The dynamic changes in olive fruit phenolic metabolism and its contribution to the activation of quiescent Colletotrichum infection.

Anthracnose, the most critical disease affecting olive fruits, is caused by Colletotrichum species. While developing olive fruits are immune to the pathogen regardless of the cultivar, the resistance level varies once the fruit ripens. The defense mechanisms responsible for this difference in resistance are not well understood. To explore this, we analyzed the phenolic metabolic pathways occurring in olive fruits and their susceptibility to the pathogen during ripening in two resistant cultivars ('Empeltre' and 'Frantoio') and two susceptible cultivars ('Hojiblanca' and 'Picudo'). Overall, resistant cultivars induced the synthesis of aldehydic and demethylated forms of phenols, which highly inhibited fungal spore germination. In contrast, susceptible cultivars promoted the synthesis of hydroxytyrosol 4-O-glucoside during ripening, a compound with no antifungal effect. This study showed that the distinct phenolic profiles between resistant and susceptible cultivars play a key role in determining olive fruit resistance to Colletotrichum species.

Self-perceived body weight and weight status: analysis of concordance by age group and sex.

OBJECTIVES: Previous studies suggest that there is discordance between actual weight status and body-weight perception. This fact has implications when it comes to designing public health interventions. The aim of this study was to estimate the prevalence of the different categories of weight status and body-weight perception and to analyse their concordance in a representative Spanish population sample. STUDY DESIGN: Cross-sectional study. METHODS: Data were sourced from the 2018 Galician Risk Behaviour Data System, with the target population being all persons aged 16 years and above. We collected data on self-perceived body weight and assessed weight status on the basis of body mass index (BMI). BMI was estimated using self-reported measures of weight and height. To estimate concordance, Cohen's kappa coefficient, both unweighted and weighted with Cicchetti weights, was calculated. RESULTS: Data were obtained for 7853 individuals aged 16 years and above, whereas the overall unweighted concordance was 0.393 (95%CI: 0.377-0.409), with an agreement percentage of 61.6%, weighted concordance was 0.503 (0.490-0.517), with an agreement percentage of 86.6%. The highest concordance between self-perceived body weight and weight status was observed in women. By age group, the highest concordance was observed in the youngest group (16-24 years) for the BMI categories of underweight and overweight, and in the 45-64 age group for the category of obesity. CONCLUSIONS: The results highlight the existence of differences between self-perceived body weight and weight status, according to sex and age.

Burnout is related to executive dysfunction in primary healthcare professionals working in rural areas. / El burnout se asocia con la disfunción ejecutiva en profesionales de atención primaria que trabajan en zonas rurales.

INTRODUCTION: Healthcare professionals are especially vulnerable to burnout, which implies a hypothalamus-pituitary-adrenal dysregulation that could impact the integrity of brain structures needed for cognitive processing. However, a scarce number of studies have analyzed the relationship between burnout and executive functions in this population, and possible modulator factors have not been clarified. This study aims to characterize the burnout level of primary healthcare professionals working in rural areas, and to analyze its relationship with executive functioning, considering the possible modulating role of optimism. SUBJECTS AND METHODS: In this cross-sectional study, 32 primary healthcare professionals were recruited from the Carcastillo Health Center (Spain) and underwent an assessment in which burnout was assessed using the Maslach Burnout Inventory - Human Services Survey. Optimism and executive functions were also evaluated. RESULTS: 43.8%, 59.4%, and 56.3% of participants experienced high levels of burnout via emotional exhaustion, depersonalization, and personal accomplishment. The path analysis showed that emotional exhaustion was associated with poorer Trail Making Test scores (ß = -0.37, SE = 0.17, p = 0.024, Cohen's f2 = 0.15), but optimism was not a significant moderator of this relationship (p = 0.24). The proposed model yielded excellent fit (CFI = 1.00, RMSEA = 0.0001, SRMR = 0.0001, and ?2(3) = 6.07, p = 0.11). CONCLUSIONS: These results suggest that burnout in healthcare professionals could have a detrimental effect on the efficiency of health systems. This has relevant implications, especially for professionals characterized by both work pressure and high cognitive demands, and highlights a need to implement occupation-specific approaches for prevention.

