The effect of age, diagnosis, and their interaction on vertex-based measures of cortical thickness and surface area in autism spectrum disorder.

Autism spectrum disorder (ASD) is a lifelong neurodevelopmental condition that is accompanied by an atypical development of brain maturation. So far, brain development has mainly been studied during early childhood in ASD, and using measures of total or lobular brain volume. However, cortical volumetric measures are a product of two distinct biological neuroanatomical features, cortical thickness, and surface area, which most likely also have different neurodevelopmental trajectories in ASD. Here, we therefore examined age-related differences in cortical thickness and surface area in a cross-sectional sample of 77 male individuals with ASD ranging from 7 to 25 years of age, and 77 male neurotypical controls matched for age and FSIQ. Surface-based measures were analyzed using a general linear model (GLM) including linear, quadratic, and cubic age terms, as well as their interactions with the main effect of group. When controlling for the effects of age, individuals with ASD had spatially distributed reductions in cortical thickness relative to controls, particularly in fronto-temporal regions, and also showed significantly reduced surface area in the prefrontal cortex and the anterior temporal lobe. We also observed significant group × age interactions for both measures. However, while cortical thickness was best predicted by a quadratic age term, the neurodevelopmental trajectory for measures of surface area was mostly linear. Our findings suggest that ASD is accompanied by age-related and region-specific reductions in cortical thickness and surface area during childhood and early adulthood. Thus, differences in the neurodevelopmental trajectory of maturation for both measures need to be taken into account when interpreting between-group differences overall.

Moderate hyperhomocysteinemia provokes dysfunction of cardiovascular autonomic system and liver oxidative stress in rats.

Hyperhomocysteinemia (HHcy) is associated with cardiovascular disease, atherosclerosis and reactive oxygen species generation. Thus, our aim was to investigate whether there was an association between HHcy, blood pressure, autonomic control and liver oxidative stress. Male Wistar rats were divided into 2 groups and treated for 8weeks: one group (control, CO) received tap water, while the other group (methionine, ME) was given a 100mg/kg of methionine in water by gavage. Two catheters were implanted into the femoral artery and vein to record arterial pressure (AP) and heart rate (HR) and drug administration. Signals were recorded by a data acquisition system. Baroreflex sensitivity was evaluated by HR responses to AP changes induced by vasoactive drugs. HR variability and AP variability were performed by spectral analysis in time and frequency domains to evaluate the contribution of the sympathetic and parasympathetic modulation. Lipid peroxidation and antioxidant enzyme activities were evaluated by measuring superoxide dismutase, catalase and glutathione peroxidase in liver homogenates. The ME group presented a significant increase in systolic arterial pressure (118±9 vs 135±6mmHg), diastolic arterial pressure (81±6 vs. 92±4) and mean arterial pressure (95±7 vs. 106±6). In addition, pulse interval variability presented a significant decrease (41%), while the low frequency component of AP was significantly increased (delta P=6.24mmHg(2)) in the ME group. We also found a positive association between lipid peroxidation and cardiac sympathetic modulation, sympathetic and vagal modulation ratio and systolic pressure variability. Collectively, these findings showed that HHcy induced dysfunction of cardiovascular autonomic system and liver oxidative stress.

Sleep deprivation alters gene expression and antioxidant enzyme activity in mice splenocytes.

Cellular defence against the formation of reactive oxygen species (ROS) involves a number of mechanisms in which antioxidant enzymes such as catalase (CAT) and superoxide dismutase (SOD) play an important role. The relation between sleep deprivation and oxidative stress has not yet been completely elucidated. Although some authors did not find evidence of this relationship, others found alterations in some oxidative stress markers in response to sleep deprivation. Thus, the objective of this study was to identify changes induced by sleep deprivation in the activity and gene expression of antioxidant enzymes in mice splenocytes, ideally corroborating a better understanding of the observed effects related to sleep deprivation, which could be triggered by oxidative imbalance. Splenocytes from mice sleep deprived for 72 h showed no significant difference in CAT and CuZnSOD gene expression compared with normal sleep mice. However, sleep-deprived mice did show higher MnSOD gene expression than the control group. Concerning enzymatic activity, CuZnSOD and MnSOD significantly increased after sleep deprivation, despite the expression in CuZnSOD remained unchanged. Moreover, CAT activity was significantly lower after sleep deprivation. The data suggest that the antioxidant system is triggered by sleep deprivation, which in turn could influence the splenocytes homoeostasis, thus interfering in physiological responses.

