Teaching and learning pharmacology in Brazil before COVID-19 pandemic: a case study in Rio de Janeiro.

BACKGROUND: Knowledge of pharmacology is crucial for physicians to perform rational and safe medicine. Medical professionals are responsible for prescribing drugs and a weak performace of those can result in medication errors leading to disability, hospitalization, and death, among other situations. It occurs worldwide, including in Brazil, so that learning pharmacology impacts on public health service. We aim to investigate the current pharmacology educational practices in medical schools in the state of Rio de Janeiro, Brazil. METHODS: We surveyed 14 of 22 medical schools in Rio de Janeiro. Pharmacology teachers (n=16) and medical students (n=89) answered a semi-structured questionnaire that included questions about the staff characteristics, pharmacology content, teacher's concepts, and common practices and resources that were used in pharmacology classes. RESULTS: Our results revealed that the medical schools had similar overall curriculums. Pharmacology teachers work more than 30hs a week (75%) and conducted both research and teaching (62.5%). We also found that the multimedia projector was the most common resource (71.9%), and passive pedagogical methodologies (e.g., expository classes) remain a current strategy in pharmacology classes (89.9%). In general, medical students are poorly motivated (55%), which may be related to their performance in assessments. In addition, students believe that pharmacology is a complex (52%) or very complex subject (46%) since for its full understanding the student needs concepts from other disciplines, which can have an impact on the performance and motivation of students. As a result, these medical students do not fully understand the integration between pharmacology's basic concepts and their clinical applications. CONCLUSION: These data seem to demonstrate that the adopted teaching and learning pharmacology strategies and methodologies can be improved in Rio de Janeiro.

The scientific publication of the Memórias do Instituto Oswaldo Cruz (1909-2020): a history of contribution to the biomedical sciences.

BACKGROUND: The Memórias do Instituto Oswaldo Cruz (MIOC) is one of the first scientific journals created in Brazil and currently one of the most important biomedical journals in South America. Knowledge of the main themes disseminated over time and its main contributors can contribute towards a better understanding of its trajectory and future. OBJECTIVES: Map the journal's scientific publication between 1909 and 2020. METHODS: Data from three scientific databases was combined, alongside bibliometrics and network analysis to analyse publication records between 1909 and 2020. FINDINGS: Publications increased substantially since the 1980s. The main publishing organisations are Brazilian. Excluding Brazil, the main publishing countries are the USA, Argentina, and Colombia. During the entire investigated period, the main themes refer to Chagas disease, schistosomiasis, and Leishmaniasis. During some periods, publications followed disease outbreaks in Brazil (e.g., dengue fever and yellow fever). MAIN CONCLUSIONS: Since its foundation in 1909, the MIOC has focused on infectious and parasitic diseases. The editorial changes implemented from the 1980s onwards led MIOC to a relevant growth concerning annual publications and its transformation into an important communication vehicle for researchers from several Brazilian organisations besides Fiocruz, as well as organisations from other countries, especially within Latin America.

A processual view on the use of problem-based learning in high school physiology teaching.

In problem-based learning (PBL), the steps and processes present in the PBL tutorial cycle are essential for constructive, self-directed, collaborative, and contextual student learning. This article presents a procedural study of a PBL tutorial cycle with high school students new to the method regarding human respiration and circulation physiology. We observed group dynamics and the learning process that occurred throughout the PBL tutorial cycle. The results indicate that conceptual changes were close to the planned learning objectives and that students enjoyed studying applying PBL. Moreover, a positive correlation was observed between group dynamics, self-directed learning and learning outcomes. Our results provide grounds for restructuring the tutorial cycle, especially important for novice PBL students, such as problem reformulation and the development and diversification of applied learning scaffolds. We conclude that the qualitative analysis performed herein can yield a deeper understanding of the PBL tutorial cycle and may be used to foster PBL implementation in institutions with little experience with the method and monitor its outcomes in organizations with mature PBL use.

Correct Fish Muscle AChE Extraction for Use in Environmental Risk Assessment and Ecotoxicological Studies Has Been Neglected.