TITLE: El burnout se asocia con la disfunción ejecutiva en profesionales de atención primaria que trabajan en zonas rurales.Introducción. Los profesionales sanitarios son especialmente vulnerables al burnout, lo que implica una desregulación hipotalámico-hipófiso-suprarrenal que podría impactar en la integridad de estructuras cerebrales necesarias para el procesamiento cognitivo. Escasos estudios han analizado la relación entre el burnout y las funciones ejecutivas en esta población, y no se han esclarecido sus posibles factores moduladores. Este estudio pretende caracterizar el nivel de burnout de profesionales de atención primaria de zonas rurales y analizar su relación con el funcionamiento ejecutivo, considerando el posible papel modulador del optimismo. Sujetos y métodos. En este estudio transversal, 32 profesionales de atención primaria fueron reclutados en el centro de salud de Carcastillo (España) y sometidos a una evaluación en la que se valoró el burnout mediante el Maslach Burnout Inventory-Human Services Survey, y el optimismo y las funciones ejecutivas. Resultados. El 43,8, el 59,4 y el 56,3% de los participantes experimentaron alto burnout a través del agotamiento emocional, la despersonalización y la desrealización personal. El path analysis mostró que el agotamiento emocional se asoció con peores puntuaciones en el Trail Making Test (beta = ­0,37, SE ­error estándar­ = 0,17, p = 0,024, f2 de Cohen = 0,15), pero el optimismo no fue un moderador significativo (p = 0,24). El modelo mostró un ajuste excelente (índice de ajuste comparativo = 1, error cuadrático medio de aproximación = 0,0001, residuo cuadrático medio estandarizado = 0,0001, y chi cuadrado(3) = 6,07, p = 0,11). Conclusiones. Estos resultados sugieren que el burnout en profesionales sanitarios podría tener un efecto perjudicial sobre la eficiencia del sistema sanitario. Esto tiene implicaciones relevantes, especialmente para profesionales caracterizados tanto por la presión laboral como por las altas demandas cognitivas, y pone de manifiesto la necesidad de implementar enfoques específicos para su prevención.

Hospitalizations due to and with chronic obstructive pulmonary disease in Galicia: 20 years of evolution.

OBJECTIVE: This work aims to analyze the evolution of COPD-related hospitalizations in Galicia from 1996 to 2018 both as main cause of admission (DUE TO COPD) or when coded in any diagnostic order (WITH COPD), assessing the influence of age, sex, seasonality, and other main causes of the hospitalization. METHODS: An analysis was conducted of administrative healthcare database (CMBD) data on index COPD-related hospitalizations in Galicia from 1996 to 2018. Crude, specific, and standardized rates were calculated for the entire sample and according to age and sex groups. RESULTS: In the period from 1996 to 2018, there were 310,883 index admissions WITH COPD in Galicia, of which 29.6% were DUE TO COPD. Both WITH COPD and DUE TO COPD admission rates increased, mainly in men. There was a clear seasonality that was especially relevant in the DUE TO COPD group. The mean male-to-female ratio was approximately 4:1 in both groups, although it was lower in the extreme age groups, with no change over time. The mean age at admission increased three years in men during this period; there were no changes among women. The main causes of admission in those not hospitalized DUE TO COPD were heart failure and pneumonia. CONCLUSION: The combined evaluation of records of hospital admissions WITH COPD and DUE TO COPD offers additional information for a better understanding of the trends of this disease and allows for establishing hypotheses that explain the results described, providing information for better healthcare planning.

Development of Anxiolytic and Depression-like Behavior in Mice Infected with Mycobacterium lepraemurium.

Murine leprosy is a systemic infectious disease of mice caused by Mycobacterium lepraemurium (MLM) in which the central nervous system (CNS) is not infected; nevertheless, diseased animals show measurable cognitive alterations. For this reason, in this study, we explored the neurobehavioral changes in mice chronically infected with MLM. BALB/c mice were infected with MLM, and 120 days later, the alterations in mice were evaluated based on immunologic, histologic, endocrine, neurochemical, and behavioral traits. We found increases in the levels of IL-4 and IL-10 associated with high bacillary loads. We also found increase in the serum levels of corticosterone, epinephrine, and norepinephrine in the adrenal gland, suggesting neuroendocrine deregulation. Mice exhibited depression-like behavior in the tail suspension and forced swimming tests and anxiolytic behavior in the open field and elevated plus maze tests. The neurobehavioral alterations of mice were correlated with the histologic damage in the prefrontal cortex, ventral hippocampus, and amygdala, as well as with a blood-brain barrier disruption in the hippocampus. These results reveal an interrelated response of the neuroimmune--endocrinological axis in unresolved chronic infections that result in neurocognitive deterioration.

