Assessing the reaction to and efficacy of the Screener drug discovery and development board game as a pedagogical tool in postgraduate courses.

Screener, a board game supplemented with online resources, was introduced and distributed by the Brazilian Society of Pharmacology and Experimental Therapeutics to postgraduate programs as an instructional tool for the process of drug discovery and development (DDD). In this study, we provided a comprehensive analysis of five critical aspects for evaluating the quality of educational games, namely: 1) description of the intervention; 2) underlying pedagogical theory; 3) identification of local educational gaps; 4) impact on diverse stakeholders; and 5) elucidation of iterative quality enhancement processes. We also present qualitative and quantitative assessments of the effectiveness of this game in 11 postgraduate courses. We employed the MEEGA+ online survey, comprising thirty-three close-ended unipolar items with 5-point Likert-type response scales, to assess student perceptions of the quality and utility of Screener. Based on 115 responses, the results indicated a highly positive outlook among students. In addition, we performed a preliminary evaluation of learning outcomes in two courses involving 28 students. Pre- and post-quizzes were applied, each consisting of 20 True/False questions directly aligned with the game's content. The analysis revealed significant improvement in students' performance following engagement with the game, with scores rising from 8.4 to 13.3 (P<0.0001, paired t-test) and 9.7 to 12.7 (P<0.0001, paired t-test). These findings underscore the utility of Screener as an enjoyable and effective tool for facilitating a positive learning experience in the DDD process. Notably, the game can also reduce the educational disparities across different regions of our continental country.

Assessing the reaction to and efficacy of the Screener drug discovery and development board game as a pedagogical tool in postgraduate courses

Screener, a board game supplemented with online resources, was introduced and distributed by the Brazilian Society of Pharmacology and Experimental Therapeutics to postgraduate programs as an instructional tool for the process of drug discovery and development (DDD). In this study, we provided a comprehensive analysis of five critical aspects for evaluating the quality of educational games, namely: 1) description of the intervention; 2) underlying pedagogical theory; 3) identification of local educational gaps; 4) impact on diverse stakeholders; and 5) elucidation of iterative quality enhancement processes. We also present qualitative and quantitative assessments of the effectiveness of this game in 11 postgraduate courses. We employed the MEEGA+ online survey, comprising thirty-three close-ended unipolar items with 5-point Likert-type response scales, to assess student perceptions of the quality and utility of Screener. Based on 115 responses, the results indicated a highly positive outlook among students. In addition, we performed a preliminary evaluation of learning outcomes in two courses involving 28 students. Pre- and post-quizzes were applied, each consisting of 20 True/False questions directly aligned with the game's content. The analysis revealed significant improvement in students' performance following engagement with the game, with scores rising from 8.4 to 13.3 (P<0.0001, paired t-test) and 9.7 to 12.7 (P<0.0001, paired t-test). These findings underscore the utility of Screener as an enjoyable and effective tool for facilitating a positive learning experience in the DDD process. Notably, the game can also reduce the educational disparities across different regions of our continental country.

Flavonoids from the Amazon plant Brosimum acutifolium induce C6 glioma cell line apoptosis by disrupting mitochondrial membrane potential and reducing AKT phosphorylation.

Glioblastoma, which is highly invasive and has a poor patient prognosis, is the most common type of brain tumor. Flavonoids have known antiproliferative and antineoplastic effects, such as apoptosis induction and tumor growth inhibition. We investigated the effects of treatment with three flavonoids (BAS-1, BAS-4, and BAS-6) isolated from the Amazon plant Brosimum acutifolium on the proliferation and migration of the C6 glioma cell line. Cytotoxicity was evaluated by MTT assay, and morphological changes were evaluated by phase-contrast microscopy and by transmission electron microscopy. Apoptosis was determined using Annexin V-FITC-propidium iodide (PI) staining. A hemolysis assay was used to evaluate plasma membrane injury. Antiproliferative effects were assessed by wound migration and colony formation assays. Mitochondrial transmembrane potential (ΔΨm) was determined using JC-1 dye and flow cytometry. To identify the flavonoid targets, western blotting was performed. BAS-1 and BAS-4 reduced C6 cell proliferation in a dose-dependent manner. BAS-6 showed no effect. Due to its high toxicity toward primary glial cells and its high hemolytic index, BAS-1 was not used in the remaining experiments. BAS-4 treatment did not induce cytotoxicity in primary glial cells; however, in glioma cells, it suppressed migration and invasion and led to apoptosis through mitochondrial damage, ΔΨm loss, cell cycle arrest, and reduced AKT phosphorylation, which is a component of the main cell survival pathway. We conclude that BAS-4 showed potential activity against glioma by inducing apoptosis mediated by ΔΨm loss and AKT pathway disruption, and future studies should further evaluate BAS-4 as a promising antineoplastic agent against glioblastoma.

