RESUMEN
Emerging literature suggests that after a stroke, the peri-infarct region exhibits dynamic changes in excitability. In rodent stroke models, treatments that enhance excitability in the peri-infarct cerebral cortex promote motor recovery. This increase in cortical excitability and plasticity is opposed by increases in tonic GABAergic inhibition in the peri-infarct zone beginning three days after a stroke in a mouse model. Maintenance of a favorable excitatory-inhibitory balance promoting cerebrocortical excitability could potentially improve recovery. Brevetoxin-2 (PbTx-2) is a voltage-gated sodium channel (VGSC) gating modifier that increases intracellular sodium ([Na+]i), upregulates N-methyl-D-aspartate receptor (NMDAR) channel activity and engages downstream calcium (Ca2+) signaling pathways. In immature cerebrocortical neurons, PbTx-2 promoted neuronal structural plasticity by increasing neurite outgrowth, dendritogenesis and synaptogenesis. We hypothesized that PbTx-2 may promote excitability and structural remodeling in the peri-infarct region, leading to improved functional outcomes following a stroke. We tested this hypothesis using epicortical application of PbTx-2 after a photothrombotic stroke in mice. We show that PbTx-2 enhanced the dendritic arborization and synapse density of cortical layer V pyramidal neurons in the peri-infarct cortex. PbTx-2 also produced a robust improvement of motor recovery. These results suggest a novel pharmacologic approach to mimic activity-dependent recovery from stroke.
Asunto(s)
Corteza Cerebral/efectos de los fármacos , Agonistas de Aminoácidos Excitadores/administración & dosificación , Toxinas Marinas/administración & dosificación , Actividad Motora/efectos de los fármacos , Plasticidad Neuronal/efectos de los fármacos , Oxocinas/administración & dosificación , Accidente Cerebrovascular Trombótico/tratamiento farmacológico , Animales , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Corteza Cerebral/metabolismo , Corteza Cerebral/patología , Corteza Cerebral/fisiopatología , Modelos Animales de Enfermedad , Inyecciones , Proteínas Luminiscentes/genética , Proteínas Luminiscentes/metabolismo , Ratones Transgénicos , Recuperación de la Función , Accidente Cerebrovascular Trombótico/metabolismo , Accidente Cerebrovascular Trombótico/patología , Accidente Cerebrovascular Trombótico/fisiopatologíaRESUMEN
Yessotoxins (YTX) and azaspiracids (AZAs) are marine toxins produced by phytoplanktonic dinoflagellates that get accumulated in filter feeding shellfish and finally reach human consumers through the food web. Both toxin classes are worldwide distributed, and food safety authorities have regulated their content in shellfish in many countries. Recently, YTXs and AZAs have been described as compounds with subacute cardiotoxic potential in rats owed to alterations of the cardiovascular function and ultrastructural heart damage. These molecules are also well known in vitro inducers of cell death. The aim of this study was to explore the presence of cardiomyocyte death after repeated subacute exposure of rats to AZA-1 and YTX for 15 days. Because autophagy and apoptosis are often found in dying cardiomyocytes, several autophagic and apoptotic markers were determined by western blot in heart tissues of these rats. The results showed that hearts from YTX-treated rats presented increased levels of the autophagic markers microtubule-associated protein light chain 3-II (LC3-II) and beclin-1, nevertheless AZA-1-treated hearts evidenced increased levels of the apoptosis markers cleaved caspase-3 and -8, cleaved PARP and Fas ligand. Therefore, while YTX-induced damage to the heart triggers autophagic processes, apoptosis activation occurs in the case of AZA-1. For the first time, activation of cell death signals in cardiomyocytes is demonstrated for these toxins with in vivo experiments, which may be related to alterations of the cardiovascular function.
Asunto(s)
Apoptosis/efectos de los fármacos , Autofagia/efectos de los fármacos , Toxinas Marinas/toxicidad , Miocitos Cardíacos/efectos de los fármacos , Oxocinas/toxicidad , Compuestos de Espiro/toxicidad , Animales , Biomarcadores/metabolismo , Western Blotting , Femenino , Toxinas Marinas/administración & dosificación , Venenos de Moluscos , Oxocinas/administración & dosificación , Ratas , Ratas Sprague-Dawley , Compuestos de Espiro/administración & dosificación , Factores de Tiempo , Pruebas de Toxicidad Subaguda/métodosRESUMEN
Ciguatoxins (CTXs), and possibly maitotoxins (MTXs), are responsible for Ciguatera Fish Poisoning, an important health problem for consumers of reef fish (such as inhabitants of islands in the South Pacific Ocean). The habitational range of the Gambierdiscus species is expanding, and new species are being discovered. In order to provide information on the potential health risk of the Gambierdiscus species, and one Fukuyoa species (found in the Cook Islands, the Kermadec Islands, mainland New Zealand, and New South Wales, Australia), 17 microalgae isolates were collected from these areas. Unialgal cultures were grown and extracts of the culture isolates were analysed for CTXs and MTXs by liquid chromatography tandem mass spectrometry (LC-MS/MS), and their toxicity to mice was determined by intraperitoneal and oral administration. An isolate of G. carpenteri contained neither CTXs nor MTXs, while 15 other isolates (including G. australes, G. cheloniae, G. pacificus, G.honu, and F. paulensis) contained only MTX-1 and/or MTX-3. An isolate of G. polynesiensis contained both CTXs and MTX-3. All the extracts were toxic to mice by intraperitoneal injection, but those containing only MTX-1 and/or -3 were much less toxic by oral administration. The extract of G. polynesiensis was highly toxic by both routes of administration.