Altered phagocytic capacity due to acute exposure and long-term post-exposure to pesticides used for vector-borne disease as dengue.

Spinosad and temefos are widely used pesticides for chemical control of dengue vector-borne disease (Aedes aegypti). The aim of this study was to compare the effect of acute exposure (7 days) to spinosad (0.5 mg A.I. L-1) and temefos (10 mg A.I. L-1), concentrations used by the Mexican Ministry of Health, on phagocytic capacity (PC) of mononuclear cells of guppies fish (Poecilia reticulata), as well as to assess PC in fish, at 96 days after exposure to those pesticides. Obtained results indicated that spinosad did not alter PC, while an acute exposure to temefos significantly affected phagocytosis and this parameter was maintained downed even 96 days after the acute exposure, suggesting that the immunotoxic effects of temefos may be chronic.

Death of guppy fish (Poecilia reticulata) leukocytes induced by in vivo exposure to temephos and spinosad.

Temephos and spinosad are pesticides used for control of vector-borne diseases such as dengue, chikungunya and zika. However, the inadequate use of these substances has affected the health of non-target organisms. The aim of this study was to evaluate and compare, the effects of temephos and spinosad on leukocyte viability and death, using guppy fish (Poecilia reticulate) as a model organism. Guppies were exposed to temephos (10 mg/L) and spinosad (0.5 mg/L) for 7, 14, and 21 days. Afterwards, they were placed in pesticide-free fish tanks (7, 35, and 70 days) for recovery. The results showed that exposure to temephos caused leukocyte death, even at 35 days of recovery. Contrarily, the exposure to spinosad did not cause leukocyte death. This research show, for the first time, that a single dose of temephos causes apoptosis up to 56 days post-exposition, indicating that this pesticide induces chronic effects on immune response cells.

Influence of the diagnostic protocol and age on the prostate cancer incidence rate in Castilla y León according to the national registry 2010.

OBJECTIVE: Cross-sectional descriptive observational study of incidence and association, to determine whether the higher incidence of prostate cancer in Castilla y León (with respect to the national rate) could be due to modifiable factors. LOCATION: University Hospital Río Hortega. PARTICIPANTS: New prostate cancer diagnoses. MAIN MEASUREMENTS: Incidence rate (IR). Age, family history, symptoms, comorbidity, rectal examination, ultrasound volume (cc), PSA (ng/mL), cylinders, volume cylinder ratio, Gleason, TNM and D'Amico groups. RESULTS: Castilla y León showed the highest prostate cancer IR in Spain (141.1 per 100,000 inhabitants per year), with a peak of early incidence (65-74 years) and significant differences in < 64 and 65-74 years. Age at diagnosis was the lowest (Castilla y León, 66.9 ±7.1 vs. Spain, 69.1 ±â€¯8.2 years; P < .001). No differences: family history, symptoms, comorbidity and PSA. The number of cylinders was 10.7 ±â€¯1.8. In multivariate analysis (AUC = 0.801; P < .001), they were more frequent in Castilla y León: grade i rectal examination, non-palpable rectal examination, Gleason < 6, stage T2c and the volume cylinder ratio < 6 (only in < 64 years: OR 5.2; 95% CI 1.2-22-22.3; P = .027). In Spanish regions, volume cylinder ratio showed inverse correlation with IR in < 74 years, while age showed positive correlation in all age groups. CONCLUSIONS: The higher prostate cancer IR in Castilla y León in 2010 was not associated to an older population. However, the biopsy technique influenced IR, as more cylinders were obtained in younger subjects, without conditioning overdiagnosis.

Alterations in the non-neuronal cholinergic system induced by in-vitro exposure to diazoxon in spleen mononuclear cells of Nile tilapia (O. niloticus).