Apolipoprotein E, periodontal disease and the risk for atherosclerosis: a review.

The association between cardiovascular and periodontal diseases is characterized by chronic inflammatory processes, with a high prevalence worldwide and complex genetic-environment interactions. Although apolipoprotein E4 (ApoE4), one of the isoforms coded by a polymorphic APOE gene, has been widely recognized as a risk factor for cardiovascular diseases and as an immunoinflammatory factor, less is known regarding how ApoE4 affects atherosclerosis in periodontitis patients. The aim of this review was to investigate the potential underlying mechanisms related to APOE4 that could increase the risk of periodontal disease and, ultimately, of atherosclerosis. There have only been a few studies addressing apoE polymorphisms in patients with chronic periodontitis. To date, no studies have been performed that have assessed how ApoE4 affects atherosclerotic disease in chronic periodontitis patients. Although clinical studies are warranted, experimental studies have consistently documented the presence of periodontal pathogens, which are usually found in the oral cavity and saliva, in the atherosclerotic plaques of ApoE-deficient mice. In addition, in this review, the potential role of the APOE4 allele as an example of antagonistic pleiotropy during human evolution and its relation to oral health is discussed.

Chronic exposure to inorganic mercury induces biochemical and morphological changes in the salivary glands of rats.

Mercury exposure is considered to be a public health problem due to the generation of toxic effects on human health as a result of environmental and occupational conditions. The inorganic form of mercury (HgCl2) can cause several biological changes in cells and tissues through its cumulative toxic potential, but little has been experimentally proven about the effects of inorganic mercury on salivary glands, an important modulator organ of oral health. This study analyzes the effects of prolonged low dose exposure to HgCl2 on the salivary glands of rats. Adult animals received a dose of 0.375 mg kg-1 day-1 over a period of 45 days. The parotid and submandibular glands were collected for analysis of the mercury levels and evaluation of oxidative stress, histological parameters and immunomodulation for metallothionein I and II (MT-I/II). In this investigation, biochemical and tissue changes in the salivary glands were verified due to the mercury levels, causing reduction in antioxidant capacity against peroxyl radicals, with consequent cellular lipid peroxidation and an increase in nitrite levels, volumetric changes and cytoskeletal damage in the submandibular glands, with less severe damage to the parotid glands. The results also have shown the occurrence of a cytoprotection mechanism due to increased MT-I/II expression, but not enough to avoid the morphology and oxidative damage. This evidence highlights, for the first time, that inorganic mercury is able to alter the morphology and oxidative biochemistry in salivary glands when exposed for a long time in low doses.

Methylmercury inhibits prolactin release in a cell line of pituitary origin.

Heavy metals, such as methylmercury, are key environmental pollutants that easily reach human beings by bioaccumulation through the food chain. Several reports have demonstrated that endocrine organs, and especially the pituitary gland, are potential targets for mercury accumulation; however, the effects on the regulation of hormonal release are unclear. It has been suggested that serum prolactin could represent a biomarker of heavy metal exposure. The aim of this study was to evaluate the effect of methylmercury on prolactin release and the role of the nitrergic system using prolactin secretory cells (the mammosomatotroph cell line, GH3B6). Exposure to methylmercury (0-100 µM) was cytotoxic in a time- and concentration-dependent manner, with an LC50 higher than described for cells of neuronal origin, suggesting GH3B6 cells have a relative resistance. Methylmercury (at exposures as low as 1 µM for 2 h) also decreased prolactin release. Interestingly, inhibition of nitric oxide synthase by N-nitro-L-arginine completely prevented the decrease in prolactin release without acute neurotoxic effects of methylmercury. These data indicate that the decrease in prolactin production occurs via activation of the nitrergic system and is an early effect of methylmercury in cells of pituitary origin.

