Ana Paula de Melo Loureiro

Peripheral Oxidative Stress Biomarkers in Mild Cognitive Impairment and Alzheimer's Disease

Oxidative stress has been associated with normal aging and Alzheimers disease (AD). However, little is known about oxidative stress in mild cognitive impairment (MCI) patients who present a high risk for developing AD. The aim of this study was to investigate plasma production of the lipid peroxidation marker, malonaldehyde (MDA) and to determine, in erythrocytes, the enzymatic antioxidant activity of catalase, glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione S-transferase (GST) in 33 individuals with MCI, 29 with mild probable AD and 26 healthy aged subjects. GR/GPx activity ratio was calculated to better assess antioxidant defenses. The relationship between oxidative stress and cognitive performance was also evaluated by the Mini Mental State Examination (MMSE). AD patients showed higher MDA levels than both MCI and healthy elderly subjects. MCI subjects also exhibited higher MDA levels compared to controls. Catalase and GPx activity were similar in MCI and healthy individuals but higher in AD. GR activity was lower in MCI and AD patients than in healthy aged subjects. Additionally, GR/GPx ratio was higher in healthy aged subjects, intermediate in MCI and lower in AD patients. No differences in GST activity were detected among the groups. MMSE was negatively associated with MDA levels (r = -0.31, p = 0.028) and positively correlated with GR/GPx ratio in AD patients (r = 0.68, p < 0.001). MDA levels were also negatively correlated to GR/GPx ratio (r = -0.31, p = 0.029) in the AD group. These results suggest that high lipid peroxidation and decreased antioxidant defenses may be present early in cognitive disorders.

Lipid Peroxidation Is Associated with the Severity of Periodontal Disease and Local Inflammatory Markers in Patients with Type 2 Diabetes

CONTEXT Periodontitis is the most common lytic disease of bone and is recognized as a common complication of diabetes. Lipid peroxidation (LPO) is increased in diabetes and may be related to modulation of the inflammatory response. LPO levels in patients with diabetes and periodontal disease have not been evaluated. OBJECTIVE The aim of this study was to evaluate the levels of LPO and its correlation with periodontal status and inflammatory cytokines in type 2 diabetic and nondiabetic patients. DESIGN AND SETTING This is a cross-sectional study involving Brazilian patients recruited at the State University of São Paulo. PATIENTS The sample comprised 120 patients divided into four groups based upon diabetic and dyslipidemic status: poorly controlled diabetics with dyslipidemia, well-controlled diabetics with dyslipidemia, normoglycemic individuals with dyslipidemia, and healthy individuals. MAIN OUTCOME MEASURES Blood analyses were carried out for fasting plasma glucose, glycated hemoglobin, and lipid profile. Periodontal examinations were performed, and gingival crevicular fluid was collected. LPO levels were evaluated by measuring oxidized low-density lipoprotein (ELISA) and malondialdehyde (HPLC). Cytokines were evaluated by the multiplex bead technique. RESULTS LPO evaluated by malondialdehyde in plasma and gingival crevicular fluid was significantly increased in diabetes groups. Significant correlations between LPO markers and periodontal parameters indicate a direct relationship between these levels and the severity of inflammation and secretion of inflammatory cytokines, particularly in diabetic patients. CONCLUSION These findings suggest an important association for LPO with the severity of the local inflammatory response to bacteria and the susceptibility to periodontal disease in diabetic patients.

Burnt sugarcane harvesting: Particulate matter exposure and the effects on lung function, oxidative stress, and urinary 1-hydroxypyrene

Non-mechanised sugarcane harvesting preceded by burning exposes workers and the people of neighbouring towns to high concentrations of pollutants. This study was aimed to evaluate the respiratory symptoms, lung function and oxidative stress markers in sugarcane workers and the residents of Mendonça, an agricultural town in Brazil, during the non-harvesting and harvesting periods and to assess the population and individual exposures to fine particulate matter (PM(2.5)). Sugarcane workers and healthy volunteers were evaluated with two respiratory symptom questionnaires, spirometry, urinary 1-hydroxypyrene levels, and the measurement of antioxidant enzymes and plasma malonaldehyde during the non-harvesting and harvesting periods. The environmental assessment was determined from PM(2.5) concentration. PM(2.5) level increased from 8 μg/m³ during the non-harvesting period to 23.5 μg/m³ in the town and 61 μg/m³ on the plantations during the harvesting period. Wheezing, coughing, sneezing, and breathlessness increased significantly in both groups during the harvesting period, but more markedly in workers. A decrease in lung function and antioxidant enzyme activity was observed in both populations during harvesting; this decrease was greater among the sugarcane workers. The urinary 1-hydroxypyrene levels only increased in the sugarcane workers during the harvesting period. The malonaldehyde levels were elevated in both groups, with a higher increase observed in the workers. This research demonstrates the exposure of sugarcane workers and the inhabitants of a neighbouring town to high PM(2.5) concentrations during the sugarcane harvest period. This exposure was higher among the sugarcane workers, as illustrated by both higher PM(2.5) concentrations in the sugarcane fields and higher urinary 1-hydroxypyrene levels in the volunteers in this group. The higher incidence of respiratory symptoms, greater decrease in lung function and more marked elevation of oxidative stress markers among the sugarcane workers during the harvest confirms the greater effect magnitude in this population and a dose-dependent relationship between pollution and the observed effects.

