Bioinspired gelatin/bioceramic composites loaded with bone morphogenetic protein-2 (BMP-2) promote osteoporotic bone repair.

There are currently several commercialized products approved by the Food and Drug Administration and the European Medicines Agency based on the use of recombinant human BMP-2 for the treatment of non-unions long fractures and spinal fusion. However, the adverse effects recorded with the use of BMPs suggest the need for drug delivery carriers that allow reducing the required doses and improve their cost-effectiveness. Herein, we have developed a new osteoconductive scaffold that reduces the required doses of BMP-2 for promoting bone regeneration in an osteoporotic defect model. The composite is, in brief, a gelatin-based 3D scaffold reinforced with either calcium sulfate or hydroxyapatite as an inorganic osteoconductive biomaterial. To this end, the organic/inorganic composite systems showed high hydration capacity and good in vitro degradability. The incorporation of 7.5% (m/v) ceramic compounds resulted in scaffolds with stiffer Young modulus (179 and 75 kPa for CaSO4_7 and HA_7, respectively) than bare gelatin hydrogels (48 kPa). Studies with human bone-marrow derived mesenchymal stem cells (hBM-MSCs) revealed that the 3D scaffolds promote cell adhesion and proliferation along with osteogenic differentiation capabilities. Specifically, downregulation of stemness (Nanog, Oct4) genes and upregulation of osteogenic markers (ALP, Col1a1, Fmod) by two fold were observed over 10 days under basal culture conditions. Promisingly, the sustained in vitro release of BMP-2 observed from the porous reinforced scaffolds allowed us to address the critical-sized osteoporotic mice calvarial defects with a relatively low growth factor doses (600 ng BMP-2/scaffold) compared to conventional doses at 2-15 micrograms. Overall, this study demonstrates the promising potential of osteoconductive gelatin/calcium bioceramics composites as osteogenic growth factors delivery carriers for bone-regeneration via ultra-low growth factor doses.

Biofabrication of a shape-stable auricular structure for the reconstruction of ear deformities.

Bioengineering of the human auricle remains a significant challenge, where the complex and unique shape, the generation of high-quality neocartilage, and shape preservation are key factors. Future regenerative medicine-based approaches for auricular cartilage reconstruction will benefit from a smart combination of various strategies. Our approach to fabrication of an ear-shaped construct uses hybrid bioprinting techniques, a recently identified progenitor cell population, previously validated biomaterials, and a smart scaffold design. Specifically, we generated a 3D-printed polycaprolactone (PCL) scaffold via fused deposition modeling, photocrosslinked a human auricular cartilage progenitor cell-laden gelatin methacryloyl (gelMA) hydrogel within the scaffold, and cultured the bioengineered structure in vitro in chondrogenic media for 30 days. Our results show that the fabrication process maintains the viability and chondrogenic phenotype of the cells, that the compressive properties of the combined PCL and gelMA hybrid auricular constructs are similar to native auricular cartilage, and that biofabricated hybrid auricular structures exhibit excellent shape fidelity compared with the 3D digital model along with deposition of cartilage-like matrix in both peripheral and central areas of the auricular structure. Our strategy affords an anatomically enhanced auricular structure with appropriate mechanical properties, ensures adequate preservation of the auricular shape during a dynamic in vitro culture period, and enables chondrogenically potent progenitor cells to produce abundant cartilage-like matrix throughout the auricular construct. The combination of smart scaffold design with 3D bioprinting and cartilage progenitor cells holds promise for the development of clinically translatable regenerative medicine strategies for auricular reconstruction.

Multiscale modelling and homogenisation of fibre-reinforced hydrogels for tissue engineering.

Tissue engineering aims to grow artificial tissues in vitro to replace those in the body that have been damaged through age, trauma or disease. A recent approach to engineer artificial cartilage involves seeding cells within a scaffold consisting of an interconnected 3D-printed lattice of polymer fibres combined with a cast or printed hydrogel, and subjecting the construct (cell-seeded scaffold) to an applied load in a bioreactor. A key question is to understand how the applied load is distributed throughout the construct. To address this, we employ homogenisation theory to derive equations governing the effective macroscale material properties of a periodic, elastic-poroelastic composite. We treat the fibres as a linear elastic material and the hydrogel as a poroelastic material, and exploit the disparate length scales (small inter-fibre spacing compared with construct dimensions) to derive macroscale equations governing the response of the composite to an applied load. This homogenised description reflects the orthotropic nature of the composite. To validate the model, solutions from finite element simulations of the macroscale, homogenised equations are compared to experimental data describing the unconfined compression of the fibre-reinforced hydrogels. The model is used to derive the bulk mechanical properties of a cylindrical construct of the composite material for a range of fibre spacings and to determine the local mechanical environment experienced by cells embedded within the construct.

