Far-UV-C irradiation promotes synergistic bactericidal action against adhered cells of Escherichia coli and Staphylococcus epidermidis.

The contamination of indoor areas is a global health problem that can cause the dispersion of infectious diseases. In that sense, it is urgent to find new strategies applying a lower concentration of the traditional chemicals used for cleaning and disinfection. Ultraviolet radiation (UV), in particular far-UV-C (200-225 nm), has emerged as a successful, powerful, easy-to-apply, and inexpensive approach for bacterial eradication that still requires scientific assessment. This study investigated new strategies for disinfection based on far-UV-C (222 nm) combined with chlorine and mechanical cleaning, providing an innovative solution using low doses. The bactericidal activity of far-UV-C (222 nm) was tested at an intensity of irradiation from 78.4 µW/cm2 to 597.7 µW/cm2 (for 1 min) against Escherichia coli and Staphylococcus epidermidis adhered on polystyrene microtiter plates. It was further tested in combination with mechanical cleaning (ultrasounds for 1 min) and free chlorine (0.1, 0.5, and 1 mg/L for 5 min). The triple combination consisting of mechanical cleaning + free chlorine (0.5 mg/L) + far-UV-C (54 mJ/cm2) was tested against cells adhered to materials found in hospital settings and other public spaces: polyvinyl chloride (PVC), stainless steel (SS), and polyetheretherketone (PEEK). Disinfection with far-UV-C (54 mJ/cm2) and free chlorine at 0.5 mg/L for 5 min allowed a total reduction of culturable E. coli cells and a logarithmic reduction of 2.98 ± 0.03 for S. epidermidis. The triple combination of far-UV-C, free chlorine, and mechanical cleaning resulted in a total reduction of culturable cells for both adhered bacteria. Bacterial adhesion to PVC, SS, and PEEK occurred at distinct extents and influenced the bactericidal activity of the triple combination, with logarithmic reductions of up to three. The overall results highlight that, based on culturability assessment, far-UV-C (54 mJ/cm2) with chlorine (0.5 mg/L; 5 min) and mechanical cleaning (1 min) as an efficient disinfection strategy using mild conditions. The combination of culturability and viability assessment of disinfection is recommended to detect regrowth events and increase the effectiveness in microbial growth control.

The impact of potassium peroxymonosulphate and chlorinated cyanurates on biofilms of Stenotrophomonas maltophilia: effects on biofilm control, regrowth, and mechanical properties.

The activity of two chlorinated isocyanurates (NaDCC and TCCA) and peroxymonosulphate (OXONE) was evaluated against biofilms of Stenotrophomonas maltophilia, an emerging pathogen isolated from drinking water (DW), and for the prevention of biofilm regrowth. After disinfection of pre-formed 48 h-old biofilms, the culturability was reduced up to 7 log, with OXONE, TCCA, and NaDCC showing more efficiency than free chlorine against biofilms formed on stainless steel. The regrowth of biofilms previously exposed to OXONE was reduced by 5 and 4 log CFU cm-2 in comparison to the unexposed biofilms and biofilms exposed to free chlorine, respectively. Rheometry analysis showed that biofilms presented properties of viscoelastic solid materials, regardless of the treatment. OXONE reduced the cohesiveness of the biofilm, given the significant decrease in the complex shear modulus (G*). AFM analysis revealed that biofilms had a fractured appearance and smaller bacterial aggregates dispersed throughout the surface after OXONE exposure than the control sample. In general, OXONE has been demonstrated to be a promising disinfectant to control DW biofilms, with a higher activity than chlorine. The results also show the impact of the biofilm mechanical properties on the efficacy of the disinfectants in biofilm control.

Photodynamic therapy and combinatory treatments for the control of biofilm-associated infections.

