Globotriaosylsphingosine induces oxidative DNA damage in cultured kidney cells.

Fabry disease (FD) is a lysosomal disorder caused by mutations leading to a deficient activity α-galactosidase A with progressive and systemic accumulation of its substrates. Substrates deposition is related to tissue damage in FD, but the underlying molecular mechanisms remain not completely understood. DNA damage has been associated with disease progression in chronic diseases and was recently described in high levels in Fabry patients. Once renal complications are major morbidity causes in FD, we investigated the effects of the latest biomarker for FD - globotriaosylsphingosine (lyso-Gb3) in a cultured renal lineage - human embryonic kidney cells (HEK-293 T) - on DNA damage. In concentrations found in Fabry patients, lyso-Gb3 induced DNA damage (by alkaline comet assay) with oxidative origin in purines and pyrimidines (by comet assay with endonucleases). These data provide new information about a deleterious effect of lyso-Gb3 and could be useful to studies looking for new therapeutic strategies to FD.

Biomolecules damage and redox status abnormalities in Fabry patients before and during enzyme replacement therapy.

Fabry disease (FD) is caused by deficient activity of the lysosomal enzyme α-galactosidase A. Its substrates, mainly globotriaosylceramide (Gb3), accumulate and seem to induce other pathophysiological findings of FD. Once enzyme replacement therapy (ERT) is not completely efficient on preventing disease progress in FD patients, elucidating the underlying mechanisms in FD pathophysiology is essential to the development of additional therapeutic strategies. We investigated 58 Fabry patients (23 male and 35 female) subdivided into two groups (at diagnosis and during long-term ERT) and compared them to healthy individuals. Fabry patients at diagnosis presented altered glutathione (GSH) metabolism (higher GSH levels, lower glutathione peroxidase - GPx - and normal glutathione reductase - GR - activities), higher lipid peroxidation levels (thiobarbituric acid reactive species - TBARS - and malondialdehyde - MDA), nitric oxide (NO(.)) equivalents and urinary Gb3. Fabry patients on ERT presented GSH metabolism similar to controls, although lipid peroxidation and urinary levels of NO(.) equivalents remained higher whereas Gb3 levels were lower than at diagnosis but still higher than controls. These data demonstrated that redox impairment occurs in Fabry patients before and after ERT, probably as a consequence of Gb3 accumulation, providing targets to future therapy approaches using antioxidants in combination with ERT in FD.

DNA damage in Fabry patients: An investigation of oxidative damage and repair.

Fabry disease (FD) is a lysosomal storage disorder associated with loss of activity of the enzyme α-galactosidase A. In addition to accumulation of α-galactosidase A substrates, other mechanisms may be involved in FD pathophysiology, such as inflammation and oxidative stress. Higher levels of oxidative damage to proteins and lipids in Fabry patients were previously reported. However, DNA damage by oxidative species in FD has not yet been studied. We investigated basal DNA damage, oxidative DNA damage, DNA repair capacity, and reactive species generation in Fabry patients and controls. To measure oxidative damage to purines and pyrimidines, the alkaline version of the comet assay was used with two endonucleases, formamidopyrimidine DNA-glycosylase (FPG) and endonuclease III (EndoIII). To evaluate DNA repair, a challenge assay with hydrogen peroxide was performed. Patients presented significantly higher levels of basal DNA damage and oxidative damage to purines. Oxidative DNA damage was induced in both DNA bases by H2O2 in patients. Fabry patients presented efficient DNA repair in both assays (with and without endonucleases) as well as significantly higher levels of oxidative species (measured by dichlorofluorescein content). Even if DNA repair be induced in Fabry patients (as a consequence of continuous exposure to oxidative species), the repair is not sufficient to reduce DNA damage to control levels.

Oxidative stress and inflammation in mucopolysaccharidosis type IVA patients treated with enzyme replacement therapy.