Bactericidal coating to prevent early and delayed implant-related infections.

The occurrence of an implant-associated infection (IAI) with the formation of a persisting bacterial biofilm remains a major risk following orthopedic biomaterial implantation. Yet, progress in the fabrication of tunable and durable implant coatings with sufficient bactericidal activity to prevent IAI has been limited. Here, an electrospun composite coating was optimized for the combinatorial and sustained delivery of antibiotics. Antibiotics-laden poly(ε-caprolactone) (PCL) and poly`1q`(lactic-co glycolic acid) (PLGA) nanofibers were electrospun onto lattice structured titanium (Ti) implants. In order to achieve tunable and independent delivery of vancomycin (Van) and rifampicin (Rif), we investigated the influence of the specific drug-polymer interaction and the nanofiber coating composition on the drug release profile and durability of the polymer-Ti interface. We found that a bi-layered nanofiber structure, produced by electrospinning of an inner layer of [PCL/Van] and an outer layer of [PLGA/Rif], yielded the optimal combinatorial drug release profile. This resulted in markedly enhanced bactericidal activity against planktonic and adherent Staphylococcus aureus for 6 weeks as compared to single drug delivery. Moreover, after 6 weeks, synergistic bacterial killing was observed as a result of sustained Van and Rif release. The application of a nanofiber-filled lattice structure successfully prevented the delamination of the multi-layer coating after press-fit cadaveric bone implantation. This new lattice design, in conjunction with the multi-layer nanofiber structure, can be applied to develop tunable and durable coatings for various metallic implantable devices. This is particularly appealing to tune the release of multiple antimicrobial agents over a period of weeks to prevent early and delayed onset IAI.

Structure-activity relationships and mechanism of action of tetragomycin derivatives as inhibitors of Staphylococcus aureus staphyloxanthin biosynthesis.

Despite the main strategy to overcome bacterial resistance has focused on the development of more potent antimicrobial agents, the evolutionary pressure caused by such drugs makes this strategy limited. Molecules that interfere with virulence factors appear as a promising alternative though, as they cause reduced selective pressure. As a matter of fact, staphyloxanthin biosynthesis inhibition (STXBI) has been pursued as promising strategy to reduce S. aureus virulence. Herein, we report the inhibitory profile of 27 tetrangomycin derivatives over staphyloxanthin production. The experimental result showed that naphthoquinone dehydro-α-lapachone (25 - EC50 = 57.29 ± 1.15 µM) and 2-Isopropylnaphtho[2,3-b]furan-4,9-dione (26 EC50 = 82.10 ± 1.09 µM) are the most potent compounds and suggest that hydrogen acceptor groups and lipophilic moieties decorating the naphthoquinone ring are crucial for STXBI. In addition, we present an in situ analysis, through RAMAN spectroscopy, that is inexpensive and might be employed to probe the mechanism of action of staphyloxanthin biosynthesis inhibitors. Therefore, our molecular simplification strategies afforded promising lead compounds for the development of drugs that modulate S. aureus staphyloxanthin biosynthesis.

Lives and Economic Loss in Brazil due to Lack of Radiotherapy Access in Cervical Cancer: A Cost-Effectiveness Analysis.