Several articles published in the field of ecotoxicology and environmental risk assessment have failed to adequately use fish muscle cholinesterases as biomarkers. This letter seeks to underline the importance of developing and applying correct protocols for the extraction of these enzymes from the tissues of these animals.

Open educational resources in immunology education.

The use of computers as a pedagogical resource is currently on the rise. In the case of immunology, students present difficulties in visualizing molecular phenomena. Thus the use of animations and simulations available on the internet might facilitate the learning of complex immunological concepts. In this context, it is important to map and assess the currently available resources that may be used for educational purposes. This study comprises the search and analysis of educational immunology software freely available on the internet, which can aid students and health professionals in effective learning and continuing education scenarios. A detailed search in English on the existence of free software was carried out on websites and scientific databases. The results clearly indicate a lack of freely available and scientifically validated immunology educational software, despite the existence of several software programs that could be used as auxiliary teaching tools.

The evolution of environmental metalloproteomics over the last 15 years through bibliometric techniques.

Metalloproteomic studies in environmental scenarios are of significant value in elucidating metal uptake, trafficking, accumulation and metabolism linked to biomolecules in biological systems. The advent of this field occurred in the early 2000s, and it has since become an interesting and growing area of interdisciplinary research, although the number of publications in Environmental Metalloprotemics is still very low compared to other metallomic areas. In this context, the evolution of Environmental Metalloprotemics in the last decades was evaluated herein through the use of bibliometric techniques, identifying variables that may aid researchers in this area to form collaborative networks with established scientists in this regard, such as main authors, published articles, institutions, countries and established collaborations involved in academic research on this subject. Results indicate a growing trend of publications over time, reflecting the interest of the scientific community in Environmental Metalloprotemics, but also demonstrated that the research interactions in this field are still country- and organization-specific. Higher amounts of publications are observed from the late 2000's onwards, related to the increasing technological advances in the area, such as the development of techniques combining atomic spectroscopy and biochemical or proteomic techniques. The retrieved publications also indicate that the recent advances in genomic, proteomic and metallomic areas have allowed for extended applications of Environmental Metalloprotemics in non-model organisms. The results reported herein indicate that Environmental Metalloprotemics seems to now be reaching a more mature stage, in which analytical techniques are now well established and can be routinely applied in environmental scenarios, benefitting researchers and allowing for further insights into this fascinating field.

Effects of sub-lethal and chronic lead concentrations on blood and liver ALA-D activity and hematological parameters in Nile tilapia.

Liver and blood δ-aminolevulinic acid dehydratase (ALA-D) inhibition by exposure to sub-lethal lead concentrations over time in Nile tilapia (Oreochromis niloticus) were investigated. All three lead concentrations (1mgkg(-1), 10mgkg(-1) and 100mgkg(-1)) significantly inhibited ALA-D activity in blood (319±29.2; 180±14.6 and 172±19µmols(-1)h(-1)L(-1) respectively) and liver (302±5.84; 201±41.4 and 93±22.1µmols(-1)h(-1)L(-1)) 24h after injection relative to controls (blood: 597±37.0µmols(-1)h(-1)L(-1); liver: 376±23.1µmols(-1)h(-1)L(-1)). Blood ALA-D was greatly inhibited in all but the highest lead dose. Fish were then exposed to 1mgkg(-1) lead for 9 days, and presented short-term hyperglycemia, decreased hemoglobin and hematocrit values and time-dependent blood ALA-D activity inhibition, corroborating blood ALA-D activity as being more suitable for investigating lead effects, showing dose and time-dependent ALA-D inhibition after lead exposure. The results of the present study also demonstrated that fish size affects blood ALA-D activity, as fish from the 24-h assay, which were slightly smaller (approximately 200g), showed higher ALA-D inhibition in response to lead exposure when compared to the fish from the 9-day assay (approximately 500g). Thus, fish size should always be taken into account both in the field and in laboratory settings, and efforts should be made to obtain uniform fish size samples for biomarker studies.

Problem-Based Learning in Medical Education: A Global Research Landscape of the Last Ten Years (2013-2022).