Mucopolysaccharidosis type IVA (MPS IVA) is an inborn error of glycosaminoglycan (GAG) catabolism due to the deficient activity of N-acetylgalactosamine-6-sulfate sulfatase that leads to accumulation of the keratan sulfate and chondroitin 6-sulfate in body fluids and in lysosomes. The pathophysiology of this lysosomal storage disorder is not completely understood. The aim of this study was to investigate oxidative stress parameters, pro-inflammatory cytokine and GAG levels in MPS IVA patients. We analyzed urine and blood samples from patients under ERT (n=17) and healthy age-matched controls (n=10-15). Patients presented a reduction of antioxidant defense levels, assessed by a decrease in glutathione content and by an increase in superoxide dismutase activity in erythrocytes. Concerning lipid and protein damage, it was verified increased urine isoprostanes and di-tyrosine levels and decreased plasma sulfhydryl groups in MPS IVA patients compared to controls. MPS IVA patients showed higher DNA damage than control group and this damage had an oxidative origin in both pyrimidine and purine bases. Interleukin 6 was increased in patients and presented an inverse correlation with GSH levels, showing a possible link between inflammation and oxidative stress in MPS IVA disease. The data presented suggest that pro-inflammatory and pro-oxidant states occur in MPS IVA patients even under ERT. Taking these results into account, supplementation of antioxidants in combination with ERT can be a tentative therapeutic approach with the purpose of improving the patient's quality of life. To the best of our knowledge, this is the first study relating MPS IVA patients with oxidative stress.

Hyperprolinemia induces DNA, protein and lipid damage in blood of rats: antioxidant protection.

The present study investigated the effects of hyperprolinemia on oxidative damage to biomolecules (protein, lipids and DNA) and the antioxidant status in blood of rats. The influence of the antioxidants on the effects elicited by proline was also examined. Wistar rats received two daily injections of proline and/or vitamin E plus C (6th-28th day of life) and were killed 12h after the last injection. Results showed that hyperprolinemia induced a significant oxidative damage to proteins, lipids and DNA demonstrated by increased carbonyl content, malondialdehyde levels and a greater damage index in comet assay, respectively. The concomitant antioxidants administration to proline treatment completely prevented oxidative damage to proteins, but partially prevented lipids and DNA damage. We also observed that the non-enzymatic antioxidant potential was decreased by proline treatment and partially prevented by antioxidant supplementation. The plasma levels of vitamins E and C significantly increased in rats treated exogenously with these vitamins but, interestingly, when proline was administered concomitantly with vitamin E plus C, the levels of these vitamins were similar to those found in plasma of control and proline rats. Our findings suggest that hyperprolinemia promotes oxidative damage to the three major classes of macromolecules in blood of rats. These effects were accomplished by decrease in non-enzymatic antioxidant potential and decrease in vitamins administered exogenously, which significantly decreased oxidative damage to biomolecules studied. These data suggest that antioxidants may be an effective adjuvant therapeutic to limit oxidative damage caused by proline.

Experimental evidence for protein oxidative damage and altered antioxidant defense in patients with medium-chain acyl-CoA dehydrogenase deficiency.

The objective of this study was to test whether macromolecule oxidative damage and altered enzymatic antioxidative defenses occur in patients with medium-chain acyl coenzyme A dehydrogenase (MCAD) deficiency. We performed a cross-sectional observational study of in vivo parameters of lipid and protein oxidative damage and antioxidant defenses in asymptomatic, nonstressed, MCAD-deficient patients and healthy controls. Patients were subdivided into three groups based on therapy: patients without prescribed supplementation, patients with carnitine supplementation, and patients with carnitine plus riboflavin supplementation. Compared with healthy controls, nonsupplemented MCAD-deficient patients and patients receiving carnitine supplementation displayed decreased plasma sulfhydryl content (indicating protein oxidative damage). Increased erythrocyte superoxide dismutase (SOD) activity in patients receiving carnitine supplementation probably reflects a compensatory mechanism for scavenging reactive species formation. The combination of carnitine plus riboflavin was not associated with oxidative damage. These are the first indications that MCAD-deficient patients experience protein oxidative damage and that combined supplementation of carnitine and riboflavin may prevent these biochemical alterations. Results suggest involvement of free radicals in the pathophysiology of MCAD deficiency. The underlying mechanisms behind the increased SOD activity upon carnitine supplementation need to be determined. Further studies are necessary to determine the clinical relevance of oxidative stress, including the possibility of antioxidant therapy.

