Occurrence of BMAA Isomers in Bloom-Impacted Lakes and Reservoirs of Brazil, Canada, France, Mexico, and the United Kingdom.

The neurotoxic alkaloid ß-N-methyl-amino-l-alanine (BMAA) and related isomers, including N-(2-aminoethyl glycine) (AEG), ß-amino-N-methyl alanine (BAMA), and 2,4-diaminobutyric acid (DAB), have been reported previously in cyanobacterial samples. However, there are conflicting reports regarding their occurrence in surface waters. In this study, we evaluated the impact of amending lake water samples with trichloroacetic acid (0.1 M TCA) on the detection of BMAA isomers, compared with pre-existing protocols. A sensitive instrumental method was enlisted for the survey, with limits of detection in the range of 5−10 ng L−1. Higher detection rates and significantly greater levels (paired Wilcoxon's signed-rank tests, p < 0.001) of BMAA isomers were observed in TCA-amended samples (method B) compared to samples without TCA (method A). The overall range of B/A ratios was 0.67−8.25 for AEG (up to +725%) and 0.69−15.5 for DAB (up to +1450%), with absolute concentration increases in TCA-amended samples of up to +15,000 ng L−1 for AEG and +650 ng L−1 for DAB. We also documented the trends in the occurrence of BMAA isomers for a large breadth of field-collected lakes from Brazil, Canada, France, Mexico, and the United Kingdom. Data gathered during this overarching campaign (overall, n = 390 within 45 lake sampling sites) indicated frequent detections of AEG and DAB isomers, with detection rates of 30% and 43% and maximum levels of 19,000 ng L−1 and 1100 ng L−1, respectively. In contrast, BAMA was found in less than 8% of the water samples, and BMAA was not found in any sample. These results support the analyses of free-living cyanobacteria, wherein BMAA was often reported at concentrations of 2−4 orders of magnitude lower than AEG and DAB. Seasonal measurements conducted at two bloom-impacted lakes indicated limited correlations of BMAA isomers with total microcystins or chlorophyll-a, which deserves further investigation.

Recombinant expression and antigenicity of two peptide families of neurotoxins from Androctonus sp

Background: Scorpion neurotoxins such as those that modify the mammalian voltagegated sodium ion channels (Nav) are the main responsible for scorpion envenomation. Their neutralization is crucial in the production of antivenoms against scorpion stings. Methods: In the present study, two in silico designed genes ­ one that codes for a native neurotoxin from the venom of the Anatolian scorpion Androctonus crassicauda, named Acra 4 ­ and another non-native toxin ­ named consensus scorpion toxin (SccTx) obtained from the alignment of the primary structures of the most toxic neurotoxins from the Middle Eastern and North African scorpions ­ were recombinantly expressed in E. coli Origami. Results: Following bacterial expression, the two expressed neurotoxins, hereafter named HisrAcra4 and HisrSccTx, were obtained from inclusion bodies. Both recombinant neurotoxins were obtained in multiple Cys-Cys isoforms. After refolding, the active protein fractions were identified with molecular masses of 8,947.6 and 9,989.1 Da for HisrAcra4 and HisrSccTx, respectively, which agreed with their expected theoretical masses. HisrAcra4 and HisrSccTx were used as antigens to immunize two groups of rabbits, to produce either anti-HisrAcra4 or anti-HisrSccTx serum antibodies, which in turn could recognize and neutralize neurotoxins from venoms of scorpion species from the Middle East and North Africa. The antibodies obtained from rabbits neutralized the 3LD50 of Androctonus australis, Leiurus quinquestriatus hebraeus and Buthus occitanus venoms, but they did not neutralize A. crassicauda and A. mauritanicus venoms. In addition, the anti-HisrAcra4 antibodies did not neutralize any of the five scorpion venoms tested. However, an antibody blend of anti-HisrAcra4 and anti-HisrSccTx was able to neutralize A. crassicauda and A. mauritanicus venoms. Conclusions: Two recombinant Nav neurotoxins, from different peptide families, were used as antigens to generate IgGs for neutralizing scorpion venoms of species from the Middle East and North Africa.(AU)

The cyanobacterial saxitoxin exacerbates neural cell death and brain malformations induced by Zika virus.

