Search results for "peroxidation"
showing 10 items of 308 documents
Selective effects of some anesthetics and detergents on lipid peroxidation of mouse heart homogenates.
1991
Abstract 1. 1. The effects of some anesthetics and detergents on the Fe2+/ascorbate-stimulated non-enzymatic lipid peroxidation potential and on the NADPH-dependent enzymatic lipid peroxidation capacity were characterized in mouse heart homogenates. 2. 2. Chlorpromazine turned out to be the most efficient inhibitor, causing a 50% inhibition at a concentration of 0.03 mM in the non-enzymatic assay, and at a concentration of 0.02 mM in the enzymatic assay. 3. 3. Tetracaine was about a 10-times weaker inhibitor with IC50-values of 0.25 mM. High concentration of dibucaine (1 mM) exerted a 60% inhibition in the non-enzymatic assay, but lidocaine and procaine had no prominent effect with the conc…
Cocaine hepatotoxicity: two different toxicity mechanisms for phenobarbital-induced and non-induced rat hepatocytes.
1993
Abstract Hepatocytes isolated from both phenobarbital-induced and control rats were short-term cultured and exposed to cocaine (8–2000 μM) for varying times. Intracellular lactate dehydrogenase activity, free calcium levels ([Ca 2+ ] i ), reduced glutathione (GSH) and lipid peroxidation were investigated to evaluate the toxic effect of cocaine on hepatocytes. Cytochrome P450 induction by phenobarbital potentiated the in vitro cytotoxicity of cocaine by a factor of 13 (IC 50 = 84 μ M induced cells vs 1100 μM in non-induced cells). This difference in the susceptibility of the two types of hepatocytes to cocaine correlated well with the activity of cytochrome P450 2 B 1 2 . Rapid depletion of …
Tissue oxygenation in brain, muscle and fat in a rat model of sleep apnea: differential effect of obstructive apneas and intermittent hypoxia.
2011
Study Objectives: To test the hypotheses that the dynamic changes in brain oxygen partial pressure (PtO 2) in response to obstructive apneas or to intermittent hypoxia differ from those in other organs and that the changes in brain PtO 2 in response to obstructive apneas is a source of oxidative stress. Design: Prospective controlled animal study. Setting: University laboratory. Participants: 98 Sprague-Dawley rats. Interventions: Cerebral cortex, skeletal muscle, or visceral fat tissues were exposed in anesthetized animals subjected to either obstructive apneas or intermittent hypoxia (apneic and hypoxic events of 15 s each and 60 events/h) for 1 h. Measurements and Results: Arterial oxyge…
Enhanced lipid peroxidation and platelet activation as potential contributors to increased cardiovascular risk in the low-HDL phenotype
2013
Background Low high‐density lipoprotein ( HDL ) levels are major predictors of cardiovascular ( CV ) events, even in patients on statin treatment with low‐density lipoprotein ( LDL ) at target. In animal models HDL s protect LDL from oxidation and blunt platelet activation. Our study aimed to examine whether HDL levels are related to in vivo oxidative stress and platelet activation, as determinants of atherothrombosis. Methods and Results Urinary 8‐iso‐PGF 2α and 11‐dehydro‐TXB 2 , in vivo markers of oxidative stress and platelet activation, respectively, were measured in 65 coronary heart disease (CHD) normocholesterolemic patients with HDL ≤35 mg/ dL , and in 47 CHD patients with HDL >…
Vitamin A Deficiency Increases Protein Catabolism and Induces Urea Cycle Enzymes in Rats
2010
Chronic vitamin A deficiency induces a substantial delay in the rates of weight and height gain in both humans and experimental animals. This effect has been associated with an impaired nutrient metabolism and loss of body protein. Therefore, we analyzed the effect of vitamin A deficiency on endogenous proteolysis and nitrogen metabolism and its reversibility with all-trans retinoic acid (RA). Male weanling rats, housed in pairs, were pair-fed a vitamin A-deficient (VAD) or control diet until they were 60 d old. A group of deficient rats were further treated with daily intraperitoneal injections of all-trans RA for 10 d. Final body and tissue (i.e. liver and heart) weights were significantl…