Therapeutic concentration of morphine reduces oxidative stress in glioma cell line

Morphine is a potent analgesic opioid used extensively for pain treatment. During the last decade, global consumption grew more than 4-fold. However, molecular mechanisms elicited by morphine are not totally understood. Thus, a growing literature indicates that there are additional actions to the analgesic effect. Previous studies about morphine and oxidative stress are controversial and used concentrations outside the range of clinical practice. Therefore, in this study, we hypothesized that a therapeutic concentration of morphine (1 μM) would show a protective effect in a traditional model of oxidative stress. We exposed the C6 glioma cell line to hydrogen peroxide (H2O2) and/or morphine for 24 h and evaluated cell viability, lipid peroxidation, and levels of sulfhydryl groups (an indicator of the redox state of the cell). Morphine did not prevent the decrease in cell viability provoked by H2O2 but partially prevented lipid peroxidation caused by 0.0025% H2O2 (a concentration allowing more than 90% cell viability). Interestingly, this opioid did not alter the increased levels of sulfhydryl groups produced by exposure to 0.0025% H2O2, opening the possibility that alternative molecular mechanisms (a direct scavenging activity or the inhibition of NAPDH oxidase) may explain the protective effect registered in the lipid peroxidation assay. Our results demonstrate, for the first time, that morphine in usual analgesic doses may contribute to minimizing oxidative stress in cells of glial origin. This study supports the importance of employing concentrations similar to those used in clinical practice for a better approximation between experimental models and the clinical setting.

Therapeutic concentration of morphine reduces oxidative stress in glioma cell line.

Morphine is a potent analgesic opioid used extensively for pain treatment. During the last decade, global consumption grew more than 4-fold. However, molecular mechanisms elicited by morphine are not totally understood. Thus, a growing literature indicates that there are additional actions to the analgesic effect. Previous studies about morphine and oxidative stress are controversial and used concentrations outside the range of clinical practice. Therefore, in this study, we hypothesized that a therapeutic concentration of morphine (1 µM) would show a protective effect in a traditional model of oxidative stress. We exposed the C6 glioma cell line to hydrogen peroxide (H2O2) and/or morphine for 24 h and evaluated cell viability, lipid peroxidation, and levels of sulfhydryl groups (an indicator of the redox state of the cell). Morphine did not prevent the decrease in cell viability provoked by H2O2 but partially prevented lipid peroxidation caused by 0.0025% H2O2 (a concentration allowing more than 90% cell viability). Interestingly, this opioid did not alter the increased levels of sulfhydryl groups produced by exposure to 0.0025% H2O2, opening the possibility that alternative molecular mechanisms (a direct scavenging activity or the inhibition of NAPDH oxidase) may explain the protective effect registered in the lipid peroxidation assay. Our results demonstrate, for the first time, that morphine in usual analgesic doses may contribute to minimizing oxidative stress in cells of glial origin. This study supports the importance of employing concentrations similar to those used in clinical practice for a better approximation between experimental models and the clinical setting.

Comparative study of mercury speciation in commercial fishes of the Brazilian Amazon.

Mercury is responsible for serious episodes of environmental pollution throughout the world, especially in the Amazon. This toxicity has led regulatory agencies to focus on fish as the target organism for protecting the health of humans and other sensitive organisms. Unfortunately, in the Amazon area, different sampling strategies and the wide variety of sampling areas and fish species make it extremely difficult to determine relationships across geographic regions or over time to ascertain historical trends. Thus, the aim of this work was to achieve three main objectives: a comparative study of mercury contamination in fish of Itaituba (Tapajós, located downstream of the largest gold-mining region in Amazon) and Belém (an area non-exposed to mercury pollution of anthropogenic origin), perform an analysis of inorganic mercury (IHg) versus monomethylmercury (MeHg) contents, and, finally, compare mercury contamination in Tapajós over time. Five piscivorous species were obtained in Itaituba and Belém. Also, four non-piscivorous species were collected in Itaituba. For the first time, mercury speciation showed that (1) current MeHg levels in piscivorous species in Tapajós are higher than those of the non-exposed area, (2) piscivorous species from Itaituba (dourada, filhote, and sarda) contained mercury levels above the World Health Organization safety limit (~17%) and/or above the US Environmental Protection Agency tissue residue criterion (40%), (3) increased MeHg is usually accompanied by increased IHg, and (4) the mean total mercury concentrations for piscivorous species in Itaituba were within the same range and, associated uncertainties as those previously reported, although a remarkable decreasing trend over time was observed for mean total Hg concentrations in non-piscivorous species from Itaituba. The present study supports the importance of continuous monitoring of both populations in the Amazon Rivers. Our results will better assist the development of preventive strategies and governmental actions to confront the problem of mercury contamination in the Amazon.

