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Biomedical subjects

A Favier

Publications and source records attributed to A Favier.

At least 127 records · Page 7Linked to original sources
PubMed1994

Xanthine oxidase activity and lipid peroxide content following different types of ischemia in the isolated rat heart.

It is currently believed that reactive oxygen species are produced in the heart post-ischemia reperfusion, causing pathophysiological disorders. Studies reported in the literature dealing with this subject have generated contradictory findings. The aim of this study was to assess the catalytic activity of the superoxide anion-producing enzyme xanthine oxidase, and the level of lipid peroxides in isolated rat heart muscle undergoing ischemia of varying duration and severity followed by reperfusion. Three levels of ischemia were investigated: total, and partial at either 0.10 or 0.35 ml/min (residual flow rate). Three different periods of ischemia were examined in each case. After each period of ischemia, followed by 10 min of reperfusion, the heart was frozen in liquid nitrogen. Xanthine oxidase activity and lipid peroxide levels were assayed in the cardiac homogenate and in the centrifuged supernatant, respectively. In the different experimental protocols studied here, both cardiac xanthine oxidase and lipid peroxide levels remained statistically unchanged compared to the continuously perfused control hearts. Moreover, in a recent study (Boucher et al., FEBS Lett. 203, 261-264, 1992), we were unable to detect reactive oxygen species in perfusate upon reperfusion of ischemic rat hearts. These results suggest that changes in xanthine oxidase activity during myocardial ischemia-reperfusion, and lipid peroxidation, as assessed by measuring thiobarbituric acid reactants and lipid hydroperoxides, are not predominant phenomena in ischemia-reperfusion-induced injury, at least in the experimental model used in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Antioxidant status and lipid peroxidation in patients infected with HIV.

Deficiency in antioxidant micronutrients have been observed in patients with AIDS. These observations concerning only some isolated nutrients demonstrate a defect in zinc, selenium, and glutathione. An increase in free radical production and lipid peroxidation has been also found in these patients, and takes a great importance with recent papers presenting an immunodeficiency and more important an increase in HIV-1 replication secondary to free radicals overproduction. We have assessed different studies, trying to obtain a global view of the antioxidant status of these patients. In adults we observe a progressive decrease for zinc, selenium, and vitamin E with the severity of disease, except that selenium remains normal at stage II. However, the main dramatic decrease concerns carotenoids whose level at stage II is only half the normal value. To understand if these decreases in antioxidant and increases in oxidative stress occur secondary to the aggravation of the disease or, conversely, are responsible for it, we undertook a longitudinal survey of asymptotic patients. The preliminary results of this evaluation are presented. Paradoxically, lipid peroxidation is higher at stage II than at stage IV. This may be consecutive to a more intense overproduction of oxygen free radicals by more viable polymorphonuclear (PMN) at the asymptomatic stage. The free radicals production and lipid peroxidation seem secondary to a direct induction by the virus of PMN stimulation and cytokines secretion. N-Acetyl cysteine or ascorbate have been demonstrated in cell culture to be capable of blocking the expression of HIV-1 after oxidative stress and N-acetyl cysteine inhibits in vitro TNF-induced apoptosis of infected cells. In regard to all these experimental data, few serious and large trials of antioxidants have been conducted in HIV-infected patients, although some preliminary studies using zinc or selenium have been performed. In our opinion it is now time to evaluate in humans the beneficial effect of antioxidants. The more promising candidates for presenting synergistic effects when associated with N-acetyl cysteine seem to be beta-carotene, selenium and zinc.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Comparison of two digestion methods for the determination of selenium in biological samples.

Two digestion methods for the determination of selenium in biological samples have been compared: a classic digestion in a heating block by means of wet acid-ashing (HNO3-HClO4) and a microwave digestion in an open-vessel system by heating under reflux with HNO3-H2O2. The two methods were used to determine Se in plasma samples and different reference materials. There was no difference between the mean results, and the correlation coefficient for wet acid-ashing versus microwave digestion was 0.94. The two methods yielded accurate results for the certified materials analysed.

Humans↗
PubMed1994

Zinc changes in blood and urine during cyclic parenteral nutrition: relationships with amino acid metabolism.