Higher frequency of paraoxonase gene polymorphism and cardiovascular impairment among Brazilian Fabry Disease patients.

OBJECTIVES: Paraoxonase (PON1) plays a role in preventing the oxidation of lipoproteins and protecting against atherosclerosis. Several polymorphisms have been described in the gene encoding this enzyme, which are related to different enzymatic activities. Fabry Disease (FD) is a lysosomal storage disease associated with cardiomyopathy, early-onset stroke, renal failure, among other features. The objective of the current study was to investigate the PON1 polymorphisms Gln192Arg and Leu55Met in FD patients and correlate them with clinical symptoms. DESIGN AND METHODS: A total of 106 subjects with FD and 26 healthy individuals were selected for the study. Both polymorphisms were assessed in the DNA of blood samples using PCR-RFLP. Hardy-Weinberg equilibrium was calculated for the genotypes and statistical analyses were realized using the Chi-Squared test with Yates correction. RESULTS: The allele frequencies of the polymorphism Gln192Arg for FD patients and control were 0.38 and 0.25, respectively. A comparison of the frequencies for Gln192Arg polymorphism between FD patients and controls revealed a significant difference. The clinical information was obtained from 41 patients. Patients with the Gln192Arg polymorphism showed different cardiovascular manifestations. CONCLUSIONS: The higher frequency of the Gln192Arg polymorphism among FD patients highlighted the possibility of a correlation between the PON1 genetic variation and the phenotypes because the disease has a wide range of symptoms not explained exclusively by mutations on the GLA gene.

Expert recommendations for the laboratory diagnosis of MPS VI.

Mucopolysaccharidosis VI (MPS VI) is a lysosomal storage disease caused by a deficiency of N-acetylgalactosamine 4-sulfatase (arylsulfatase B, ASB). This enzyme is required for the degradation of dermatan sulfate. In its absence, dermatan sulfate accumulates in cells and is excreted in large quantities in urine. Specific therapeutic intervention is available; however, accurate and timely diagnosis is crucial for maximal benefit. To better understand the current practices for diagnosis and to establish diagnostic guidelines, an international MPS VI laboratory diagnostics scientific summit was held in February of 2011 in Miami, Florida. The various steps in the diagnosis of MPS VI were discussed including urinary glycosaminoglycan (uGAG) analysis, enzyme activity analysis, and molecular analysis. The following conclusions were reached. Dilute urine samples pose a significant problem for uGAG analysis and MPS VI patients can be missed by quantitative uGAG testing alone as dermatan sulfate may not always be excreted in large quantities. Enzyme activity analysis is universally acknowledged as a key component of diagnosis; however, several caveats must be considered and the appropriate use of reference enzymes is essential. Molecular analysis supports enzyme activity test results and is essential for carrier testing, subsequent genetic counseling, and prenatal testing. Overall the expert panel recommends caution in the use of uGAG screening alone to rule out or confirm the diagnosis of MPS VI and acknowledges enzyme activity analysis as a critical component of diagnosis. Measurement of another sulfatase enzyme to exclude multiple sulfatase deficiency was recommended prior to the initiation of therapy. When feasible, the use of molecular testing as part of the diagnosis is encouraged. A diagnostic algorithm for MPS VI is provided.

Endurance exercise training increases APPL1 expression and improves insulin signaling in the hepatic tissue of diet-induced obese mice, independently of weight loss.

Hepatic insulin resistance is the major contributor to fasting hyperglycemia in type 2 diabetes. The protein kinase Akt plays a central role in the suppression of gluconeogenesis involving forkhead box O1 (Foxo1) and peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC-1α), and in the control of glycogen synthesis involving the glycogen synthase kinase beta (GSK3ß) in the liver. It has been demonstrated that endosomal adaptor protein APPL1 interacts with Akt and blocks the association of Akt with its endogenous inhibitor, tribbles-related protein 3 (TRB3), improving the action of insulin in the liver. Here, we demonstrated that chronic exercise increased the basal levels and insulin-induced Akt serine phosphorylation in the liver of diet-induced obese mice. Endurance training was able to increase APPL1 expression and the interaction between APPL1 and Akt. Conversely, training reduced both TRB3 expression and TRB3 and Akt association. The positive effects of exercise on insulin action are reinforced by our findings that showed that trained mice presented an increase in Foxo1 phosphorylation and Foxo1/PGC-1α association, which was accompanied by a reduction in gluconeogenic gene expressions (PEPCK and G6Pase). Finally, exercised animals demonstrated increased at basal and insulin-induced GSK3ß phosphorylation levels and glycogen content at 24 h after the last session of exercise. Our findings demonstrate that exercise increases insulin action, at least in part, through the enhancement of APPL1 and the reduction of TRB3 expression in the liver of obese mice, independently of weight loss.