AIMS: Among all malignancies, the use of radiotherapy incurs the highest survival benefit within cervical cancers. Radiotherapy, however, remains underutilised for cervical cancers within the Brazilian public health system (BPHS). The objective of this study was to estimate the potential health and monetary benefits for universal access to radiotherapy and chemoradiotherapy (CRT) for untreated cervical cancer patients in the BPHS. MATERIALS AND METHODS: Using 2016 data on Brazilian cervical cancer incidence and availability of radiotherapy/CRT in the BPHS, the number of cancer deaths due to radiotherapy/CRT underutilisation was estimated. The incremental effectiveness was calculated by life-year gain. The indirect costs from mortality-related productivity loss (MRPL) were estimated based on life expectancy, wage and labour force participation rate. MRPL was compared with direct medical costs after being adjusted to 2016 US dollars. This study was conducted from the payer's perspective; both costs and effectiveness were discounted at a rate of 3%. The incremental cost-effectiveness ratio (ICER) was calculated to determine the cost-effectiveness of radiotherapy for cervical cancer in Brazil. One-way sensitivity analyses were carried out to assess the robustness of the model. RESULTS: The total number of life-years lost due to lack of universal access to radiotherapy and CRT per year were 27 199 and 31 627, respectively. The annual cost to match the radiotherapy gap was $10.5 million, with an additional cost of $3 million to close the CRT gap. The mean years of potential life lost per death was 20.5. The cost per life saved was $7942 for radiotherapy alone (ICER $388/life-year) and $8774 for CRT (ICER $429/life-year). MRPL due to shortage of radiotherapy and CRT were $59 million and $69 million, respectively. CONCLUSION: Providing universal access to radiotherapy/CRT for cervical cancer patients in the BPHS is highly cost-effective and should be prioritised as an impactful public health initiative.

Avaliação psicométrica em português do indicador de dor crônica de Helsinki em cães com sinais crônicos de osteoartrite / Psychometric testing in Portuguese of Helsinki's chronic pain index for dogs with chronic signs of osteoarthritis

Objetivou-se determinar a validade, a confiabilidade e a sensibilidade do indicador de dor crônica de Helsinki (IDCH) em português, além de estabelecer correlação entre a plataforma de pressão em cães com displasia coxofemoral (DCF). O questionário foi preenchido por tutores de 40 animais com DCF e por 16 tutores de cães saudáveis. Os animais com DCF foram tratados com carprofeno 4,4mg/kg (GT= 21) ou placebo (GP= 19), administrados uma vez ao dia, durante quatro semanas. A avaliação consistiu no preenchimento do questionário (IDCH), na escala analógica visual de dor (EAVdor) e na escala analógica visual de locomoção (EAVloc) com duas semanas (A1) e imediatamente antes do tratamento (A2), duas (S2) e quatro (S4) semanas de tratamento e após duas semanas do término do tratamento (S6). A consistência interna dos dados foi considerada excelente (alfa de Cronbach = 0,89). Houve correlação moderada entre o IDCH e a EAVdor e boa entre o IDCH e a EAVloc, porém não houve diferença entre o grupo tratado com carprofeno e placebo no IDCH. Não houve correlação entre os dados da plataforma de pressão e o IDCH. O questionário apresentou validade de constructo, critério e fidedignidade e pode-se empregá-lo em países de língua portuguesa em cães com osteoartrite.(AU)

We aimed to determine validity, reliability, and sensitivity of Helsinki's chronic pain index (HCPI) and stablish a correlation between HCPI in dogs with hip dysplasia (HD) using pressure sensitive walkway. Forty-owners of dogs with HD and 16 owners of health dogs filled a questionnaire. Dogs with HD were treated with carprofen 4.4mg/kg (GT n= 21) or with placebo (GP n= 19), both were administered once a day for 4 weeks. Evaluation was performed by the owners using the questionnaire (HCPI), the Visual Analogue Scale for pain (VASpain) and the VAS for locomotion (VASloc). The evaluation was performed 2 weeks before the treatment began (A1), immediately after treatment (A2), two (S2), four (S4) and two weeks after the end of treatment (S6) and the lameness was evaluated by pressure sensitive walkway. The internal consistency of the data was considered excellent (Cronbach´α coefficient= 0.89). There was a moderate correlation between the HCPI and VASpain. For VASloc the correlation was good. However, there was no difference between treatments, indicating low sensibility. No correlation was observed between pressure sensitive walkway and HCPI. We concluded that the questionnaire has construct and criterion validity, reliability and can be applied in dogs with osteoarthritis in Portuguese-speaking countries.(AU)

Nanoparticles of methylene blue enhance photodynamic therapy.