Asunto(s)
Ciguatoxinas/toxicidad , Dinoflagelados/química , Toxinas Marinas/toxicidad , Oxocinas/toxicidad , Administración Oral , Animales , Cromatografía Liquida , Intoxicación por Ciguatera/epidemiología , Ciguatoxinas/administración & dosificación , Ciguatoxinas/aislamiento & purificación , Femenino , Inyecciones Intraperitoneales , Toxinas Marinas/administración & dosificación , Toxinas Marinas/aislamiento & purificación , Ratones , Oxocinas/administración & dosificación , Oxocinas/aislamiento & purificación , Océano Pacífico , Especificidad de la Especie , Espectrometría de Masas en Tándem , Pruebas de ToxicidadRESUMEN
Yessotoxin (YTX) is a marine phycotoxin produced by dinoflagellates and accumulated in filter feeding shellfish. Although no human intoxication episodes have been reported, YTX content in shellfish is regulated by many food safety authorities due to their worldwide distribution. YTXs have been related to ultrastructural heart damage in vivo, but the functional consequences in the long term have not been evaluated. In this study, we explored the accumulative cardiotoxic potential of YTX in vitro and in vivo. Preliminary in vitro evaluation of cardiotoxicity was based on the effect on hERG (human ether-a-go-go related gene) channel trafficking. In vivo experiments were performed in rats that received repeated administrations of YTX followed by recordings of electrocardiograms, arterial blood pressure, plasmatic cardiac biomarkers, and analysis of myocardium structure and ultrastructure. Our results showed that an exposure to 100 nM YTX for 12 or 24 h caused an increase of extracellular surface hERG channels. Furthermore, remarkable bradycardia and hypotension, structural heart alterations, and increased plasma levels of tissue inhibitor of metalloproteinases-1 were observed in rats after four intraperitoneal injections of YTX at doses of 50 or 70 µg/kg that were administered every 4 days along a period of 15 days. Therefore, and for the first time, YTX-induced subacute cardiotoxicity is supported by evidence of cardiovascular function alterations related to its repeated administration. Considering international criteria for marine toxin risk estimation and that the regulatory limit for YTX has been recently raised in many countries, YTX cardiotoxicity might pose a health risk to humans and especially to people with previous cardiovascular risk.
Asunto(s)
Cardiotoxinas/toxicidad , Enfermedades Cardiovasculares/metabolismo , Corazón/efectos de los fármacos , Oxocinas/toxicidad , Animales , Células CHO , Cardiotoxicidad , Cardiotoxinas/administración & dosificación , Cardiotoxinas/química , Células Cultivadas , Cricetulus , Canal de Potasio ERG1/metabolismo , Humanos , Inyecciones Intraperitoneales , Conformación Molecular , Venenos de Moluscos , Oxocinas/administración & dosificación , Oxocinas/química , Ratas , Ratas Sprague-DawleyRESUMEN
Epidemiological studies demonstrated that the number of emergency-room visits for respiratory indications increases during periods of Florida Red Tides. The purpose of this study was to examine whether or not repeated brevetoxin inhalation, as may occur during a Florida Red Tide, affects pulmonary responses to influenza A. Male F344 rats were divided into four groups: (1) sham aerosol/no influenza; (2) sham aerosol/influenza; (3) brevetoxin/no influenza; and (4) brevetoxin/influenza. Animals were exposed by nose-only inhalation to vehicle or 50 µg brevetoxin-3/m3, 2 h/d for 12 d. On d 6 of aerosol exposure, groups 2 and 4 were administered 10,000 plaque-forming units of influenza A, strain HKX-31 (H3N2), by intratracheal instillation. Subgroups were euthanized at 2, 4, and 7 d post influenza treatment. Lungs were evaluated for viral load, cytokine content, and histopathologic changes. Influenza virus was cleared from the lungs over the 7-d period; however, there was significantly more virus remaining in the group 4 lungs compared to group 2. Influenza virus significantly increased interleukins-1α and -6 and monocyte chemotactic protein-1 in lung; brevetoxin exposure significantly enhanced the influenza-induced response. At 7 d, the severity of perivascular and peribronchiolar inflammatory cell infiltrates was greatest in group 4. Bronchiolitis persisted, with low incidence and severity, only in group 4 at d 7. These results suggest that repeated inhalation exposure to brevetoxin may delay virus particle clearance and recovery from influenza A infection in the rat lung.