Association of oxidative stress markers and C-reactive protein with multidimensional indexes in COPD.

To evaluate the oxidative stress and the C-reactive protein (CRP) in chronic obstructive pulmonary disease (COPD) patients and their correlation between the severity of the disease according to GOLD criteria and multidimensional indexes such as BODE index. A blood sample was collected for thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), catalase, glutathione (GSH), homocysteine (HCY) and CRP analysis from 45 stable COPD patients. Lung function, body nutritional status, dyspnea and 6-min walk test (6MWT) were evaluated. Patients with GOLD stage IV presented a higher value for the TBARS than stage I patients (4.47 + 1.58 versus 2.27 + 1.04 nmol/mL, p < 0.05). CRP was higher for GOLD IV (2.46 + 3.68 mg/dL) than other stages (GOLD I: 0.39 + 0.25, GOLD II: 0.39 + 0.18 and GOLD III: 0.48 + 0.36 mg/dL, p < 0.05). Oxidative stress markers measured as TBARS presented a negative correlation between forced expiratory volume in the first second (FEV(1)) post bronchodilatador (% predicted; r = -0.39, p = 0.01) and positive correlations with Modified Medical Research Council Scale (MMRC) dyspnea index (r = 0.40, p = 0.01), multidimensional index (r = 0.49, p = 0.001) and BODE index (r = 0.51, p = 0.001).

Fatores preditores do alcance das metas de um programa de intervenção em nipo-brasileiros / Predictors of goal achievement in an intervention program among Japanese-Brazilians

Identificar fatores da linha de base preditores do alcance das metas do programa de intervenção no estilo de vida após 12 meses em população de nipo-brasileiros, empregando-se modelos de regressão logística ajustados. Em 2005, 321 participantes eram portadores de excesso de peso e houve maior chance [OR (IC95 por cento)] de alcance da meta de perda de peso após 12 meses entre mulheres [2,45 (1,33; 4,13)], indivíduos de maior idade [1,03 (1,00; 1,06)] e menor chance entre portadores de morbidades no início do estudo [0,33 (0,14; 0,77)]. Dos 261 indivíduos sedentários, o alcance da meta de atividades físicas foi inversamente relacionado ao exercício de atividades profissionais [0,40 (0,17; 0,95)]. Não se verificou fatores da linha de base associados ao alcance das metas do consumo de legumes, verduras e frutas e gorduras saturadas da dieta após 12 meses. Indivíduos de maior idade, mulheres, não portadores de morbidades e sem exercício de atividades profissionais na linha de base apresentaram maior chance de alcance das metas após 12 meses de intervenção no estilo de vida.

The aim of this study was to identify baseline factors associated with achieving goals after a 12-month lifestyle intervention program in a Japanese-Brazilian population, using adjusted logistic regression models. In 2005, 321 participants were overweight. The odds [OR (IC95 percent)] of reaching the goals after 12 months of intervention were directly related to female gender [2.35 (1.34, 4.13)] and older age [1.03 (1.00, 1.06)] and inversely related to baseline morbidity [0.33 (0.14, 0.77)]. Of the 261 sedentary individuals, achieving the goal for physical activity was inversely related to working [0.44 (0.17, 0.95)]. No baseline predictors were found for reaching the goal of fruit and vegetable consumption or saturated fat intake after 12 months. At baseline, women, older individuals, and individuals without diseases or not working showed increased odds of achieving the goals after 12 months of the lifestyle intervention.

Homocysteine thiolactone induces cardiac dysfunction: role of oxidative stress.

