Evidence that oxidative stress is increased in plasma from patients with maple syrup urine disease

Long-chain 3-hydroxy fatty acids accumulating in LCHAD and MTP deficiencies induce oxidative stress in rat brain

Accumulation of long-chain 3-hydroxy fatty acids is the biochemical hallmark of long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) and mitochondrial trifunctional protein (MTP) deficiencies. These disorders are clinically characterized by neurological symptoms, such as convulsions and lethargy, as well as by cardiomyopathy and muscle weakness. In the present work we investigated the in vitro effect of 3-hydroxydodecanoic (3HDA), 3-hydroxytetradecanoic (3HTA) and 3-hydroxypalmitic (3HPA) acids, which accumulate in these disorders, on important oxidative stress parameters in cerebral cortex of young rats in the hope to clarify the mechanisms leading to the brain damage found in patients affected by these disorders. It was first verified that these compounds significantly induced lipid peroxidation, as determined by increased thiobarbituric acid-reactive substances levels. In addition, carbonyl formation was significantly increased and sulfhydryl content decreased by 3HTA and 3HPA, which indicates that these fatty acids elicit protein oxidative damage. 3HTA and 3HPA also diminished the reduced glutathione (GSH) levels, without affecting nitrate and nitrite production. Finally, we observed that the addition of the antioxidants and free radical scavengers trolox and deferoxamine (DFO) was able to partially prevent lipid oxidative damage, whereas DFO fully prevented the reduction on GSH levels induced by 3HTA. Our present data showing that 3HDA, 3HTA and 3HPA elicit oxidative stress in rat brain indicate that oxidative damage may represent an important pathomechanism involved in the neurologic symptoms manifested by patients affected by LCHAD and MTP deficiencies.

Profiling of oxidative stress in patients with inborn errors of metabolism

Free radical formation resulting in oxidative stress is a hallmark of mitochondrial dysfunction. Indeed, oxidative stress has been demonstrated to be an underlying pathophysiologic process in various inborn errors of metabolism. Metabolic profiling of oxidative stress may provide a non-specific measure of disease activity that may further enable physicians to monitor disease. In the present study, we investigated two markers of oxidative damage in urinary samples from IEM subjects and controls: F-2 isoprostanes, a measure of lipid peroxidation and di-tyrosine, a measure of protein oxidation. We also determined urinary antioxidant activity in these samples. Subsets of IEM patients showed significantly higher levels of the damage markers isoprostanes and di-tyrosine. Of note, patients with cobalamin disorders (i.e., CblB and CblC) consistently had the highest levels of oxidative damage markers. Lower urine antioxidant capacity was seen in all subject categories, particularly cobalamin disorders and propionic acidemia. Longitudinal studies in subjects with MSUD showed good concordance between markers of oxidative damage and acute decompensation. Overall, quantifying oxidative stress offers a unique perspective to IEM. These measures may provide a means of addressing mitochondrial function in IEM and aid in the development of therapeutic targets and clinical monitoring in this diverse set of disorders.

Protein phosphatase 2Cm is a critical regulator of branched-chain amino acid catabolism in mice and cultured cells

The branched-chain amino acids (BCAA) are essential amino acids required for protein homeostasis, energy balance, and nutrient signaling. In individuals with deficiencies in BCAA, these amino acids can be preserved through inhibition of the branched-chain-alpha-ketoacid dehydrogenase (BCKD) complex, the rate-limiting step in their metabolism. BCKD is inhibited by phosphorylation of its E1alpha subunit at Ser293, which is catalyzed by BCKD kinase. During BCAA excess, phosphorylated Ser293 (pSer293) becomes dephosphorylated through the concerted inhibition of BCKD kinase and the activity of an unknown intramitochondrial phosphatase. Using unbiased, proteomic approaches, we have found that a mitochondrial-targeted phosphatase, PP2Cm, specifically binds the BCKD complex and induces dephosphorylation of Ser293 in the presence of BCKD substrates. Loss of PP2Cm completely abolished substrate-induced E1alpha dephosphorylation both in vitro and in vivo. PP2Cm-deficient mice exhibited BCAA catabolic defects and a metabolic phenotype similar to the intermittent or intermediate types of human maple syrup urine disease (MSUD), a hereditary disorder caused by defects in BCKD activity. These results indicate that PP2Cm is the endogenous BCKD phosphatase required for nutrient-mediated regulation of BCKD activity and suggest that defects in PP2Cm may be responsible for a subset of human MSUD.