Homocysteine contribution to DNA damage in cystathionine ß-synthase-deficient patients.

High blood levels of homocysteine (Hcy) are found in patients affected by homocystinuria, a genetic disorder caused by deficiency of cystathionine ß-synthase (CBS) activity, as well as in nutritional deficiencies (vitamin B12 or folate) and in abnormal renal function. We previously demonstrated that lipid and protein oxidative damage is increased and the antioxidant defenses diminished in plasma of CBS-deficient patients, indicating that oxidative stress is involved in the pathophysiology of this disease. In the present work, we extended these investigations by evaluating DNA damage through the comet assay in peripheral leukocytes from CBS-deficient patients, as well as by analyzing of the in vitro effect of Hcy on DNA damage in white blood cells. We verified that DNA damage was significantly higher in the CBS-deficient patients under treatment based on a protein-restricted diet and pyridoxine, folic acid, betaine and vitamin B12 supplementation, when compared to controls. Furthermore, the in vitro study showed a concentration-dependent effect of Hcy inducing DNA damage. Taken together, the present data indicate that DNA damage occurs in treated CBS-deficient patients, possibly due to high Hcy levels.

Protein and lipid damage in maple syrup urine disease patients: l-carnitine effect.

Maple syrup urine disease (MSUD) is an inborn error of metabolism biochemically characterized by elevated levels of the branched chain amino acids (BCAA) leucine, isoleucine, valine and the corresponding branched-chain α-keto acids. This disorder is clinically characterized by ketoacidosis, seizures, coma, psychomotor delay and mental retardation whose pathophysiology is not completely understood. Recent studies have shown that oxidative stress may be involved in neuropathology of MSUD. l-Carnitine (l-Car) plays a central role in the cellular energy metabolism because it transports long-chain fatty acids for oxidation and ATP generation. In recent years many studies have demonstrated the antioxidant role of this compound. In this work, we investigated the effect of BCAA-restricted diet supplemented or not with l-Car on lipid peroxidation and in protein oxidation in MSUD patients. We found a significant increase of malondialdehyde and of carbonyl content in plasma of MSUD patients under BCAA-restricted diet compared to controls. Furthermore, patients under BCAA-restricted diet plus l-Car supplementation presented a marked reduction of malondialdehyde content in relation to controls, reducing the lipid peroxidation. In addition, free l-Car concentrations were negatively correlated with malondialdehyde levels. Our data show that l-Car may have an antioxidant effect, protecting against the lipid peroxidation and this could represent an additional therapeutic approach to the patients affected by MSUD.

Oxidative stress in Niemann-Pick type C patients: a protective role of N-butyl-deoxynojirimycin therapy.

Niemann-Pick type C (NPC) is a rare neurodegenerative disorder biochemically characterized by the accumulation of cholesterol and glycosphingolipids in late endosomes and lysosomes of the affected patients. N-butyl-deoxynojirimycin is the only approved drug for patients with NPC disease. It inhibits glycosphingolipid synthesis, therefore reducing intracellular lipid storage. Although the mechanisms underlying the neurologic damage in the NPC disease are not yet well established, in vitro and in vivo studies suggest an involvement of reactive species in the pathophysiology of this disease. In this work we aimed to evaluate parameters of lipid and protein oxidation, measured by thiobarbituric acid-reactive species (TBA-RS) and protein carbonyl formation, respectively, as well as the enzymatic and non-enzymatic antioxidant defenses in plasma, erythrocytes and fibroblasts from NPC1 patients, at diagnosis and during treatment with N-butyl-deoxynojirimycin. We found a significant increase of TBA-RS in plasma and fibroblasts, as well as increased protein carbonyl formation and decreased total antioxidant status (TAS) in plasma of untreated NPC1 patients as compared to the control group. In addition, erythrocyte glutathione peroxidase (GSH-Px) activity was increased, whereas CAT and SOD activities were normal in these patients. We also observed that patients treated with N-butyl-deoxynojirimycin normalized plasma TBA-RS and TAS, as well as erythrocyte GSH-Px activity. Taken together, the present data indicate that oxidative stress is increased in patients with NPC1 disease and that treatment with N-butyl-deoxynojirimycin is able to confer protection against this pathological process.