Asunto(s)
Subtipo H3N2 del Virus de la Influenza A/crecimiento & desarrollo , Pulmón/efectos de los fármacos , Pulmón/inmunología , Toxinas Marinas/toxicidad , Infecciones por Orthomyxoviridae/inmunología , Infecciones por Orthomyxoviridae/virología , Oxocinas/toxicidad , Administración Intranasal , Animales , Bronquiolitis Viral/inmunología , Bronquiolitis Viral/patología , Bronquiolitis Viral/virología , Citocinas/metabolismo , Susceptibilidad a Enfermedades , Floraciones de Algas Nocivas , Inmunidad Mucosa/efectos de los fármacos , Subtipo H3N2 del Virus de la Influenza A/inmunología , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Pulmón/patología , Pulmón/virología , Masculino , Toxinas Marinas/administración & dosificación , Infecciones por Orthomyxoviridae/metabolismo , Infecciones por Orthomyxoviridae/patología , Oxocinas/administración & dosificación , Distribución Aleatoria , Ratas , Ratas Endogámicas F344 , Factores de Tiempo , Carga ViralRESUMEN
Brevetoxins (PbTx) are potent lipid soluble polyether neurotoxins produced by the marine dinoflagellate Karenia brevis, an organism linked to periodic red tide blooms. Brevetoxins exert their toxicity by interacting with neurotoxin receptor site five associated with domain IV of the alpha subunit of the voltage gated sodium channel. Brevetoxin binding to tissues that contain voltage gated sodium channels on excitable cells results in membrane depolarization, repetitive firing, and increase in sodium currents. Brevetoxins have been linked to deaths in marine mammals, which are exposed through ingestion of organisms harboring high brevetoxin concentrations and through the inhalation of aerosolized brevetoxins. Humans are also at risk, primarily through respiratory exposure which can result in a severe inflammatory response. The purpose of this study was to determine the effect of four brevetoxins on Jurkat E6-1 cell proliferation, to assess their variability in potency, genotoxicity, and to determine if brevetoxin causes cell death, specifically through an apoptotic or necrotic mechanism. PbTx 2, 3, 6, and 9 were tested at concentrations of 10(-4)-10(-12) M to determine the IC(50) values and effect on cell proliferation. The IC(50) concentration was then used in the single cell gel electrophoresis assay to determine genotoxicity. The ability to induce apoptosis was then assessed with the Vybrant apoptosis assay, caspase activation assays and PARP cleavage. Results from the cellular proliferation assays demonstrated that high doses of PbTxs inhibit the ability of Jurkat cells to proliferate while lower doses caused an increase in proliferation and that PbTx2 is the most cytotoxic brevetoxin followed by brevetoxins 6, 3, and 9. Brevetoxins 2, 3, and 6 all caused significant DNA damage. A 4 h exposure to brevetoxins 2, 3, 6, and 9 at values close to the IC(50) values resulted in apoptosis positive staining in Jurkat E6-1 cells. High doses of brevetoxins 2 and 6 resulted in activation of caspases 3/7 and 8 and cleavage of poly (ADP-ribose) polymerase (PARP). The conclusions are that brevetoxins affect cell proliferation in a dose-dependent fashion, are genotoxic, and cause cell death through an apoptotic mechanism.
Asunto(s)
Apoptosis/efectos de los fármacos , Daño del ADN/efectos de los fármacos , Toxinas Marinas/toxicidad , Oxocinas/toxicidad , Caspasas/efectos de los fármacos , Caspasas/metabolismo , Proliferación Celular/efectos de los fármacos , Ensayo Cometa , Relación Dosis-Respuesta a Droga , Humanos , Concentración 50 Inhibidora , Células Jurkat , Toxinas Marinas/administración & dosificación , Pruebas de Mutagenicidad , Mutágenos/administración & dosificación , Mutágenos/toxicidad , Oxocinas/administración & dosificación , Factores de TiempoRESUMEN
The aim of the present study was to determine whether the intraperitoneal LD(50) for yessotoxin (YTX) in mice varies with strain or gender. Thirty-six male and 36 female mice, of body weight 16-20 g, from each of the strains ICR (CD-1), Swiss (CFW-1) and NMRI were employed. They were not fasted before YTX treatment. At each dose, nine mice were injected with YTX solutions at 1.0 mL/20 g body weight, and observed for 24h. Symptoms and time to death were recorded. Within each mouse strain and gender arm, the study was performed as a basic four level Response Surface Pathway designed trial with nine mice at each dose level. YTX was isolated from a culture of Protoceratium reticulatum. The LD(50) values for female and male mice, respectively, were estimated as 380 and 462 microg/kg for the ICR, 269 and 328 microg/kg for the Swiss, and 314 and 412 microg/kg for the NMRI strains. The increases in LD(50) from female to male mice were found to be 22% for ICR, 22% for Swiss and 31% for NMRI. The largest difference in LD(50) among mouse strains was detected between the ICR and Swiss strains, where the deviation was 41% in both females and males. The difference between mouse strains was found significant (p = 0.03). For all three strains, females were more susceptible than males, with a difference in LD(50) of 1.2-1.3-fold. The largest difference between the least- and most-susceptible strain was 1.4-fold for both females and males. The largest difference in LD(50), 1.7-fold, was observed between female Swiss and male ICR mice. The difference between genders was not significant (p = 0.12). These results indicate that other factors, like handling of the animals, and the source and handling of the toxin, may significantly influence the outcome of studies on acute toxicity since the reported differences in LD(50) vary by a factor of about seven.