This study investigates the cardiac functioning in male Wistar rats after treatments with methionine and homocysteine thiolactone (HcyT). The rats were distributed into 3 groups and treated for 8 weeks. Group I was the control (CO) group, given water, group II was treated with methionine, and group III with HcyT (100 mg/kg). Morphometric and functional cardiac parameters were evaluated by echocardiography. Superoxide dismutase (SOD), catalase, and glutathione S-transferase activities, chemiluminescence, thiobarbituric acid reactive substances, and immunocontent were measured in the myocardium. Hyperhomocysteinemiawas observed in rats submitted to the both treatments. The results showed diastolic function was compromised in HcyT group, seen by the increase of E/A (peak velocity of early (E) and late (A) diastolic filling) ratio, decrease in deceleration time of E wave and left ventricular isovolumic relaxation time. Myocardial performance index was increased in HcyT group and was found associated with increased SOD immunocontent. HcyT group demonstrated an increase in SOD, catalase, and glutatione S-transferase activity, and chemiluminescence and thiobarbituric acid reactive substances. Overall, these results indicated that HcyT induces a cardiac dysfunction and could be associated with oxidative stress increase in the myocardium.

Sleep deprivation-induced gnawing-relationship to changes in feeding behavior in rats.

We have recently reported that food spillage increases during sleep deprivation in rats, which may lead to an overestimation of food intake in this condition. The objective of this study was to verify whether sleep deprivation induces an increase in gnawing behavior that could account for increased food spillage and apparent increase in food intake. We introduced wood blocks as objects for gnawing and determined the effects of their availability on food consumption and food spillage during sleep deprivation. Wood block availability reduced the amount of food removed from hoppers and decreased the amount of food spilled. However, weight loss still occurred during the sleep deprivation period, especially in the first 24 h, and it was related to a reduction in food intake. Sleep deprivation causes an increase in stereotyped gnawing behavior which largely accounts for increased food spillage observed during deprivation. Specifically, the observed increase in food removed from feeders seems to be due to an increase in gnawing and not to increased hunger. However, even when appropriately corrected for spillage, food intake decreased in the first 24 h of sleep deprivation, which accounted for most of the body weight loss seen during the 96 h of sleep deprivation.

Impact of hypertension and hyperhomocysteinemia on arterial thrombosis in primary antiphospholipid syndrome.

The aim of this study was to evaluate traditional risk factors for coronary artery disease (CAD), homocysteine, anti-oxidized low-density lipoprotein (anti-oxLDL), anti-lipoprotein lipase (anti-LPL) and endothelin-1 (ET-1) in patients with primary anti-phospholipid syndrome (APS), furthermore verify possible association among these variables and arterial thrombosis. Thirty-eight women with primary APS and 30 age-and-sex-matched controls were evaluated. Patients presented higher-LDL and triglycerides levels and lower-HDL levels than controls. Anti-LPL antibodies were not detected in both groups. The mean number of risk factors was higher in patients than in controls (P = 0.030). Anti-oxLDL antibodies, homocysteine and ET-1 mean levels were similar between groups, but abnormal homocysteine levels were found only among primary APS patients (P = 0.031). Hypertension and the presence of at least one risk factor for CAD were more prevalent in patients with arterial involvement than those without. Homocysteine levels and mean number of risk factors for CAD were significantly higher in patients with arterial thrombosis than controls. In a multivariate analysis hypertension was the only independently associated with arterial thrombosis (OR 14.8, 95% CI = 2.1-100.0, P = 0.006). This study showed that in primary APS patients other risk factors besides anti-phospholipid antibodies contribute for the occurrence of arterial events and the most important factor was hypertension.

Association of increased levels of homocysteine and peripheral arterial disease in a Japanese-Brazilian population.

OBJECTIVES: Our aim was to evaluate the possible association between homocysteine levels and peripheral arterial disease (PAD) in a population-based study of Japanese-Brazilians. MATERIALS AND METHODS: This cross-sectional study was derived from a population-based survey on the prevalence of diabetes and associated diseases conducted in Japanese-Brazilians. A total of 1330 male and female subjects aged>or=30 years were submitted to clinical examination and laboratory procedures including homocysteine measurement. The ankle-brachial index (ABI) was calculated; subjects with ABI values <0.9 were diagnosed with PAD. The evaluable population included 1008 subjects. Logistic regression was used taking PAD as the dependent variable. RESULTS: Mean age of the population was 56.5 years and overall prevalence of PAD was 20%. A worse cardiovascular profile was found in male patients, including significantly higher homocysteine levels (11.9+/-1.8 vs. 9.1+/-1.1micromol/L, p<0.001). Men with PAD had higher prevalence rates of hyperhomocysteinemia compared to women (22.7% vs 7.6%). Univariate analysis showed an odds ratio of hyperhomocysteinemia for PAD of 1.51 [1.02-2.25] in men and 1.69 [1.06-2.68] in women. After adjustment for other cardiovascular risk factors, higher levels of homocysteine were only significantly related to PAD in men. CONCLUSION: In a Japanese-Brazilian population, elevated levels of homocysteine are associated with PAD in men. Prospective studies are necessary to confirm this finding.