Background: Problem-based learning (PBL) constructs a curriculum that merges theory and practice by employing clinical scenarios or real-world problems. Originally designed for the pre-clinical phase of undergraduate medicine, PBL has since been integrated into diverse aspects of medical education. Therefore, this study aims to map the global scientific landscape related to PBL in medical education in the last ten years. Methods: We combined bibliometrics and network analysis to analyze the metadata of related research articles published between 2013 and 2022 and indexed in the Web of Science Core Collection. Results: Our results show an annual publication rate of 9.42%. The two main journals disseminating research on this subject are BMC Medical Education and Medical Teacher. Education & Educational Research and Health Care Sciences & Services are the two most frequent research areas, and also the two most central nodes of the related network. The USA and China are the most publishing countries, while the Netherlands and Canada are the most collaborative. The Maastricht University holds the position of most publishing and collaborative research organization. The University of California ranks second in publications, while the University of Toronto is the second most central research organization. Conclusions: Our study provides an overview of the last ten years of publications related to PBL and medical education, and we hope it can be of interest to educators, researchers, and students involved with this subject. Supplementary Information: The online version contains supplementary material available at 10.1007/s40670-024-02003-1.

Principles of problem-based learning for training and professional practice in ecotoxicology.

Problem-based learning (PBL) is a protagonist of constructivism widely used successfully in higher education. PBL is a learner-centered instructional and curricular approach that can use real problems for the development of the teaching and learning process. On the other hand, the complexity of knowledge of Ecotoxicology, as well as the importance of this field for Environmental Health and society demand reflections and proposals for the training of professionals who work in this field. Therefore, in accordance with the principles of PBL, this strategy can effectively contribute to the training and professional practice of ecotoxicologists. We report herein the importance of the principles of PBL for the training of ecotoxicologists, including the discussion of a case study using fish biomarkers for the development of this teaching strategy. Teaching ecotoxicology through PBL principles allowed students to develop several advantages for Ecotoxicology training through the discussion of an authentic, real life problem that engaged them in its discussion, functioning as a stimulus for learning. The students were able to develop laboratory skills, group work competences, understand basic concepts and fundamentals of Ecotoxicology and become empowered regarding skills and competences for future practice.

Conexões históricas entre as políticas de rastreamento do câncer de colo do útero e a educação profissional em citopatologia no Brasil / Historical connections between cervical cancer screening policies and professional education in cytopathology in Brazil / Conexiones históricas entre las políticas de rastreo del cáncer de cuello uterino y la formación profesional en citopatología en Brasil

Resumo Os técnicos em citopatologia são fundamentais para o rastreamento do câncer de colo do útero, porém existem lacunas na sua formação. Nesta revisão de literatura, com abordagem qualitativa, realizada na Biblioteca Virtual em Saúde e na SciELO, sem recorte temporal, descrevemos o histórico das políticas públicas de combate ao câncer de colo de útero, relacionando-o à história da educação profissional técnica em citopatologia, analisando as conexões entre tais sequências de eventos. Numa perspectiva histórica, a educação profissional em anatomia patológica se deu principalmente pela formação em serviço, porém o campo da formação técnica em citopatologia destoa desse modelo. Esforços diversos para estruturar os currículos na área e reduzir as discrepâncias nessa formação foram realizados. Contudo, disputas entre interesses político-econômicos, marcando a divisão técnica do trabalho no país, somadas a embates corporativos no trabalho em citopatologia, e o descompasso entre ações de educação e de rastreamento impediram a materialização efetiva desses esforços. A demanda pela incorporação de novas tecnologias acentua ainda mais a fragilidade na formação da categoria. Somente com ações governamentais concretas de formação e de regulamentação profissional será possível transformar esse cenário, favorecendo o desenvolvimento e a ampliação das campanhas de detecção precoce do câncer.

