Assessment of Diet-Related Changes on Albendazole Absorption, Systemic Exposure, and Pattern of Urinary Excretion in Treated Human Volunteers.

Soil-transmitted-helminth (STH) infections are a persistent global public health problem. Control strategies for STH have been based on the use of mass drug administration (MDA) mainly targeting preschool- and school-aged-children, although there is increasing interest in expanding treatment to include adults and others through community-wide MDA. Coverage assessment is critical to understanding the real effectiveness of albendazole (ALB) treatment in those MDA programs. The work described here aims to (i) evaluate the effect of type of diet (a heavy or light meal) and fasting before ALB treatment on the systemic disposition of ALB and its metabolites in treated human volunteers and (ii) evaluate the potential feasibility of detecting albendazole metabolites in urine. The data reported here demonstrate that the systemic availability of the active ALB-sulfoxide (ALBSO) metabolite was enhanced more than 2-fold after food ingestion (a heavy or light meal). ALB dissolution improvement related to the ingestion of food may modify the amount of drug/metabolites reaching the parasite, affecting drug efficacy and the overall success of MDA strategies. The measurement in urine samples of the amino-ALB-sulfone (NHALBSO2) derivative and ALBSO for up to 96 h suggests that it may be feasible to develop a noninvasive tool to evaluate compliance/adherence to ALB treatment.

Higher antioxidant defences in plasma and low density lipoproteins from rugby players.

BACKGROUND: Even if physical activity constitutes a well-known antiatherogenic factor, the precise mechanisms underlying this protective effect are not completely clear. MATERIALS AND METHODS: Lipid and antioxidant profiles were evaluated in 15 well-trained rugby players and 15 sedentary controls. Lipoprotein fractions were separated by sequential ultracentrifugation and alpha-tocopherol content was determined in each fraction by high-performance liquid chromatography. Susceptibility to in vitro oxidation was also measured in intermediate and low density lipoproteins isolated from both groups of subjects as the production of conjugated dienes. RESULTS: Although the sportsmen were not receiving any special diet or vitamin supplementation they showed a slightly improved lipoprotein profile, mainly represented by increased high density lipoprotein-cholesterol levels (P < 0.05), and an enhanced antioxidant status. The latter was evidenced by an increment in total radical antioxidant potential (P < 0.001), higher ascorbic acid (P < 0.005) and alpha-tocopherol (P < 0.05) plasma concentrations, and elevated activities of superoxide dismutase (P < 0.001) and arylesterase (P < 0.01). Moreover, only the fraction of intermediate and low density lipoproteins from rugby players presented higher alpha-tocopherol content in comparison with sedentary controls (484 +/- 67 vs. 377 +/- 123 microg dL(-1), respectively; P < 0.01). Nevertheless, the susceptibility to in vitro oxidation of this lipoprotein fraction was not different between both groups. CONCLUSIONS: Given that intermediate density and low density lipoproteins represent the most atherogenic fraction, this finding, in combination with the improved lipid and antioxidant status, would add to the link between regular physical activity and protection against cardiovascular disease.

Chromium (VI) induces oxidative stress in the mouse brain.

Potassium dichromate was given to female Swiss mice (25 mg/kg per day) orally in water for 1-3 days. Brain homogenates were prepared to evaluate the occurrence of oxidative stress in this organ through the measurement of the antioxidant defense levels. and the extent of lipid peroxidation. In addition, mitochondrial fractions were isolated from brain homogenates to determine the production of reactive oxygen species in this subcellular fraction. The administration of potassium dichromate for 3 days caused increases of 72 and 74% in superoxide dismutase and catalase activities, respectively, in the homogenates. The treatment with this metal for 3 days increased brain homogenate chemiluminescence and thiobarbituric acid-reactive substances by 34 and 29%, respectively. The brain contents of the non-enzymatic antioxidants alpha-tocopherol and sulfhydryl groups decreased by 35 and 32%, respectively. Ascorbic acid levels were not modified by the administration of potassium dichromate. Finally, there was a significant increment in the mitochondrial production of oxidants in the brain of treated mice as compared with controls. These results suggest that chromium(VI) produces an increased formation of reactive oxygen species and brain lipid peroxidation. The increase in the antioxidant enzyme activities reflects an adaptive response against oxidative stress, while the reduction in the levels of non-enzymatic antioxidants might be due to their reaction with reactive oxygen species generated during the metabolism of chromium(VI).

Evaluation of total reactive antioxidant potential (TRAP) of tissue homogenates and their cytosols.