Oxidative stress parameters in urine from patients with disorders of propionate metabolism: a beneficial effect of L:-carnitine supplementation.

Propionic (PA) and methylmalonic (MMA) acidurias are inherited disorders caused by deficiency of propionyl-CoA carboxylase and methylmalonyl-CoA mutase, respectively. Affected patients present acute metabolic crises in the neonatal period and long-term neurological deficits. Treatments of these diseases include a protein restricted diet and L: -carnitine supplementation. L: -Carnitine is widely used in the therapy of these diseases to prevent secondary L: -carnitine deficiency and promote detoxification, and several recent in vitro and in vivo studies have reported antioxidant and antiperoxidative effects of this compound. In this study, we evaluated the oxidative stress parameters, isoprostane and di-tyrosine levels, and the antioxidant capacity, in urine from patients with PA and MMA at the diagnosis, and during treatment with L: -carnitine and protein-restricted diet. We verified a significant increase of isoprostanes and di-tyrosine, as well as a significant reduction of the antioxidant capacity in urine from these patients at diagnosis, as compared to controls. Furthermore, treated patients presented a marked reduction of isoprostanes and di-tyrosine levels in relation to untreated patients. In addition, patients with higher levels of protein and lipid oxidative damage, determined by di-tyrosine and isoprostanes levels, also presented lower urinary concentrations of total and free L: -carnitine. In conclusion, the present results indicate that treatment with low protein diet and L: -carnitine significantly reduces urinary biomarkers of protein and lipid oxidative damage in patients with disorders of propionate metabolism and that L: -carnitine supplementation may be specially involved in this protection.

Globotriaosylceramide is correlated with oxidative stress and inflammation in Fabry patients treated with enzyme replacement therapy.

Fabry disease is an X-linked inborn error of glycosphingolipid catabolism due to deficient activity of α-galactosidase A that leads to accumulation of the enzyme substrates, mainly globotriaosylceramide (Gb3), in body fluids and lysosomes of many cell types. Some pathophysiology hypotheses are intimately linked to reactive species production and inflammation, but until this moment there is no in vivo study about it. Hence, the aim of this study was to investigate oxidative stress parameters, pro-inflammatory cytokines and Gb3 levels in Fabry patients under treatment with enzyme replacement therapy (ERT) and finally to establish a possible relation between them. We analyzed urine and blood samples of patients under ERT (n=14) and healthy age-matched controls (n=14). Patients presented decreased levels of antioxidant defenses, assessed by reduced glutathione (GSH), glutathione peroxidase (GPx) activity and increased superoxide dismutase/catalase (SOD/CAT) ratio in erythrocytes. Concerning to the damage to biomolecules (lipids and proteins), we found that plasma levels of malondialdehyde (MDA) and protein carbonyl groups and di-tyrosine (di-Tyr) in urine were increased in patients. The pro-inflammatory cytokines IL-6 and TNF-α were also increased in patients. Urinary Gb3 levels were positively correlated with the plasma levels of IL-6, carbonyl groups and MDA. IL-6 levels were directly correlated with di-Tyr and inversely correlated with GPx activity. This data suggest that pro-inflammatory and pro-oxidant states occur, are correlated and seem to be induced by Gb3 in Fabry patients.

Experimental evidence of oxidative stress in plasma of homocystinuric patients: a possible role for homocysteine.