Glutamate induces glutathione efflux mediated by glutamate/aspartate transporter in retinal cell cultures.

This study was undertaken in order to characterize the role of the glutamate/aspartate transporter (GLAST) in the glutathione (GSH) efflux induced by glutamate. Our results demonstrated that retinal cell cultures exhibit two mechanisms of GSH release, one Na(+)-independent and other Na(+)-dependent. Glutamate and aspartate induced GSH efflux only in presence of Na(+). Treatment with PCD (L-trans-Pyrrolidine-2,4-dicarboxylate), a transportable glutamate uptake blocker, increased GSH release indicating that GSH can be carried by glutamate transporters in retinal cell cultures. Added to this, treatment with zinc ion cultures, a recognized inhibitor of GLAST blocked GSH efflux evoked by glutamate. Treatment with NMDA antagonist (MK-801) did not have any effect on the GSH release induced by glutamate. These results suggest that glutamate induces GLAST-mediated release of GSH from retinal cell cultures and this could represent an important mechanism of cellular protection against glutamate toxicity in the CNS.

Mercury in the Tapajós River basin, Brazilian Amazon: a review.

This paper presents a review about mercury contamination and human exposure in the Tapajós River basin (Brazil), one of the major tributaries of the Amazon impacted by traditional gold mining from the mid 1980s. The most recent review in this region was published more than ten years ago and since then many articles about environment and especially human populations have revealed new aspects of mercury toxicology. Additionally, new biomarkers of mercury exposure and toxicity have been studied in these populations. However, there are still many open, about both mercury's biogeochemical cycle and mercury health risks. Further environmental and human risk research directions are proposed.

Mercury exposure and antioxidant defenses in women: a comparative study in the Amazon.

Mercury is a hazardous metal that has become an important issue of environmental contamination in Amazon areas. Human intoxication by mercury causes sensory deficits, motor dysfunction, delayed psychomotor development, genotoxicity, and several other health problems. One of the major cellular mechanisms of mercury toxicity is the oxidative stress which may lead to membrane peroxidation and generation of reactive oxygen species. The antioxidant defense, which includes scavenger compounds such as glutathione and antioxidant enzymes such as catalase, might prevent these injuries to occur. Thus, the objective of this work was to evaluate hair mercury levels and the strength of antioxidant defenses, evaluated by glutathione levels and catalase activity in the blood of exposed and non-exposed women living in Amazon populations. For each location, no statistically significant difference (P<0.05) was detected for age versus mercury content. However, women from populations under the influence of gold mining activity exhibit high mercury levels in hair samples, above the tolerance limit accepted by the World Health Organization. In addition, a significant correlation was found between high mercury content, high glutathione level, and lower catalase activity. These data suggest that chronic mercury intoxication may deplete antioxidant enzymatic activity, which can be used as an important peripheral marker. Knowledge originated by this monitoring will better assist the development of preventive strategies and governmental actions against the problem of mercury contamination.

Mercury pollution and childhood in Amazon riverside villages.