Organophosphate pesticides as diazinon disrupt the neuroimmune communication, affecting the innate and adaptive immune response of the exposed organisms. Since the target molecule of diazinon is typically the acetylcholinesterase enzyme (AChE), the existence of a non-neuronal cholinergic system in leukocytes makes them susceptible to alterations by diazinon. Therefore, the aim of this work was to evaluate the activity of AChE, acetylcholine (ACh) concentration, and the expression of nicotinic ACh receptors (nAChR) and muscarinic ACh receptors (mAChR) in spleen mononuclear cells (SMNC) of Nile tilapia (O. niloticus) exposed in vitro to diazoxon, a diazinon metabolite. SMNC were exposed in-vitro to 1 nM, 1 µM, and 10 µM diazoxon for 24 h. The enzyme activity of AChE was then evaluated by spectrophotometry, followed by ACh quantification by ultra-performance liquid chromatography. Finally, mAChR and nAChR expression was evaluated by RT-qPCR. The results indicate that AChE levels are significantly inhibited at 1 and 10 µM diazoxon, while the relative expression of (M3, M4, and M5) mAChR and (ß2) nAChR is reduced significantly as compared against SMNC not exposed to diazoxon. However, ACh levels show no significant difference with respect to the control group. The data indicate that diazoxon directly alters elements in the cholinergic system of SMNC by AChE inhibition or indirectly through the interaction with AChR, which is likely related to the immunotoxic properties of diazinon and its metabolites.

In-vitro effect of diazoxon, a metabolite of diazinon, on proliferation, signal transduction, and death induction in mononuclear cells of Nile tilapia fish (Oreochromis niloticus).

The immune response of teleosts (bonefish) is altered by diazinon (DZN), an organophosphate pesticide. It has been suggested that such alteration is due to the extraneuronal cholinergic system in fish leukocytes that renders these cells a target of pesticides. Diazoxon (DZO), the oxon metabolite of DZN, has been attributed immunotoxic effects. Still, to date there are no reports on the effects of DZO upon parameters involved in the signaling cascade of immune response cells. Therefore, this work evaluated the effect of DZO on key parameters of cell signaling (intracellular Ca2+ flux, ERK 1/2 phosphorylation), cell proliferation, and antiproliferative processes (apoptosis, senescence, mitochondrial membrane potential) in spleen mononuclear cells of Nile tilapia fish. The results obtained show that DZO does not affect cell proliferation but causes a lack of response to stimulation with PMA and ionomycin to release intracellular calcium. In addition, it inhibits ERK 1/2 phosphorylation and causes loss of mitochondrial membrane potential, apoptosis, and senescence. These results suggest that the lack of cell response to release intracytoplasmic Ca2+ inhibits ERK which disrupts the mitochondrial membrane potential, leading to cell apoptosis and senescence. These findings prove that DZO significantly affects key parameters involved in the survival of immune response cells.

[Chemotherapy at the end of life: Uncommon clinical practice?] / Quimioterapia al final de la vida: ¿práctica clínica poco frecuente?

BACKGROUND: In view of the apparent increase in the aggressiveness of palliative chemotherapy, the purpose of this study was to find out and analyse the characteristics of cancer patients treated in our hospital, and who received chemotherapy near the end of life. PATIENTS AND METHODS: Retrospective, observational study in oncology-haematological patients who received chemotherapy between January 2016 and May 2017, and who died in that same period. Data on sociodemographic and clinical variables were collected. In order to determine the risk factors for receiving chemotherapy in the last month of life, a multivariate logistic regression model was developed and subsequently validated using "bootstrap" re-sampling techniques. RESULTS: A total of 293 patients who received chemotherapy during the study period died. The median time between the last cycle of chemotherapy and death was 52 (0-459) days. Chemotherapy was received in their last month of life in 98 (33.4% of patients. the multivariate analysis indicated that the low chemo-sensitivity of the tumour, the particular medical oncologist, and the fact of dying in the hospital setting, were associated with an increased risk of receiving chemotherapy in the last month of life. CONCLUSIONS: A worrying percentage of patients receive chemotherapy near the end of life. This makes it difficult to receive high-quality palliative care, as well as to die in a familiar environment. It is necessary to review the decision-making process in advanced cancer patients.

Effect of diazinon, an organophosphate pesticide, on signal transduction and death induction in mononuclear cells of Nile tilapia fish (Oreochromis niloticus).

Diazinon (DZN) is an organophosphate pesticide characterized by inhibiting the enzyme acetylcholinesterase (AChE) (E.C. 3.1.1.7), affecting the nervous system. There is currently enough evidence proving this pesticide also affects the immune response; however, the immunotoxicity mechanisms through which these substances exerts toxic effects remain unclear. For that reason, this work evaluated the effect of diazinon on the intracellular calcium flux, ERK1/2 phosphorylation (pERK1/2), apoptosis, senescence, and mitochondrial membrane potential (ΔΨm) in spleen mononuclear cells (SMNC) of Nile tilapia, a teleost fish of commercial and ecological relevance. The results obtained indicate that diazinon causes significant damage in all evaluated parameters, which play an essential role in intracytoplasmic signaling of immune cells, suggesting these signal pathways could be related with the immunotoxicity mechanism of these type of pesticides.