Homocystinuria is an inherited disorder biochemically characterized by high urinary excretion of homocystine and increased levels of homocysteine (Hcy) and methionine in biological fluids. Affected patients usually have a variety of clinical and pathologic manifestations. Previous experimental data have shown a relationship between Hcy and oxidative stress, although very little was reported on this process in patients with homocystinuria. Therefore, in the present study we evaluated parameters of oxidative stress, namely carbonyl formation, malondialdehyde (MDA) levels, sulfhydryl content and total antioxidant status (TAS) in patients with homocystinuria at diagnosis and under treatment with a protein restricted diet supplemented by pyridoxine, folate, betaine, and vitamin B(12). We also correlated plasma Hcy and methionine concentrations with the oxidative stress parameters examined. We found a significant increase of MDA levels and carbonyl formation, as well as a reduction of sulfhydryl groups and TAS in plasma of homocystinuric patients at diagnosis relatively to healthy individuals (controls). We also verified that Hcy levels were negatively correlated with sulfhydryl content and positively with MDA levels. Furthermore, patients under treatment presented a significant reduction of the content of MDA, Hcy and methionine concentrations relatively to patients at diagnosis. Taken together, the present data indicate that lipid and protein oxidative damages are increased and the antioxidant defenses diminished in plasma of homocystinuric patients, probably due to increased reactive species elicited by Hcy. It is therefore presumed that oxidative stress participates at least in part in the pathogenesis of homocystinuria.

Oxidative stress in patients with mucopolysaccharidosis type II before and during enzyme replacement therapy.

Mucopolysaccharidosis type II (MPS II) is a lysosomal storage disorder caused by deficiency of the enzyme iduronate-2-sulfatase, responsible for the degradation of glycosaminoglycans dermatan and heparan sulfate. Once the generation of free radicals is involved in the pathogenesis of many diseases, including some inborn errors of metabolism, the aim of this study was to evaluate blood oxidative stress parameters in MPS II patients, before and during 6 months of enzyme replacement therapy. We found significantly increased levels of malondialdehyde and carbonyl groups in plasma as well as erythrocyte catalase activity in patients before treatment compared to the control group. Plasma sulfhydryl group content and total antioxidant status were significantly reduced before treatment, while superoxide dismutase enzyme was not altered at this time when compared to controls. During enzyme replacement therapy, there was a significant reduction in levels of malondialdehyde when compared to pretreatment. Sulfhydryl groups were significantly increased until three months of treatment in MPS II patients in comparison to pretreatment. There were no significant alterations in plasma total antioxidant status and carbonyl groups as well as in catalase and superoxide dismutase activities during treatment in relation to pretreatment. The results indicate that MPS II patients are subject to lipid and protein oxidative damage and present reduction in non-enzymatic antioxidants, suggesting a possible involvement of free radicals in the pathophysiology of this disease. Also, the results may suggest that enzyme replacement therapy seems to protect against lipid peroxidation and protein damage in these patients.

Effects of insulin and clonazepam on DNA damage in diabetic rats submitted to the forced swimming test.

Diabetes mellitus (DM) is a chronic hyperglycemic state. DM may be associated with moderate cognitive deficits and neurophysiologic/structural changes in the brain (diabetic encephalopathy). Psychiatric manifestations seem to accompany this encephalopathy, since the prevalence of depression in diabetic patients is much higher than in the general population, and clonazepam is being used to treat this complication. The excessive production of oxygen free radicals that may occur in diabetes induces a variety of lesions in macromolecules, including DNA. In this work, we analyzed DNA damage in leukocytes from streptozotocin-induced diabetic rats submitted to the forced swimming test. The DNA damage index was significantly elevated (DI=61.00 ± 4.95) in the diabetic group compared to the control group (34.00 ± 1.26). Significant reductions of the damage index were observed in diabetic animals treated with insulin (45.00 ± 1.82), clonazepam (52.00 ± 1.22), or both agents (39.00 ± 5.83, not significantly different from control levels). Insulin plus clonazepam can protect against DNA damage in stressed diabetic rats.

Protein and lipid oxidative damage in streptozotocin-induced diabetic rats submitted to forced swimming test: the insulin and clonazepam effect.

Diabetes may modify central nervous system functions and is associated with moderate cognitive deficits and changes in the brain, a condition that may be referred to as diabetic encephalopathy. The prevalence of depression in diabetic patients is higher than in the general population, and clonazepam is being used to treat this complication. Oxidative stress may play a role in the development of diabetes complications. We investigated oxidative stress parameters in streptozotocin-induced diabetic rats submitted to forced swimming test (STZ) and evaluated the effect of insulin (STZ-INS) and/or clonazepam (STZ-CNZ and STZ-INS-CNZ) acute treatment on these animal model. Oxidative damage to proteins measured as carbonyl content in plasma was significantly increased in STZ group compared to STZ treated groups. Malondialdehyde plasma levels were significantly reduced in STZ-INS and STZ-INS-CNZ groups when compared to STZ rats, being significantly reduced in STZ-INS-CNZ than STZ-INS rats. The activities of the antioxidant enzymes catalase, superoxide dismutase and glutathione peroxidase showed no significant differences among all groups of animals. These findings showed that protein and lipid damage occurs in this diabetes/depression animal model and that the associated treatment of insulin and clonazepam is capable to protect against oxidative damage in this experimental model.