The advent of antimicrobial resistance has added considerable impact to infectious diseases both in the number of infections and healthcare costs. Furthermore, the relentless emergence of multidrug-resistant bacteria, particularly in the biofilm state, has made mandatory the discovery of new alternative antimicrobial therapies that are capable to eradicate resistant bacteria and impair the development of new forms of resistance. Amongst the therapeutic strategies for treating biofilms, antimicrobial photodynamic therapy (aPDT) has shown great potential in inactivating several clinically relevant micro-organisms, including antibiotic-resistant 'priority bacteria' declared by the WHO as critical pathogens. Its antimicrobial effect is centred on the basis that harmless low-intensity light stimulates a non-toxic dye named photosensitizer, triggering the production of reactive oxygen species upon photostimulation. In addition, combination therapies of aPDT with other antimicrobial agents (e.g. antibiotics) have also drawn considerable attention, as it is a multi-target strategy. Therefore, the present review highlights the recent advances of aPDT against biofilms, also covering progress on combination therapy.

Biofilm formation under high shear stress increases resilience to chemical and mechanical challenges.

The effect that the hydrodynamic conditions under which biofilms are formed has on their persistence is still unknown. This study assessed the behaviour of Pseudomonas fluorescens biofilms, formed on stainless steel under different shear stress (τw) conditions (1, 2 and 4 Pa), to chemical (benzalkonium chloride - BAC, glutaraldehyde - GLUT and sodium hypochlorite - SHC) and mechanical (20 Pa) treatments (alone and combined). The biofilms formed under different τw  showed different structural characteristics. Those formed under a higher τw were invariably more tolerant to chemical and mechanical stresses. SHC was the biocide which caused the highest biofilm killing and removal, followed by BAC. The sequential exposure to biocides and mechanical stress was found to be insufficient for effective biofilm control. A basal layer containing biofilm cells mostly in a viable state remained on the surface of the cylinders, particularly for the 2 and 4 Pa-generated biofilms.

Health-related quality of life of inpatients and outpatients with TB in rural Malawi.

INTRODUCTION: Patients being treated for TB may suffer reductions in health-related quality of life (HRQoL). This study aims to assess the extent of such reductions and the trajectory of HRQoL over the course of treatment in rural Malawi.METHODS: We collected patient demographic and socioeconomic status, TB-related characteristics, and HRQoL data (i.e., EQ-5D and a visual analogue scale VAS) from adults (age ≥18 years) being treated for TB in 12 primary health centers and one hospital in rural Thyolo District, Malawi, from 2014 to 2016. Associations between HRQoL and patient characteristics were estimated using multivariable linear regression.RESULTS: Inpatients (n = 197) consistently showed lower median HRQoL scores and suffered more severe health impairments during hospitalization than outpatients (n = 156) (EQ5D and VAS: 0.79, 55 vs. 0.84, 70). Longer treatment duration was associated with higher HRQoL among outpatients (EQ5D: 0.034 increase per 2 months, 95%CI 0.012-0.057). We found no substantial associations between patients´ demographic and socioeconomic characteristics and HRQoL in this setting.CONCLUSION: HRQoL scores among patients receiving treatment for TB in rural Malawi differ by clinical setting and duration of treatment, with greater impairment among inpatients and those early in their treatment course.

Influence of the Adopted Balloon Modeling Strategies in the Stent Deployment Procedure: An In-Silico Analysis.

PURPOSE: As the promoter of the stent expansion, the balloon plays a very important role, offering a strong influence on the deployment process. Balloon-artery interaction is pointed as a probable cause of restenosis, stressing the relevance of balloon modeling when simulating the stenting procedure. In this work, an in-silico study of the balloon modeling strategies is performed. METHODS: Ultrasonic-microcasting is a novel technology that allows obtaining stents manufactured in magnesium alloys, being suggested as a promising solution. However, this technique demands superior stent strut thickness, which may have an impact on the stent deployment procedure. The influence of the balloon modeling is studied through the simulation of different balloon geometries (open- or taper-ended) and material constitutive model (linear elastic or hyperelastic) on the expanded configuration of a stent manufactured through ultrasonic-microcasting. RESULTS: The results obtained suggest that the choice of balloon type has small impact in terms of demanded pressure to inflate the balloon and in the stent final radius achieved at fully-expanded configuration. Additionally, it was proved that the balloon-type influences the stent expanded profile along its length and diameter as a result of the different deformation behavior exhibited by the balloon. CONCLUSION: The hyperelastic taper-ended balloon suggests being the model that better correlates with both experimental and clinical results regarding the expanded balloon profile during the procedure.