Asunto(s)
Ratones Endogámicos , Venenos de Moluscos/toxicidad , Oxocinas/toxicidad , Animales , Femenino , Dosificación Letal Mediana , Masculino , Ratones , Venenos de Moluscos/administración & dosificación , Oxocinas/administración & dosificación , Factores SexualesRESUMEN
The Florida red tide dinoflagellate, Karenia brevis, is the major harmful algal bloom dinoflagellate of the Gulf of Mexico and plays a destructive role in the region. Blooms of K. brevis can produce brevetoxins: ladder-shaped polyether (LSP) compounds, which can lead to adverse human health effects, such as reduced respiratory function through inhalation exposure, or neurotoxic shellfish poisoning through consumption of contaminated shellfish. The endogenous role of the brevetoxins remains uncertain. Recent work has shown that some forms of NADPH dependent thioredoxin reductase (NTR) are inhibited by brevetoxin-2 (PbTx-2). The study presented herein reveals that high toxin and low toxin K. brevis, which have a ten-fold difference in toxin content, also show a significant difference in their ability, not only to produce brevetoxin, but also in their cellular redox status and distribution of xanthophyll cycle pigments. These differences are likely due to the inhibition of NTR by brevetoxin. The work could shed light on the physiological role that brevetoxin fills for K. brevis.
Asunto(s)
Dinoflagelados/efectos de los fármacos , Floraciones de Algas Nocivas/efectos de los fármacos , Toxinas Marinas/administración & dosificación , Oxocinas/administración & dosificación , Proteínas Protozoarias/metabolismo , Reductasa de Tiorredoxina-Disulfuro/metabolismo , Proteínas Algáceas/metabolismo , Oxidación-Reducción , Fotosíntesis/efectos de los fármacos , Percepción de Quorum/efectos de los fármacosRESUMEN
Neurotoxins from algal blooms have been reported to cause mortality in a variety of species, including sea birds, sea mammals and fish. Farmed fish cannot escape harmful algal blooms and their potential toxins, thus they are more vulnerable for exposure than wild stocks. Sublethal doses of the toxins are likely to affect fish behaviour and may impair cognitive abilities. In the present study, changes in the metabolic activity in different parts of the Atlantic salmon (Salmo salar) brain involved in central integration and cognition were investigated after exposure to sublethal doses of three algal-produced neurotoxins; saxitoxin (STX), brevetoxin (BTX) and domoic acid (DA). Fish were randomly selected to four groups for i.p. injection of saline (control) or one of the neurotoxins STX (10 microg STX/kg bw), BTX (68 microg BTX/kg bw) or DA (6 mg DA/kg bw). In addition, 14C-2-deoxyglucose was i.m. injected to measure brain metabolic activity by autoradiography. The three regions investigated were telencephalon (Tel), optic tectum (OT) and cerebellum (Ce). There were no differences in the metabolic activity after STX and BTX exposure compared to the control in these regions. However, a clear increase was observed after DA exposure. When the subregions with the highest metabolic rate were pseudocoloured in the three brain regions, the three toxins caused distinct differences in the respective patterns of metabolic activation. Fish exposed to STX displayed similar patterns as the control fish, whereas fish exposed to BTX and DA showed highest metabolic activity in subregions different from the control group. All three neurotoxins affected subregions that are believed to be involved in cognitive abilities in fish.