Prevention by L-carnitine of DNA damage induced by propionic and L-methylmalonic acids in human peripheral leukocytes in vitro.

Propionic acidemia (PAemia) and methylmalonic acidemia (MMAemia) are inborn errors of propionate metabolism characterized by the accumulation of, respectively, propionic and l-methylmalonic acids (and their metabolites) in the blood and tissues of affected patients. The conditions lead to severe metabolic complications in the neonatal period and to long-term neurological manifestations. Treatment for these disorders consists of a protein-restricted diet, supplemented with synthetic formulas of amino acids, but excluding isoleucine, threonine, valine and methionine; and l-carnitine, to promote detoxication. In vitro and in vivo studies have demonstrated that lipid and protein oxidative damage may be involved in the pathophysiology of these diseases, but DNA damage has not been fully investigated. In this work, we evaluated in vitro the effects of PA and MMA, in the presence or absence of l-carnitine, on DNA damage in peripheral leukocytes, as determined by the alkaline comet assay, using silver staining and visual scoring. PA and MMA induced a DNA damage index (DI) significantly higher than that of the control group. l-Carnitine significantly reduced PA- and MMA-induced DNA damage, in a concentration-dependent manner. Our findings indicate that PA and MMA induce DNA damage and l-carnitine is able to prevent this damage.

Simvastatin treatment prevents oxidative damage to DNA in whole blood leukocytes of dyslipidemic type 2 diabetic patients.

Type 2 diabetes (T2D) is associated with increased oxidative stress as indicated by elevated levels of lipid peroxidation and protein oxidation products. Since reactive oxygen species (ROS) can cause damage to biological macromolecules including DNA, this study investigated oxidative damage to DNA using the alkaline (pH > 13) comet assay in peripheral whole blood leukocytes sampled from 15 dyslipidemic T2D patients treated with simvastatin (20 mg/day), 15 dyslipidemic T2D patients not treated with simvastatin, 20 non-dyslipidemic T2D patients, and 20 healthy individuals (controls). Our results showed a greater DNA migration in terms of damage index (DI) (p < 0.01) in the dyslipidemic T2D patients not treated with statin (DI = 67.70 +/- 10.89) when compared to the dyslipidemic T2D patients under statin treatment (DI = 47.56 +/- 7.02), non-dyslipidemic T2D patients (DI = 52.25 +/- 9.14), and controls (DI = 13.20 +/- 6.40). Plasma malondialdehyde (MDA) and C-reactive protein (CRP) levels were also increased and total antioxidant reactivity (TAR) and paraoxonase activity (PON1) decreased in non-dyslipidemic T2D patients and dyslipidemic T2D non-treated with simvastatin. We also found that DI was inversely correlated with TAR (r = -0.61, p < 0.05) and PON1 (r = -0.67, p < 0.01). In addition, there was a significant positive correlation between DI and CRP (r = 0.80, p < 0.01). Our results therefore indicate that simvastatin treatment plays a protective role on oxidative damage to DNA in dyslipidemic T2D patients probably reflecting a general decrease in oxidative stress in these patients.

Apolipoprotein, C-reactive protein and oxidative stress parameters in dyslipidemic type 2 diabetic patients treated or not with simvastatin.

