, it is determined that 45 and 36% of the fluorescence emission arising from the native and partially inactivated enzyme, respectively, are due to Trp residues exposed to the solvent. Michaelis-Menten constants (K(in)) of 0.296 and 0.511 (mg/ml) and maximum initial rates (Vmax) of 0.295 and 0.190 (mg/ml min) are determined for the native and the partially inactivated enzyme solutions, respectively. The same inactivation profile is found when the denaturing effect of increasing urea concentration on both the native and partially inactivated lysozyme is studied. It is postulated that the partially inactivated lysozyme solution is composed of one protein fraction with enzymatic activity similar to that of the native enzyme and also of a mixture of fractions (47% of the total enzyme) with very low activity and characterized by a high tryptophan photo-oxidation.

Kinetics↗