Medium-chain fatty acids accumulating in MCAD deficiency elicit lipid and protein oxidative damage and decrease non-enzymatic antioxidant defenses in rat brain

Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is the most frequent disorder of fatty acid oxidation with a similar prevalence to that of phenylketonuria. Affected patients present tissue accumulation of the medium-chain fatty acids octanoate (OA), decanoate (DA) and cis-4-decenoate. Clinical presentation is characterized by neurological symptoms, such as convulsions and lethargy that may develop into coma and sudden death. The aim of the present work was to investigate the in vitro effect of OA and DA, the metabolites that predominantly accumulate in MCADD, on oxidative stress parameters in rat cerebral cortex homogenates. It was first verified that both DA and OA significantly increased chemiluminescence and thiobarbituric acid-reactive species levels (lipoperoxidation) and decreased the non-enzymatic antioxidant defenses, measured by the decreased total antioxidant capacity. DA also enhanced carbonyl content and oxidation of sulfhydryl groups (protein damage) and decreased reduced glutathione (GSH) levels. We also verified that DA-induced GSH decrease and sulfhydryl oxidation were not observed when cytosolic preparations (membrane-free supernatants) were used, suggesting a mitochondrial mechanism for these actions. Our present data show that the medium-chain fatty acids DA and OA that most accumulate in MCADD cause oxidative stress in rat brain. It is therefore presumed that this pathomechanism may be involved in the pathophysiology of the neurologic symptoms manifested by patients affected by MCADD.

Amino acids levels and lipid peroxidation in maple syrup urine disease patients

OBJECTIVE

In the present study we correlated the amino acids, branched-chain alpha-keto acids and alpha-hydroxy acids levels with the thiobarbituric acid-reactive species (TBARS) measurement, a lipid peroxidation parameter, in plasma from treated MSUD patients in order to examine whether these accumulated metabolites could be associated to the oxidative stress present in MSUD.

DESIGN AND METHODS

TBARS, amino acids, branched-chain alpha-keto acids and alpha-hydroxy acids concentrations were measured in plasma samples from treated MSUD patients.

RESULTS

We verified that plasma TBARS was increased, whereas tryptophan and methionine concentrations were significantly reduced. Furthermore TBARS measurement was inversely correlated to methionine and tryptophan levels.

CONCLUSIONS

Considering that methionine and tryptophan have antioxidant activities, the data suggest that the imbalance of these amino acids may be involved with lipid peroxidation in MSUD.

Oxidative stress induction by cis-4-decenoic acid: relevance for MCAD deficiency

Patients affected by medium-chain acyl-CoA dehydrogenase deficiency (MCADD) suffer from acute episodes of encephalopathy whose underlying mechanisms are poorly known. The present work investigated the in vitro effect of cis-4-decenoic acid (cDA), which accumulates in MCADD, on important parameters of oxidative stress in cerebral cortex of young rats. cDA markedly induced lipid peroxidation, as verified by the increased levels of spontaneous chemiluminescence and thiobarbituric acid-reactive substances. Furthermore, cDA significantly increased carbonyl formation and sulphydryl oxidation, which is indicative of protein oxidative damage, and promoted 2',7'-dihydrodichlorofluorescein oxidation. It was also observed that the non-enzymatic tissue antioxidant defenses were decreased by cDA, whereas the antioxidant enzyme activities catalase, superoxide dismutase and glutathione peroxidase were not altered. Moreover, cDA-induced lipid peroxidation and GSH reduction was totally blocked by free radical scavengers, suggesting that reactive species were involved in these effects. The data indicate that oxidative stress is induced by cDA in rat brain in vitro and that oxidative damage might be involved in the pathophysiology of the encephalopathy in MCADD.