Dissociation of the effects of ethanol on memory, anxiety, and motor behavior in mice tested in the plus-maze discriminative avoidance task.

RATIONALE: Several studies have shown the amnestic effects of ethanol (ETOH). However, while memory tasks in rodents can be markedly influenced by anxiety-like behavior and motor function, ETOH induces anxiolysis and different effects on locomotion, depending on the dose. OBJECTIVE: Verify the effects of ETOH in mice tested in the plus-maze discriminative avoidance task (PMDAT) concomitantly evaluating memory, anxiety-like behavior, and motor behavior. METHODS: ETOH acutely or repeatedly treated mice were submitted to the training session in a modified elevated plus-maze with two open and two enclosed arms, aversive stimuli in one of the enclosed arms, and tested 24 h later without aversive stimuli. Learning/memory, locomotion, and anxiety-related behavior were evaluated by aversive arm exploration, number of entries in all the arms and open arms exploration, respectively. RESULTS: Acute ETOH: (1) either increased (1.2-1.8 g/kg) or decreased (3.0 g/kg) locomotion; (2) decreased anxiety levels (1.2-3.0 g/kg); and (3) induced learning deficits (1.2-3.0 g/kg) and memory deficits (0.3-3.0 g/kg). After repeated treatment, sensitization and tolerance to hyperlocomotion and anxiolysis induced by 1.8 g/kg ETOH were observed, respectively, and tolerance to the amnestic effect of 0.6 (but not 1.8) g/kg ETOH occurred. CONCLUSION: Neither the anxiolytic nor the locomotor effects of ETOH seem to be related to its amnestic effect in the PMDAT. Additionally, data give support to the effectiveness of the PMDAT in simultaneously evaluating learning, memory, anxiety-like behavior, and motor activity by different parameters. Possible relationships between the behavioral alterations found are discussed.

Increased concentration of plasma homocysteine in children with systemic lupus erythematosus.

OBJECTIVE: Studies in adults with SLE have evidenced increase of homocysteine related, mainly, to thromboembolic events. The aim of our study was to evaluate plasma homocysteine concentration in children with systemic lupus erythematosus (SLE) and its correlation with renal involvement, serum and erythrocyte folate, vitamin B12, antiphospholipid antibodies, estimated creatinine clearance and dyslipidemia. METHODS: Thirty-two children (29 females) with SLE and 32 healthy controls (29 females) matched for age and sex were included in the study. The mean age of patients and controls was 14.2 years (range from 10 to 18 years). Only one patient presented one thrombotic event. Plasma homocysteine, erythrocyte and serum folate, vitamin B12, lipid profile, antiphospholipid antibodies and estimated creatinine clearance were evaluated. Raised homocysteine concentration was defined as equal or more than 12.9 mol/L. RESULTS: Raised homocysteine concentration was detected in 15 (46.9%) children with SLE with an important statistical difference in relation to control group (p < 0.001). A positive correlation was found between plasma homocysteine concentration and renal involvement (odds ratio 11.1 [95% CI 1.50-82.24], p = 0.01) based on the presence of renal biopsy, abnormalities of urine sediment and/or serum creatinine. However, when we performed the estimated creatinine clearance the correlation with homocysteine concentration was not positive. We did not observe abnormalities in serum and erythrocyte folate and vitamin B12 in our patients. However, they presented significant higher concentrations of TC total cholesterol (p = 0.005) and of LDL low-density lipoprotein (p = 0.02) than controls. CONCLUSION: Elevated plasma homocysteine concentration is frequent in children with SLE. We believe that these results may signalize to the possibility of complications in our patients later in life. Further long-term and prospective studies are needed in order to determine the real role of the homocysteine concentration as a risk factor in children.

Sleep disturbances, oxidative stress and cardiovascular risk parameters in postmenopausal women complaining of insomnia.