Muscarinic acetylcholine receptor expression in brain and immune cells of Oreochromis niloticus.

Nervous and immune systems maintain a bidirectional communication, expressing receptors for neurotransmitters and cytokines. Despite being well established in mammals, this has been poorly described in lower vertebrates as fishes. Experimental evidence shows that the neurotransmitter acetylcholine (ACh) regulates the immune response. In this research, we evaluated mRNA levels of muscarinic acetylcholine receptor (mAChR) in spleen mononuclear cells of Nile tilapia (Oreochromis niloticus) and compared the expression levels of immune cells with the brain. The mAChR subtypes (M2-M5A) were detected in both tissues, but mAChRs mRNA levels were higher in immune cells. This data have a potential use in biomedical and comparative immunology fields.

Phagocytosis and ROS production as biomarkers in Nile tilapia (Oreochromis niloticus) leukocytes by exposure to organophosphorus pesticides.

Organophosphorus pesticides (OPs) are broad-spectrum insecticides. One of the commonly used OPs is diazinon (DZN). The aim of this study was to evaluate the immunotoxic effect of DZN on phagocytic parameters of blood leukocytes using the teleost fish Oreochromis niloticus as a study model. For this purpose, fish were exposed in vivo to 0.97, 1.95 and 3.97 mg/L of DZN for 6 and 24 h. Our results indicated that phagocytic active cells decreased in fish exposed in vivo to 0.97 and 1.95 mg/L of DZN for 6 and 24 h. Regarding ROS production, H2O2 and O2- levels were higher on fish exposed to 1.95 mg/L for 6 and 24 h, while H2O2 production increased at 0.97 mg/L for 24 h. From this we can conclude that phagocytic parameters are sensitive to assess the effect of acute intoxication with organophosphorus pesticides on Nile tilapia.

Using the modified Dixon technique to evaluate incidental adrenal lesions on 3T MRI. / Valoración mediante Dixon modificado de las lesiones suprarrenales incidentales en RM 3T.

OBJECTIVES: To use the mDIXON-Quant sequence to quantify the fat fraction of adrenal lesions discovered incidentally on CT studies. To analyze the relation between the signal loss between in-phase and out-of-phase T1-weighted sequences and the fat fraction in mDIXON-Quant. To compare the sensitivity and specificity of the two methods for characterizing adrenal lesions. MATERIAL AND METHODS: This prospective descriptive study included 31 patients with incidentally discovered adrenal lesions evaluated with 3T MRI using in-phase and out-of-phase T1-weighted sequences and mDIXON-Quant; the fat fraction of the adrenal lesions was measured by mDIXON-Quant and by calculating the percentage of signal loss between in-phase and out-of-phase T1-weighted sequences. RESULTS: The percentage of signal loss was significantly higher in the group of patients with adenoma (61.3% ± 20.4% vs. 5.1% ± 5.8% in the group without adenoma, p<0.005). The mean fat fraction measured by mDIXON-Quant was also higher for the adenomas (26.9% ±10.8% vs. 3.4% ± 3.0%, p<0.005).The area under the ROC curve was 0.99 (0.96 - 1.00) for the percentage of signal loss and 0.98 (0.94 - 1.00) for the fat fraction measured by mDIXON-Quant. The cutoffs obtained were 24.42% for the percentage of signal loss and 9.2% for the fat fraction measured by mDIXON-Quant. The two techniques had the same values for diagnostic accuracy: sensitivity 96% (79.6 - 99.9), specificity 100% (39.8 - 100.0), positive predictive value 100% (85.8 - 100.0), and negative predictive value 80% (28.4 - 99.5). CONCLUSION: The fat fraction measured by the modified Dixon technique can differentiate between adenomas and other adrenal lesions with the same sensitivity and specificity as the percentage of signal loss between in-phase and out-of-phase T1-weighted sequences.

Cholinergic alterations by exposure to pesticides used in control vector: Guppies fish (Poecilia reticulta) as biological model.