The northeast (NE) region of Brazil commonly goes through drought periods, which favor cyanobacterial blooms, capable of producing neurotoxins with implications for human and animal health. The most severe dry spell in the history of Brazil occurred between 2012 and 2016. Coincidently, the highest incidence of microcephaly associated with the Zika virus (ZIKV) outbreak took place in the NE region of Brazil during the same years. In this work, we tested the hypothesis that saxitoxin (STX), a neurotoxin produced in South America by the freshwater cyanobacteria Raphidiopsis raciborskii, could have contributed to the most severe Congenital Zika Syndrome (CZS) profile described worldwide. Quality surveillance showed higher cyanobacteria amounts and STX occurrence in human drinking water supplies of NE compared to other regions of Brazil. Experimentally, we described that STX doubled the quantity of ZIKV-induced neural cell death in progenitor areas of human brain organoids, while the chronic ingestion of water contaminated with STX before and during gestation caused brain abnormalities in offspring of ZIKV-infected immunocompetent C57BL/6J mice. Our data indicate that saxitoxin-producing cyanobacteria is overspread in water reservoirs of the NE and might have acted as a co-insult to ZIKV infection in Brazil. These results raise a public health concern regarding the consequences of arbovirus outbreaks happening in areas with droughts and/or frequent freshwater cyanobacterial blooms.

Neuroprotective properties of RT10, a fraction isolated from Parawixia bistriata spider venom, against excitotoxicity injury in neuron-glia cultures

Background: L-Glutamate (L-Glu), the major excitatory neurotransmitter in the mammalian Central Nervous System (CNS), is essential to cognitive functions. However, when L-Glu is accumulated in large concentrations at the synaptic cleft, it can induce excitotoxicity that results in secondary damage implicated in many neurological disorders. Current therapies for the treatment of neurological disorders are ineffective and have side effects associated with their use; therefore, there is a need to develop novel treatments. In this regard, previous studies have shown that neuroactive compounds obtained from the venom of the spider Parawixia bistriata have neuroprotective effects in vitro and in vivo. In this sense, this work aimed to evaluate potential neuroprotective effects of fraction RT10, obtained from this spider venom, on primary cultures of neuron and glial cells subjected to glutamate excitotoxicity insults. Methods: Primary cultures of neurons and glia were obtained from the cerebral tissue of 1-day-old postnatal Wistar rats. After 7 days in vitro (DIV), the cultures were incubated with fraction RT10 (0.002; 0.02; 0.2 and 2 µg/µL) or riluzole (100 µM) for 3-hours before application of 5 mM L-Glu. After 12 hours, the resazurin sodium salt (RSS) test was applied to measure metabolic activity and proliferation of living cells, whereas immunocytochemistry for MAP2 was performed to measure neuronal survival. In addition, the cells were immunolabeled with NeuN and GFAP in baseline conditions. Results: In the RSS tests, we observed that pre-incubation with RT10 before the excitotoxic insults from L-Glu resulted in neuroprotection, shown by a 10% reduction in the cell death level. RT10 was more effective than riluzole, which resulted in a cell-death reduction of 5%. Moreover, qualitative analysis of neuronal morphology (by MAP2 staining, expressed as fluorescence intensity (FI), an indirect measure of neuronal survival)...(AU)

Ontogenetic Change in the Venom of Mexican Black-Tailed Rattlesnakes (Crotalus molossus nigrescens).

Ontogenetic changes in venom composition have important ecological implications due the relevance of venom in prey acquisition and defense. Additionally, intraspecific venom variation has direct medical consequences for the treatment of snakebite. However, ontogenetic changes are not well documented in most species. The Mexican Black-tailed Rattlesnake (Crotalus molossus nigrescens) is large-bodied and broadly distributed in Mexico. To document venom variation and test for ontogenetic changes in venom composition, we obtained venom samples from twenty-seven C. m. nigrescens with different total body lengths (TBL) from eight states in Mexico. The primary components in the venom were detected by reverse-phase HPLC, western blot, and mass spectrometry. In addition, we evaluated the biochemical (proteolytic, coagulant and fibrinogenolytic activities) and biological (LD50 and hemorrhagic activity) activities of the venoms. Finally, we tested for recognition and neutralization of Mexican antivenoms against venoms of juvenile and adult snakes. We detected clear ontogenetic venom variation in C. m. nigrescens. Venoms from younger snakes contained more crotamine-like myotoxins and snake venom serine proteinases than venoms from older snakes; however, an increase of snake venom metalloproteinases was detected in venoms of larger snakes. Venoms from juvenile snakes were, in general, more toxic and procoagulant than venoms from adults; however, adult venoms were more proteolytic. Most of the venoms analyzed were hemorrhagic. Importantly, Mexican antivenoms had difficulties recognizing low molecular mass proteins (<12 kDa) of venoms from both juvenile and adult snakes. The antivenoms did not neutralize the crotamine effect caused by the venom of juveniles. Thus, we suggest that Mexican antivenoms would have difficulty neutralizing some human envenomations and, therefore, it may be necessary improve the immunization mixture in Mexican antivenoms to account for low molecular mass proteins, like myotoxins.