Mercury is a hazardous metal responsible for environmental contamination and human intoxication. Methylmercury, a very toxic organic compound, bio-accumulates through food chain, and is responsible for chronic mercury exposure of riverside Amazonian communities with a diet rich in fish. Uncertainties about the reference exposure dose that could have damaging consequences for nervous system development makes necessary the biomonitoring of these Amazonian populations, especially children. In this work, a comparative study was performed in exposed and non-exposed children living in the Amazon. A total of 168 children were analyzed to find possible correlations between gender, age, location, and hair mercury content. For each location, no statistically significant differences (P<0.05) were detected for gender and age versus mercury content. However, mean mercury levels in hair samples may indicate a tendency of boys to average higher hair concentrations. Also, in the community with highest levels of mercury, the limit of 10 micro g/g of mercury was surpassed by 65% of 2-6 years and 50% of 7-12 years children but only by 27% of 0-1 year babies, pointing to a lower bioaccumulation and/or the existence of a protection mechanism in babies. Log normal distributions of mercury concentrations for each location showed that children from populations under influence of gold mining activity contain the highest mercury levels in hair samples, though this intoxication may have decreased when compared to previous studies. Knowledge originated by this monitoring will better assist in the development of prevention strategies and government actions targeting the mercury contamination of Amazonian environment.

Comparative study of human exposure to mercury in riverside communities in the Amazon region

Four populations in the Amazon area were selected for a comparative study of mercury-exposed and non-exposed populations: São Luiz do Tapajós, Barreiras, Panacauera, and Pindobal Grande. The highest mercury levels in human hair samples were found in São Luiz do Tapajós and Barreiras, greatly exceeding the limits established by the World Health Organization. Panacauera showed an intermediate level below 9 µg/g. This was the first comparative and simultaneous evaluation of mercury exposure in the Amazon area. Also, thanks to this type of monitoring, we were able to eliminate the uncertainties about the reference dose. On the basis of these data, we can conclude that the mercury levels detected in exposed populations of the Tapajós River basin may be dangerous not only because they are above the World Health Organization limits, but also because the simultaneous mercury detection in non-exposed populations with similar characteristics provided a valid control and revealed lower mercury levels. Our results support the importance of continuous monitoring in both exposed and non-exposed populations.

Methylmercury intoxication activates nitric oxide synthase in chick retinal cell culture

The visual system is a potential target for methylmercury (MeHg) intoxication. Nevertheless, there are few studies about the cellular mechanisms of toxicity induced by MeHg in retinal cells. Various reports have indicated a critical role for nitric oxide synthase (NOS) activation in modulating MeHg neurotoxicity in cerebellar and cortical regions. The aim of the present study is to describe the effects of MeHg on cell viability and NOS activation in chick retinal cell cultures. For this purpose, primary cultures were prepared from 7-day-old chick embryos: retinas were aseptically dissected and dissociated and cells were grown at 37°C for 7-8 days. Cultures were exposed to MeHg (10 µM, 100 µM, and 1 mM) for 2, 4, and 6 h. Cell viability was measured by MTT method and NOS activity by monitoring the conversion of L-[H³]-arginine to L-[H³]-citrulline. The incubation of cultured retina cells with 10 and 100 µM MeHg promoted an increase of NOS activity compared to control (P < 0.05). Maximum values (P < 0.05) were reached after 4 h of MeHg incubation: increases of 81.6 ± 5.3 and 91.3 ± 3.7 percent, respectively (data are reported as mean ± SEM for 4 replicates). MeHg also promoted a concentration- and time-dependent decrease in cell viability, with the highest toxicity (a reduction of about 80 percent in cell viability) being observed at the concentration of 1 mM and after 4-6 h of incubation. The present study demonstrates for the first time the modulation of MeHg neurotoxicity in retinal cells by the nitrergic system.

Comparative study of human exposure to mercury in riverside communities in the Amazon region.

Four populations in the Amazon area were selected for a comparative study of mercury-exposed and non-exposed populations: São Luiz do Tapajós, Barreiras, Panacauera, and Pindobal Grande. The highest mercury levels in human hair samples were found in São Luiz do Tapajós and Barreiras, greatly exceeding the limits established by the World Health Organization. Panacauera showed an intermediate level below 9 microg/g. This was the first comparative and simultaneous evaluation of mercury exposure in the Amazon area. Also, thanks to this type of monitoring, we were able to eliminate the uncertainties about the reference dose. On the basis of these data, we can conclude that the mercury levels detected in exposed populations of the Tapajós River basin may be dangerous not only because they are above the World Health Organization limits, but also because the simultaneous mercury detection in non-exposed populations with similar characteristics provided a valid control and revealed lower mercury levels. Our results support the importance of continuous monitoring in both exposed and non-exposed populations.