OBJECTIVE: The aim of this work was to investigate cardiovascular risk factors and oxidative stress parameters as well as sleep disturbances in polysomnography recordings of 38 postmenopausal women with insomnia. METHODS: Polysomnography recordings were performed on subjects for sleep analysis. Oxidative stress parameters were analyzed by measuring blood concentration of catalase, superoxide dismutase (SOD), thiobarbituric acid reactive substances (TBARS) and glutathione. For cardiovascular risk factors, we measured plasma levels of homocysteine, folic acid and vitamin B6. RESULTS: Findings of polysomnography recordings revealed: 68% experienced decreased sleep efficiency, 50% had apnea, 7.8% had periodic leg movements and 2.6% had bruxism (involuntary gnashing and grinding of the teeth during sleep). Our results showed that the majority of our subjects presented normal concentrations of the parameters studied according to standards reached in our laboratory. The only notable exception was TBARS. In this case, only 21% displayed normal values. We also found inverse correlations between SOD activity and both age and time of menopause. CONCLUSIONS: Although all women complained of insomnia, 50% of them demonstrated apnea during polysomnography recordings. Of the parameters measuring oxidative stress, only TBARS levels were increased in our sample. Some clinical data, such as time of onset of menopause, may be associated with the oxidative stress status of these women, probably due to the lack of estrogen and to sleep disturbances, such as apnea.

Therapeutic and pathogenetic animal models for Dolichos pruriens.

The therapeutic and pathogenetic effects of Dolichos pruriens were evaluated using experimental models in rats. In the therapeutic experiment Wistar rats were housed in a heated environment (25+/-3 degrees C) to induce itch, and treated with ascending potencies D. pruriens (6 cH, 9 cH, 12 cH and 30 cH), each for 10 days. The positive control group received vehicle (ethanol 30% in water). The negative control group received no treatment and were kept at a standard temperature. In the pathogenetic experiment, all animals were kept at a temperature of 20+/-3 degrees C and treated for 30 consecutive days with D. pruriens 6 or 30 cH, or ethanol vehicle, or no treatment. The experiments were performed blind. The statistical analysis used Bartlett's test, followed by ANOVA/Tuckey-Krammer or Kruskal-Wallis/Dunn. The results point to the existence of therapeutic effects, with inhibition of the itching, skin lesions and fur thinning produced by heat, more evident in later observations, with the 9 12, and 30 cH potencies (Kruskal-Wallis/Dunn; P=0.001). No changes were observed in the other parameters, such as open field activity and laterality of the itching. In the pathogenetic experiment, no changes were observed in any parameters examined. We conclude that the proposed experimental model demonstrates the therapeutic effect of D. pruriens, but not its pathogenetic effects.

Plasma total homocysteine in Brazilian overweight and non-overweight adolescents: a case-control study.

OBJECTIVE: To test the hypothesis that overweight adolescents have higher plasma total homocysteine (tHcy) levels than non-overweight adolescents and to explore the association between plasma tHcy levels with folate, vitamin B12 and some risk factors for CVD in both groups. METHODS: A case-control study conductec with 239 adolescentes aged 15-19 years in the city of São Paulo, Brazil; 86 overweight and 153 non-overweight frequency matched by age, gender, pubertal and socioeconomic status. tHcy, folate, vitamin B12, lipid profile, glucose, insulin and insulin resistance were measured. RESULTS: No significant differences were found in tHcy, folate and vitamin B12 levels between overweight and non-overweight groups. The geometric means of tHcy were elevated in both groups (overweight: 11.8 micromol/L; non-overweight: 11.6 micromol/L) higher for boys than for girls (P < or = 0.001). Folate deficiency was identified in 68.6% of total studied population. Triacylglycerol, LDL cholesterol, insulin resistance were higher and HDL cholesterol was lower in overweight that non-overweight adolescents. In the multiple linear regression model, in overweight group, tHcy was independently associated with age (P = 0.041), sex (P = 0.004) and folate (P = 0.022) and in non-overweight group, with age (P = 0.049), sex (P < 0.001), folate (P = 0.018) and vitamin B12 (P = 0.030). CONCLUSIONS: Obesity was not a determinant factor of tHcy levels. Age, sex and folate were independent determinants of plasma tHcy levels. The high prevalence of folate deficiency may have been responsible for the elevated tHcy levels in these adolescents, increasing the risk for future development of CVD.