Neurotoxins in a water supply reservoir: An alert to environmental and human health.

Reservoirs are important source of power generation, recreation, and water supply. Nevertheless, human activities have favored the bloom of toxic cyanobacteria in many reservoirs, which has resulted in environmental, social, and economic problems. This study aims to evaluate the water quality of a reservoir in South Brazil through the analysis of cyanobacteria and cyanotoxins PSTs (Paralytic Shellfish Toxins) and biomarkers of environmental contamination in fish. For this purpose, water samples and fish (Geophagus brasiliensis) (Perciformes: Cichlidae) were collected from September 2013 to May 2014. The fish G. brasiliensis were separated in two groups. The first one "site group" was euthanized after the sampling and their weight and length were measured. The blood, brain, muscle and liver were collected for chemical, biochemical and genetics biomarkers analysis. The second group "depuration group" was submitted to depuration experiment for 40 days in clean water. After that, the same procedures as for the first group were carried out. Cylindrospermopsis raciborskii was the dominant cyanobacteria found in the reservoir, and it showed a density above the recommended limit by Brazilian legislation of 20,000 cells/mL. Results showed that the fish accumulate PSTs in the Reservoir and these were not eliminated after 40 days. The biochemical and genotoxic biomarkers showed a significant difference between "site groups" and "depuration groups", which suggests a recovery of the antioxidant system and a reduction of cellular damage after 40 days in clean water. In conjunction with results reported earlier by others, Alagados Reservoir, in South Brazil, appears to have a persistent contamination of cyanotoxins. Moreover, the mixture of contaminants which may be present in the water body can explain the seasonal differences in fish at the sampled points.

Immunodetection of the "brown" spider (Loxosceles intermedia) dermonecrotoxin with an scFv-alkaline phosphatase fusion protein.

Bites by spiders from Loxosceles genus often lead to a wide variance in envenomation profile of patients and diagnosis is difficult due to the number of diseases that mimic loxoscelism. In such a context, it is of interest to consider the design of standardized recombinant colorimetric antibodies for diagnosis and specific detection of individual circulating toxins in biological fluids of envenomed patients. We have previously prepared a monoclonal murine IgG (LiMab7) that reacts with Loxosceles intermedia venom components of 32-35kDa and neutralizes the dermonecrotic activity of the venom. Here, we re-engineered LiMab7 into a colorimetric bifunctional protein consisting in the corresponding single-chain antibody fragment (scFv) fused to alkaline phosphatase (AP) of Escherichia coli. The immune tracer was tested in two different types of immunoassays and it proved to be efficient in both. Thus, this recombinant fusion protein (scFv-LiMab7/AP) can be used for rapid and specific immunotitration of L. intermedia venom with a linear range of 39-20000ng/mL and a detection limit of 39ng/mL without any cross-reaction.

Toxic Trichodesmium bloom occurrence in the southwestern South Atlantic Ocean.

Harmful Trichodesmium blooms have been reported on the continental slope of the southwestern South Atlantic Ocean; we sampled six such blooms. The highest saxitoxin concentration was observed where the number of colonies was proportionally greater relative to the total density of trichomes. Trichodesmium blooms are harmful to shrimp larvae and may lead to plankton community mortality. This study is the first record of neurotoxic blooms in the open waters of the South Atlantic.

Botulismo en caninos: revisión de literatura / Botulism in dogs: review article / Botulismo em cães: revisão de literatura

El botulismo es una enfermedad causada por la ingestión de toxinas producidas por Clostridium botulinum, bacteria gram-positiva, anaerobia y formadora de esporas, que está ampliamente distribuida en la naturaleza, suelo y sedimentos de lagos y mares. En caninos, la enfermedad ocurre principalmente por la ingestión de la toxina preformada presente en alimentos deteriorados o carcasas en descomposición. Después de ser absorbida, la toxina migra por vía hematógena hasta las terminaciones nerviosas y bloquea la liberación de acetilcolina en la membrana presináptica de la unión neuromuscular, resultando en parálisis completa de la neurona motora inferior. Los caninos afectados presentan parálisis flácida ascendente de la musculatura esquelética, aunque la sensibilidad y la conciencia sean mantenidas. El diagnóstico presuntivo se hace basado en la historia del animal, así como en las manifestaciones clínicas. La técnica estándar para el diagnóstico definitivo es la inoculación intraperitoneal de suero sanguíneo de los animales sospechosos en ratones. El tratamiento de soporte es fundamental para la recuperación. El pronóstico es bueno, excepto en casos con infecciones secundarias o otras complicaciones. La recuperación es completa generalmente entre 2 a 3 semanas. En los casos más severos puede ocurrir muerte por parálisis de la musculatura respiratoria. La profilaxis de la enfermedad en los caninos está basada en la restricción del consumo de alimentos deteriorados o carcasas en putrefacción(AU)