Methylmercury intoxication activates nitric oxide synthase in chick retinal cell culture.

The visual system is a potential target for methylmercury (MeHg) intoxication. Nevertheless, there are few studies about the cellular mechanisms of toxicity induced by MeHg in retinal cells. Various reports have indicated a critical role for nitric oxide synthase (NOS) activation in modulating MeHg neurotoxicity in cerebellar and cortical regions. The aim of the present study is to describe the effects of MeHg on cell viability and NOS activation in chick retinal cell cultures. For this purpose, primary cultures were prepared from 7-day-old chick embryos: retinas were aseptically dissected and dissociated and cells were grown at 37 degrees C for 7-8 days. Cultures were exposed to MeHg (10 microM, 100 microM, and 1 mM) for 2, 4, and 6 h. Cell viability was measured by MTT method and NOS activity by monitoring the conversion of L-[H3]-arginine to L-[H3]-citrulline. The incubation of cultured retina cells with 10 and 100 microM MeHg promoted an increase of NOS activity compared to control (P < 0.05). Maximum values (P < 0.05) were reached after 4 h of MeHg incubation: increases of 81.6 +/- 5.3 and 91.3 +/- 3.7%, respectively (data are reported as mean +/- SEM for 4 replicates). MeHg also promoted a concentration- and time-dependent decrease in cell viability, with the highest toxicity (a reduction of about 80% in cell viability) being observed at the concentration of 1 mM and after 4-6 h of incubation. The present study demonstrates for the first time the modulation of MeHg neurotoxicity in retinal cells by the nitrergic system.

[Mercury and neurotoxicity]. / Mercurio y neurotoxicidad.

INTRODUCTION AND AIMS: Mercury is a metal that is widely used in hundreds of applications nowadays. This metal has proved to be extremely toxic in humans, especially for the central nervous system, both in cases of exposure from everyday applications (e.g. dental fillings) and from environmental exposure. Unfortunately, most of the research carried out on this metal is relatively recent and many questions remain unanswered. The aim of this work is to review all the knowledge we have at the present time about the mechanisms of action of this metal. DEVELOPMENT: To do so, we discuss the latest scientific findings about the toxic processes that are activated, as well as its effects on the cellular cytoskeleton, its genotoxicity or the production of compounds that have been linked to neurodegeneration. CONCLUSIONS: Its prolonged period of latency, ambiguous symptoms and the activation of generalised toxic mechanisms call for urgent efforts to be made in basic research to help determine as clearly as possible the way this metal acts in the body. This knowledge will provide us not only with the way to obtain therapies but also with the hope of developing biomarkers that make it possible to carry out early and reliable diagnoses of the damage done and of individual susceptibility.

Protective role of melatonin against MPTP-induced mouse brain cell DNA fragmentation and apoptosis in vivo.

OBJECTIVES: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin that induces a Parkinsonian-type syndrome in animals which is similar to Parkinson's disease in humans. MPTP toxicity partially depends on the production of free radicals which in turn play a key role in the apoptotic death of neurons. In the present study melatonin, a potent free radical scavenger with antiapoptotic properties, was given to determine whether it would reduce oxidative stress in mice treated with MPTP. MATERIALS AND METHODS: Male mice were given MPTP with or without melatonin and the brain was studied either 6h, 24h, 7 days or 15 days after the last MPTP injection. RESULTS: The results show that melatonin counteracted in vivo MPTP-induced apoptosis in midbrain neurons at 6 and 24 h after MPTP treatment, and partially prevented apoptosis at 7 and 15 days after MPTP administration. MPTP treatment also produced time-dependent cell damage, whereas melatonin reduced the percentage of damaged cells at all time points, the effect being most evident at 15 days after treatment. Moreover, melatonin counteracted MPTP-dependent DNA fragmentation in the midbrain and striatum at 7 and 15 days after drug administration. CONCLUSION: These results support a role for melatonin in protecting neurons against MPTP toxicity in vivo, and suggest that its antiapoptotic action is one of the mechanisms by which melatonin protects neuronal cells from neurotoxic insults.