Breast cancer is the most commonly diagnosed cancer and the second leading cause of death related to cancer among women worldwide. Screening and advancements in treatment have improved survival rate of women suffering from this ailment. Novel therapeutic techniques may further reduce cancer related mortality. One of several emerging therapeutic options is Photodynamic Therapy (PDT) that uses light activated photosensitizer (PS) inducing cell death by apoptosis and/or necrosis. Nanotechnology has made contribution to improve photosensitizer for PDT, increasing the efficiency of therapy using gold and silver nanoparticles. Efforts have been done to develop better mechanism to improve PS and consequently PDT effects. In this study, we investigate the efficacy of the PDT using gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) when mixed to methylene blue (MB) in the treatment of the human breast adenocarcinoma cell line (MDA-MB-468). The MDA-MB-468 was treated in the presence of different MB concentrations with/without AuNPs or AgNPs. The colloidal solution of AgNPs showed a plasmon resonance band at 411 nm in UV-visible range and a bimodal size distribution. The results of viability analysis showed that cells treated with nanoparticles exhibited higher cytotoxicity than cells treated with only MB, improving the efficiency of the treatment in the tumor cells. The cytotoxicity effect of MB associated with AgNPs on MDA-MB-468 cell line could be related to increased reactive oxygen species production due to the release of Ag+ ions from nanoparticles surface, suggesting that the association between FS and AgNPs has potential as a PDT agent.

Radiographic measurements of the hindlimbs in crab-eating foxes (Cerdocyon thous, Linnaeus, 1766).

Life expectancy of crab-eating foxes in captivity is approximately 11 years, which favours the development of diseases including orthopaedic disorders. However, to understand disorders that may affect these animals, it is worth determining a normal range of measurements. Therefore, this study aimed to evaluate radiographic measurements of joint angles of the hindlimbs and the ratio of patellar ligament length to patellar length in healthy crab-eating foxes. Fifteen captive crab-eating foxes (Cerdocyon thous), eight males and seven females, aged more than 1 year old, weighing 5.5-7.9 kg were used. Anatomic and mechanical femoral joint angles were assessed in ventrodorsal radiographic views, and mediolateral views were taken to measure patellar ligament length and patellar length, and the tibial plateau angle. The right and left hindlimbs were evaluated. All measurements were conducted in triplicate by the same investigator. No statistically significant differences were observed between sides in the radiographic measurements. The anatomic lateral proximal femoral angle and the anatomic lateral distal femoral angle recorded mean values of 95.43° and 92.75°, respectively. The mechanical lateral proximal femoral angle and the mechanical lateral distal femoral angle recorded mean values of 93.39° and 96.75°, respectively. Inclination angles measured according to the Tomlinson, Hauptman A and Hauptman B methods were 133.80°, 147.32° and 128.63°, respectively. The tibial plateau recorded 18.77°, and the ratio of the patellar ligament length to the patellar length was 1.99. In conclusion, the collected data are important to characterize the normal values of crab-eating fox limbs.

FTIR study of secondary structure changes in Epidermal Growth Factor by gold nanoparticle conjugation.

Conformation of protein is vital to its function, but may get affected when processing to manufacture products. It is therefore important to understand structural changes during each step of production. In this study, we investigate secondary structure changes in the targeting protein Epidermal Growth Factor (EGF) during synthesis of theranostic bifunctional nanoparticle, devised for Photodynamic therapy of breast cancer. We acquired FTIR spectra of EGF; unconjugated, post treatment with α-lipoic acid, attached to gold nanoparticle, and bound to the bifunctional nanoprobe. We observed decreasing disordered structures and turns, and increasing loops, as the synthesis process progressed. There was an overall increase in ß-sheets in final product compared to pure EGF, but this increase was not linear and fluctuated. Previous crystal structure studies on EGF-EGFR complex have shown loops and ß-sheets to be important in the binding interaction. Since our study found increase in these structures in the final product, no adverse effect on binding function of EGF was expected. This was confirmed by functional assays. Such studies may help modify synthesis procedures, and thus secondary structures of proteins, enabling increased functionality and optimum results.

Assessing bioink shape fidelity to aid material development in 3D bioprinting.