Botulism is a disease caused by ingestion of toxins produced by Clostridium botulinum, a gram positive bacterium, anaerobic spore-forming, which are widely distributed in nature, soil and sediments of lakes and seas. In dogs, the disease mainly occurs by ingestion of preformed toxin present in spoiled food or rotting carcasses. Once absorbed, the toxin migrates through hematogenous until the nerve endings and blocks the release of acetylcholine at the presynaptic membrane of the neuromuscular junction, resulting in complete paralysis of the lower motor neuron. The affected dogs have ascending flaccid paralysis of the skeletal muscles, although the sensitivity and awareness are maintained. Initial diagnosis is carried out through the history of the animal as well as clinical manifestations. The standard technique for definitive diagnosis is intraperitoneal inoculation of blood serum of suspected animals in mice. Supportive care is essential to recovery. The prognosis is good if there is no development of secondary infections or other complications. The recovery is complete after a period of 2 to 3 weeks. In more severe cases, death can occur due to paralysis of the respiratory muscles. The prevention of the disease in dogs is based on restricting the consumption of spoiled food or rotting carcasses(AU)

O botulismo é uma enfermidade causada pela ingestão de toxinas produzidas pelo Clostridium botulinum, bactéria gram-positiva, anaeróbica e formadora de esporos, que está amplamente distribuída na natureza, no solo e em sedimentos de lagos e mares. Em cães, a doença ocorre principalmente pela ingestão da toxina pré-formada presente em alimentos deteriorados ou carcaças em decomposição. Após a absorção, a toxina migra por via hematógena até as terminações nervosas e bloqueia a liberação da acetilcolina na membrana pré-sináptica da junção neuromuscular, resultando em paralisia completa do neurônio motor inferior. Os cães acometidos apresentam paralisia flácida ascendente da musculatura esquelética, embora a sensibilidade e a consciência sejam mantidas. O diagnóstico presuntivo é realizado com base no histórico do animal e nas manifestações clínicas. A técnica padrão para o diagnóstico definitivo é a inoculação intraperitoneal de soro sanguíneo dos animais suspeitos em camundongos. O tratamento de suporte é fundamental para a recuperação. O prognóstico é bom, exceto nos casos com infecções secundárias ou outras complicações. A recuperação é completa geralmente entre 2 a 3 semanas. Nos casos mais severos, pode ocorrer a morte por paralisia da musculatura respiratória. A profilaxia da doença nos cães é baseada na restrição ao consumo de alimentos deteriorados ou carcaças em putrefação(AU)

Botulismo en caninos: revisión de literatura / Botulism in dogs: review article / Botulismo em cães: revisão de literatura

El botulismo es una enfermedad causada por la ingestión de toxinas producidas por Clostridium botulinum, bacteria gram-positiva, anaerobia y formadora de esporas, que está ampliamente distribuida en la naturaleza, suelo y sedimentos de lagos y mares. En caninos, la enfermedad ocurre principalmente por la ingestión de la toxina preformada presente en alimentos deteriorados o carcasas en descomposición. Después de ser absorbida, la toxina migra por vía hematógena hasta las terminaciones nerviosas y bloquea la liberación de acetilcolina en la membrana presináptica de la unión neuromuscular, resultando en parálisis completa de la neurona motora inferior. Los caninos afectados presentan parálisis flácida ascendente de la musculatura esquelética, aunque la sensibilidad y la conciencia sean mantenidas. El diagnóstico presuntivo se hace basado en la historia del animal, así como en las manifestaciones clínicas. La técnica estándar para el diagnóstico definitivo es la inoculación intraperitoneal de suero sanguíneo de los animales sospechosos en ratones. El tratamiento de soporte es fundamental para la recuperación. El pronóstico es bueno, excepto en casos con infecciones secundarias o otras complicaciones. La recuperación es completa generalmente entre 2 a 3 semanas. En los casos más severos puede ocurrir muerte por parálisis de la musculatura respiratoria. La profilaxis de la enfermedad en los caninos está basada en la restricción del consumo de alimentos deteriorados o carcasas en putrefacción