Abstract Cytopathology technicians are fundamental for cervical cancer screening, but there are gaps in their training. In this literature review, with a qualitative approach, carried out in the Virtual Health Library and in SciELO, without temporal clipping, we describe the history of public policies to combat cervical cancer, relating it to the history of technical professional education in cytopathology, analyzing the connections between such sequences of events. In a historical perspective, professional education in pathological anatomy was mainly through in-service training, but the field of technical training in cytopathology differs from this model. Various efforts have been made to structure curricula in the area and reduce discrepancies in this training. However, disputes between political and economic interests, marking the technical division of labor in the country, added to corporate clashes in the work on cytopathology, and the mismatch between education and screening actions prevented the effective materialization of these efforts. The demand for the incorporation of new technologies further accentuates the fragility in the formation of the category. Only with concrete government actions of training and professional regulation will it be possible to transform this scenario, favoring the development and expansion of campaigns for early detection of cancer in Brazil.

Resumen Los técnicos en citopatología son fundamentales para el rastreo del cáncer de cuello uterino, pero existen lagunas en su formación. En esta revisión bibliográfica, con abordaje cualitativo, realizada en la Biblioteca Virtual en Salud y en SciELO, sin marco temporal, se describe la historia de las políticas públicas de combate al cáncer de cuello uterino, relacionándola con la historia de la formación técnico-profesional en citopatología, analizando las conexiones entre tales secuencias de eventos. Desde una perspectiva histórica, la formación profesional en anatomía patológica se basó principalmente en la formación en servicio, pero el campo de la formación técnica en citopatología difiere de este modelo. Se han hecho varios esfuerzos para estructurar los planes de estudio en el área y reducir las discrepancias en esta formación. Sin embargo, las disputas entre intereses políticos y económicos, que marcan la división técnica del trabajo en el país, sumadas a los enfrentamientos empresariales en el trabajo de citopatología, y la discrepancia entre las acciones de educación y de rastreo impidieron la materialización efectiva de estos esfuerzos. La demanda por la incorporación de nuevas tecnologías acentúa aún más la fragilidad en la formación de la categoría. Solo con acciones gubernamentales concretas de capacitación y regulación profesional será posible transformar este escenario, favoreciendo el desarrollo y la expansión de las campañas de detección temprana del cáncer en Brasil.

Conexões históricas entre as políticas de rastreamento do câncer de colo do útero e a educação profissional em citopatologia no Brasil / Historical connections between cervical cancer screening policies and professional education in cytopathology in Brazil

Os técnicos em citopatologia são fundamentais para o rastreamento do câncer de colo do útero, porém existem lacunas na sua formação. Nesta revisão de literatura, com abordagem qualitativa, realizada na Biblioteca Virtual em Saúde e na SciELO, sem recorte temporal, descrevemos o histórico das políticas públicas de combate ao câncer de colo de útero, relacionando-o à história da educação profissional técnica em citopatologia, analisando as conexões entre tais sequências de eventos. Numa perspectiva histórica, a educação profissional em anatomia patológica se deu principalmente pela formação em serviço, porém o campo da formação técnica em citopatologia destoa desse modelo. Esforços diversos para estruturar os currículos na área e reduzir as discrepâncias nessa formação foram realizados. Contudo, disputas entre interesses político-econômicos, marcando a divisão técnica do trabalho no país, somadas a embates corporativos no trabalho em citopatologia, e o descompasso entre ações de educação e de rastreamento impediram a materialização efetiva desses esforços. A demanda pela incorporação de novas tecnologias acentua ainda mais a fragilidade na formação da categoria. Somente com ações governamentais concretas de formação e de regulamentação profissional será possível transformar esse cenário, favorecendo o desenvolvimento e a ampliação das campanhas de detecção precoce do câncer.

The importance of an efficient extraction protocol for the use of fish muscle cholinesterases as biomarkers.