This study evaluates the possibility of obtaining total reactive antioxidant potential (TRAP) indexes in homogenates and their cytosolic fractions by a procedure based on the quenching of luminol luminescence induced by the thermolysis of 2,2'-azo-bis(2-amidinopropane). Measurements were performed in rat brain, liver, kidney, and heart homogenates. TRAP indexes can be easily determined both in homogenates and their cytosolic fractions. The results obtained indicate that heart homogenates are the least and liver homogenates the most protected of the systems considered. Glutathione is the measured antioxidant that contributes the most to TRAP values, while uric acid makes a significant contribution only in liver. A calculation of theoretical TRAP values from the measured concentrations of the main antioxidants (glutathione, uric acid, ascorbic acid, and alpha-tocopherol) for the different homogenates shows that, in most tissues (liver, brain, and kidney), nearly 50% of the experimentally determined TRAP values are not accounted for. This difference is mainly due to the contribution of proteins to the measured TRAP.

Myocardial oxidative stress and antioxidants in hypertension as a result of nitric oxide synthase inhibition.

Rats were made hypertensive by the administration of the nitric oxide synthase inhibitor nitro-L-arginine (LNA, 2.74 mmol/L) in drinking water for 7 d. Hearts from hemodynamically assessed animals were analyzed for lipid peroxidation (LPO), gamma-glutamylcysteine-synthetase (gamma-GCS), glutathione disulfide reductase (GR), glutathione peroxidase (GSHPx), catalase (CAT), superoxide dismutase (SOD), and total radical trapping potential (TRAP) activities. LNA treatment increased the mean arterial blood pressure by 46% and the heart rate by 22% without changing plasma renin activity. LNA treatment resulted in a 30% increase in LPO. gamma-GCS was reduced by 48% and GR by 36% in the cardiac tissue of hypertensive rats as compared to controls. The activity of nonselenium GSHPx was reduced by 27%, and selenium-dependent GSHPx activity in the heart was not affected by LNA treatment. In hypertensive rats, SOD activity was increased by 16%, and CAT was decreased by 46%. TRAP was lower (27%) in the myocardium of hypertensive rats than in that of controls. These data suggest that LNA-induced hypertension is associated with increased myocardial oxidative stress.

Chromium(VI) induces oxidative stress in the mouse brain.

Potassium dichromate was given to female Swiss mice (25 mg/kg per day) orally in water for 1-3 days. Brain homogenates were prepared to evaluate the occurrence of oxidative stress in this organ through the measurement of the antioxidant defense levels, and the extent of lipid peroxidation. In addition, mitochondrial fractions were isolated from brain homogenates to determine the production of reactive oxygen species in this subcellular fraction. The administration of potassium dichromate for 3 days caused increases of 72 and 74% in superoxide dismutase and catalase activities, respectively, in the homogenates. The treatment with this metal for 3 days increased brain homogenate chemiluminescence and thiobarbituric acid-reactive substances by 34 and 29%, respectively. The brain contents of the non-enzymatic antioxidants alpha-tocopherol and sulfhydryl groups decreased by 35 and 32%, respectively. Ascorbic acid levels were not modified by the administration of potassium dichromate. Finally, there was a significant increment in the mitochondrial production of oxidants in the brain of treated mice as compared with controls. These results suggest that chromium(VI) produces an increased formation of reactive oxygen species and brain lipid peroxidation. The increase in the antioxidant enzyme activities reflects an adaptive response against oxidative stress, while the reduction in the levels of non-enzymatic antioxidants might be due to their reaction with reactive oxygen species generated during the metabolism of chromium(VI).

Regional vulnerability to oxidative stress in a model of experimental epilepsy.

We evaluated oxidative stress associated with a model of experimental epilepsy. Male Wistar rats were injected i.p. with 150 mg/kg convulsant 3-mercaptopropionic acid and decapitated in two stages: during seizures or in the post-seizure period. Spontaneous chemiluminescence, levels of thiobarbituric acid reactive substances, total antioxidant capacity and antioxidant enzyme activities were measured in cerebellum, hippocampus, cerebral cortex and striatum. In animals killed at seizure, increases of 42% and 90% were observed in spontaneous chemiluminescence of cerebellum and cerebral cortex homogenates, respectively, accompanied by a 25% increase in cerebral cortex levels of thiobarbituric acid reactive substances. In the post-seizure stage, emission completely returned to control levels in cerebral cortex and partly in cerebellum, thus showing oxidative stress reversibility in time. Hippocampus and striatum seemed less vulnerable areas to oxidative damage. A 30% decrease in glutathione peroxidase activity was only observed in cerebral cortex during seizures, while catalase and superoxide dismutase remained unchanged in all four areas during either stage. Likewise, total antioxidant capacity was unaffected in any of the studied areas. It is suggested that oxidative stress in this model of epilepsy arises from an increase in oxidant species rather than from depletion of antioxidant defences.