Asunto(s)
Encéfalo/efectos de los fármacos , Ácido Kaínico/análogos & derivados , Toxinas Marinas/toxicidad , Neurotoxinas/toxicidad , Oxocinas/toxicidad , Salmo salar/metabolismo , Saxitoxina/toxicidad , Animales , Conducta Animal/efectos de los fármacos , Encéfalo/metabolismo , Isótopos de Carbono/análisis , Cerebelo/efectos de los fármacos , Cerebelo/metabolismo , Desoxiglucosa/metabolismo , Eucariontes/química , Ácido Kaínico/administración & dosificación , Ácido Kaínico/toxicidad , Toxinas Marinas/administración & dosificación , Neurotoxinas/administración & dosificación , Oxocinas/administración & dosificación , Distribución Aleatoria , Saxitoxina/administración & dosificación , Colículos Superiores/efectos de los fármacos , Colículos Superiores/metabolismo , Telencéfalo/efectos de los fármacos , Telencéfalo/metabolismoRESUMEN
Brevetoxins are a family of potent lipid-soluble neurotoxins produced by the dinoflagellate Karenia brevis, the organism responsible for Florida red tide. Brevetoxins aerosolized by surf and wind produce irritation of the eyes, nose, and throat in people on or near red tide-affected beaches. The effects of chronic exposures to brevetoxins on healthy and health-compromised individuals are not known. The purpose of this study was to investigate the pulmonary uptake, tissue distribution, and excretion of polyether brevetoxin-3 in mice, a rodent model for investigating the potential systemic adverse health effects associated with repeated brevetoxin inhalation. Male CBA/CaJ mice were administered [3H]brevetoxin-3 by intratracheal instillation. Groups of 3 mice were sacrificed immediately after instillation and at 0.5, 3, 6, 12, 24, 48, and 96 h postinstillation. Four additional mice were placed into metabolism cages for excreta collection up to 168 h postinstillation. Brevetoxin-3 distributed rapidly to all tissues, with the highest initial doses in the liver and gastrointestinal tract. Elimination half-times ranged from approximately 28 h for fat, heart, intestines, kidneys, liver, and muscle to approximately 90 h for brain and testes. The total dose to tissue ranged from 39 ng brevetoxin equivalents-h/g for testes to 406 ng brevetoxin equivalents-h/g for liver. Approximately 90% of excretion had occurred within 96 h, with 11 and 64% of the initial brevetoxin dose excreted in urine and feces, respectively. These results are consistent with earlier reports of rapid absorption and widespread tissue distribution of brevetoxins in rats.
Asunto(s)
Ciguatoxinas/farmacocinética , Toxinas Marinas/farmacocinética , Oxocinas/farmacocinética , Administración por Inhalación , Animales , Ciguatoxinas/administración & dosificación , Ciguatoxinas/toxicidad , Modelos Animales de Enfermedad , Monitoreo del Ambiente , Heces/química , Exposición por Inhalación , Masculino , Toxinas Marinas/administración & dosificación , Toxinas Marinas/toxicidad , Ratones , Ratones Endogámicos CBA , Oxocinas/administración & dosificación , Oxocinas/toxicidad , Distribución TisularRESUMEN
OBJECTIVES: This study aims to investigate antimicrobial ingredients from Sappan Lignum and to evaluate their synergy on methicillin-resistant Staphylococcus aureus strains with antibiotics. METHODS: Bioactivity-guided phytochemical procedures were used to screen the active compounds. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were assayed by broth microdilution. The synergy was evaluated through checkerboard microdilution and loss of viability assays. KEY FINDINGS: Protosappanins A (PsA) and B (PsB) were identified from Sappan Lignum extracts. They showed active against both S. aureus and MRSA with MIC or MIC50 at 64 (PsA) and 128 (PsB) mg/L alone. When they were used in combination with antibiotics, they showed best synergy with amikacin and gentamicin with MIC50 (mg/L) of amikacin reduced more significantly from 32 to four (with PsA) and eight (with PsB), and the fractional inhibitory concentration index (FICI) ranged between 0.078 and 0.500 (FICI50 = 0.375). Moreover, the resistance of MRSA towards amikacin and gentamicin could be reversed by the Clinical and Laboratory Standards Institute criteria. The combined bactericidal mode could as well be synergy. PsA and PsB showed very low cytotoxicity in comparison with their promising activity against MRSA. CONCLUSIONS: Protosappanins A and B showed both alone activities and resistance reversal effects of amikacin and gentamicin against MRSA, which warrant further investigations for potential combinatory therapy of MRSA infection.
Asunto(s)
Antibacterianos/farmacología , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Oxocinas/farmacología , Fenoles/farmacología , Amicacina/farmacología , Antibacterianos/administración & dosificación , Antibacterianos/aislamiento & purificación , Caesalpinia/química , Línea Celular , Línea Celular Tumoral , Farmacorresistencia Bacteriana/efectos de los fármacos , Sinergismo Farmacológico , Gentamicinas/farmacología , Humanos , Pruebas de Sensibilidad Microbiana , Oxocinas/administración & dosificación , Oxocinas/aislamiento & purificación , Fenoles/administración & dosificación , Fenoles/aislamiento & purificaciónRESUMEN
We developed a radioimmunoassay (RIA) using a sheep anti-brevetoxin antiserum to evaluate detection of brevetoxin on blood collection cards from mice treated with the brevetoxin congener PbTx-3. The RIA has high affinity for PbTx-3 [half-maximal effective concentration (EC(50)) +/- SE = 1.2 +/- 0.2 nM; n = 10] and recognizes both type 1 and type 2 brevetoxins, but not ciguatoxin. Direct comparison of the RIA with a radiolabeled [(3)H]-PbTx-3 receptor-binding assay (RBA) revealed excellent sensitivity, congener selectivity, and minimal interference from blood matrix. We first analyzed blood samples from an acute time course exposure, using a maximal nonlethal dose [180 microg/kg body weight (bw)] for 0.5, 1, 2, 4, and 24 hr. Mean blood brevetoxin levels were 36 nM at 30 min and stayed above 20 nM during the 1-4 hr time points. We next analyzed blood brevetoxin levels after longer exposure (0.5, 1, 2, 3, 4, or 7 days). Mean blood brevetoxin levels were 26.0 nM at 0.5 days, decreased to 8.2 nM at 1.0 day, and maintained a significant level (p < 0.05) of 1.3 nM at day 2. We next determined the lowest measurable dose using increasing concentrations of PbTx-3 (10-300 micro g/kg bw). Analysis of the blood samples at 60 min revealed a linear relationship between administered and internal doses (r(2) = 0.993). All doses of brevetoxin administered were detectable at 1 hr, with significant levels found for the lowest administered dose of 10 micro g/kg bw--a dose that was 10-fold lower than the lowest observable effect level. This RIA provides an optimal first-tier detection of brevetoxin from blood collection cards and, used in combination with the RBA and liquid chromatography-mass spectrometry, should provide a complete panel of methods to biomonitor brevetoxin exposure.