Serum Zn, ultrafiltrable Zn and amino acids in serum and urine samples of twenty-seven patients receiving cyclic (12 h/24 h) parenteral nutrition were measured. These samples were collected in patients after a 12 h period of parenteral nutrition, and in the evening after 12 h without parenteral nutrition. The same determinations were performed in ten control subjects who followed the same sampling scheme. Total serum ultrafiltrable Zn showed no significant variations in the patients during parenteral nutrition, and was not significantly different in the two groups although the proportion of the Zn present in the ultrafiltrable fraction was elevated. Serum cystine levels were significantly higher (P = 0.05) in the patients than the control subjects, and cystine excretion was also higher in patients (P < 0.05) and increased after parenteral nutrition (56.0 (SE 6.5) v. 147.1 (SE 20.6) mumol/12 h; P < 0.001). Histidine levels did not vary significantly in serum after parenteral nutrition and were not different in the patients in comparison with the control subjects. Histidine excretion was not different in the two groups but increased significantly during parenteral nutrition (P < 0.05). Serum albumin was significantly depressed in the patients compared with the control subjects (45.3 (SE 1.5) v. 33.9 (SE 1.5) g/l; P < 0.001). These results suggest that cystine infusion and excretion relate to the changes occurring in serum Zn and in urinary Zn excretion.

Adolescent↗
PubMed1994

Stimulation of glutathione peroxidase activity decreases HIV type 1 activation after oxidative stress.

Am important aspect of human immunodeficiency virus (HIV-1) infection is the regulation of its expression by nuclear factor kappa B (NF-kappa B) by redox-controlled signal transduction pathways. In this study, we demonstrate that selenium supplementation can effectively increase glutathione peroxidase (GPx) activity in latently infected T lymphocytes. The Se-supplemented cells exhibited an important protection against the cytotoxic and reactivating effects of hydrogen peroxide (H2O2). Concomitantly, NF-kappa B activation by H2O2 was also decreased in Se-supplemented cells. Selenium stimulation of GPx activity also induces a protective effect against cell activation by tumor necrosis factor alpha (TNF-alpha) but less significantly by phorbol esters such as PMA. These Se-mediated effects were specific because they were not found when AP-1 DNA-binding activity was studied after H2O2-induced stress. Hyperthermia was also studied because it could promote intracellular electron leakage in electron transport chains. Elevating the temperature to 42 degrees C did not induce NF-kappa B directly. Rather, it sensitized infected cells to subsequent oxidative stress by H2O2, demonstrating the importance of hyperthermia, often associated with opportunistic infections in the development of immunodeficiency. In this case, Se induced partial protection against the sensitizing effect of hyperthermia.

Antioxidants↗
PubMed1994

Comparison of three commercial kits and a microbiological assay for the determination of vitamin B12 in serum.

Different methods are available for cobalamin determination in serum. Microbiological and radio ligand binding assays are the most commonly used. Kits involving non-isotopic competitive-binding assay have been recently commercialized. In the present work, cobalamins were determined in 146 patient sera, using four methods: a microbiological method, two no boil radio ligand binding assay kits (Magic B12 FOL (NB) from Ciba-Corning and SimulTRAC SNB No Boil from Becton Dickinson) and a non-isotopic kit with acridinium ester labelled cobalamin (Magic Lite from Ciba-Corning). Median (range) cobalamin concentrations in pmol l-1 were 317 (15-1291) using the microbiological method, 355 (25-3469) using the Magic Lite kit, 355 (35-2312) using the Magic B12 FOL (NB) kit and 380 (37-2021) using the SimulTRAC SNB No Boil kit. The ANOVA test indicated that differences between methods were statistically significant (p < 0.01). Competitive-binding methods gave higher results than the microbiological method. Although correlation coefficients were not excellent (0.88 < r < 0.96), the results obtained with the different methods were generally similar and confirmed that competitive methods are useful for detecting low serum concentration of vitamin B12.

Biological Assay↗
PubMed1994

[Automatization of colorimetric serum zinc determination using the Bayer RA 1000 autoanalyzer].

