Renato Matos Lopes

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.

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.

PHARMAVIRTUA: Educational Software for Teaching and Learning Basic Pharmacology.

information and communication technologies have become important tools for teaching scientific subjects such as anatomy and histology as well as other, nondescriptive subjects like physiology and pharmacology ([8][1]–[10][2]). Software has been used to facilitate the learning of specific concepts

Virtual immunology: Software for teaching basic immunology

As immunology continues to evolve, many educational methods have found difficulty in conveying the degree of complexity inherent in its basic principles. Today, the teaching–learning process in such areas has been improved with tools such as educational software. This article introduces “Virtual Immunology,” a software program available free of charge in Portuguese and English, which can be used by teachers and students in physiology, immunology, and cellular biology classes. We discuss the development of the initial two modules: “Organs and Lymphoid Tissues” and “Inflammation” and the use of interactive activities to provide microscopic and macroscopic understanding in immunology. Students, both graduate and undergraduate, were questioned along with university level professors about the quality of the software and intuitiveness of use, facility of navigation, and aesthetic organization using a Likert scale. An overwhelmingly satisfactory result was obtained with both students and immunology teachers. Programs such as “Virtual Immunology” are offering more interactive, multimedia approaches to complex scientific principles that increase student motivation, interest, and comprehension.

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.

Facebook in educational research: a bibliometric analysis

Facebook has become the object of research in different areas. The present study presents a bibliometric analysis of the scientific literature related to the use of this social network in educational research. To this end, bibliometric techniques were applied in the analysis of scientific articles indexed at the Web of Science Core Collection, from Thomson Reuters, and linked to the research areas of Education/Educational Research. This resulted in the identification of, among others, developments in scientific production, the most important journals that publish papers on the topic, the main authors and the main articles published in the area. The results indicate the growth of scientific production in the area from 2008 onwards, pointing to Computers and Education as the most relevant journal by number of publications (22) and impact factor and indicate that authors from the United States, Australia, Taiwan, United Kingdom and South Africa stand out in the construction of knowledge on educational research applying Facebook. Moreover, the ego-network of the Educational Research area shows that this area coexists with other areas of knowledge in the use of social networking, such as Computer Science, Linguistics and Health Sciences, indicating an interdisciplinary and transversal nature in different areas of research.

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 2000s 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.

Aprendizagem Baseada em Casos Investigativos e a Formação de Professores: O Potencial de Uma Aula Prática de Volumetria para Promover o Ensino Interdisciplinar

Investigative Case-Based Learning and Teacher Education: the Use of Volumetry to Promote Interdisciplinary Teaching. The Ministry of Education is employing efforts to restructure the curricula of high school in Brazil, including the Innovative Education Program in High School, which seeks to implement interdisciplinary activities in schools. This paper presents the conceptions of teachers in the area of Natural Sciences of High School of the State of Rio de Janeiro on the potential of a practice of Volumetry, used to determine the acidity of soft drinks and inserted in the application of Problem-Based Learning, to promote interdisciplinary teaching. Our results indicate that the activities developed are able to integrate knowledge from all disciplines that make up the curriculum of high school.

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 utilização de uma história em quadrinhos como estratégia de ensino sobre o uso racional de medicamentos

Este trabalho apresenta a criacao e a avaliacao de uma historia em quadrinhos e um texto paradidatico como recurso educacional para ensino sobre os riscos da automedicacao. Foi utilizado como exemplo um paciente acometido por um quadro de intoxicacao alimentar. O estudo foi realizado com 52 estudantes do Ensino Medio, por meio da aplicacao de questionarios e realizacao de entrevistas semiestruturadas. A metodologia de analise foi qualitativa. Os resultados apontaram que a historia em quadrinhos motivou os participantes do estudo e despertou-lhes grande interesse, em aprender sobre outros assuntos ligados a medicamentos e enfermidades. Os dados obtidos indicaram que a Historia em Quadrinhos e o texto paradidatico contribuiram para o aprendizado dos estudantes sobre os riscos da automedicacao e intoxicacao alimentar.