Clóvis Paniz

Importance of the lipid peroxidation biomarkers and methodological aspects FOR malondialdehyde quantification

Free radicals induce lipid peroxidation, playing an important role in pathological processes. The injury mediated by free radicals can be measured by conjugated dienes, malondialdehyde, 4-hydroxynonenal, and others. However, malondialdehyde has been pointed out as the main product to evaluate lipid peroxidation. Most assays determine malondialdehyde by its reaction with thiobarbituric acid, which can be measured by indirect (spectrometry) and direct methodologies (chromatography). Though there is some controversy among the methodologies, the selective HPLC-based assays provide a more reliable lipid peroxidation measure. This review describes significant aspects about MDA determination, its importance in pathologies and biological samples treatment.

The influence of the hemodialysis treatment time under oxidative stress biomarkers in chronic renal failure patients.

UNLABELLED Oxidative stress possibly helps to promote the progression and complication of chronic renal failure (CRF). Hemodialysis (HD) may aggravate oxidative stress. In addition long time of treatment may intensify the oxidative stress. Thus, the aim of this study was to evaluate the effect of prolonged HD treatment under parameters of the oxidative stress. METHODS Plasmatic thiobarbituric acid reactive substances (TBARS), plasmatic malondialdehyde (MDA), blood delta-aminolevulinate dehydratase (ALA-D) activity, ALA-D reactivation index, and erythrocytic reduced glutathione (GSH) were measured into two different groups of HD patients: recent treatment (n=36; HD duration: 17.7+/-1.71 months), and long time of treatment (n=26; HD duration: 82.2+/-6.32 months), and in a control group (n=40). RESULTS Plasmatic TBARS and MDA levels were both elevated in HD patients. However, only MDA levels had positive correlation with time of HD treatment. Blood ALA-D activity was decreased in HD patients. The ALA-D reactivation index showed increase in HD patients, and it had correlation with the time of HD treatment. Erythrocytic GSH levels were increased in HD patients. CONCLUSIONS Our results indicated that MDA levels and ALA-D reactivation index may be the better biomarkers to evaluate chronic oxidative stress in comparison with others markers analyzed in this study.

The relationships between exogenous and endogenous antioxidants with the lipid profile and oxidative damage in hemodialysis patients

BackgroundWe sought to investigate the relationships among the plasma levels of carotenoids, tocopherols, endogenous antioxidants, oxidative damage and lipid profiles and their possible effects on the cardiovascular risk associated with hemodialysis (HD) patients.MethodsThe study groups were divided into HD and healthy subjects. Plasma carotenoid, tocopherol and malondialdehyde (MDA) levels, as well as erythrocyte reduced glutathione (GSH), were measured by HPLC. Blood antioxidant enzymes, kidney function biomarkers and the lipid profiles were analyzed by spectrophotometric methods.ResultsPlasma lycopene levels and blood glutathione peroxidase (GPx) activity were significantly decreased in HD patients compared with healthy subjects. Total cholesterol, low-density lipoprotein cholesterol (LDL-c), creatinine, urea, MDA, GSH, superoxide dismutase (SOD) and catalase (CAT) were significantly increased in HD (p < 0.05). Lycopene levels were correlated with MDA (r = -0.50; p < 0.01), LDL-c (r = -0.38; p = 0.01) levels, the LDL-c/HDL-c index (r = -0.33; p = 0.03) and GPx activity (r = 0.30; p = 0.03). Regression models showed that lycopene levels were correlated with LDL-c (β estimated = -31.59; p = 0.04), while gender was correlated with the TC/HDL-c index and triglycerides. Age did not present a correlation with the parameters evaluated. GPx activity was negatively correlated with MDA levels and with the LDL-c/HDL-c and CT/HDL-c indexes.ConclusionsLycopene may represent an additional factor that contributes to reduced lipid peroxidation and atherogenesis in hemodialysis patients.