A colorimetric method for the determination of zinc in serum was adapted for use with the Bayer RA 1000 autoanalyzer. Zinc is dissociated from proteins by guanidinium hydrochloride and complexed with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N- sulfopropylamino-)phenol (5-Br-PAPS). Precision (within-run CVs from 1.4 to 4.2%; between-run CVs from 3.5 to 8.1%), accuracy (93 to 103%) and detection limit (1.15 mumol/l) were sufficient for routine determinations. Moreover, results obtained with the proposed Bayer RA 1000 method were in good agreement with those obtained by flame atomic absorption spectrometry (FAAS) which could be considered the reference method. For 119 sera, the correlation coefficient r was found to be 0.958 and the regression line was as follows: serum zinc (RA 1000) = 0.96 serum zinc (FAAS) + 0.8 mumol/l. Moreover, 98% of the differences between colorimetry and FAAS were within the range Md +/- 1.96 SDd, where Md is the mean of the differences and SDd is the standard deviation of the differences.

Autoanalysis↗
PubMed1994

Improved enzymatic assay for plasma hydroperoxides, inactivation of interfering enzymes.

The involvement of free oxygen radicals in the pathology of certain diseases explains the growing interest in the assay of lipid peroxides. Assay of polyunsaturated fatty acid degradation products is currently performed by measuring the so-called thiobarbituric acid-reacting substances, of which malondialdehyde is the best known. The fact that this assay is controversial and that a second index of free radical attack would be useful to confirm the peroxidative process prompted us to undertake this work. We propose an improved enzymatic technique for assay of lipid hydroperoxides in biological fluids. Our aim has been to improve the technique already described by Heath and Tappel, which cannot be used as described by the authors. In fact, the presence of endogenous enzymes such as glutathione peroxidase and glutathione reductase in the sample interferes with the reaction and makes the results unreliable. Elimination of these endogenous enzymes by deproteinization before assay of the lipid hydroperoxides in the plasma gives a simple, reliable, and reproducible assay if the experimental procedures described in this work are followed.

Clinical Enzyme Tests↗
PubMed1994

Serum trace elements in Zairian mothers and their newborns.

OBJECTIVES: Pregnant women in developing countries might be at risk of trace element deficiencies. These deficiencies could have deleterious effects on fetus. Therefore, serum trace elements were determined at delivery in Zairian mothers and their newborns. DESIGN: Prospective study. SETTING: Maternity ward of Kinshasa University Hospital (Zaire). SUBJECTS: 166 pregnant women admitted for delivery and their newborns. MAIN OUTCOME MEASURES: Zinc, copper and selenium were determined by atomic absorption spectrometry. Haematocrit, lymphocyte count, transferrin, ferritin and anthropometric indices (birth weight, length, head and arm circumferences; mother weight) were also evaluated. RESULTS: Serum selenium concentrations were high [mothers: 0.76-1.56 mumol/l (60-124 micrograms/l), newborns: 0.45-1.21 mumol/l (36-96 micrograms/l)]; zinc concentrations were low [mothers: 3.9-11.9 mumol/l (253-773 micrograms/l), newborns: 5.8-17.4 mumol/l (378-1130 micrograms/l)] and copper concentrations were in the range of previous works [mothers: 16.2-49.0 mumol/l (1020-3088 micrograms/l), newborns: 0.7-14.3 mumol/l (44-900 micrograms/l)]. Mother serum indices, age, weight and parity had little influence on newborn serum trace elements. In umbilical serum, copper was correlated to selenium (r = 0.340, P < 0.01); selenium (r = 0.310, P < 0.001) and copper (r = 0.404, P < 0.001) were correlated to transferrin. Newborn selenium (r = 0.310, P < 0.001) and copper (r = 0.257, P < 0.01) concentrations were related to head circumference. Newborn selenium concentration varied according to birth weight [< 2500 g: 0.58-0.86 mumol/l (45-67 micrograms/l); > 2500 g: 0.48-1.20 mumol/l (37-94 micrograms/l). Umbilical serum copper concentration was related to birth length (r = 0.197, P < 0.05). CONCLUSIONS: These results suggest that: (1) copper and selenium status at delivery in Zairian mothers are similar to those in developed countries, whereas zinc status is poor; (2) trace element and nutritional status in the mother and fetus are independent.

