Biomedical subjects
Publications and source records attributed to Antonio Ayala.
The selective loss of a particular subset of neurons is a common feature of neurodegenerative disorders. A failure in respiratory chain complex activities in mitochondria seems to be a causative factor. The aim of this review is to describe the most important toxins affecting the mitochondrial function, which could be involved in the incidence of some of these diseases: MPTP, rotenone and 3-nitropropionic (3-NPA).
Elongation Factor-2 (eEF-2) is the protein that catalyzes the translocation of the ribosome through mRNA. Not all oxidants affect eEF-2, which is extremely sensitive to oxidative stress caused mainly by lipid peroxidant compounds such as cumene hydroperoxide and t-butyl hydroperoxide. Lipid peroxides constitute a potential hazard to living organisms because of their direct reactivity with a variety of biomolecules and the ability to decompose into free radicals and reactive aldehydes. In this "in vitro" study, we show the effect of three of these aldehydes on the levels of hepatic eEF-2. The results suggest that the toxicity associated with prooxidant-mediated hepatic lipid peroxidation on protein synthesis can originate from the interaction of the aldehydic end products of lipid peroxidation with eEF-2.
The objective of the work was to study the relationship between the oxidative state of the mother and the newborn at the moment of birth. We measured oxidative stress markers (carbonyl groups, lipid peroxides and total antioxidant capacity (TAC)) and found a good correlation between the oxidative state of the normal mother and the neonate, since a high mother oxidative stress corresponds to an even higher oxidative stress of the newborn in umbilical cord blood. We also found that smoking mothers and their newborns had a higher concentration of the carbonyl group, lipid peroxides and less TAC. Newborns from these mothers weighed significantly less than others at birth. These data suggest a need for interest in monitoring the oxidative state of mothers during the pregnancy period, especially taking into account that the oxidative level could be involved in later risks of metabolic diseases for both mother and newborn.
INTRODUCTION: Critically ill patients suffer from oxidative stress caused by reactive oxygen species (ROS) and reactive nitrogen species (RNS). Although ROS/RNS are constantly produced under normal circumstances, critical illness can drastically increase their production. These patients have reduced plasma and intracellular levels of antioxidants and free electron scavengers or cofactors, and decreased activity of the enzymatic system involved in ROS detoxification. The pro-oxidant/antioxidant balance is of functional relevance during critical illness because it is involved in the pathogenesis of multiple organ failure. In this study the objective was to evaluate the relation between oxidative stress in critically ill patients and antioxidant vitamin intake and severity of illness. METHODS: Spectrophotometry was used to measure in plasma the total antioxidant capacity and levels of lipid peroxide, carbonyl group, total protein, bilirubin and uric acid at two time points: at intensive care unit (ICU) admission and on day seven. Daily diet records were kept and compliance with recommended dietary allowance (RDA) of antioxidant vitamins (A, C and E) was assessed. RESULTS: Between admission and day seven in the ICU, significant increases in lipid peroxide and carbonyl group were associated with decreased antioxidant capacity and greater deterioration in Sequential Organ Failure Assessment score. There was significantly greater worsening in oxidative stress parameters in patients who received antioxidant vitamins at below 66% of RDA than in those who received antioxidant vitamins at above 66% of RDA. An antioxidant vitamin intake from 66% to 100% of RDA reduced the risk for worsening oxidative stress by 94% (ods ratio 0.06, 95% confidence interval 0.010 to 0.39), regardless of change in severity of illness (Sequential Organ Failure Assessment score). CONCLUSION: The critical condition of patients admitted to the ICU is associated with worsening oxidative stress. Intake of antioxidant vitamins below 66% of RDA and alteration in endogenous levels of substances with antioxidant capacity are related to redox imbalance in critical ill patients. Therefore, intake of antioxidant vitamins should be carefully monitored so that it is as close as possible to RDA.
Oxidative stress seems to play an important role in the pathophysiology of essential hypertension. Due to its antioxidant features, we studied the protective action of folic acid in hypertensive patients, their food supplemented for 2 weeks with this vitamin. Several oxidative stress parameters were measured in the serum of these patients. The results show that folic acid supplementation improves levels of oxidative stress markers in individuals with hypertension, overall in those patients whose initial parameter values were highest.