During extrusion-based bioprinting, the deposited bioink filaments are subjected to deformations, such as collapse of overhanging filaments, which compromises the ability to stack several layers of bioink, and fusion between adjacent filaments, which compromises the resolution and maintenance of a desired pore structure. When developing new bioinks, approaches to assess their shape fidelity after printing would be beneficial to evaluate the degree of deformation of the deposited filament and to estimate how similar the final printed construct would be to the design. However, shape fidelity has been prevalently assessed qualitatively through visual inspection after printing, hampering the direct comparison of the printability of different bioinks. In this technical note, we propose a quantitative evaluation for shape fidelity of bioinks based on testing the filament collapse on overhanging structures and the filament fusion of parallel printed strands. Both tests were applied on a hydrogel platform based on poloxamer 407 and poly(ethylene glycol) blends, providing a library of hydrogels with different yield stresses. The presented approach is an easy way to assess bioink shape fidelity, applicable to any filament-based bioprinting system and able to quantitatively evaluate this aspect of printability, based on the degree of deformation of the printed filament. In addition, we built a simple theoretical model that relates filament collapse with bioink yield stress. The results of both shape fidelity tests underline the role of yield stress as one of the parameters influencing the printability of a bioink. The presented quantitative evaluation will allow for reproducible comparisons between different bioink platforms.

Osteology and radiology of the Maned Wolf (Chrysocyon brachyurus) pelvic limb.

This study describes the osteology and radiology of the pelvic limb in maned wolves. Ten (five live and five dead) maned wolves (Chrysocyon brachyurus), five males and five females, aged from 2 to 7 years old were used. Digital radiographs were taken and recorded for both pelvic limbs in all animals. Osteology was correlated with the radiographic images. The pelvis had a rectangular shape, and the obturator foramen (foramen obturatum) was oval. The femoral neck (collum femoris) was short and thick. The greater trochanter (trochanter major) extended proximally to near the dorsum of the femoral head (caput ossis femoris). The lateral femoral condyle (condylus lateralis) was larger than the medial condyle (condylus medialis), and the intercondylar fossa (fossa intercondylaris) had a slightly oblique orientation. The proximal tibia displayed medial and lateral condyles with the medial larger. The femur was slightly shorter than the tibia. Seven tarsal bones (ossa tarsi) were present, four long metatarsal bones (ossa metatarsalia II - V) and a short first metatarsal bone (os metatarsal I).

Antifungal activity of tyrosol and farnesol used in combination against Candida species in the planktonic state or forming biofilms.

AIM: This study examined the antifungal activity of the combination of tyrosol and farnesol against Candida albicans and Candida glabrata in the planktonic state or forming biofilms. METHODS AND RESULTS: The effect of drug association against Candida planktonic cells was assessed by the fractional inhibitory concentration index. Mono- and dual-species biofilms were developed during 24 h and then treated with the compounds for 3 days, with two daily treatments of 1 min each. After, the total biomass, metabolic activity and the number of cultivable cells were quantified. Planktonic cells of the two species showed a similar susceptibility to the drug combination, however, a synergistic effect was only verified for C. glabrata. Regarding biofilm susceptibility, significant reductions in C. glabrata biomass, metabolism of C. albicans and mixed biofilms, and cultivable cells of single biofilms were verified for the drug combination, indicating an additive effect. For all other experiments, the effects were classified as indifferent. CONCLUSION: The combined use of tyrosol and farnesol was advantageous for some of the analysed parameters against Candida species. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings may contribute to the development of oral care products containing tyrosol and farnesol to combat oral infections caused by Candida species.

Salivary Cortisol Responses and Session Ratings of Perceived Exertion to a Rugby Match and Fatigue Test.

This study compared the effects of an official rugby match and a fatigue test on the salivary cortisol responses of 13 rugby players. We also examined the relationship between this cortisol response and session ratings of perceived exertion (session-RPE). We collected saliva before and after the match and fatigue test and assessed physical effort intensity via session-RPE using a CR-10 scale. We measured cortisol concentration by enzyme-linked immunosorbent assays. Results were greater session-RPE and cortisol concentrations for the rugby match, compared with the fatigue test. There was a significant difference between cortisol concentrations obtained pre- and postmatch ( p < .022) and significant correlations between cortisol response and session-RPE sampling in both the rugby match ( r = .81; p < .001) and fatigue test ( r = .91; p < .001). This study provides evidence of greater perceived effort and higher cortisol concentrations in actual competition versus a fatigue test. Our data further support session-RPE as a relatively inexpensive close correlate of a stress biomarker (cortisol response). Thus, session-RPE can be used by coaches as a valid indication of training loads and adequate recovery time after exertion.

Synthesis and characterization of gold nanostructured Chorin e6 for Photodynamic Therapy.

