Is the antidepressant effect of ketamine separate from its psychotomimetic effect? A review of rodent models.

Ketamine is an NMDA (N-methyl-d-aspartate) glutamate receptor antagonist, which has a myriad of dose-dependent pharmacological and behavioral effects, including anesthetic, sedative, amnestic, analgesic, and anti-inflammatory properties. Intriguingly, ketamine at subanesthetic doses displays a relevant profile both in mimicking symptoms of schizophrenia and also as the first fast-acting treatment for depression. Here, we present an overview of the state-of-the-art knowledge about ketamine as an antidepressant as well as a pharmacological model of schizophrenia in animal models and human participants. Ketamine's dual effect appears to arise from its mechanism of action involving NMDA receptors, with both immediate and downstream consequences being triggered as a result. Finally, we discuss the feasibility of a unified approach linking the glutamatergic hypothesis of schizophrenia to the promising preclinical and clinical success of ketamine in the treatment of refractory depression.

Enhanced HPLC Method for Boar Taint Quantification.

Boar taint is an unpleasant odour found in the carcasses of entire male pigs, resulting from androstenone and skatole accumulation during pubertal development, and impacting pork quality. This study proposes the validation of an adapted chromatographic method for quantifying skatole and androstenone in the pigs' liquid fat using fluorescence detection. A good chromatographic separation was achieved, with skatole (SKA) and androstenone (AND) elution at 4.4 and 9.9 min., respectively. An external calibration method was applied, with calibration curves correlation coefficient of 0.9999 for both analytes. Detection limit values were 1.53 and 16.02 ng/g for SKA and AND, respectively. SKA recovery was 99.72±2.34 % (2.34 % RSD) and 102.84±1.62 % (1.57 % RSD) for AND. Results showed good precision values (repeatability <2.46 % RSD for SKA, <6.85 % RSD for AND; intermediate precision <2.87 % RSD for SKA, <6.98 % RSD for AND). The method's robustness was tested and the values were within the reference ranges. The validation results proved that the adaptation of an existing method resulted in good assessments of robustness, reliability and accuracy.

Dolor crónico tras la cirugía de mama: incidencia, factores de riesgo e impacto en la calidad de vida / Chronic pain after breast surgery: Incidence, risk factors and impact on quality of life

Introducción y objetivos: El cáncer de mama es la neoplasia más frecuentemente diagnosticada y el dolor crónico postoperatorio (DCPO) es un problema relacionado con la terapia crecientemente reconocido. Evaluamos la incidencia del DCPO, sus características, factores asociados e impacto en la calidad de vida (CdV) del paciente.Materiales y métodosSe realizó un estudio prospectivo observacional de 6meses en pacientes tratados mediante cirugía de mama en un hospital universitario terciario. Los datos se recopilaron utilizando diversos cuestionarios: Pain Catastrophizing Scale, Brief Pain Inventory-Short Form, Douleur Neuropathique 4, European Organization for Research and Treatment of Cancer Quality of Life Questionnaire y Breast Cancer Module.ResultadosUn total de 112 pacientes completaron el estudio, de los cuales aproximadamente un tercio (34,8%) desarrollaron DCPO y casi todos ellos dolor neuropático potencial. El DCPO interfirió con la vida diaria de los pacientes y redujo su CdV. La diabetes (p=0,028), la catastrofización (p=0,042) y la gravedad del dolor posoperatorio agudo (p<0,001) se asociaron a DCPO.ConclusionesEste estudio amplía nuestra comprensión sobre el DCPO y muestra el impacto de este síndrome. Los profesionales sanitarios deben ser conscientes del DCPO, y tomar medidas para prevenirlo y tratarlo, proporcionando a los pacientes la información suficiente. (AU)

Introduction and objectives: Breast cancer is the most frequently diagnosed malignancy, and chronic pain after breast surgery (CPBS) is an increasingly recognized therapy-related problem. We evaluated CPBS incidence, characteristics, associated factors, and impact on patient quality of life (QoL).Materials and methodsSix-month observational prospective study in patients undergoing breast surgery in a tertiary university hospital. Data were collected using several questionnaires: Pain Catastrophizing Scale, Brief Pain Inventory-Short Form, Douleur Neuropathique 4 Questionnaire, and European Organization for Research and Treatment of Cancer Quality of Life Questionnaire and its Breast Cancer Module.ResultsA total of 112 patients completed the study. Approximately, one third (34.8%) developed CPBS, almost all with potentially neuropathic pain. CPBS interfered with patients’ daily life and reduced their QoL. Diabetes (p=.028), catastrophizing (p=.042), and acute postoperative pain severity (p<.001) were associated with CPBS.ConclusionsThis study broadens our understanding of CPBS and shows the impact of this syndrome. Healthcare workers need to be aware of CPBS and take steps to prevent and treat it, and provide patients with adequate information. (AU)

Detection of Nucleic Acids of the Fish Pathogen Yersinia ruckeri from Planktonic and Biofilm Samples with a CRISPR/Cas13a-Based Assay.