Asunto(s)
Exposición a Riesgos Ambientales , Toxinas Marinas/sangre , Oxocinas/sangre , Radioinmunoensayo/métodos , Animales , Anticuerpos/análisis , Cromatografía Liquida , Femenino , Toxinas Marinas/administración & dosificación , Espectrometría de Masas , Ratones , Ratones Endogámicos ICR , Oxocinas/administración & dosificación , Radioinmunoensayo/veterinaria , Sensibilidad y Especificidad , OvinosRESUMEN
The acute toxicity of yessotoxin (YTX), homoyessotoxin (homoYTX) and 45-hydroxy-homoyessotoxin (45-OH-homoYTX) has been studied in comparison to that of okadaic acid (OA), the main diarrhogenic toxin, both after intraperitoneal (i.p.) and oral administration. After i.p. administration, homoYTX and YTX showed similar lethality (LD(50)=444 microg/kg and 512 microg/kg), higher than that of OA (LD(50)=225 microg/kg), while 750 microg/kg of 45-OH-homoYTX did not cause death. OA induced the already known toxic signs: before death, mice were motionless and cyanotic; small intestine and liver damage were shown at post-mortem. Mice treated with YTX and homoYTX were restless and jumped before death; necroscopy did not show major changes. After oral treatment, 2 mg/kg of OA induced diarrhoea and body weight loss, causing 4/5 deaths; necroscopy and/or histology revealed degenerative lesions to small intestine, forestomach and liver (confirmed by increased plasma transaminase), but no myocardium alterations. On the contrary, the oral treatment with YTX (1 and 2 mg/kg) and its derivatives (1 mg/kg) did not cause any death or signs of toxicity, except some ultrastructural myocardiocyte alterations, adjacent to capillaries, such as cytoplasmic protrusions (YTX, 1 and 2 mg/kg), fibrillar alteration (YTX, 1 mg/kg) or mitochondria assemblage (45-OH-homoYTX). Altogether, our data show that YTX and its derivatives are less toxic than OA after acute oral and i.p. treatments, at doses which may represent up to 100 times of the possible human daily intake.
Asunto(s)
Éteres Cíclicos/toxicidad , Hígado/efectos de los fármacos , Venenos de Moluscos/toxicidad , Oxocinas/toxicidad , Administración Oral , Animales , Éteres Cíclicos/administración & dosificación , Femenino , Etiquetado Corte-Fin in Situ , Inyecciones Intraperitoneales , Dosificación Letal Mediana , Hígado/enzimología , Hígado/patología , Hígado/ultraestructura , Pruebas de Función Hepática , Ratones , Microscopía Electrónica , Moluscos , Venenos de Moluscos/administración & dosificación , Ácido Ocadaico/administración & dosificación , Ácido Ocadaico/toxicidad , Oxocinas/administración & dosificaciónRESUMEN
A short-term toxicity study after 7 days oral daily administration of yessotoxin (YTX; 2 mg/kg/day), homoYTX (1 mg/kg/day), 45-hydroxy-homoYTX (1 mg/kg/day) and of the main diarrhoetic shellfish toxin okadaic acid (OA; 1 mg/kg/day) was carried out in mice. Symptoms, lethality, food consumption, body and organ weights, gross pathology and histopathology of the main organs and tissues, leukocytes formula as well as plasmatic levels of transaminases, lactate dehydrogenase and creatinine phosphokinase were evaluated. Heart tissue was studied also hystochemically for the presence of apoptotic nuclei and by transmission electron microscopy. No mortality, signs of toxicity or cumulative effects were induced by the repeated oral exposure to YTXs. Only ultrastructural changes in the cardiac muscle cells near the capillaries, such as package of rounded mitochondria and alteration of the cells boundary were observed, without any increase of lactate dehydrogenase, an index of cardiac damage. OA induced diarrhoea, body weight loss, reduced food consumption, and the death of 2/5 mice after 5 days. Necroscopy and/or light microscopy analysis revealed toxic effects mainly at forestomach (ulceration and hyperplasia), liver and, indirectly to body weight loss of mice, atrophic signs in the lymphoid organs and exocrine pancreas. Electron microscopy of heart tissue showed alterations of mitochondria and fibers in myocardiocytes, although no apoptotic change was recorded.