Esterase activity found in muscle extracts is useful to evaluate harmful effects of anticholinesterase pollutants. Yet, most procedures applied in the extraction of fish muscle esterases in order to investigate their activity as a biomarker of environmental exposure comprise the homogenization of muscle tissue in low-salt solutions, followed by centrifugation to separate the supernatant as the enzyme source. However, acetylcholinesterase (AChE), the main target in these monitoring efforts, is a membrane-bound protein and is only present in muscle extracts if homogenization is carried out using chaotropic high-salt solutions. In this context, four extraction procedures using muscle tissue from six fish species were evaluated in order to establish a reproducible and reliable AChE assay for the determination of this biomarker. Results indicate that over 80% of AChE activity might be lacking in low-salt supernatants, and that the highest activities are obtained after extraction with solutions containing either 1molL-1 NaCl or 1molL-1 NaCl plus 3% Triton X-100, preserving almost 100% esterase activity over acetylthiocholine as substrate after centrifugation. Thus, many studies in the literature suffer from theoretical flaws and report erroneous AChE activity, since typical muscle AChE activity, the end-point biomarker for anticholinesterase pollutants, may have not been consistently assayed.

A Educação permanente em Saúde e as aprendizagens de Agentes comunitários de saúde para o enfrentamento à Pandemia de Covid-19: uma experiência no interior do BrasiL. / Permanent Health Education and the learning of Community Health Agents to face the COVID-19 Pandemic: an Experience in the Interior of Brazil.

O Agente Comunitário de Saúde (ACS) é um profissional inserido em equipes multidisciplinares do Sistema Único de Saúde (SUS) e que atua na linha de frente no combate ao Sars-Cov-02, causador da Covid-19. O artigo busca evidências da educação não formal de ACS ao analisar um recorte da produção brasileira de março a julho de 2020 voltada para o ensino e o enfrentamento ao novo coronavírus e traz resultados emergentes de rodas de conversa com ACS em Unidades de Saúde de uma pequena cidade do interior do Brasil, buscando elos entre a produção investigada e possíveis aprendizagens adquiridas por esses profissionais na transpandemia. Os resultados evidenciaram a educação não formal dos ACS e importantes legados dessa educação para suas práticas comunitárias em saúde.

The scientific publication of the Memórias do Instituto Oswaldo Cruz (1909-2020): a history of contribution to the biomedical sciences

BACKGROUND The Memórias do Instituto Oswaldo Cruz (MIOC) is one of the first scientific journals created in Brazil and currently one of the most important biomedical journals in South America. Knowledge of the main themes disseminated over time and its main contributors can contribute towards a better understanding of its trajectory and future. OBJECTIVES Map the journal's scientific publication between 1909 and 2020. METHODS Data from three scientific databases was combined, alongside bibliometrics and network analysis to analyse publication records between 1909 and 2020. FINDINGS Publications increased substantially since the 1980s. The main publishing organisations are Brazilian. Excluding Brazil, the main publishing countries are the USA, Argentina, and Colombia. During the entire investigated period, the main themes refer to Chagas disease, schistosomiasis, and Leishmaniasis. During some periods, publications followed disease outbreaks in Brazil (e.g., dengue fever and yellow fever). MAIN CONCLUSIONS Since its foundation in 1909, the MIOC has focused on infectious and parasitic diseases. The editorial changes implemented from the 1980s onwards led MIOC to a relevant growth concerning annual publications and its transformation into an important communication vehicle for researchers from several Brazilian organisations besides Fiocruz, as well as organisations from other countries, especially within Latin America.

Histology for the visually impaired: a study applying models at universities in spain and Brazil / Histología para discapacitados visuales: un estudio aplicando modelos en universidades de españa y Brasil

SUMMARY: This study aimed to develop models that reproduce histological slide images and evaluate them with blind and sighted students from an inclusion perspective. A questionnaire with questions about the ideal characteristics of a model was answered by visually impaired (VI) students. Based on the responses and optical microscopy images from histological atlases, nine models were constructed with standardized materials. The models were tested at different times with VI students and with students who see. Our results indicate that morphology teaching, according to the students themselves, should make use of extra resources, such as models. The ideal characteristics for model efficiency as a teaching tool were representative textures and reliefs. The models built were evaluated by blind students in Spain and sighted students in Brazil because, from an inclusive perspective, it is ideal that the same material can meet the demands of all types of students. The use of the developed models enhanced learning in both groups, even when combined with microscopes for sighted students. According to student opinions, the use of relief models can represent an important pedagogical strategy used to teach morphological. The importance of developing that materials was also highlighted from an inclusion perspective, as these materials can be used in mixed classes, all students together, in cooperative learning. This study aids morphological subject teachers who teach visually impaired students to know where to start on the path to an inclusive and pedagogically coherent learning process.