Botulism is a disease caused by ingestion of toxins produced by Clostridium botulinum, a gram positive bacterium, anaerobic spore-forming, which are widely distributed in nature, soil and sediments of lakes and seas. In dogs, the disease mainly occurs by ingestion of preformed toxin present in spoiled food or rotting carcasses. Once absorbed, the toxin migrates through hematogenous until the nerve endings and blocks the release of acetylcholine at the presynaptic membrane of the neuromuscular junction, resulting in complete paralysis of the lower motor neuron. The affected dogs have ascending flaccid paralysis of the skeletal muscles, although the sensitivity and awareness are maintained. Initial diagnosis is carried out through the history of the animal as well as clinical manifestations. The standard technique for definitive diagnosis is intraperitoneal inoculation of blood serum of suspected animals in mice. Supportive care is essential to recovery. The prognosis is good if there is no development of secondary infections or other complications. The recovery is complete after a period of 2 to 3 weeks. In more severe cases, death can occur due to paralysis of the respiratory muscles. The prevention of the disease in dogs is based on restricting the consumption of spoiled food or rotting carcasses

O botulismo é uma enfermidade causada pela ingestão de toxinas produzidas pelo Clostridium botulinum, bactéria gram-positiva, anaeróbica e formadora de esporos, que está amplamente distribuída na natureza, no solo e em sedimentos de lagos e mares. Em cães, a doença ocorre principalmente pela ingestão da toxina pré-formada presente em alimentos deteriorados ou carcaças em decomposição. Após a absorção, a toxina migra por via hematógena até as terminações nervosas e bloqueia a liberação da acetilcolina na membrana pré-sináptica da junção neuromuscular, resultando em paralisia completa do neurônio motor inferior. Os cães acometidos apresentam paralisia flácida ascendente da musculatura esquelética, embora a sensibilidade e a consciência sejam mantidas. O diagnóstico presuntivo é realizado com base no histórico do animal e nas manifestações clínicas. A técnica padrão para o diagnóstico definitivo é a inoculação intraperitoneal de soro sanguíneo dos animais suspeitos em camundongos. O tratamento de suporte é fundamental para a recuperação. O prognóstico é bom, exceto nos casos com infecções secundárias ou outras complicações. A recuperação é completa geralmente entre 2 a 3 semanas. Nos casos mais severos, pode ocorrer a morte por paralisia da musculatura respiratória. A profilaxia da doença nos cães é baseada na restrição ao consumo de alimentos deteriorados ou carcaças em putrefação

Presynaptic neuromuscular action of a methanolic extract from the venom of Rhinella schneideri toad

Rhinella schneideri, previously known as Bufo paracnemis, is a common toad in many regions of Brazil. Its venom exerts important cardiovascular effects on humans and other animals. Although this toad venom has been the subject of intense investigations, little is known about its neuromuscular activity. The neurotoxicity of a methanolic extract of R. schneideri venom was tested on mouse phrenic nerve-diaphragm (PND) preparations mounted for conventional twitch tension recording – in response to indirect stimulation – and for electrophysiological measurements.

Presynaptic neuromuscular action of a methanolic extract from the venom of Rhinella schneideri toad

Rhinella schneideri, previously known as Bufo paracnemis, is a common toad in many regions of Brazil. Its venom exerts important cardiovascular effects on humans and other animals. Although this toad venom has been the subject of intense investigations, little is known about its neuromuscular activity. The neurotoxicity of a methanolic extract of R. schneideri venom was tested on mouse phrenic nerve-diaphragm (PND) preparations mounted for conventional twitch tension recording – in response to indirect stimulation – and for electrophysiological measurements.

Presynaptic neuromuscular action of a methanolic extract from the venom of Rhinella schneideri toad

Rhinella schneideri, previously known as Bufo paracnemis, is a common toad in many regions of Brazil. Its venom exerts important cardiovascular effects on humans and other animals. Although this toad venom has been the subject of intense investigations, little is known about its neuromuscular activity. The neurotoxicity of a methanolic extract of R. schneideri venom was tested on mouse phrenic nerve-diaphragm (PND) preparations mounted for conventional twitch tension recording in response to indirect stimulation and for electrophysiological measurements.(AU)

Neurotoxic effect of linamarin in rats associated with cassava (Manihot esculenta Crantz) consumption.