Evolution of two-step magnetic transition on nanogranular Gd5Si1.3Ge2.7 thin film.

A multi-functional Gd5Si1.3Ge2.7 thin film deposited by pulsed laser ablation in the form of an ensemble of nanoparticles was studied for 18 thermal cycles via electron transport measurements together with structural and magnetic characterization. A general negative thermal dependency of the resistivity (ρ) is observed, which contrasts with the metallic-like behavior observed in bulk Gd5Si x Ge4-x compounds. This general trend is interrupted by a two-step, positive-slope transition in ρ(T) throughout the [150, 250] K interval, corresponding to two consecutive magnetic transitions: a fully coupled magnetostructural followed by a magnetic order on heating. An avalanche-like behavior is unveiled by the ∂ρ/∂T(T) curves and is explained based on the severe strains induced cyclically by the magnetostructural transition, leading to a cycling evolution of the transition onset temperature ([Formula: see text]/∂n ∼ 1.6 K/cycle, n being the number of cycles). Such behavior is equivalent to the action of a pressure of 0.56 kBar being formed and building up at every thermal cycle due to the large volume induced change across the magnetostructural transition. Moreover the thermal hysteresis, detected in both ρ and magnetization versus temperature curves, evolves significantly along the cycles, decreasing as n increases. This picture corroborates the thermal activation energy enhancement-estimated via an exponential fitting of the ∂ρ/∂T(T) in the avalanche regime. This work demonstrates the importance of using a short-range order technique, to probe both magnetic and magnetostructural transitions and their evolution with thermal cycles.

Influence of surface copper content on Stenotrophomonas maltophilia biofilm control using chlorine and mechanical stress.

This work aimed to evaluate the action of materials with different copper content (0, 57, 96 and 100%) on biofilm formation and control by chlorination and mechanical stress. Stenotrophomonas maltophilia isolated from drinking water was used as a model microorganism and biofilms were developed in a rotating cylinder reactor using realism-based shear stress conditions. Biofilms were characterized phenotypically and exposed to three control strategies: 10 mg l-1 of free chlorine for 10 min, an increased shear stress (a fluid velocity of 1.5 m s-1 for 30s), and a combination of both treatments. These shock treatments were not effective in biofilm control. The benefits from the use of copper surfaces was found essentially in reducing the numbers of non-damaged cells. Copper materials demonstrated better performance in biofilm prevention than chlorine. In general, copper alloys may have a positive public health impact by reducing the number of non-damaged cells in the water delivered after chlorine exposure.

Multiple drug hypersensitivity syndrome to antituberculosis drugs: a case report

No disponible

Prolonged exposure of Stenotrophomonas maltophilia biofilms to trace levels of clofibric acid alters antimicrobial tolerance and virulence.