RESUMEN: Este estudio tuvo como objetivo desarrollar modelos que reproduzcan imágenes histológicas de diapositivas y las evalúen con estudiantes ciegos y videntes desde una perspectiva de inclusión. Los estudiantes no videntes respondieron un cuestionario con preguntas sobre las características ideales de un modelo. En base a las respuestas y las imágenes de microscopía óptica de los atlas histológicos, se construyeron nueve modelos con materiales estandarizados. Los modelos fueron probados en diferentes momentos con estudiantes no videntes y con estudiantes videntes. Nuestros resultados indican que en la enseñanza de la morfología, según los propios estudiantes, se debe hacer uso de recursos adicionales tal como los modelos. Las características ideales para la eficiencia del modelo como herramienta de enseñanza fueron las texturas y relieves representativos. Los modelos construidos fueron evaluados por estudiantes ciegos en España y estudiantes videntes en Brasil. Desde una perspectiva inclusiva, es ideal que un mismo material pueda satisfacer las demandas de todo tipo de estudiantes. El uso de los modelos desarrollados mejoró el aprendizaje en ambos grupos, incluso cuando se combinó con microscopios para estudiantes videntes. Según las opiniones de los estudiantes, el uso de modelos en relieve puede representar una importante estrategia pedagógica utilizada en la enseñanza de la morfología. También se destacó la importancia de desarrollar esos materiales desde una perspectiva de inclusión, ya que estos materiales pueden ser utilizados en clases mixtas, todos los estudiantes juntos, en aprendizaje cooperativo. Este estudio ayuda a los profesores de asignaturas morfológicas que enseñan a los estudiantes con discapacidad visual a conocer la vía hacia un proceso de aprendizaje inclusivo y pedagógicamente coherente.

Bioconcentration and Acute Intoxication of Brazilian Freshwater Fishes by the Methyl Parathion Organophosphate Pesticide.

Three species of freshwater Brazilian fishes (pacu, Piaractus mesopotamicus; piavussu, Leporinus macrocephalus, and curimbatá, Prochilodus lineatus) were exposed to an acute dose of 5 ppm methyl parathion organophosphate pesticide. Three to five individuals per species were exposed, one at a time, to 40 liters tap water spiked with Folidol 600. Pesticide concentrations and cholinesterase (ChE) activities were evaluated in serum, liver, brain, heart, and muscle. The bioconcentration of methyl parathion was similar for all studied fishes. Brain tissue showed the highest pesticide concentration, reaching 80 ppm after exposure for 30 min to methyl parathion. Three to 5 hours of 5 ppm methyl parathion exposure provoked the death of all P. lineatus at 92% brain AChE inhibition, whereas fish from the other two species survived for up to 78 hours with less than 80% brain AChE inhibition. Our results indicate that acute toxic effects of methyl parathion to fish are correlated with brain AChE sensitivity to methyl paraoxon.

An Artemia franciscana bioassay for the monitoring of lipophilic phycotoxins in marine bivalve mollusc cultures: An alternative to screening testing? / Bioensaios com Artemia franciscana para monitoramento de ficotoxinas lipofílicas em cultivo de moluscos bivalves marinhos: Uma alternativa para teste de alarme?

No Brasil, a malacocultura é desenvolvida principalmente no estado de Santa Catarina, seguida por São Paulo e Rio de Janeiro. No curso do desenvolvimento das atividades da maricultura brasileira, a legislação se adaptou aos requisitos sanitários necessários à comercialização de bivalves. No entanto, o monitoramento de ficotoxinas é um desafio, devido a métodos de referência frequentemente caros. Nesse contexto, o objetivo deste estudo foi avaliar o uso de métodos ecotoxicológicos e bioanalíticos alternativos usando a Artemia franciscana (artemia). Os resultados confirmam que, embora as correlações entre o ensaio de referência em camundongos e os ensaios com artemia não sejam altas, o ensaio alternativo com artemia pode ser incorporado aos programas de monitoramento de ficotoxinas, pois os extratos metanólicos do hepatopâncreas de mexilhões (Perna perna) contendo DSP resultaram em altas taxas de letalidade. Portanto, estudos adicionais de ajustes metodológicos e a inclusão de outros modelos enzimáticos e toxicológicos são necessários para avaliar essas diferenças, e são encorajadas associações entre métodos ecotoxicológicos como métodos de alarme precoce.