Association Among Microalbuminuria and Oxidative Stress Biomarkers in Patients With Type 2 Diabetes

Aim Hyperglycemia in diabetes mellitus (DM) may be one of the most important factors responsible for the development of oxidative stress, which promotes the main complications in DM patients. Therefore, this study evaluated if the hyperglycemia could be related to oxidative stress biomarkers, lipid profile, and renal function in type 2 diabetes patients without clinic complications. Methods Plasmatic malondialdehyde (MDA), serum protein carbonyl (PCO), serum creatinine levels, microalbuminuria, glycated hemoglobin, and lipid profile were analyzed in 37 type 2 diabetic patients and 25 subjects with no diabetes. Results Serum creatinine levels were within the reference values, but microalbuminuria presented increased levels in all the patients compared with controls (P < 0.05) and above of the reference values. The MDA, PCO, low-density lipoprotein, and triglyceride levels showed positive correlation with microalbuminuria levels. Moreover, glycated hemoglobin presented positive correlation with MDA, PCO, and microalbuminuria levels. Conclusions The hyperglycemia could be responsible for the increase of the microalbuminuria levels and for the oxidation process in lipids and proteins in DM patients. Therefore, we suggested that the microvascular lesion is a direct consequence from hyperglycemia and an indirect one from the increased oxidative stress. Malondialdehyde and protein carbonyl levels could be suggested as additional biochemical evaluation to verify tissue damage in type 2 DM patients.

Butyrylcholinesterase activity is reduced in haemodialysis patients: Is there association with hyperhomocysteinemia and/or oxidative stress?

OBJECTIVES To quantify serum butyrylcholinesterase activity in haemodialysis patients and to evaluate if the homocysteine levels and/or oxidative stress biomarkers have an effect on butyrylcholinesterase. MATERIALS AND METHODS Blood samples were collected from patients and healthy subjects (control). The plasma homocysteine and TBARS levels; serum butyrylcholinesterase activity; blood delta aminolevulinic acid dehydratase (ALA-D) activity and methahaemoglobin were analyzed. The mortality of the patients was also evaluated after 3 years. RESULTS The homocysteine was increased and butyrylcholinesterase decreased compared to control (p<0.05). TBARS and methahaemoglobin were increased and ALA-D decreased (p<0.05). The following correlations were found: homocysteine with butyrylcholinesterase (-0.44); methahaemoglobin (0.41); ALA-D (-0.68); and TBARS (0.66). The partial correlation between homocysteine with butyrylcholinesterase, withdrawn the effect of TBARS, was -0.30; all p<0.05. Moreover, it was observed that 22% of the patients died due to cardiovascular problems. CONCLUSION Thus, our findings support a direct association between the reduction of butyrylcholinesterase by the increase of homocysteine and an indirect effect by increase in oxidative stress.

Aspectos gerais e diagnóstico clinicolaboratorial da intoxicação por paraquat

INTRODUCTION: Paraquat is a herbicide widely used in agriculture. It is a very toxic product, fatally poisoning mainly by the lack of an efficient antidote to revert the clinical state. FISIOPATHOLOGY: Toxicological effects are decurrent of oxidative stress. The most important target organ is the lung, which can display edema, hemorrhage, interstitial inflammation and fibroses, culminating in serious respiratory failure and death. Moreover, it is nephrotoxic, hepatotoxic, miotoxic and neurotoxic. TREATMENT: Besides aiming the decrease of absorption and stimulating the excretion of absorbed paraquat, the poisoning treatment nowadays is based on measures that decrease oxidative stress using antioxidants, consequently reverting clinical state, mainly the pulmonary. Diagnostic methods: Among the available quantitative methods, the chromatographic are the most reported ones for biological samples. However, capillary electrophoresis and immunoassay methods can be used. Immunoassays stand out for being typically found in hospital laboratories, while chromatographic and electrophoretic methods are not. On the other hand, a simple and fast urinary reaction with sodium dithionite is very utilized because it is predictive in acute poisoning suspect. CONCLUSION: In the presence of high morbimortality potential in paraquat intoxications, the reversion of pulmonary toxicity with antioxidants is extensively studied, but a specific antidote is not established. In laboratorial diagnostic, chromatographic, electrophoretic and immunologic techniques are applied to paraquat quantification, although in clinical toxicology the sodium dithionite reaction is still significant.