Adolescent↗
PubMed1993

Blood and liver lipid peroxide status after chronic ethanol administration in rats.

During the last decades a vast number of reports have aimed at elucidating the mechanisms behind alcohol-related organ injury, but the manner in which ethanol induces, e.g., liver damage is still an enigma. Increased oxidative stress has been put forward as one possible mechanism behind alcohol-related tissue damage. This paper focuses on the effect of chronic ethanol consumption on antioxidant status and lipid peroxide levels in blood and liver of rats. Alcohol was given twice daily in a total dose of 5 g ethanol/kg body wt. per day divided into two 2.5 g ethanol/kg body wt. doses as a 50% water solution, by gavage over 4 weeks. Chronic ethanol ingestion led neither to a significant change in lipid peroxide formation nor to a significant change in enzymatic antioxidant activities. Only concentrations of oxidized glutathione and of other non-enzymatic antioxidant such as vitamin E showed a tendency to decrease after alcohol application. The data presented could serve to emphasize no involvement of free radical-induced lipoperoxidation in the pathogenesis of ethanolic liver diseases.

Alcoholism↗
PubMed1993

Gas chromatographic-mass spectrometric determination of 5-hydroxymethyluracil in human urine by stable isotope dilution.

A method for the determination of 5-hydroxymethyluracil in urine is described. 5-Hydroxymethyluracil was extracted by reversed-phase chromatography and quantified by gas chromatography-mass spectrometry as tert.-butyldimethylsilyl derivative. Since natural 5-hydroxymethyluracil contained ca. 22% of M + 2 species, an internal standard consisting of [1,3-15N2,5-2H2]hydroxymethyluracil was used to correct losses during extraction, evaporation and derivatization. Between-run precision of this method was 7.79%, and concentrations as low as 1.87 nM could be measured. This sensitivity and precision could not be obtained with trimethylsilyl derivatives.

Gas Chromatography-Mass Spectrometry↗
PubMed1993

[Current aspects about the role of zinc in nutrition].

The role played by zinc in biology is now better known, and numerous biochemical mechanisms, such as immunity or actions on several hormones and more than 200 enzymes, have proved to be zinc-dependent. Thus, many functions are disturbed when this trace metal is deficient, including, for example, taste and appetite, cell multiplication, growth, pregnancy, fertility, defence against bacteria and brain functions. Zinc intake has been found to be unexcessive and indeed, at the limit of sufficiency in the French population. Groups at risk, such as neonates, growing children, pregnant women and elderly people, should have a higher zinc intake provided by dietary measures or supplementation. Zinc supplementation has been shown to exert a beneficial effect in randomized studies concerning children's growth, acne, old people's immunity or low female fertility. Such supplementation must be balanced and given in moderate doses since zinc interacts with other foodstuffs, and an excess of zinc can be as bad as its deficiency in our nutrition.

Aged↗
PubMed1993

Reference values for serum zinc and selenium of French healthy children.

Age - and sex-specific reference intervals derived from a healthy pediatric population are presented for zinc, selenium and related analytes in serum. No strong correlations were found between age, sex and trace elements in serum. Serum variables were discussed to assess their ability as biochemical indicators of micronutrient status in the field of biological epidemiology.

Adolescent↗
PubMed1993

Effect of iron overload in the isolated ischemic and reperfused rat heart.