Asunto(s)
Apoptosis/efectos de los fármacos , Éteres Cíclicos/toxicidad , Venenos de Moluscos/toxicidad , Miocardio/ultraestructura , Ácido Ocadaico/toxicidad , Oxocinas/toxicidad , Administración Oral , Animales , Análisis Químico de la Sangre , Constitución Corporal , Ingestión de Alimentos/efectos de los fármacos , Éteres Cíclicos/administración & dosificación , Femenino , Histocitoquímica , Etiquetado Corte-Fin in Situ , L-Lactato Deshidrogenasa/metabolismo , Leucocitos/efectos de los fármacos , Ratones , Microscopía Electrónica , Venenos de Moluscos/administración & dosificación , Ácido Ocadaico/administración & dosificación , Oxocinas/administración & dosificación , Estómago/patología , Pruebas de Toxicidad Aguda , Transaminasas/sangreRESUMEN
Histological and immunocytochemical investigations were performed on different organs (brain, duodenum and thymus) of mice following lethal (420 microg/kg) or sublethal (10 microg/kg) intraperitoneal injection of yessotoxin (YTX). No morpho-functional modifications were observed in large neurons of the cerebral and cerebellar cortex with the sub-lethal dose, nor in the cerebral cortex with the lethal dose. The duodenum also did not show significant alterations. However, there was an inflammation response to the toxin, in which blood cells and cytokines were involved. This was more evident with the lethal YTX dose. The thymus and, in general, the immune system are the main targets of YTX at both the concentrations used. Furthermore, the alterations present in the thymus may support tumorigenic implications.
Asunto(s)
Éteres Cíclicos/toxicidad , Sistema Inmunológico/efectos de los fármacos , Oxocinas/toxicidad , Timo/efectos de los fármacos , Análisis de Varianza , Animales , Apoptosis/efectos de los fármacos , Encéfalo/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Duodeno/efectos de los fármacos , Éteres Cíclicos/administración & dosificación , Histocitoquímica , Inmunohistoquímica , Inyecciones Intraperitoneales , Ratones , Venenos de Moluscos , Oxocinas/administración & dosificaciónRESUMEN
Brevetoxins and ciguatoxins are two classes of phycotoxins which exert their toxic effect by binding to site-5 of voltage-gated sodium channels. Sodium channels, a family of at least 10 structurally different proteins, are responsible for the rising phase of the action potential in membranes of neuronal, cardiac and muscular excitable cells. This work is a comparative study of the binding properties and the cytotoxic effects of ciguatoxins and brevetoxins on human embryonic cells (HEK) stably expressing either the skeletal muscle (Na(v)1.4), or the cardiac (Na(v)1.5) sodium channel alpha-subunit isoforms. We report that type A (PbTx-1) and type B (PbTx-3 and PbTx-2) brevetoxins as well as ciguatoxins target both cardiac and muscle channels; type B brevetoxins show isoform selectivity, presenting a lower affinity for the heart than the skeletal muscle channel. The lower selectivity of type B brevetoxins for heart sodium channels may result from a more rigid backbone structure than is found in type A brevetoxins and ciguatoxins.
Asunto(s)
Toxinas Marinas/farmacología , Neurotoxinas/farmacología , Oxocinas/farmacología , Canales de Sodio/efectos de los fármacos , Animales , Encéfalo/efectos de los fármacos , Línea Celular/efectos de los fármacos , Ciguatoxinas/administración & dosificación , Ciguatoxinas/química , Ciguatoxinas/farmacología , Dinoflagelados , Relación Dosis-Respuesta a Droga , Humanos , Concentración 50 Inhibidora , Activación del Canal Iónico/efectos de los fármacos , Toxinas Marinas/administración & dosificación , Toxinas Marinas/química , Músculo Esquelético/efectos de los fármacos , Miocardio/metabolismo , Neurotoxinas/administración & dosificación , Neurotoxinas/química , Especificidad de Órganos , Oxocinas/administración & dosificación , Oxocinas/química , Unión Proteica , Isoformas de Proteínas , Relación Estructura-ActividadRESUMEN
Pediatric drug development is challenging when a product is studied for a pediatric disease that has a different underlying etiology and pathophysiology compared to the adult disease. Neurogenic bladder dysfunction (NBD) is such a therapeutic area with multiple unsuccessful development programs. The objective of this study was to critically evaluate clinical trial design elements that may have contributed to unsuccessful drug development programs for pediatric NBD. Trial design elements of drugs tested for pediatric NBD were identified from trials submitted to the U.S. Food and Drug Administration. Data were extracted from publically available FDA reviews and labeling and included trial design, primary endpoints, enrollment eligibilities, and pharmacokinetic data. A total of four products were identified. Although all four programs potentially provided clinically useful information, only one drug (oxybutynin) demonstrated efficacy in children with NBD. The lack of demonstrable efficacy for the remainder of the products illustrates that future trials should give careful attention to testing a range of doses, using objectively measured, clinically meaningful endpoints, and selecting clinical trial designs that are both interpretable and feasible. Compiling the drug development experience with pediatric NBD will facilitate an improved approach for future drug development for this, and perhaps other, therapeutic areas.