Cassava (Manihot esculenta Crantz) is a plant widely used for food consumption in different processed products in rural areas of Africa, Asia, and Latin America. Cassava is a good source of carbohydrates and micronutrients. However, if it is not adequately processed or the consumer has nutritional deficiencies, then its cyanogenic glycoside (i.e., linamarin and lotaustralin) content makes it potentially neurotoxic. In the present study, the neurotoxic effects of different concentrations of linamarin (0.075, 0.15, 0.22, and 0.30 mg/kg) contained in cassava juice were evaluated in the open field and swim tests to identify locomotor alterations in adult male Wistar rats. The linamarin concentration in cassava juice was determined by high-performance liquid chromatography, and the juice was administered intraesophageally for 28 days. The results suggested that the consumption of linamarin in cassava juice increased the number of crossings and rearings in the open field test and caused behavioral deficiency, reflected by lateral swimming, in the swim test on days 21 and 28 of treatment. These alterations are possibly related to neuronal damage caused by linamarin in cassava juice in structures of the central nervous system involved in motor processing.

Determinação de efeitos citotóxicos de terpenos presentes em plantas do gênero Erythroxylum em um modelo de células astrocitárias / Determination of cytotoxic effects of terpenes present in plants from the genus Erythroxylum in models of astrocytic cells

Casos de intoxicação em humanos e animais têm sido relatados após o consumo de frutos de plantas do gênero Erythroxylum (Erythroxylaceae), com sintomatologia psicoativa e sugestiva de dano neurotóxico. O gênero Erythroxylum (Erythroxylaceae) é quimicamente caracterizado por apresentar em suas folhas e frutos, alcaloides tropanos, embora terpenos e ácidos graxos esterificados com triterpenos tenham, também, sido isolados nas folhas e frutos da espécie Erythroxylum passerinum. As células gliais, especialmente os astrócitos são fundamentais para o controle da homeostasia e metabolismo de xenobióticos estando intimamente relacionadas às funções de neuroproteção e neurotoxicidade no sistema nervoso central (SNC) Neste estudo investigamos os efeitos citotóxicos dos terpenos AEP-1 e Lupeol presentes em frutos de E. passerinum em um modelo de células gliais de origem astrocitária a linhagem GL-15. As células foram tratadas com os terpenos nas concentrações de 100, 250, 400 e 500 ?g/mL e analisadas após 24 e 72 h. A análise dos efeitos sobre a viabilidade celular, investigados pelo ensaio do MTT, demonstrou efeito tempo- e concentração-dependente para ambos os terpenos. A exposição ao terpeno AEP-1 induziu redução na viabilidade celular em 10% e 15% nas culturas após 24 h de tratamento com 100 ?g/mL e 250 ?g/mL, respectivamente. Nas culturas expostas por 24 e 72h nas maiores concentrações do Lupeol, foi observada uma redução na viabilidade celular. Também foi verificado que 24 h após a exposição das células a 100 e 250?g/mL dos terpenos as células aderentes apresentaram importantes alterações na morfologia, com contração do citoplasma e aumento das projeções celulares, evidenciadas através microscopia de contraste de fase e marcação imunocitoquímica (ICQ) da expressão das proteínas do citoesqueleto ?-tubulina e GFAP [...]

Cases of poisoning in humans and animals have been reported after consumption of fruits of plants of the genus Erythroxylum (Erythroxylaceae) with symptoms suggestive of psychoactive and neurotoxic damage. The genus Erythroxylum (Erythroxylaceae) is chemically characterized by presenting in its leaves and fruit, tropanes alkaloids, although terpenes and triterpenes esterified with fatty acids have also been isolated in the leaves and fruit of species Erythroxylum passerinum. Glial cells, especially astrocytes are crucial for the control of homeostasis and metabolism of xenobiotics is closely related to the functions of neuroprotection and neurotoxicity in the central nervous system (CNS) We investigated the cytotoxic effects of terpenes AEP-1 present in fruits and Lupeol E. passerinum in a model of glial origin of astrocytic lineage GL-15. Cells were treated with terpenes at concentrations of 100, 250, 400 and 500 μg/mL and analyzed after 24 and 72 h. Analysis of the effects on cell viability, investigated by the MTT assay, demonstrated effect time-and concentration-dependent for both terpenes. Exposure to AEP-1 terpene induced reduction in cellular viability by 10% and 15% in cultures after 24 h treatment with 100 μg/mL and 250 μg/mL, respectively. In cultures exposed for 24 and 72 hours at the highest concentrations of Lupeol was observed a reduction in cell viability. It was also observed that after 24 h exposure of cells to 100 to 250μg/mL of terpenes adherent cells showed significant changes in morphology, with contraction of the cytoplasm and increased cellular projections evidenced by phase contrast microscopy and labeling immunocytochemistry (ICC) of the expression of cytoskeletal proteins α-tubulin and GFAP [...]