The presence of pharmaceuticals in water sources, including in drinking water (DW), is increasingly being recognized as an emerging and global concern for the environment and public health. Based on the principles of the "One Health" initiative, the present work aims to understand the effects of clofibric acid (CA), a lipid regulator, on the behavior of a selected bacterium isolated from drinking water (DW). Biofilms of the opportunistic pathogen Stenotrophomonas maltophilia were exposed to CA for 12 weeks at 170 and 17000 ng/L. The effects of CA were evaluated on planktonic S. maltophilia susceptibility to chlorine and antibiotics (amoxicillin, ciprofloxacin, erythromycin, kanamycin, levofloxacin, oxacillin, spectinomycin, tetracycline and trimethoprim-sulfamethoxazole), biofilm formation, motility, siderophores production and on the adhesion and internalization of the human colon adenocarcinoma cell line (HT-29). It was found that CA did not affect planktonic S. maltophilia tolerance to chlorine exposure. Additionally, no effects were observed on biofilm formation, motility and siderophores production. However, biofilms formed after CA exposure were more tolerant to chlorine disinfection and lower CFU reductions were obtained. Of additional concern was the effect of CA exposure on S. maltophilia increased tolerance to erythromycin. CA exposure also slightly reduced S. maltophilia ability to invade HT-29 cells. In conclusion, this work reinforces the importance of studying the effects of non-antibiotic contaminants on the behavior of environmental microorganisms, particularly their role as drivers affecting resistance evolution and selection.

Perfil metabólico de vacas Holandês e mestiças Holandês x Jersey no periparto / Metabolic profile of Holstein and crossbred Holstein x Jersey cows in the peripartum

O objetivo do presente trabalho foi determinar e comparar o perfil metabólico de vacas Holandês (H) e mestiças Holandês x Jersey (HxJ) no periparto. Avaliaram-se 24 vacas, sendo 11 vacas Holandês e 13 mestiças Holandês x Jersey. Semanalmente, coletou-se sangue para a determinação das concentrações séricas de glicose, beta-hidroxibutirato (BHB), proteína total, albumina, aspartato aminotransferase (AST), creatinoquinase (CK), cálcio total, cálcio iônico, magnésio, fósforo inorgânico e colesterol. Avaliou-se também o peso vivo e o escore de condição corporal (ECC). Os dados foram submetidos à análise de variância com medidas repetidas no tempo. As vacas Holandês apresentaram maior peso vivo. Não houve diferença entre os grupamentos genéticos para ECC. Foi observada tendência de maiores concentrações séricas de BHB, AST e maior concentração de cálcio iônico em vacas mestiças Holandês x Jersey. Vacas mestiças Holandês x Jersey e Holandês apresentaram perfil energético similar durante o período de transição pré e pós-parto na maioria dos indicadores, com exceção do cálcio, que foi maior nas vacas mestiças, e do fósforo, que foi superior nas vacas Holandês.(AU)

The aim of this study was to determine and compare the metabolic profile of Holstein (H) and crossbred Holstein x Jersey (HxJ) on peripartum. For this, 24 cows were evaluated, 11 Holstein and 13 crossbreeds Holstein x Jersey. Weekly, venous blood sample were collected to determine concentration of glucose, beta-hydroxybutyrate (BHBA), total protein, albumin, aspartate aminotransferase (AST), creatine kinase (CK), total calcium, ionic calcium, magnesium, inorganic phosphorus and cholesterol. Body weight (BW) and body condition score (BCS) were also evaluated. The data were submitted to analysis of variance with repeated measures in time. Holstein cows presented higher BW, however, there was no difference for BCS in compare to crossbreed Holstein x Jersey cows. Tendency for higher serum concentrations of BHBA, AST and higher concentration of ionic calcium was observed in crossbreed cows in comparison to the Holstein. The energetic profile during the pre and postpartum transition period is similar for both genetic groups with higher concentrations of BHBA on the first week of lactation, however, with a tendency of higher serum concentrations of BHBA for crossbreed cows. Higher concentrations of ionic calcium were observed in crossbreed cows and higher concentrations of phosphorus in Holstein cows on peripartum. Holstein and Holtein x Jersey crossbreed cows have a similar energy profile during the pre and postpartum transition period in most of the indicators, except for calcium that was higher in crossbred cows and higher phosphorus in Holstein cows.(AU)

The role of surface copper content on biofilm formation by drinking water bacteria.