Oxidative stress is induced in female carriers of X-linked adrenoleukodystrophy

X-linked adrenoleukodystrophy (X-ALD) is a peroxisomal disease biochemically characterized by the accumulation of very long chain fatty acids (VLCFA), particularly hexacosanoic (C26:0) and tetracosanoic acids (C24:0) in different tissues and in biological fluids and clinically characterized by central and peripheral demyelination and adrenal insufficiency. A considerable number of heterozygotes (HTZ) for X-ALD develop neurological symptoms like spinal cord involvement resembling milder forms of adrenomyeloneuropathy. However, the mechanisms of brain damage in hemizygotes and heterozygotes X-ALD individuals are poorly understood. Considering that oxidative stress was involved in various neurodegenerative disorders and that in a previous study we showed evidence that oxidative stress is probably involved in the pathophysiology of X-ALD symptomatic patients, in the present study we evaluated various oxidative stress parameters, namely thiobarbituric acid-reactive substances (TBA-RS), total antioxidant status (TAS) and total antioxidant reactivity (TAR) in plasma of HTZ individuals for X-ALD. It was observed that female carriers present a significant increase of TBA-RS measurement, indicating a stimulation of lipid peroxidation, as well as a decrease of TAR, reflecting a deficient capacity to rapidly handle an increase of reactive species. These results indicate that oxidative stress is involved in the pathophysiology of heterozygotes for X-ALD.

Oxidative stress in plasma from maple syrup urine disease patients during treatment

Maple Syrup Urine Disease (MSUD) is an autosomal recessive metabolic disorder caused by a deficiency of branched-chain alpha-keto acid dehydrogenase complex activity leading to accumulation of the branched-chain amino acids leucine, isoleucine and valine and their corresponding branched-chain alpha-keto acids. Affected patients usually present hypoglycemia, ketoacidosis, convulsions, poor feeding, coma, psychomotor delay and mental retardation. Considering that the pathophysiology of MSUD is still poorly understood, in this study we evaluated some parameters of oxidative stress, namely thiobarbituric acid-reactive substances (TBARS), total antioxidant reactivity (TAR) and total antioxidant status (TAS) in plasma from treated MSUD patients presenting high and low plasma leucine levels. We verified a significant increase of TBARS (lipid peroxidation) and a decrease of TAR (capacity to rapidly react with free radicals) in plasma from treated MSUD patients with low and with high plasma levels of leucine compared to the control group. It was also verified that TAS (quantity of tissue antioxidants) was not altered in plasma from treated MSUD patients with low and high blood leucine levels. Finally, we found no correlation between leucine, valine and isoleucine levels with the various parameters of oxidative stress. These results are indicative that increased lipid oxidative damage and decreased antioxidant defenses occur in plasma of MSUD patients and that the accumulating branched-chain amino acids are probably not directly associated to oxidative stress in this disorder.

Induction of oxidative stress by the metabolites accumulating in 3-methylglutaconic aciduria in cerebral cortex of young rats

3-methylglutaconic (MGT), 3-methylglutaric (MGA) and occasionally 3-hydroxyisovaleric (OHIVA) acids accumulate in a group of diseases known as 3-methylglutaconic aciduria (MGTA). Although the clinical presentation of MGTA is mainly characterized by neurological symptoms, the mechanisms of brain damage in this disease are poorly known. In the present study we investigated the in vitro effect of MGT, MGA and OHIVA on various parameters of oxidative stress in cerebral cortex from young rats. Thiobarbituric acid-reactive substances (TBA-RS) and chemiluminescence were significantly increased by MGT, MGA and OHIVA, indicating that these metabolites induce lipid oxidative damage. Furthermore, the addition of melatonin, alpha-tocopherol and superoxide dismutase plus catalase fully prevented MGT-induced increase on TBA-RS, suggesting that free radicals were involved in this effect. These metabolites also provoked protein oxidative damage determined by increased carbonyl formation and sulfhydryl oxidation, but did not induce superoxide generation in submitochondrial particles. It was also verified that MGA and MGT significantly decreased the non-enzymatic antioxidant defenses in cerebral cortex supernatants and that melatonin and alpha-tocopherol totally blocked MGA-induced GSH reduction. The data indicate that the metabolites accumulating in MGTA elicit oxidative stress in vitro in the cerebral cortex. It is therefore presumed that this pathomechanism may be involved in the brain damage observed in patients affected by MGTA.

Maple syrup urine disease in treated patients: biochemical and oxidative stress profiles

OBJECTIVE

The objective of this study was to evaluate and correlate the biochemical and oxidative stress profiles in MSUD patients during the dietary treatment.

DESIGN AND METHODS

Plasma samples from treated MSUD patients were used to evaluate the biochemical profile and oxidative stress parameters.

RESULTS

It was observed that glucose, total cholesterol, albumin and creatinine are reduced and that aspartate aminotransferase and lactate dehydrogenase activities are increased in plasma from MSUD patients under treatment. Besides, it was verified an increase of thiobarbituric acid-reactive species (TBARS) and a decrease of total antioxidant reactivity (TAR).