It has been suggested that iron might play a pivotal role in the development of reperfusion-induced cellular injury through the activation of oxygen free radical producing reactions. The present study examined the effects of myocardial iron overload on cardiac vulnerability to ischemia and reperfusion. Moreover, the effect of the iron chelator deferoxamine in reversing ischemia-reperfusion injury was studied. Animals were treated with iron dextran solution (i.m. injection, 25 mg every third day during a 5 week period). The control group received the same treatment without iron. Isolated rat hearts were perfused at constant flow (11 ml/min) and subjected to a 15 minute period of global normothermic ischemia followed by reperfusion for 15 minutes. The effects of iron overload were investigated using functional and biochemical parameters, as well as ultrastructural characteristics of the ischemic-reperfused myocardium compared with placebo values. The results suggest that (a) a significant iron overload was obtained in plasma and hepatic and cardiac tissues (x2.5, x16, and x8, respectively) after chronic intramuscular administration of iron dextran (25 mg); (b) during normoxia, iron overload was associated with a slight reduction in cardiac function and an increase in lactate dehydrogenase (LDH) release (x1.5); (c) upon reperfusion, functional recovery was similar whether the heart had been subjected to iron overload or not. However, in the control group left ventricular end-diastolic pressure remained higher than in preischemic conditions, an effect that was not observed in the iron-overloaded group. Moreover, LDH release was markedly increased in the iron-loaded group (x4.2); (d) iron overload was associated with a significant worsening of the structural alterations observed during reperfusion, particularly at the mitochondrial and sarcomere level; (e) after 15 minutes of reperfusion, the activity of the anti-free-radical enzyme, glutathione peroxidase (GPX), was significantly reduced in iron-overloaded hearts, whereas catalase activity was increased; (e) the overall modifications observed in the presence of iron overload were prevented by deferoxamine. In conclusion, this study underlines the possible role of cardiac iron in the development of injury associated with ischemia and reperfusion, and the possible importance of the use of an iron-chelating agent in anti-ischemic therapy.

Animals↗
PubMed1993

Effect of zinc on superoxide-dependent hydroxyl radical production in vitro.

Trace elements play an important role in oxygen metabolism and therefore in the formation of free radicals. Whereas iron and copper are usually the main enhancers of free radical formation, other trace elements, such as zinc and selenium, protect against the harmful effects of these radicals. To investigate the different protective mechanisms of zinc on radical formation, we examined the effects of added zinc and copper on superoxide dismutase activity. We also studied the effects of copper and iron on xanthine oxidase activity and on the Haber-Weiss cycle (iron, superoxide, and hydrogen peroxide), which generates hydroxyl radicals in vitro. The hypoxanthine/xanthine oxidase radical generating system contained a variety of different physiological ligands for binding the iron. This study confirmed the inhibitory effect of copper on xanthine oxidase activity. Moreover, it demonstrated that zinc inhibited hydroxyl radical formation when this formation was catalyzed by a citrate-iron complex in the hypoxanthine/xanthine oxidase reaction. Finally, human blood plasma inhibited citrate-iron-dependent hydroxyl radical formation under the same conditions. Although trace elements seemed responsible for this antioxidant activity of plasma, it is likely that zinc played no role as a plasma antioxidant. Indeed, calcium appeared to be responsible for most of this effect under our experimental conditions.

Copper↗
PubMed1993

Lipid peroxides and antioxidant defenses in accelerated transplantation-associated coronary arteriosclerosis.

Accelerated coronary artery disease develops in most if not all heart transplant recipients within the first year after transplantation. Increased lipid peroxidation seems to be involved in atherogenesis. In these patients we have investigated whether there is an association between lipid peroxidation, reduced antioxidant defenses, and some conventional coronary risk factors. Lipid peroxides, lipids, uric acid, albumin, antioxidant enzymes and their cofactors (the trace elements selenium, iron, copper, and zinc) have been determined in heart transplant recipients compared with nonrecipients with coronary artery disease. Lipid peroxides (p = 0.002) and uric acid (p = 0.01) were higher and zinc (p = 0.001) was lower in heart transplant recipients. Thirteen of 30 transplant recipients compared with one of 30 nonrecipients (p < 0.001) had very low (less than 10 mumol/L) zinc levels. Antioxidant enzymes and other trace elements were not significantly different. In univariate regression analysis, zinc correlated positively with albumin (p = 0.02) and negatively with lipid peroxides (p < 0.05). Uricemia had a strongly positive correlation with hydroperoxides (r = 0.45; p = 0.0001). In stepwise multivariate regression analysis, lipids, uricemia, creatinine, and zinc were significant (p < or = 0.004) predictors of the lipid peroxide level. Cyclosporine and corticosteroid dosages were significant (p = 0.01) determinants of zinc concentration in the transplant recipients. Although a causal relationship between increased lipid peroxidation and accelerated arteriosclerosis is not definitely demonstrated, the results of this analysis suggest new insights into conventional coronary disease risk factors and possible therapeutic interventions; further controlled trials are needed.

Adult↗