Copper pipes are conventionally used to supply tap water. Their role in biofilm prevention remains to be understood. This study evaluates the ability of selected surface materials with different copper contents (0, 57, 79, 87, 96, 100% of copper) to control biofilm formation and regrowth. Further experiments were performed to assess copper leaching and corrosion under conditions mimicking real plumbing systems. Acinetobacter calcoaceticus and Stenotrophomonas maltophilia isolated from a drinking water distribution system were used as model bacteria. All the copper materials showed positive results on the control of single and dual species biofilms presenting high reductions of bacterial culturability > 4 log CFU per cm2. The antimicrobial action of the selected materials seem not to be related to copper leaching or to the formation of reactive oxygen species. However, bacterial-copper contact demonstrated damage to bacterial membranes. The alloy containing 96% copper was the most promising surface in reducing biofilm culturability and viability, and was the only surface able to avoid the regrowth of single species biofilms when in contact with high nutrient concentrations. The alloy with 87% copper was shown to be unsuitable for use in chlorinated systems due to the high copper leaching observed when exposed to free chlorine. The presence of viable but non-culturable bacteria was remarkable, particularly in dual species biofilms. The overall results provide novel data on the role of copper alloys for use under chlorinated and unchlorinated conditions. Copper alloys demonstrated comparable or even higher biofilm control effects than elemental copper surfaces.

Posterior urethral valves: comparison of clinical outcomes between postnatal and antenatal cohorts.

BACKGROUND: Posterior urethral valves (PUVs) constitute the most common infravesical urinary obstruction in boys and are often accompanied by severe consequences to the lower and upper urinary tract. Currently, about two-thirds of diagnosis of PUVs has been suspected by prenatal ultrasonography findings. The aim of this study was to compare long-term clinical outcomes in two groups of patients with PUVs, with antenatal vs. postnatal diagnosis. STUDY DESIGN: This was a retrospective cohort study of 173 patients with PUVs systematically followed up in a tertiary center. Median follow-up time was 66.5 months (interquartile range [IQ], 11.4-147.9 months) for those patients who survived neonatal period. Seventy-nine (45.6%) patients were followed up for more than 5 years and 55 (32%) for more than 10 years. For analysis, the cohort was stratified into two groups according to the clinical presentation (prenatal vs. postnatal). The events of interest were urinary tract infection (UTI), surgical interventions, proteinuria, hypertension, chronic kidney disease (CKD), and death. Survival analyses were performed to evaluate time until occurrence of the events. RESULTS: Sixty-two patients (35.8%) were diagnosed by fetal sonography. Patients of postnatal group presented a higher incidence rate of UTI episodes (6.5, 95% confidence interval [CI], 4.9-8.3) than antenatal group (1.2, 95% CI, 0.4-2.7) (P < 0.001). Thirty-six patients (21%) presented hypertension, and 77 (44.5%) had persistent mild proteinuria. There was no significant difference in the estimated incidence of hypertension (P = 0.28) and proteinuria (P = 0.78) between antenatal and postnatal groups. The cumulative incidence of CKD stage ≥3 was estimated to be about 37% at 10 years of age, and 56% at 18 years of age. By survival analysis, there was no significant difference in the estimated incidence of CKD stage ≥3 (log-rank = 0.32, P = 0.57) and CKD stage 5 (log-rank = 1.08, P = 0.28, Figure) between antenatal and postnatal groups. Of 173 patients included in the analysis, 13 (7.5%) died during follow-up with a median age of 2.6 months (IQ, 15 days-62 months). Survival analyses have not shown any significant difference in the estimated incidence of death between antenatal and postnatal groups (log-rank = 1.38, P = 0.24). CONCLUSION: The study findings did not corroborate the initial hypothesis that the rates of renal function declining in patients with PUVs would be attenuated by an early diagnosis and intervention after antenatal diagnosis.

Effect of Zirconia Pigmentation on Translucency.