Photodynamic therapy is an alternative treatment for cancer based on cellular uptake of a photosensitizer, illuminated with an appropriate wavelength in the presence of oxygen. A cascade of reactions generates reactive oxygen species leading to cell death. Using carbodiimide chemistry, chlorin e6 (Ce6) was covalently bonded to thiourea, and (via the sulphur end group) to gold nanoparticles (AuNPs), forming the Ce6-AuNP complex. Ce6 absorbs in the range 650-680nm, where the coefficient of biological tissue absorption is low (part of the therapeutic window), which is ideal for biological application. Transmission Electron Microscopy, UV-vis spectroscopy, Fourier transform Infrared Spectroscopy and Zeta potential measurements were completed to characterize the Ce6-AuNP complex. The bare AuNPs have an average diameter of 18±4nm. A line of human breast carcinoma cells (MDA-MB-468) was used to determine whether Ce6 functionalization to AuNPs potentiate its activity. Trypan blue assays were used to assess cell viability. In the absence of light, Ce6 either alone or bounded to AuNPs was not cytotoxic. When irradiated at 660nm, the cytotoxicity of Ce6-AuNP was higher than Ce6 alone for MDA-MB-468 cells using 4h incubation. AuNPs without Ce6 showed no cytotoxic.

Magneto immunoassays for Plasmodium falciparum histidine-rich protein 2 related to malaria based on magnetic nanoparticles.

Magneto immunoassay-based strategies for the detection of Plasmodium falciparum histidine-rich protein 2 (HRP2) related to malaria are described for the first time by using magnetic micro- and nanoparticles. The covalent immobilization of a commercial monoclonal antibody toward the HRP2 protein in magnetic beads and nanoparticles was evaluated and compared. The immunological reaction for the protein HRP2 was successfully performed in a sandwich assay on magnetic micro- and nanoparticles by using a second monoclonal antibody labeled with the enzyme, horseradish peroxidase (HRP). Then, the modified magnetic particles were easily captured by a magneto sensor made of graphite-epoxy composite (m-GEC) which was also used as the transducer for the electrochemical detection. The performance of the immunoassay-based strategy with the electrochemical magneto immunosensors was successfully evaluated and compared with a novel magneto-ELISA based on optical detection using spiked serum samples. Improved sensitivity was obtained when using 300 nm magnetic nanoparticles in both cases. The electrochemical magneto immunosensor coupled with magnetic nanoparticles have shown better analytical performance in terms of limit of detection (0.36 ng mL(-1)), which is much lower than the LOD reported by other methods. Moreover, at a low level of HRP2 concentration of 31.0 ng mL(-1), a signal of 15.30 µA was reached with a cutoff value of 0.34 µA, giving a clear positive result with a non-specific adsorption ratio of 51. Due to the high sensitivity, this novel strategy offers great promise for rapid, simple, cost-effective, and on-site detection of falciparum malaria disease in patients, but also to screen out at-risk blood samples for prevention of transfusion-transmitted malaria.

Cadmium-induced disruption of environmental exploration and chemical communication in matrinxã, Brycon amazonicus.

The effects of cadmium exposure on both environment exploration and behavioral responses induced by alarm substance in matrinxã (Brycon amazonicus), a fish species endemic to the Amazon basin, were investigated. Fish exposed to 9.04+/-0.07 microg/L waterborne cadmium for 96h followed by 24h depuration period in clean water, were video-recorded for 15 min, followed by immediate introduction of conspecific skin extract to the tank and a new 30 min period of fish video-recording. Cd-exposed matrinxã showed a significantly lowered locomotor activity (t-test t(12)=2.7; p=0.025) and spatial distribution (t-test t(12)=2.4; p=0.03) relative to the unexposed control fish prior to the alarm substance introduction, and did not present any significant reaction when the skin extract was introduced. The control fish, in opposite, showed a higher level of activity and spatial distribution prior the skin extract contact and significantly decreased their response after the chemical stimulus (locomotion-repeated-measure ANOVA F(1,11)=5.6; p=0.04; spatial distribution F(1,11)=19.4; p=0.001). In conclusion, exposure to a low level of cadmium affects both the environment exploration performance and the conspecific chemical communication in matrinxã. If the reduced environmental exploration performance of Cd-exposed fish is an adjustment to the compromised chemical communication or an independent effect of cadmium is the next step to be investigated.