Comparative study on the susceptibility of freshwater species to copper-based pesticides.

Copper compounds have been intentionally introduced into water bodies as aquatic plant herbicides, algicides and molluscicides. Copper-based fertilizers and fungicides have been widely used in agriculture as well. Despite the fact that copper is an essential element for all biota, elevated concentrations of this metal have been shown to affect a variety of aquatic organisms. Nonetheless, comparative studies on the susceptibility of different freshwater species to copper compounds have seldom been performed. This study was conducted to compare toxicity of copper-based pesticides (copper oxychloride, cuprous oxide and copper sulfate) to different freshwater target (Raphidocelis subcapitata, a planktonic alga and Biomphalaria glabrata, a snail) and non-target (Daphnia similis, a planktonic crustacean and Danio rerio, a fish) organisms. Test water parameters were as follows: pH = 7.4 +/- 0.1; hardness 44 +/- 1 mg/l as CaCO3; DO 8-9 mg/l at the beginning and > 4 mg/l at the end; temperature, fish and snails 25 +/- 1 degrees C, Daphnia 20 +/- 2 degrees C, algae 24 +/- 1 degrees C. D. similis (immobilization), 48-h EC50s (95% CLs) ranging from 0.013 (0.011-0.016) to 0.043 (0.033-0.057) mg Cu/l, and R. subcapitata (growth inhibition), 96-h IC50s from 0.071 (0.045-0.099) to 0.137 (0.090-0.174) mg Cu/l, were the most susceptible species. B. glabrata (lethality), 48-h LC50s from 0.179 (0.102-0.270) to 0.854 (0.553-1.457) mg Cu/l, and D. rerio (lethality), 48-h LC50s 0.063 (0.045-0.089), 0.192 (0.133-0.272) and 0.714 (0.494-1.016) mg Cu/l, were less susceptible than Daphnia to copper-based pesticides. Findings from the present study therefore suggest that increased levels of copper in water bodies is likely to adversely affect a variety of aquatic species.

Cholinesterase activity of muscle tissue from freshwater fishes: characterization and sensitivity analysis to the organophosphate methyl-paraoxon.

The biochemical characterization of cholinesterases (ChE) from different teleost species has been a critical step in ensuring the proper use of ChE activity levels as biomarkers in environmental monitoring programs. In the present study, ChE from Oreochromis niloticus, Piaractus mesopotamicus, Leporinus macrocephalus, and Prochilodus lineatus was biochemically characterized by specific substrates and inhibitors. Moreover, muscle tissue ChE sensitivity to the organophosphate pesticide methyl-paraoxon was evaluated by determining the inhibition kinetic constants for its progressive irreversible inhibition by methyl-paraoxon as well as the 50% inhibitory concentration (IC50) for 30 min for each species. The present results indicate that acetylcholinesterase (AChE) must be present in the muscle from P. mesopotamicus, L. macrocephalus, and P. lineatus and that O. niloticus possesses an atypical cholinesterase or AChE and butyrylcholinesterase (BChE). Furthermore, there is a large difference regarding the sensitivity of these enzymes to methyl-paraoxon. The determined IC50 values for 30 min were 70 nM (O. niloticus), 258 nM (P. lineatus), 319 nM (L. macrocephalus), and 1578 nM (P. mesopotamicus). The results of the present study also indicate that the use of efficient methods for extracting these enzymes, their kinetic characterization, and determination of sensitivity differences between AChE and BChE to organophosphate compounds are essential for the determination of accurate ChE activity levels for environmental monitoring programs.