Chemiluminescence and antioxidant levels during peroxisome proliferation by fenofibrate.

Fenofibrate, the hypolipidemic drug and peroxisome proliferator, was given to mice (0.23% w/w in the diet) during 1-3 weeks and H2O2 and TBARS steady state concentrations, liver chemiluminescence and antioxidant levels were measured. Administration of fenofibrate during 2 weeks induced an increase of 89% in H2O2 steady state concentration. Spontaneous chemiluminescence was decreased by 57% during fenofibrate treatment, while no significant effect was observed on TBARS concentration. Hydroperoxide-initiated chemiluminescence was decreased by 56% after 15 days of fenofibrate treatment, probably due to an increase in endogenous antioxidant levels. Total and oxidized glutathione increased gradually after fenofibrate administration, obtaining maximal increases of 67% and 58% respectively, after 22 days of treatment. An increase of 55% was found in ubiquinol levels in treated mice, as compared with the controls. alpha-tocopherol content was decreased by 51% in the liver of fenofibrate-treated mice. According to our findings, the high rate of H2O2 production associated with peroxisome proliferation, would not lead to an increase in lipid peroxidation. This can be explained by the presence of high levels of ubiquinols, which act as an antioxidant. The increased production of H2O2, would lead to DNA damage directly, and not through lipid peroxidation processes.

Hydrogen peroxide metabolism during peroxisome proliferation by fenofibrate.

Fenofibrate, the hypolipidemic drug and peroxisome proliferator, was given to mice (0.23% w/w in the diet) during 1-3 weeks and enzyme activities, H2O2 concentration, and H2O2 production rate were determined. A maximal increase of 150% in liver/body weight ratio was observed after 3 weeks of treatment. Acyl-CoA oxidase, catalase and uricase activities were increased by 712%, 506% and 41% respectively by treatment with fenofibrate. Se- and non Se-glutathione peroxidase and Mn-superoxide dismutase activities were increased by 331%, 188% and 130% respectively in the liver of 2 weeks-treated mice. Cu-Zn superoxide dismutase activity was not affected by fenofibrate treatment. H2O2 steady-state concentration showed an increase of 89% after 2 weeks of treatment. H2O2 production rates, and the steady-state concentrations of the intermediates HO, R and ROO, calculated using experimental data, were higher in the liver of fenofibrate-treated mice than in control animals. According to our findings, the imbalance between H2O2 production and its degradation by its metabolizing enzymes during peroxisome proliferation, would result in an increased level of H2O2 steady-state concentration, with the resulting oxidative stress which may lead to the generation of oxidative damage and to the induction of liver carcinogenesis.

Changes in cathepsin B and lipofuscin during development and aging in rat brain and heart.

While results with inhibitors of thiol proteases have led to the suggestion that the progressive increase with age of lipofuscin in post-mitotic and some stable cells may be due to an age-related decline in the activity of these enzymes (Ivy et al., 1989), no direct evidence has been yet presented to support this hypothesis. In this study Wistar female rats were killed at age of 5, 14, and 24 months and the amounts of lipofuscin were histologically quantitated in neurons of the left cerebral parietal cortex and in cardiac myocytes of left ventricle. The sites of cathepsin B activity histochemically detected were quantitated in sections from left cerebral parietal cortex and left ventricle, and the activity of this enzyme was also measured biochemically in brain and heart homogenates. In line with previous findings, the amounts of lipofuscin in neurons and cardiac myocytes increased linearly during development and aging (from 5 to 14 and from 14 to 24 mo.). The sites of cathepsin B activity histochemically detected in sections from cerebral cortex significantly increased from 5 to 14 mo., but remained unchanged from 14 to 24 mo, while in sections from the left cardiac ventricle these sites of activity remained unchanged during development, and significantly increased during aging. On the other hand the biochemically determined activities of cathepsin B in brain and heart homogenates remained unchanged from 5 to 14 mo., but significantly decreased from 14 to 24 mo. These results suggest that the increase in lipofuscin with age may not be due to an age-wise decline in cathepsin B activity.