Yersinia ruckeri is the cause of hemorrhagic septicemia, known as enteric redmouth disease, in salmonid fish species. This bacterial pathogen can form biofilms on abiotic surfaces of aquaculture settings or even on the surfaces of the fish themselves, contributing to their persistence in the aquatic environment. Detection methods for this and other fish pathogens can be time-consuming and lack specificity and sensitivity, limiting timely monitoring, the treatment of microbial infections, and effective control of their transmission in aquaculture settings. Rapid and sensitive detection methods for nucleic acids can be crucial for an appropriate surveillance of bacterial pathogens, and the CRISPR/Cas-based assays have emerged as a good alternative since it has been proven to be a useful tool for the rapid, specific, and sensitive detection of viruses and some bacteria. In this study, we explored the capability of the CRISPR/Cas13a system (SHERLOCK) to specifically detect both DNA and RNA (gene transcripts) from planktonic and biofilm samples of the bacterial fish pathogen Y. ruckeri. The assay was designed to detect the gyrA gene and the small noncoding RNAs (sRNAs) MicA and RprA from planktonic cultures and biofilm samples prepared in marine broth. The specific crRNA designed for these gene targets included a 28 nt specific gene sequence, and a scaffold sequence necessary for Cas13-binding. For all the assays, the nucleic acids obtained from samples were previously subjected to isothermal amplification with the recombinase polymerase amplification (RPA) method and the subsequent T7 transcription of the RPA amplicons. Finally, the detection of nucleic acids of Y. ruckeri was by means of a reporter signal released by the Cas13a collateral RNA cleavage triggered upon target recognition, measured by fluorescence- or lateral-flow-based readouts. This CRISPR/Cas13a-based assay was able to specifically detect both DNA and sRNAs from the Y. ruckeri samples, and the sensitivity was comparable to that obtained with qPCR analysis, highlighting the potential applicability of this CRISPR/Cas13a-based assay for fish pathogen surveillance.

Hepatocellular Carcinoma in Ceará: Epidemiology and Treatment in a Reference Liver Transplant Center in Northeast Brazil.

Hepatocellular carcinoma remains a significant worldwide malignancy and an important cause of cancer-related death. The incidence is increasing globally. In Latin America, there is no consistent data on the epidemiology of hepatocellular carcinoma. However, Brazil is considered a country with an intermediate incidence of this liver neoplasm. In the state of Ceará, situated in the northeast region of Brazil, there are no consistent clinical and epidemiologic data on the actual incidence and the treatment of hepatocellular carcinoma. The purpose of this article is to describe epidemiologic characteristics and treatment forms of patients with hepatocellular carcinoma who were treated in a Liver Transplant Center. A retrospective observational study was conducted using the database from the register of 299 patients with hepatocellular carcinoma between June 2004 and February 2022. Only patients born in Ceará were included. Therefore, most patients were eligible, based on the Milan Criteria, to undergo liver transplantation with a Model End Stage Liver Disease score of 12.48 ± 4.66 points, and the waiting list time was approximately 7 months with 8.7% hepatocellular carcinoma recurrence after liver transplant. A total of 38.5 % of cases were outside the Milan criteria at the time of cancer diagnosis, and transarterial chemoembolization was the main treatment choice. In conclusion, the diagnosis of hepatocellular carcinoma in Ceará mainly occurs in male patients with hepatitis C or alcoholism, with a mean age of 61.55 years and a previous diagnosis of liver disease. Liver transplantation was the best curative therapeutic form in patients with cirrhosis and hepatocellular carcinoma in Ceará, where a significant number of patients were diagnosed with intermediate and advanced-stage hepatocellular carcinoma, so public health policies are important for the screening and monitoring of liver disease.

Chronic pain after breast surgery: incidence, risk factors and impact on quality of life.