Phoneutria nigriventer spider toxin Tx2-6 causes priapism and death: a histopathological investigation in mice.

Phoneutria nigriventer spider bite causes priapism, an effect attributed to the peptide toxins Tx2-5 and Tx2-6 and involving nitric oxide. Tx2-6 (MW = 5287) is known to delay the inactivation of Sodium channels in the same fashion as many other venom toxins. In the present study we evaluated the i.p. dose that induces priapism and the other symptoms in mice. Animals killed by the toxin or crude venom (0.85 mg/kg) were autopsied and a pathological study of brain, lung, kidney, liver and heart was undertaken using standard techniques. The same protocol was employed with animals injected with crude venom. Results showed that priapism is the first sign of intoxication, followed by piloerection, abundant salivation and tremors. An i.p. injection of about 0.3 µg/kg induced only priapism with minimal side-effects. The most remarkable histological finding was a general vascular congestion in all organs studied. Penis showed no necrosis or damage. Lungs showed vascular congestion and alveolar hemorrhage. Heart showed also sub-endothelial hemorrhage. Brain showed only a mild edema and vascular congestion. Results obtained with crude venom closely resemble those of purified toxin. We conclude that Tx2-6 have profound effects on the vascular bed especially in lungs and heart, which may be the cause of death. Interestingly brain tissue was less affected and the observed edema may be attributed to respiratory impairment. To the best of our knowledge this is the first histopathological investigation on this toxin and venom suggesting a possible cause of death.

Venomic and antivenomic analyses of the Central American coral snake, Micrurus nigrocinctus (Elapidae).

The proteome of the venom of Micrurus nigrocinctus (Central American coral snake) was analyzed by a "venomics" approach. Nearly 50 venom peaks were resolved by RP-HPLC, revealing a complex protein composition. Comparative analyses of venoms from individual specimens revealed that such complexity is an intrinsic feature of this species, rather than the sum of variable individual patterns of simpler composition. Proteins related to eight distinct families were identified by MS/MS de novo peptide sequencing or N-terminal sequencing: phospholipase A(2) (PLA(2)), three-finger toxin (3FTx), l-amino acid oxidase, C-type lectin/lectin-like, metalloproteinase, serine proteinase, ohanin, and nucleotidase. PLA(2)s and 3FTxs are predominant, representing 48 and 38% of the venom proteins, respectively. Within 3FTxs, several isoforms of short-chain α-neurotoxins as well as muscarinic-like toxins and proteins with similarity to long-chain κ-2 bungarotoxin were identified. PLA(2)s are also highly diverse, and a toxicity screening showed that they mainly exert myotoxicity, although some are lethal and may contribute to the known presynaptic neurotoxicity of this venom. An antivenomic characterization of a therapeutic monospecific M. nigrocinctus equine antivenom revealed differences in immunorecognition of venom proteins that correlate with their molecular mass, with the weakest recognition observed toward 3FTxs.

Regional brain c-fos activation associated with penile erection and other symptoms induced by the spider toxin Tx2-6

Brain areas expressing c-fos messenger RNA were mapped by quantitative in situhybridization after 1–2 h of intoxication with 10 mg/kg Tx2-6, a toxin obtained from the venom of the spider Phoneutria nigriventer. Relative to saline-treated controls, brains from toxin-treated animals showed pronounced c-fos activation in many brain areas, includingthe supraoptic nucleus, the paraventricular nucleus of the hypothalamus, the motor nucleus of the vagus, area postrema, paraventricular and paratenial nuclei of the thalamus,locus coeruleus, central amydaloid nucleus and the bed nucleus of the stria terminalis. The paraventricular hypothalamus and the bed nucleus of the stria terminalis have been implicated in erectile function in other studies. A possible role for central NO is considered. Acute stress also activates many brain areas activated by Tx2-6 as well as with NO stimulated Fos transcription. Brain areas that appear to be selectively activated by Tx2-6, include the paratenial and paraventricular thalamic nuclei, the bed nucleus of the stria terminalis and the area postrema and the dorsal motor n. of vagus in the medulla. However, direct injections of different doses of the toxin into the paraventricular hypothalamicn. failed to induce penile erection, arguing against CNS involvement in thisparticular effect.