PURPOSE: the aim of this study was to investigate the effect of shading on translucency and mean grain size of three Zirconia systems (Lava Frame, Ice Zirkon Translucent and Prettau Zirkon). MATERIALS AND METHODS: specimens pigmented in A1, A4 and a non-pigmented specimen was evaluated with Scanning Electron Microscopy and spectrophotometery. RESULTS: the transmittance ranged between 0.18 and 0.52, in Ice Zirkon Translucent A4 and Prettau Zircon non-pigmented, respectively. The pigmentation A1 and A4 significantly reduced the light transmission in all the systems evaluated (p⟨0.05), with the exception of Lava A1. The light transmittance of each ceramic system is different from each other in the three pigmentations, except for the Prettau Zirkon A1, which did not show a significant difference compared with Lava A1 (p⟩0.05). The mean grain size increased with pigmentation. The mean grain size ranged between 0.43 µm, for Prettau Zirkon non-pigmented, and 0.82 µm for Prettau Zirkon A4. CONCLUSION: Light transmission and mean grain size was affected by pigmentation of dental zirconia ceramics.

Bauhinia variegata candida Fraction Induces Tumor Cell Death by Activation of Caspase-3, RIP, and TNF-R1 and Inhibits Cell Migration and Invasion In Vitro.

Metastasis remains the most common cause of death in cancer patients. Inhibition of metalloproteinases (MMPs) is an interesting approach to cancer therapy because of their role in the degradation of extracellular matrix (ECM), cell-cell, and cell-ECM interactions, modulating key events in cell migration and invasion. Herein, we show the cytotoxic and antimetastatic effects of the third fraction (FR3) from Bauhinia variegata candida (Bvc) stem on human cervical tumor cells (HeLa) and human peripheral blood mononuclear cells (PBMCs). FR3 inhibited MMP-2 and MMP-9 activity, indicated by zymogram. This fraction was cytotoxic to HeLa cells and noncytotoxic to PBMCs and decreased HeLa cell migration and invasion. FR3 is believed to stimulate extrinsic apoptosis together with necroptosis, assessed by western blotting. FR3 inhibited MMP-2 activity in the HeLa supernatant, differently from the control. The atomic mass spectrometry (ESI-MS) characterization suggested the presence of glucopyranosides, D-pinitol, fatty acids, and phenolic acid. These findings provide insight suggesting that FR3 contains components with potential tumor-selective cytotoxic action in addition to the action on the migration of tumor cells, which may be due to inhibition of MMPs.

The action of chemical and mechanical stresses on single and dual species biofilm removal of drinking water bacteria.

The presence of biofilms in drinking water distribution systems (DWDS) is a global public health concern as they can harbor pathogenic microorganisms. Sodium hypochlorite (NaOCl) is the most commonly used disinfectant for microbial growth control in DWDS. However, its effect on biofilm removal is still unclear. This work aims to evaluate the effects of the combination of chemical (NaOCl) and mechanical stresses on the removal of single and dual species biofilms of two bacteria isolated from DWDS and considered opportunistic, Acinectobacter calcoaceticus and Stenotrophomonas maltophilia. A rotating cylinder reactor was successfully used for the first time in drinking water biofilm studies with polyvinyl chloride as substratum. The single and dual species biofilms presented different characteristics in terms of metabolic activity, mass, density, thickness and content of proteins and polysaccharides. Their complete removal was not achieved even when a high NaOCl concentrations and an increasing series of shear stresses (from 2 to 23Pa) were applied. In general, NaOCl pre-treatment did not improve the impact of mechanical stress on biofilm removal. Dual species biofilms were colonized mostly by S. maltophilia and were more susceptible to chemical and mechanical stresses than these single species. The most efficient treatment (93% biofilm removal) was the combination of NaOCl at 175mg·l-1 with mechanical stress against dual species biofilms. Of concern was the high tolerance of S. maltophilia to chemical and mechanical stresses in both single and dual species biofilms. The overall results demonstrate the inefficacy of NaOCl on biofilm removal even when combined with high shear stresses.