Vitamin E deficiency and the susceptibility to lipid peroxidation of mouse cardiac and skeletal muscles
1984
Effects of a short-term vitamin E deficiency on some lipid peroxidative properties were investigated in mouse cardiac and skeletal muscles. The concentration of vitamin E decreased 35.8% in 5 weeks and 61.2% in 12 weeks in skeletal muscle. The corresponding decrease in cardiac muscle was 65.7% in 12 weeks. Simultaneously the susceptibility of muscle homogenates to in vitro lipid peroxidation increased with 48.6% (5 weeks) and 44.5% (12 weeks) in skeletal muscle and with 101.8% (12 weeks) in cardiac muscle. Highly significant negative correlations were observed between the concentration of vitamin E and in vitro lipid peroxidation in cardiac and skeletal muscles. Also the sensitivity to Fe2+…
Inhibition of Xanthine Oxidase by Phenolic Conjugates of Methylated Quinic Acid
2003
The caffeoyl conjugates of prenylhydroquinone glucoside and of quinic acid, either in the carboxyl-free or carboxymethyl forms, isolated from Phagnalon rupestre (Asteraceae), showed inhibitory activity on lipid peroxidation induced by Fe 2+/ascorbate and by CCl4/NADPH in rat liver microsomes, with IC50 values ranging from 3 to 11 microM. After having demonstrated their effect on the xanthine oxidase-regulated superoxide production, the active compounds were tested for the direct inhibition of this enzyme. Methylated dicaffeoylquinic conjugates competitively inhibited the enzyme and the highest potency was obtained for the 4,5-diester, with an IC50 value of 3.6 microM, nearly ten times lower…
Antioxidant activity of anti-inflammatory plant extracts
2002
The antioxidant properties of twenty medical herbs used in the traditional Mediterranean and Chinese medicine were studied. Extracts from Forsythia suspensa, Helichrysum italicum, Scrophularia auriculata, Inula viscosa, Coptis chinensis, Poria cocos and Scutellaria baicalensis had previously shown anti-inflammatory activity in different experimental models. Using free radical-generating systems H. italicum. I. viscosa and F. suspensa protected against enzymatic and non-enzymatic lipid peroxidation in model membranes and also showed scavenging property on the superoxide radical. All extracts were assayed at a concentration of 100 microg/ml. Most of the extracts were weak scavengers of the hy…
Xanthine oxidase is involved in exercise-induced oxidative stress in chronic obstructive pulmonary disease
1999
In the present study, we hypothesized that exhaustive exercise in patients with chronic obstructive pulmonary disease (COPD) results in glutathione oxidation and lipid peroxidation and that xanthine oxidase (XO) contributes to free radical generation during exercise. COPD patients performed incremental cycle ergometry until exhaustion with (n = 8) or without (n = 8) prior treatment with allopurinol, an XO inhibitor. Reduced (GSH) and oxidized glutathione (GSSG) and lipid peroxides [malondialdehyde (MDA)] were measured in arterial blood. In nontreated COPD patients, maximal exercise (approximately 75 W) resulted in a significant increase in the GSSG-to-GSH ratio (4. 6 +/- 0.9% at rest vs. 9.…
Changes in glutathione status and the antioxidant system in blood and in cancer cells associate with tumour growth in vivo
1999
The relationship among cancer growth, the glutathione redox cycle and the antioxidant system was studied in blood and in tumour cells. During cancer growth, the glutathione redox status (GSH/GSSG) decreases in blood of Ehrlich ascites tumour-bearing mice. This effect is mainly due to an increase in GSSG levels. Two reasons may explain the increase in blood GSSG: (a) the increase in peroxide production by the tumour that, in addition to changes affecting the glutathione-related and the antioxidant enzyme activities, can lead to GSH oxidation within the red blood cells; and (b) an increase of GSSG release from different tissues into the blood. GSH and peroxide levels are higher in the tumour …