Description of envenomation by the gusano-pollo caterpillar (Megalopyge opercularis) in Venezuela: [review]

Lepidoptera is a large order of insects, with more than 180,000 species word-wide, showing larval stages of butterflies andmoths known as worm like caterpillars. Almost 12 families of butterflies around the world are capable of causing severe human injuries, varying from dermatitis, renal failure, hemostatic alterations, respiratory failure and neurotoxic symptoms. These caterpillars are coated in long, hair-like setae containing venom to protect themselves against aggressive predators. The setae cause a painful reaction, upon contact, due to presence of neurotoxins. These caterpillars are extensively dispersed all through North America and often, during the dry and wet seasons in tropical regions, being able to sustain two annual larval generations. There exist several species of Megalopyge caterpillars; however, Megalopyge opercularis is the most widely distributed species in Latin America and the United States. This work reports, to our knowledge, the first case of envenomation by the “gusano-pollo” (Megalopyge opercularis), a stinging caterpillar, described in Venezuela. The patient in this report presented severesymptoms, including systemic reactions such as intense hand pain irradiated to the upper arm, restricted swelling, headache, dizziness, serious chest distress and shock-like symptoms that required hospitalization. Symptoms improved upon treatment with opiaceous analgesic drugs

Lepidoptera es un orden de insectos con más de 180,000 especies descritas en el ámbito mundial, con estadios larvales de mariposas conocidas como orugas parecidas a gusanos. Cerca de 12 familias de mariposas alrededor del mundo son capaces de causar lesiones graves que van desde una dermatitis hasta la insuficiencia renal, incluyendo alteraciones de la hemostasia, fallo respiratorio y síntomas neurotóxicos. Estas orugas están cubiertas de largas cerdas, parecidas a pelos, que contienen veneno y lo usan para protegerse contra sus predadores. La cerda causa una reacción dolorosa, debido a la presencia de neurotoxinas. Estas orugas se encuentran ampliamente esparcidas en Norteamérica y a menudo durante las estaciones seca y lluviosa, en regiones tropicales, pudiendo crear 2 generaciones de larvas al año. Existen varias especies de estas orugas, sin embargo, Megalopyge opercularis es la especie más extensamente distribuida en América Latina y los Estados Unidos. Este trabajo refiere, a nuestra revisión de la literatura, el primer caso descrito de envenenamiento por el “Gusano-pollo" (Megalopyge opercularis) en Venezuela. El caso en estudio presentó síntomas muy severos, incluyendo las reacciones sistémicas, así como dolor intenso en la mano, irradiado a la parte alta del miembro, edema restringido, cefalea, mareos, opresión retroesternal y síntomas parecidos al choque, que requirieron su hospitalización. La sintomatología mejoró con opiáceos y analgésicos fuertes

Síntese e aplicações estratégicas de neurotoxinas produzidas por cianobactérias / Synthesis and strategic applications of some neurotoxins produce for cyanobacteria

As cianobactérias apresentam, distribuição variada e podem ocorrer desde as regiões frias do ártico até os trópicos, em corpos d'água doce e no ambiente marinho. Algumas espécies de cianobactérias produzem compostos com conhecida toxidade, podendo causar efeitos deletérios em seres humanos e animais. Entre estes compostos estão os com atividade neurotóxica devido aos mais variados mecanismos de ação. O objetivo geral deste projeto é a obtenção por via sintética de algumas neurotoxinas e variantes, entre elas a β-N-metil-L-alanina (L-BMAA), anatoxina-a e anatoxina-a(s), bem como algumas aplicações. Para a L-BMAA, foi buscada a determinação de rotas sintéticas viáveis para a obtenção deste aminoácido modificado sob a forma racêmica e enantiomericamente pura, além de um possível produto cíclico que pode ser gerado naturalmente a partir da L-BMAA. Algumas rotas estratégicas foram determinadas com êxito para a síntese destes compostos. Entre as aplicações dos produtos obtidos podem ser citados: (i) a determinação de um método analítico para a determinação deste aminoácido por RMN de 1H; (ii) um método analítico por LC-MS utilizando D3-L-BMAA como padrão interno e (iii) a indicação de um possível mecanismo de neurotoxidade ligado a neurodegeneração via um intermediário produzido naturalmente do equilíbrio entre L-BMAA e íons bicarbonato...