INTRODUCTION AND OBJECTIVES: Breast cancer is the most frequently diagnosed malignancy, and chronic pain after breast surgery (CPBS) is an increasingly recognized therapy-related problem. We evaluated CPBS incidence, characteristics, associated factors, and impact on patient quality of life (QoL). MATERIALS AND METHODS: Six-month observational prospective study conducted in patients undergoing breast surgery in a tertiary university hospital. Data were collected using several questionnaires: Pain Catastrophizing Scale, Brief Pain Inventory-Short Form, Douleur Neuropathique 4 Questionnaire, and European Organization for Research and Treatment of Cancer Quality of Life Questionnaire and its Breast Cancer Module. RESULTS: A total of 112 patients completed the study. Approximately, one third (34.8%) developed CPBS, and almost all with potentially neuropathic pain. CPBS interfered with patients' daily life and reduced their QoL. Diabetes (p = 0.028), catastrophizing (p = 0.042), and acute postoperative pain severity (p < 0.001) were associated with CPBS. CONCLUSIONS: This study broadens our understanding of CPBS and shows the impact of this syndrome. Healthcare workers need to be aware of CPBS and take steps to prevent and treat it, and provide patients with adequate information.

Antimicrobial effect of Pentaclethra Macroloba plant extract against Enterococcus Faecalis.

This study evaluated the antimicrobial efficacy of a new intracanal drug based on Pentaclethra macroloba extract, a plant of Amazonian origin, against Enterococcus faecalis using macrodilution test and intratubular evaluation with Confocal Laser Scanning Microscopy (CLSM). The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the pure extract of Pentaclethra macroloba andits association with calcium hydroxide and ultracall were determined. Then, thirty-three dentin cylinders were prepared and inoculated with E. faecalis, to evaluate the antimicrobial effect of the medications on the dentinal tubules with CLSM. The data was analyzed using the Kruskal-Wallis and Dunn tests. The extract in association with calcium hydroxide showed a lower CBM, and in the intratubular test all tested medications were effective against E. faecalis (P >0.05). The new intracanal drug based on P. macroloba extract has an antimicrobial effect against E. faecalis and further studies are needed for its clinical use.

Fish diversity in the rivers that drain the Baixada Maranhense and the Mearim basin in northeastern Brazil.

The Baixada Maranhense Environmental Protection Area of the Brazilian state of Maranhão encompasses a biologically rich region that includes the basins of four principal rivers, the Mearim, Pericumã, Pindaré, and Turiaçu, which form a complex of wetlands. The present study provides a comprehensive inventory of the fish fauna of the rivers that drain the Baixada Maranhense based on the identification of voucher specimens that were deposited in a scientific collection. Expeditions were conducted between 2014 and 2020. The inventory identified a total of 100 fish species representing 79 genera, 34 families, and 11 orders, which are found in both freshwater and estuarine environments. Six (Potamotrygon orbignyi, Leporinus piau, Moenkhausia loweae, Serrasalmus spilopleura, Pachypops fourcroi and Peckoltia greedoi) of the 100 taxa identified here are considered to be new records for one or more of the basins surveyed during this study, based on the existing data, while four - Colossoma macropomum, Megaleporinus macrocephalus, Cichla sp. and Cichla kelberi - are not native. The most speciose orders were the Siluriformes and Characiformes, while the most diverse families were the Loricariidae, Characidae, Auchenipteridae, Cichlidae, and Serrasalmidae. These data are consistent with the findings of most of the previous studies of freshwater ecosystems in the Neotropical region, in particular those of the rivers of Maranhão. The results of the present study represent an important advance in the understanding of the diversity of the fish fauna of the Mearim, Pericumã, Pindaré, and Turiaçu rivers, which are still poorly studied, and have likely had their diversity underestimated up to now.

Impacted estuaries on the Brazilian Amazon coast near port regions influence histological and enzymatic changes in Sciades herzbergii (Ariidae, Bloch, 1794).

Enzymatic (glutathione S-transferase, GST and catalase, CAT) and histological biomarkers in S. herzbergii are important for the analysis of impacted estuaries in port regions of the Brazilian Amazon coast. Fish specimens were collected in two areas in the rainy and dry seasons: Porto Grande (potentially impacted region) and Ilha dos Caranguejos (less impacted region). Sediment samples were collected for chemical analysis. Morphometric, histological, and enzymatic biomarker analyzes were performed. The analysis of the sediments collected in the potentially impacted region showed levels of iron, aluminum and polycyclic aromatic hydrocarbons above the limits allowed by CONAMA legislation. Histological changes in the gills and liver, as well as GST and CAT activities, were high in fish collected at the port. Analyzes suggest that fish in the potentially impacted region are subject to pollutants that compromise their health.