Evaluation of Toxic Metals and Essential Elements in Children with Learning Disabilities from a Rural Area of Southern Brazil

Children’s exposure to metals can result in adverse effects such as cognitive function impairments. This study aimed to evaluate some toxic metals and levels of essential trace elements in blood, hair, and drinking water in children from a rural area of Southern Brazil. Cognitive ability and δ-aminolevulinate dehydratase (ALA-D) activity were evaluated. Oxidative stress was evaluated as a main mechanism of metal toxicity, through the quantification of malondialdehyde (MDA) levels. This study included 20 children from a rural area and 20 children from an urban area. Our findings demonstrated increase in blood lead (Pb) levels (BLLs). Also, increased levels of nickel (Ni) in blood and increase of aluminum (Al) levels in hair and drinking water in rural children were found. Deficiency in selenium (Se) levels was observed in rural children as well. Rural children with visual-motor immaturity presented Pb levels in hair significantly increased in relation to rural children without visual-motor immaturity (p < 0.05). Negative correlations between BLLs and ALA-D activity and positive correlations between BLLs and ALA-RE activity were observed. MDA was significantly higher in rural compared to urban children (p < 0.05). Our findings suggest that rural children were co-exposed to toxic metals, especially Al, Pb and Ni. Moreover, a slight deficiency of Se was observed. Low performance on cognitive ability tests and ALA-D inhibition can be related to metal exposure in rural children. Oxidative stress was suggested as a main toxicological mechanism involved in metal exposure.

Possíveis efeitos do cobre sanguíneo sobre parâmetros hematológicos em idosas

INTRODUCTION: Copper is an essential trace element, and its homeostasis is important, mainly among the elderly, since their metabolism is associated with neurodegenerative diseases and erythropoiesis disorders, among others. OBJECTIVE: This study evaluated the association among cupremia, hematological parameters and oxidative stress. MATERIAL AND METHODS: Blood samples from 39 elderly women (study group) and 20 health individuals (control group) were collected. The concentrations of serum copper were quantified by ICP-MS. The activity and enzyme ALA-D reactivation index were determined by spectrophotometry and blood parameters were analyzed in the automated system. The results were expressed as mean ± standard deviation. RESULTS: Concentrations of copper, hematological parameters and ALA-D reactivation were within the reference values in both groups. However, ALA-D activity (11.47 ± 2.81 UL-1) was significantly lower in the study group compared to the control group. Spearman correlations (observed only in elderly women) between copper concentration versus hemoglobin, hematocrit and ALA-D activity were -0.384, -0.408 and -0.395, respectively (p < 0.05). Nonetheless, ALA reactivation index was not related to cupremia. DISCUSSION AND CONCLUSION: The results showed that copper, although it is within accepted reference values, may be involved in ALA-D inhibition, which may affect hematological parameters such as hemoglobin synthesis. Thus, the reference levels for copper in the elderly should be reviewed.

Avaliação da estabilidade do marcador plasmático do estresse oxidativo: malondialdeído

oC, utilizing thiobarbituric acid (TBA) as derivative in spectrophotometric and chromatographic analysis. The results showed that MDA was stable for 24 h after blood collection, was not stable when stored after alkaline hydrolysis, remained stable for 30 days after TBA derivatization and was stable for 3 days when stored after n-butanol extraction, all at –20 o C.

Chewable tablets of carbonyl iron as an alternative for better adherence to anemia treatment: analysis of two studies

Abstract The objective was to evaluate the acceptance of iron carbonila in theform of chewable tablets by children of two age groups, as a factorfor better adherence and effectiveness of treatment for iron deficiencyanemia . It was applied a questionnaire with 5 issues to evaluate thepharmaceutical form of study (size, taste, smell, hardness,pharmaceutical form), side effects and adherence to treatment after30 days of oral supplementation with iron. The study A is one clinicaltrial, randomized, open, with 73 children with iron deficiency ane-mia receiving 5 mg/kg/day of iron in the form of chewable tablets ofiron carbonyl (study group) or solution of ferrous sulphate (controlgroup). In study B, 15 children with iron deficiency weresupplemented with 50 mg/dia iron carbonyl. Each tablet contains25 mg of iron and were produced by Herbarium and Botanicallaboratory exclusively for these studies. The assessment of the tabletswas considered very good by all of the children. The refusal to takethe medication was 3.12% for iron carbonyl and 66.6% for solutionof ferrous sulphate in the study A. In study B no child refused themedication. There were no reports of side effects for iron carbonylin the two studies. The great acceptance of iron carbonyl in form ofchewable tablets is a positive factor in the treatment of iron deficiencyanemia, working for better adherence and effectiveness of treatment.Rev. Bras. Hematol. Hemoter. 2008;