Proteasome inhibition and ROS generation by 4-nerolidylcatechol induces melanoma cell death.

Induction of apoptotic cell death in response to chemotherapy and other external stimuli has proved extremely difficult in melanoma, leading to tumor progression, metastasis formation and resistance to therapy. A promising approach for cancer chemotherapy is the inhibition of proteasomal activity, as the half‐life of the majority of cellular proteins is under proteasomal control and inhibitors have been shown to induce cell death programs in a wide variety of tumor cell types. 4‐Nerolidylcatechol (4‐NC) is a potent antioxidant whose cytotoxic potential has already been demonstrated in melanoma tumor cell lines. Furthermore, 4‐NC was able to induce the accumulation of ubiquitinated proteins, including classic targets of this process such as Mcl‐1. As shown for other proteasomal inhibitors in melanoma, the cytotoxic action of 4‐NC is time‐dependent upon the pro‐apoptotic protein Noxa, which is able to bind and neutralize Mcl‐1. We demonstrate the role of 4‐NC as a potent inducer of ROS and p53. The use of an artificial skin model containing melanoma also provided evidence that 4‐NC prevented melanoma proliferation in a 3D model that more closely resembles normal human skin.

Formação de adutos exocíclicos com bases de DNA: implicações em mutagênese e carcinogênese

A number of ring-extended DNA adducts resulting from reaction of a,b-unsaturated aldehydes, or their epoxides, with DNA bases have been characterized in recent years. These adducts can lead to miscoding during DNA replication which, if not repaired, result in mutations that can contribute to cancer development. Recently, the use of ultrasensitive methods allowed the detection of background levels of etheno DNA adducts in tissues of untreated animals and humans suggesting the existence of endogenous sources of reactive intermediates. In this review, we briefly summarize the recent advances in the chemistry of these DNA lesions.

Exposure to lard-based high-fat diet during fetal and lactation periods modifies breast cancer susceptibility in adulthood in rats

The present study investigated whether early life exposure to high levels of animal fat increases breast cancer risk in adulthood in rats. Dams consumed a lard-based high-fat (HF) diet (60% fat-derived energy) or an AIN93G control diet (16% fat-derived energy) during gestation or gestation and lactation. Their 7-week-old female offspring were exposed to 7,12-dimethyl-benzo[a]anthracene to induce mammary tumors. Pregnant dams consuming an HF diet had higher circulating leptin levels than pregnant control dams. However, compared to the control offspring, significantly lower susceptibility to mammary cancer development was observed in the offspring of dams fed an HF diet during pregnancy (lower tumor incidence, multiplicity and weight), or pregnancy and lactation (lower tumor multiplicity only). Mammary epithelial elongation, cell proliferation (Ki67) and expression of NFκB p65 were significantly lower and p21 expression and global H3K9me3 levels were higher in the mammary glands of rats exposed to an HF lard diet in utero. They also tended to have lower Rank/Rankl ratios (P=.09) and serum progesterone levels (P=.07) than control offspring. In the mammary glands of offspring of dams consuming an HF diet during both pregnancy and lactation, the number of terminal end buds, epithelial elongation and the BCL-2/BAX ratio were significantly lower and serum leptin levels were higher than in the controls. Our data confirm that the breast cancer risk of offspring can be programmed by maternal dietary intake. However, contrary to our expectation, exposure to high levels of lard during early life decreased later susceptibility to breast cancer.

In vivo hydroquinone exposure alters circulating neutrophil activities and impairs LPS-induced lung inflammation in mice

Hydroquinone (HQ) is an environmental contaminant which causes immune toxicity. In this study, the effects of exposure to low doses of HQ on neutrophil mobilization into the LPS-inflamed lung were investigated. Male Swiss mice were exposed to aerosolized vehicle (control) or 12.5, 25 or 50ppm HQ (1h/day for 5 days). One hour later, oxidative burst, cell cycle, DNA fragmentation and adhesion molecules expressions in circulating neutrophils were determined by flow cytometry, and plasma malondialdehyde (MDA) levels were measured by HPLC. Also, 1h later the last exposures, inflammation was induced by LPS inhalation (0.1mg/ml/10min) and 3h later, the numbers of leukocytes in peripheral blood and in the bronchoalveolar lavage fluid (BALF) were determined using a Neubauer chamber and stained smears; adhesion molecules expressed on lung microvessel endothelial cells were quantified by immunohistochemistry; myeloperoxidase (MPO) activity was measured in the lung tissue by colorimetric assay; and cytokines in the BALF were determined by ELISA. In vivo HQ exposure augmented plasma MDA levels and oxidative activity of neutrophils, but did not cause alterations in cell cycle and DNA fragmentation. Under these conditions, the number of circulating leukocytes was not altered, but HQ exposure reduced LPS-induced neutrophil migration into the alveolar space, as these cells remained in the lung tissue. The impaired neutrophil migration into BALF may not be dependent on reduced cytokines secretions in the BALF and lung endothelial adhesion molecules expressions. However, HQ exposure increased the expression of β(2) and β(3) integrins and platelet-endothelial cell adhesion molecule-1 (PECAM-1) in neutrophils, which were not further enhanced by fMLP in vitro stimulation, indicating that HQ exposure activates circulating neutrophils, impairing further stimulatory responses. Therefore, it has been shown, for the first time, that neutrophils are target of lower levels of in vivo HQ exposure, which may be considered in host defense in infectious diseases.