Biomarkers and bioindicators of the environmental condition using a fish species (Pimelodus maculatus Lacepède, 1803) in a tropical reservoir in Southeastern Brazil / Biomarcadores e bioindicadores da condição ambiental usando uma espécie de peixe (Pimelodus maculatus Lacepède, 1803) em um reservatório tropical no Sudeste do Brasil

Abstract The Funil Reservoir receives a large amount of xenobiotics from the Paraíba do Sul River (PSR) from large number of industries and municipalities in the watershed. This study aimed to assess environmental quality along the longitudinal profile of the Paraíba do Sul River-Funil Reservoir system, by using biomarkers and bioindicators in a selected fish species. The raised hypothesis is that Funil Reservoir acts as a filter for the xenobiotics of the PSR waters, improving river water quality downstream the dam. Two biomarkers, the ethoxyresorufin-O-deethylase activity (EROD), measured as fluorimetricly in S9 hepatic fraction, and the micronuclei frequency (MN), observed in erythrocytes of the cytoplasm, and three bioindicators, the hepatosomatic index (HSI), gonadosomatic index (GSI) and condition factor (CF) were used in Pimelodus maculatus, a fish species widely distributed in the system. Four zones were searched through a longitudinal gradient: 1, river upstream from the reservoir; 2, upper reservoir; 3, lower reservoir; 4, river downstream of the reservoir. EROD activity and HSI and GSI had significant differences among the zones (P<0.05). The upper reservoir had the lowest EROD activity and HSI, whereas the river downstream of the reservoir had the highest EROD and lowest GSI. The river upstream from the reservoir showed the highest HSI and GSI. It is suggested that the lowest environmental condition occur at the river downstream of the reservoir, where it seems to occur more influence of xenobiotics, which could be associated with hydroelectric plant operation. The hypothesis that Funil reservoir acts as a filter decanting pollution from the Paraíba do Sul River waters was rejected. These results are novel information on this subject for a native fish species and could be useful for future comparisons with other environments.

Resumo O reservatório do Funil recebe uma grande quantidade de contaminantes xenobióticos do Rio Paraíba do Sul (RPS) provenientes de grandes indústrias e municípios situados na bacia hidrográfica. O objetivo deste estudo é avaliar a qualidade ambiental ao longo de um perfil longitudinal do sistema rio Paraíba do Sul-reservatório do Funil, através de biomarcadores e bioindicadores em uma espécie de peixe selecionada. A hipótese a ser testada é de que o reservatório do Funil funciona como filtro para poluentes xenobioticos de águas do rio Paraíba do Sul, melhorando a qualidade da água à jusante da represa. Foram usados dois biomarcadores: a atividade de etoxiresorufina-O-desetilase (EROD), medida fluorimetricamente na fração S9 hepática, e a Freqüência de Micronúcleos (MN), observada no citoplasma dos eritrócitos; e também três bioindicadores: Índice hepato-somático (IHS), Índice gonado-somático (IGS) e Fator de Condição (FC) em Pimelodus maculatus, uma espécie de peixe amplamente distribuída no sistema. Quatro zonas foram amostrados ao longo do gradiente longitudinal: 1, rio a montante do reservatório; 2, parte superior do reservatório; 3, parte inferior do reservatório; 4, rio à jusante do reservatório. A atividade de EROD, o IHS e o IGS apresentaram diferenças significativas (P<0.05) entre as zonas. A atividade EROD e o IHS foram mais baixos na parte superior do reservatório, enquanto que no rio à jusante do reservatório, a atividade de EROD foi mais alta e o IGS foi mais baixo. O rio acima do reservatório apresentou maiores IHS e IGS. É sugerido que a pior condição ambiental ocorreu no rio abaixo do reservatório, o que poderia ser associado às influências das operações da usina hidroelétrica. A hipótese de que o reservatório do Funil atue como filtro decantando a poluição do rio Paraíba do Sul foi rejeitada. Estes dados são novas informações sobre este tema para uma espécie nativa e podem ser úteis para futuras comparações outros ambientes.