Lower breast cancer survival among Black women in Brazil: a population-based retrospective study.

OBJECTIVES: To analyze the rates of breast cancer survival among Black and White women according to age and stage at diagnosis. STUDY DESIGN: A retrospective cohort study. METHODS: The study examined women registered in the population-based cancer registry of Campinas in 2010-2014. The primary variable was the declared race (White or Black). Other races were excluded. Data were linked with the Mortality Information System, and missing information was accessed by active search. Overall survival (OS) was calculated by the Kaplan-Meier method, comparisons were done by chi-squared tests, and hazard ratios were examined by Cox regression. RESULTS: The total numbers of new cases of staged breast cancer among Black and White women were 218 and 1522 cases, respectively. The rates of stages III/IV were 35.5% among White women and 43.1% among Black women (P = 0.024). The frequencies among White and Black women under 40 years old were 8.0% and 12.4% (P = 0.031), 19.6% and 26.6% (P = 0.016) for ages of 40-49 years, and 23.8% and 17.4% (P = 0.037) for ages of 60-69 years, respectively. The mean OS was 7.5 years (7.0; 8.0) among Black women and 8.4 years (8.2; 8.5) among White women. The 5-year OS was 72.3% among Black women and 80.5% among White women (P = 0.001). Black women had an age-adjusted risk of death that was 1.7 times higher (1.33; 2.20). The risk was 6.4 times higher for diagnoses in stage 0 (1.65; 24.90) and 1.5 times for diagnoses in stage IV (1.04; 2.17). CONCLUSION: The 5-year OS for women with breast cancer was significantly lower among Black women than White women. Black women were more frequently diagnosed in stages III/IV, and their age-adjusted risk of death was 1.7 times higher. Differences in access to care may explain these differences.

Stage-dependent sensitivity to Müller-Lyer visual illusion in schizophrenia patients.

RATIONALE: Schizophrenic patients show perceptual deficits, which may be detected in visual illusion tasks. Previous studies found that chronic patients show increased sensitivity to Müller-Lyer illusion as the disorder progresses, although there are a few conflicting reports in the scientific literature. To address these issues, moderate and chronic schizophrenic patients were tested on the Brentano version of the Müller-Lyer illusion task. Their performance was compared to first-degree relatives and unrelated matched controls. Chronic patients showed increased susceptibility to the illusion. Performance on the visual illusion task was not correlated to the number of years since disease onset, medication or (Positive and Negative Syndrome Scale) PANSS scores. The lack of association between illusion sensitivity and PANSS score may reflect the absence of the perceptual dimension in this scale. Based on these results, we suggest that susceptibility to the Müller-Lyer illusion is associated with the stage of schizophrenia rather than disease length.

The influence of electrolytes in the adsorption kinetics of reactive BF-5G blue dye on bone char: a mass transfer model.

The discharge of harmful dyes in water bodies is a serious pollution problem, dangerous for the ecosystem's equilibrium and human health. In this sense, the aim of this work was to determine the influence of electrolytes (NaCl, KCl, CaCl2 and MgCl2) in the adsorption of Reactive Blue BF-5G dye, the most common dye used in industrial process for fabric colouring, using bovine bone char as the adsorbent. The bovine bone char was characterized by pH of point of zero charge (pHPZC), N2 adsorption-desorption isotherms, Fourier transform-infrared spectroscopy (FT-IR) and X-ray diffractometry (XDR). The characterization revealed a mesoporous structure (pore mean diameter of 94 Šand SBET ∼107 m2 g-1) with negative charge distribution at the surface (pHPZC = 3.8). The adsorption experiments revealed that the presence of KCl enhanced the material adsorption capacity (qmax = 195 mg g-1), that the Sips isotherm best fitted the experimental data (R2 > 0.9 except for KCl solution) and the adsorption process was mono- and multilayered. The kinetic adsorption experiments indicated that the inorganic electrolytes increased the initial adsorption velocity and the data was best modelled by the surface diffusional model (SDM), implying a resistance (aqueous > CaCl2 > NaCl > MgCl2 > KCl) to mass transfer at the surface of the pores which, in turn, prevented the dye diffusion to the interior of the adsorbent (qe = 71 mg g-1). Therefore, small quantities of KCl can be used to lower the mass transfer resistance and provide higher adsorption capacity with reduced time of operation, thus increasing the overall process efficiency.