Spinosad and temephos are two of the most used pesticides in Mexico for the control of vector causing disease such as dengue, chikungunya and Zika. The aim of this study was to compare the neurotoxic effects of these two pesticides using guppy fish (Poecilia reticulata) as a model organism. Guppies were exposed for 7 and 21 days to technical grade temephos and spinosad at 1.0 and 0.07 g/L, respectively, (10 and 0.5 mg/L of active substance; concentrations recommended by the Ministery of Health of the State (Secretaría de Salud de Nayarit (SSN) Mexico)). Subsequently, acetylcholinesterase activity (AChE) and acetylcholine concentrations (ACh) in muscle tissue were determined. Temephos exposure decreased AChE activity and increased ACh concentration, whereas exposure to spinosad only increased ACh concentration. Though cholinergic alterations were more severe in fish exposed to temephos, both pesticides were equally lethal during the first seven days after exposure. Nonetheless, temephos was more lethal after 21 days.

Effects of diazinon on the lymphocytic cholinergic system of Nile tilapia fish (Oreochromis niloticus).

Fish rearing under intensive farming conditions can be easily disturbed by pesticides, substances that have immunotoxic properties and may predispose to infections. Organophosphorus pesticides (OPs) are widely used in agricultural activities; however, the mechanism of immunotoxicity of these substances is unclear. The aim of this study was to evaluate the effect of diazinon pesticides (OPs) on the cholinergic system of immune cells as a possible target of OP immunotoxicity. We evaluated ACh levels and cholinergic (nicotinic and muscarinic) receptor concentration. Additionally, AChE activity was evaluated in mononuclear cells of Nile tilapia (Oreochromis niloticus), a freshwater fish mostly cultivated in tropical regions around the world. The obtained results indicate that acute exposure to diazinon induces an increase in ACh concentration and a decrease in nAChR and mAChR concentrations and AChE activity in fish immune cells, This suggests that the non-neuronal lymphocytic cholinergic system may be the main target in the mechanism of OP immunotoxicity. This study contributes to the understanding of the mechanisms of immunotoxicity of pollutants and may help to take actions for animal health improvement.

Oxidative damage in gills and liver in Nile tilapia (Oreochromis niloticus) exposed to diazinon.

Agricultural activity demands the use of pesticides for plague control and extermination. In that matter, diazinon is one of the most widely used organophosphorus pesticides (OPs). Despite its benefits, the use of OPs in agricultural activities can also have negative effects since the excessive use of these substances can represent a major contamination problem for water bodies and organisms that inhabit them. The aim of this paper was to evaluate oxidative damage in lipids and proteins of Nile tilapia (Oreochromis niloticus) exposed acutely to diazinon (0.97, 1.95 and 3.95ppm) for 12 or 24h. The evaluation of oxidative damage was determined by quantifying lipid hydroperoxides (Fox method) and oxidized proteins (DNPH method). The data from this study suggest that diazinon induces a concentration-dependent oxidative damage in proteins, but not lipids, of the liver and gills of Nile tilapia. Furthermore, the treatment leads to a decrease in the concentration of total proteins, which can have serious consequences in cell physiology and fish development.

Assessment of pollution of the Boca de Camichin Estuary in Nayarit (Mexico) and its influence on oxidative stress in Crassostrea corteziensis oysters.

Boca de Camichin Estuary is one of the main producers of Crassostrea corteziensis oysters in Mexico, but the presence of pollutants can affect oyster production. Molluscs produce reactive oxygen species (ROS) in response to changes in the environment and pollution. These ROS induce oxidative damage in biomolecules. The main objective of this study was to evaluate pollution in the estuary and the subsequent oxidative stress in C. corteziensis oysters during the 2010 production cycle. For this aim, we performed monthly samplings in the oyster farms from January to May. We took water samples to quantify polycyclic aromatic hydrocarbon (PAH) and metal content; also, we evaluated oxidative damage (lipoperoxidation, lipidic hydroperoxides, protein oxidation) and enzyme activity (CAT, SOD, GPx, GST and AChE) in oyster gills. The results show the presence of Cu, Fe, Mn, naphthalene, benz[a]anthracene, pyrene, benz[a]pyrene and benzo[k]fluoranthene. On the other hand, AChE activity was not inhibited, which suggests that organophosphorus pollutants or carbamates were absent. Regarding oxidative stress, oysters from the estuary had oxidative damage in lipids, not proteins, and altered antioxidant enzyme activity, when compared to control organisms. Interestingly, we did not observe any correlation between the pollutants and the oxidative stress parameters evaluated in this study. Thus, we cannot rule out that a synergistic effect between the environmental variables and the pollutants is causing the oxidative stress in these oysters.