The oxidant status of an individual is assessed by determining a group of markers in noninvasive samples. One limitation when measuring these biomarkers is that they do not give information about tissue localization of oxidative stress. The present study was undertaken to establish whether the serum oxidative stress biomarkers are indicative of oxidative stress in tissues of an individual. To accomplish this, we determined a few generic markers of oxidation in serum and tissues of six groups of rats treated experimentally, to modulate their oxidative stress status. The correlation between serum and tissue levels was calculated for each marker. Also, for each tissue, the correlation between the values of these oxidative stress biomarkers was analysed. Our results show that only lipid peroxides in serum could be useful to predict the oxidative stress in tissues. No correlation was found between any of the oxidative stress markers in serum.
Different pre-treatment methods have been compared for two-dimensional mapping of individual rat cerebrospinal fluid samples based on acetone, trichloroacetic acid/acetone and methanol/acetone precipitation of proteins. Acetone precipitation following incubation with DTT gave the highest protein recovery (72%) and the largest number of protein spots (92 +/- 4) as well as minimizing the time taken.
We have evaluated the effect of N,N-bis (2-chloroethyl)-N-nitrosourea (BCNU), an inhibitor of glutathione reductase (GR), on the oxidative status along with the integrity of the nigrostriatal dopaminergic system of the rat. The oxidative status was studied by the quantification of carbonyl groups coupled to protein homogenates. Moreover, the specific oxidations in glial fibrillary acidic protein (GFAP) and neurofilament-200 (NF-200) were also measured. The results show that oxidative damage in proteins in the nigrostriatal system is confined to the striatum. Specific carbonyl groups coupled to native NF-200 and GFAP were also increased. These changes were accompanied by reactive astrocytosis in striatum but not in substantia nigra. In substantia nigra, decreased levels of dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were observed following BCNU treatment. In contrast, DA levels were increased in the striatum along with an overall decrease in the ratios of DA metabolites to DA. We also studied the mRNA levels for tyrosine hydroxylase (TH) and the dopamine transporter (DAT) by in situ hybridization. TH mRNA but not DAT mRNA was significantly induced in substantia nigra following BCNU treatment, which was consistent with significant elevations in TH enzyme amount and activity and unchanged DA uptake in striatum. All these results support the DA free radical hypothesis and the key role of the striatal glutathione system in protecting the striatal system against oxidative stress.
1-Methyl-1,2,3,4-tetrahydroisoquinoline (1-MeTIQ), an endogenous monoamine, which prevents the neurotoxic effect of 1-methyl-4-phenylpyridinium ion (MPP(+)) and other endogenous neurotoxins, has been described as being enzymatically formed in the brain by the 1-MeTIQ synthesizing enzyme (1-MeTIQse). In this paper, we report the brain's regional distribution of this enzyme in 3- and 24-month-old rats. The results show that the activity is spread throughout the brain, the highest activity being in the dopaminergic areas (striatum and substantia nigra) and in the cortex. During aging there was a 1-MeTIQse activity reduction ( approximately 50%) in the areas implicated in the ethyology of Parkinson disease (substantia nigra, striatum) and in the cerebral cortex.
Acute and chronic treatments of mice with the glutathione-depleting agent, L-buthionine-(SR)-sulfoximine (BSO), impaired the mineralocorticoid receptor (MR)-dependent biological response by inhibiting aldosterone binding. This steroid-binding inhibition was fully reversed when reducing agents were added to kidney cytosol obtained from mice treated for 5 h, but it was only partially reversed in cytosol obtained from mice treated for 10 days. Although the oligomeric structure of the MR-hsp90 heterocomplex was always unaffected, a decreased amount of MR protein was evidenced after the long term treatment. Such a deleterious effect was correlated with a post-translational modification of MR, as demonstrated by an increased level of receptor carbonylation. In addition, a failure at the elongation/termination step was also observed during the receptor translation process in a reticulocyte lysate system. Thus, a high polyribosomes/monomers ratio and both increased proteolysis and decreased ADP-ribosylatable concentration of elongation factor 2 (EF-2) were shown. Importantly, similar observations were also performed in vivo after depletion of glutathione. Notwithstanding the EF-2 functional disruption, not all renal proteins were equally affected as the MR. Interestingly, both EF-2 and MR expressed in old mice were similarly affected as in L-buthionine-(SR)-sulfoximine-treated young mice. We therefore propose that a dramatic depletion of glutathione in kidney cells mimics the cumulative effect of aging which, at the end, may lead to a renal mineralocorticoid dysfunction.