Transport properties of n-ethylene glycol aqueous solutions with focus on triethylene glycol-water.

Soret effect and diffusion in triethylene glycol (TEG)-water mixtures were investigated as a function of concentration at 25 °C by means of optical digital interferometry, with the use of a classical Soret cell. Diffusion D, thermal diffusion DT, and Soret ST coefficients are described for the full concentration range and an analysis is made individually for TEG-water mixture and within a series of n-ethylene glycol (n-EG) aqueous systems. All coefficients decrease with increasing the concentration of TEG and n-EG. ST shows a change of sign with concentration, and this change is directly related to the ability of the n-EG molecule to establish hydrogen bonding with water. Diffusion and thermal diffusion coefficients present a plateau behavior with increasing concentration, showing the occurrence of changes in the preferential interactions in aqueous solution with concentration and meaning that, at high TEG composition, ether oxygens can be involved in the molecular interactions.

The composition of the lipid, protein and mineral fractions of quail breast meat obtained from wild and farmed specimens of Common quail (Coturnix coturnix) and farmed Japanese quail (Coturnix japonica domestica).

The present study was intended to answer 2 scientific hypotheses: 1) the quail species has a significant influence in quail breast meat composition; 2) the wild quail's meat presents healthier composition than their farmed counterparts. An analysis of the pectoral muscles of wild and captive common quails (Coturnix coturnix) and domestic quails (Coturnix japonica domestica) was performed. The content of fatty acids (FA), amino acids, total cholesterol, and vitamin E, some basic macro- and microminerals in the pectoral muscles of the 2 species of the genus Coturnix were analyzed. Regarding the quail species influence on meat composition, Japanese Quail (JQ) revealed better lipid composition, characterized by lower saturated FA (SFA; less 3.17 g/100 g of total fatty acids), higher polyunsaturated FA contents (PUFA; more 5.5 g/100 g of total fatty acids) and healthier polyunsaturated FA/saturated FA (P/S) and n-6/n-3 ratios and TI value (1.08, 9.54 and 0.60 vs. 0.76, 12.58, and 0.75, correspondingly). The absence of differences observed on amino acids partial sums and ratios reveals equality between species on protein nutritional quality. On the other hand, Common Quail (CQ) proved to be a better source of copper (0.181 mg/100 g of meat), iron (2.757 mg/100 g of meat), manganese (0.020 mg/100 g of meat), and zinc (0.093 mg/100 g of meat) than JQ. The comparison of farmed and wild specimens within CQ, showed that wild birds presented lower total cholesterol (less 8.32 mg/g of fresh meat) and total PUFA (less 4.26 g/100 g of total fatty acids), and higher n-3 PUFA contents (more 1.53 g/100 g of total fatty acids), which contributed to healthier P/S and n-6/n-3 ratios, but worst PI (1.60, 8.08, and 113.1 vs. 0.76, 12.58, and 100.8, respectively). The wild species revealed higher α-tocopherol content (2.40 vs. 1.49 µg/g of fresh meat. Differences observed on their mineral composition counterbalance each other. Under intensive production system and similar feeding and management conditions, the CQ develops better nutritional qualities than JQ. The comparison of wild and farmed species within CQ reveals more similarities than differences. Quail´s meat presents good nutritional quality and introduces variability to human's diet, which is much valued by consumers.

New records of the occurrence of Megaleporinus macrocephalus (Garavello & Britski, 1988 (Characiformes, Anostomidae) from the basins of the Itapecuru and Mearim rivers in Maranhão, Northeastern Brazil / Novos registros da ocorrência de Megaleporinus macrocephalus (Garavello & Britski, 1988) (Characiformes, Anostomidae) nas bacias dos rios Itapecuru e Mearim no Maranhão, Nordeste, Brasil

The "piaussu", Megaleporinus macrocephalus is an anostomatid fish species native to the basin of the Paraguay River, in the Pantanal biome of western Brazil. However, this species has now been recorded in a number of other drainages, including those of the upper Paraná, Uruguay, Jacuí, Doce, Mucuri, and Paraíba do Sulrivers. This study presents two new records of the occurrence of M. macrocephalus, in the basins of the Itapecuru and Mearim rivers in the state of Maranhão, in the Brazilian Northeast. The piaussu is a large-bodied fish of commercial interest that is widely raised on fish farms, and its occurrence in the Itapecuru and Mearim rivers is likely the result of individuals escaping from fish tanks when they overflow during the rainy season. Morphological analyses and sequences of the Cytochrome Oxidase Subunit I (COI) gene confirmed the taxonomic identification of the specimens as M. macrocephalus. The COI sequences were 99.66% similar to those of M. macrocephalus deposited in the BOLDSystems database. These records extend the known distribution of M. macrocephalus to the basins of the Itapecuru and Mearim rivers in the Brazilian Northeast, highlighting a new case of introduction of exotic fish species into Brazilian river basins.