Design, synthesis and biological evaluation of hybrid bioisoster derivatives of N-acylhydrazone and furoxan groups with potential and selective anti-Trypanosoma cruzi activity

Hybrid bioisoster derivatives from N-acylhydrazones and furoxan groups were designed with the objective of obtaining at least a dual mechanism of action: cruzain inhibition and nitric oxide (NO) releasing activity. Fifteen designed compounds were synthesized varying the substitution in N-acylhydrazone and in furoxan group as well. They had its anti-Trypanosoma cruzi activity in amastigotes forms, NO releasing potential and inhibitory cruzain activity evaluated. The two most active compounds (6, 14) both in the parasite amastigotes and in the enzyme contain the nitro group in para position of the aromatic ring. The permeability screening in Caco-2 cell and cytotoxicity assay in human cells were performed for those most active compounds and both showed to be less cytotoxic than the reference drug, benznidazole. Compound 6 was the most promising, since besides activity it showed good permeability and selectivity index, higher than the reference drug. Thereby the compound 6 was considered as a possible candidate for additional studies.

Environmental Tobacco Smoke Induces Oxidative Stress in Distinct Brain Regions of Infant Mice

Environmental tobacco smoke (ETS) leads to the death of 600,000 nonsmokers annually and is associated with disturbances in antioxidant enzyme capacity in the adult rodent brain. However, little is known regarding the influence of ETS on brain development. The aim of this study was to determine levels of malonaldehyde (MDA) and 3-nitrotyrosine (3-NT), as well as enzymatic antioxidant activities of glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), and superoxide dismutase (SOD), in distinct brain structures. BALB/c mice were exposed to ETS twice daily for 1 h from postnatal day 5 through postnatal day 18. Acute exposure was performed for 1 h on postnatal day 18. Mice were euthanized either immediately (0) or 3 h after the last exposure. Immediately after an acute exposure there were higher GR and GST activities and MDA levels in the hippocampus, higher GPx and SOD activities in the prefrontal cortex, and higher GST activity and MDA levels in the striatum and cerebellum. Three hours later there was an increase in SOD activity and MDA levels in the hippocampus and a decrease in the activity of all enzymes in the prefrontal cortex. Immediately after final repeated exposure there were elevated levels of GST and GR activity and decreased GPx activity in the hippocampus. Moreover, a rise was found in GPx and GST activities in the prefrontal cortex and increased GST and GPx activity in the striatum and cerebellum, respectively. After 3 h the prefrontal cortex showed elevated GR and GST activities, and the striatum displayed enhanced GST activity. Data showed that enzymatic antioxidant system in the central nervous system responds to ETS differently in different regions of the brain and that a form of adaptation occurs after several days of exposure.

Diabetes and increased lipid peroxidation are associated with systemic inflammation even in well-controlled patients.

BACKGROUND The effect of the interaction between type 2 diabetes and dyslipidemia on inflammation and lipid peroxidation (LPO) has not been assessed. AIM To investigate whether diabetes coupled with dyslipidemia alters oxidative metabolism leading to increased LPO products and inflammatory status. METHODS 100 patients were divided into four groups based upon diabetic and dyslipidemic status: poorly controlled diabetes with dyslipidemia (DM-PC/D), well-controlled diabetes with dyslipidemia (DM-WC/D), normoglycemic individuals with dyslipidemia (NG/D), and normoglycemic individuals without dyslipidemia (NG/ND). Plasma was evaluated for an LPO product (MDA), antioxidant levels and inflammatory cytokines. RESULTS Diabetics presented significantly higher levels of LPO (p<0.05) and the DM-PC/D had higher levels of proinflammatory cytokines and MDA in the plasma in comparison with normoglycemics (p<0.05). Interestingly IL1-β, IL-6, and TNF-α in DM-WC/D were not statistically different from those in DM-PC/D. Normoglycemic individuals with dyslipidemia presented significantly increased levels of IL-6 and TNF-α when compared to normoglycemic without dyslipidemia (p<0.05). MDA levels were also positively correlated with the presence of DM complications (r=0.42, p<0.01). CONCLUSIONS These findings show that dyslipidemia is associated with an increased inflammatory status, even in well-controlled diabetics and in normoglycemics. Our results suggest that lipid metabolism and peroxidation are important for the development of inflammation, which is elevated in several complications associated with diabetes.