CONCLUSIONS

Our results suggest that oxidative stress occurs in treated MSUD patients and that dietary treatment and clinical conditions associated to the disease can lead to biochemical alterations in these patients.

From research methods to clinical practice in psychiatry: challenges and opportunities in the developing world

Psychiatric disorders are amongst the most prevalent, burdensome, and costly of all medical disorders. Several factors make this an exciting time for research on these conditions; these include relevant advances in (1) nosology and epidemiology; (2) neuroscience, including neurogenetics, molecular neurobiology, cognitive-affective neuroscience, and brain imaging; (3) psychopharmacological and psychotherapeutic interventions; (4) systems research in mental health, including evaluation of evidence and of costs; and (5) patient advocacy and mental health literacy. At the same time, there are important challenges facing psychiatry researchers; these include (1) limitations of current diagnostic systems; (2) problems in attracting talented researchers to neuroscience and in obtaining sufficient funding for the vast amount of needed work; (3) a relative lack of controlled pharmacotherapeutic and psychotherapeutic studies undertaken outside the context of tertiary centres in the developed world; (4) ongoing gaps in systems research, including a relative lack of research on the effects of mental health policy; and (5) stigmatization of mental illness and anti-scientific beliefs in the community. These opportunities and challenges exist in both the developed and the developing world, but their scope may differ qualitatively and quantitatively; here we present a perspective from the developing world. We conclude with a wish list for the way forwards.

Evidence for oxidative stress in tissues derived from succinate semialdehyde dehydrogenase-deficient mice

Animal models of inborn errors of metabolism are useful for investigating the pathogenesis associated with the corresponding human disease. Since the mechanisms involved in the pathophysiology of succinate semialdehyde dehydrogenase (SSADH) deficiency (Aldh5a1; OMIM 271980) are still not established, in the present study we evaluated the tissue antioxidant defences and lipid peroxidation in various cerebral structures (cortex, cerebellum, thalamus and hippocampus) and in the liver of SSADH-deficient mice. The parameters analysed were total radical-trapping antioxidant potential (TRAP) and glutathione (GSH) levels, the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), as well as thiobarbituric acid-reactive substances (TBARS). We first observed that the tissue nonenzymatic antioxidant defences were significantly reduced in the SSADH-deficient animals, particularly in the liver (decreased TRAP and GSH) and in the cerebral cortex (decreased GSH), as compared to the wild-type mice. Furthermore, SOD activity was significantly increased in the liver and cerebellum, whereas the activity of CAT was significantly higher in the thalamus. In contrast, GPx activity was significantly diminished in the hippocampus. Finally, we observed that lipid peroxidation (TBARS levels) was markedly increased in the liver and cerebral cortex, reflecting a high lipid oxidative damage in these tissues. Our data showing an imbalance between tissue antioxidant defences and oxidative attack strongly indicate that oxidative stress is involved in the pathophysiology of SSADH deficiency in mice, and likely the corresponding human disorder.

Cytoskeleton as a potential target in the neuropathology of maple syrup urine disease: insight from animal studies

In this short review we provide evidence that the branched-chain keto acids accumulating in the neurometabolic disorder maple syrup urine disease disturb rat cerebral cytoskeleton in a developmentally regulated manner. Alterations of protein phosphorylation leading to brain cytoskeletal misregulation and neural cell death caused by these metabolites are associated with energy deprivation, oxidative stress and excitotoxicity that may ultimately disrupt normal cell function and viability.

Erythrocyte glutathione peroxidase activity and plasma selenium concentration are reduced in maple syrup urine disease patients during treatment

Maple syrup urine disease (MSUD) is an inherited disorder caused by a deficiency of the branched-chain alpha-keto acid dehydrogenase complex activity. In the present study we evaluated selenium levels in plasma from MSUD patients at diagnosis and under treatment and the activities of glutathione peroxidase, catalase and superoxide dismutase in erythrocytes from treated patients. We verified that MSUD patients present a significant selenium deficiency at diagnosis, which becomes more pronounced during treatment, as well as a decrease of erythrocyte glutathione peroxidase activity during treatment. In contrast, erythrocyte catalase and superoxide dismutase activities were not altered in these patients. Our present results suggest that the reduction of an important antioxidant enzyme activity may be partially involved in the pathomechanisms of this disorder and that plasma selenium levels must be corrected through dietary supplementation in MSUD patients.