Megaleporinus macrocephalus é uma espécie de peixe anostomatídeo nativa da bacia do rio Paraguai, no bioma Pantanal do oeste do Brasil. No entanto, essa espécie já foi registrada em várias outras drenagens, incluindo as dos rios Alto Paraná, Uruguai, Jacuí, Doce, Mucuri e Paraíba do Sul. Este estudo apresenta dois novos registros da ocorrência de M. macrocephalus, nas bacias dos rios Itapecuru e Mearim, no estado do Maranhão, no nordeste brasileiro. O piaussu é um peixe de grande porte, de interesse comercial, amplamente criado em pisciculturas, e sua ocorrência nos rios Itapecuru e Mearim é provavelmente o resultado de indivíduos que escapam dos tanques quando transbordam durante a estação chuvosa. Análises morfológicas e sequências do gene da subunidade I do citocromo oxidase (COI) confirmaram a identificação taxonômica dos espécimes como M. macrocephalus. As sequências de COI foram 99,66% semelhantes às de M. macrocephalus depositadas no banco de dados BOLDSystems. Esses registros estendem a conhecida distribuição de M. macrocephalus às bacias dos rios Itapecuru e Mearim, no nordeste brasileiro, destacando um novo caso de introdução de espécies exóticas de peixes nas bacias hidrográficas brasileiras.

New records of the occurrence of Megaleporinus macrocephalus () (Characiformes, Anostomidae) from the basins of the Itapecuru and Mearim rivers in Maranhão, Northeastern Brazil

Abstract The piaussu, Megaleporinus macrocephalus is an anostomatid fish species native to the basin of the Paraguay River, in the Pantanal biome of western Brazil. However, this species has now been recorded in a number of other drainages, including those of the upper Paraná, Uruguay, Jacuí, Doce, Mucuri, and Paraíba do Sulrivers. This study presents two new records of the occurrence of M. macrocephalus, in the basins of the Itapecuru and Mearim rivers in the state of Maranhão, in the Brazilian Northeast. The piaussu is a large-bodied fish of commercial interest that is widely raised on fish farms, and its occurrence in the Itapecuru and Mearim rivers is likely the result of individuals escaping from fish tanks when they overflow during the rainy season. Morphological analyses and sequences of the Cytochrome Oxidase Subunit I (COI) gene confirmed the taxonomic identification of the specimens as M. macrocephalus. The COI sequences were 99.66% similar to those of M. macrocephalus deposited in the BOLDSystems database. These records extend the known distribution of M. macrocephalus to the basins of the Itapecuru and Mearim rivers in the Brazilian Northeast, highlighting a new case of introduction of exotic fish species into Brazilian river basins.

Resumo Megaleporinus macrocephalus é uma espécie de peixe anostomatídeo nativa da bacia do rio Paraguai, no bioma Pantanal do oeste do Brasil. No entanto, essa espécie já foi registrada em várias outras drenagens, incluindo as dos rios Alto Paraná, Uruguai, Jacuí, Doce, Mucuri e Paraíba do Sul. Este estudo apresenta dois novos registros da ocorrência de M. macrocephalus, nas bacias dos rios Itapecuru e Mearim, no estado do Maranhão, no nordeste brasileiro. O piaussu é um peixe de grande porte, de interesse comercial, amplamente criado em pisciculturas, e sua ocorrência nos rios Itapecuru e Mearim é provavelmente o resultado de indivíduos que escapam dos tanques quando transbordam durante a estação chuvosa. Análises morfológicas e sequências do gene da subunidade I do citocromo oxidase (COI) confirmaram a identificação taxonômica dos espécimes como M. macrocephalus. As sequências de COI foram 99,66% semelhantes às de M. macrocephalus depositadas no banco de dados BOLDSystems. Esses registros estendem a conhecida distribuição de M. macrocephalus às bacias dos rios Itapecuru e Mearim, no nordeste brasileiro, destacando um novo caso de introdução de espécies exóticas de peixes nas bacias hidrográficas brasileiras.