BACKGROUND AND AIMS: Oxidative stress is considered an important factor in the development of diabetic complications that causes a variety of changes such as oxidative modification of membrane lipids, nucleic acids and cellular proteins. Dyslipidemia is frequently associated with diabetes and cardiovascular disease. In this context, the objective of this study was to evaluate oxidative modifications of plasma proteins and lipids in non dyslipidemic type 2 diabetic (T2D) patients, in dyslipidemic T2D patients treated or not with simvastatin and in healthy subjects to investigate whether treatment with low doses of simvastatin plays a protective role on the lipid and protein oxidative damage in these patients. METHODS: We determined oxidative damage of plasma proteins by carbonyl assay and total thiol group determination. We also characterized the membrane damage in terms of lipid peroxidation by measuring malonaldehyde (MDA) in nondyslipidemic T2D patients, dyslipidemic T2D patients treated with simvastatin (20 mg/day), dyslipidemic T2D patients not treated with simvastatin and in healthy age-matched control subjects. RESULTS: Our results showed that dyslipidemic T2D patients not treated with simvastatin had significantly higher plasma protein carbonyl groups and MDA when compared to dyslipidemic T2D patients treated with simvastatin and control group. Thiol concentrations from dyslipidemic T2D patients not treated with simvastatin were significantly lower than treated patients and controls. It was verified that the thiols groups were inversely correlated with apolipoprotein B and positively correlated with apolipoprotein A-I. CONCLUSIONS: These results demonstrated that treatment with low doses of simvastatin can minimize the protein and lipid oxidative damage in dyslipidemic T2D patients.

Reduction of lipid and protein damage in patients with disorders of propionate metabolism under treatment: a possible protective role of L-carnitine supplementation.

Disorders of propionate metabolism are autosomal recessive diseases clinically characterized by acute metabolic crises in the neonatal period and long-term neurological deficits whose pathophysiology is not completely established. There are increasing evidences demonstrating antioxidant properties for L-carnitine, which is used in the treatment of propionic and methylmalonic acidemias to increase the excretion of organic acids accumulated in tissues and biological fluids of the affected patients. In this work we aimed to evaluate lipid (malondialdehyde content) and protein (carbonyl formation and sulfhydryl oxidation) oxidative damage in plasma from patients with propionic and methylmalonic acidemias at the moment of diagnosis and during treatment with L-carnitine. We also correlated the parameters of oxidative damage with plasma total, free and esterified L-carnitine levels. We found a significant increase of malondialdehyde and carbonyl groups, as well as a reduction of sulfhydryl groups in plasma of these patients at diagnosis compared to controls. Furthermore, patients under treatment presented a marked reduction of the content of protein carbonyl groups, similar to controls, and malondialdehyde content in relation to patients at diagnosis. In addition, plasma total and free L-carnitine concentrations were negatively correlated with malondialdehyde levels. Taken together, the present data indicate that treatment significantly reduces oxidative damage in patients affected by disorders of propionate metabolism and that l-carnitine supplementation may be involved in this protection.

Effect of short- and long-term exposition to high phenylalanine blood levels on oxidative damage in phenylketonuric patients.

Phenylketonuria is the most frequent disturbance of amino acid metabolism. Treatment for phenylketonuric patients consists of phenylalanine intake restriction. However, there are patients who do not adhere to treatment and/or are not submitted to neonatal screening. These individuals are more prone to develop brain damage due to long-lasting toxic effects of high levels of phenylalanine and/or its metabolites. Oxidative stress occurs in late-diagnosed phenylketonuric patients, probably contributing to the neurological damage in this disorder. In this work, we aimed to compare the influence of time exposition to high phenylalanine levels on oxidative stress parameters in phenylketonuric patients who did not adhere to protein restricted diet. We evaluated a large spectrum of oxidative stress parameters in plasma and erythrocytes from phenylketonuric patients with early and late diagnosis and of age-matched healthy controls. Erythrocyte glutathione peroxidase activity and glutathione levels, as well as plasma total antioxidant reactivity were significantly reduced in both groups of patients when compared to the control group. Furthermore, protein oxidative damage, measured by carbonyl formation and sulfhydryl oxidation, and lipid peroxidation, determined by malondialdehyde levels, were significantly increased only in patients exposed for a long time to high phenylalanine concentrations, compared to early diagnosed patients and controls. In conclusion, exposition to high phenylalanine concentrations for a short or long time results in a reduction of non-enzymatic and enzymatic antioxidant defenses, whereas protein and lipid oxidative damage only occurs in patients with late diagnosis.