Asunto(s)
Compuestos de Bencidrilo/uso terapéutico , Cresoles/uso terapéutico , Ácidos Mandélicos/uso terapéutico , Toxinas Marinas/uso terapéutico , Oxocinas/uso terapéutico , Fenilpropanolamina/uso terapéutico , Quinazolinas/uso terapéutico , Vejiga Urinaria Neurogénica/tratamiento farmacológico , Adolescente , Antagonistas de Receptores Adrenérgicos alfa 1/administración & dosificación , Antagonistas de Receptores Adrenérgicos alfa 1/farmacocinética , Antagonistas de Receptores Adrenérgicos alfa 1/uso terapéutico , Área Bajo la Curva , Compuestos de Bencidrilo/administración & dosificación , Compuestos de Bencidrilo/farmacocinética , Niño , Preescolar , Cresoles/administración & dosificación , Cresoles/farmacocinética , Preparaciones de Acción Retardada , Humanos , Lactante , Ácidos Mandélicos/administración & dosificación , Ácidos Mandélicos/farmacocinética , Toxinas Marinas/administración & dosificación , Toxinas Marinas/farmacocinética , Antagonistas Muscarínicos/administración & dosificación , Antagonistas Muscarínicos/farmacocinética , Antagonistas Muscarínicos/uso terapéutico , Oxocinas/administración & dosificación , Oxocinas/farmacocinética , Fenilpropanolamina/administración & dosificación , Fenilpropanolamina/farmacocinética , Quinazolinas/administración & dosificación , Quinazolinas/farmacocinética , Comprimidos , Tartrato de TolterodinaRESUMEN
The cellular localization of A-kinase anchoring proteins (AKAPs), protein kinase A (PKAs) and phosphodiesterases (PDEs) is a key step to the spatiotemporal regulation of the second messenger adenosine 3',5'-cyclic monophosphate (cAMP). In this paper the cellular distribution of the mitochondrial AKAP 149-PKA-PDE4A complex and its implications in the cell death induced by YTX treatment, a known PDE modulator, was studied. K-562 cell line was incubated with YTX for 24 or 48 h. Under these conditions AKAP 149, PKA and type-4A PDE (PDE4A) levels were measured in the cytosol, in the plasma membrane and in the nucleus. Apoptotic hallmarks were also measured after the same conditions. In addition, YTX effect on cell viability was checked after AKAP 149 and PDE4A silencing. The results obtained show a decrease in AKAP 149-PKA-PDE4A levels in cytosol after YTX exposure. 24h after the toxin addition, the complex expression increased in the plasma membrane and after 48 h in the nucleus domain. Furthermore Bcl-2 levels were decreased and the expression of caspase 3 together with caspase 8 activity were increased after 24h of toxin incubation but not after 48 h. These results suggest apoptotic cell death at 24h and a non-apoptotic cell death after 48 h. When AKAP 149 and PDE4A were silenced YTX did not induce cellular death. In summary, AKAP 149-PKA-PDE4A complex localization is related with YTX effect in K-562 cell line. When this complex is mainly located in the plasma membrane apoptosis is activated while when the complex is in the nuclear domain non-apoptotic cellular death or cellular differentiation is activated. Therefore AKAP 149-PKA-PDE4A distribution and integrity have a key role in cellular survival.
Asunto(s)
Proteínas de Anclaje a la Quinasa A/metabolismo , Supervivencia Celular/genética , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 4/metabolismo , Proteínas de Anclaje a la Quinasa A/genética , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/genética , Supervivencia Celular/efectos de los fármacos , AMP Cíclico/metabolismo , Proteínas Quinasas Dependientes de AMP Cíclico/genética , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 4/genética , Citosol/efectos de los fármacos , Citosol/metabolismo , Humanos , Venenos de Moluscos , Complejos Multiproteicos/genética , Complejos Multiproteicos/metabolismo , Oxocinas/administración & dosificación , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genéticaRESUMEN
The polyethers yessotoxin (YTX) and okadaic acid (OA) are two marine algal toxins frequently associated as edible shellfish contaminants. Seafood contamination by these compounds, also at low concentrations and for a long period of time, can increase the possibility of their simultaneous and repeated ingestion, with possible synergistic toxic effects. Thus, in vivo toxicity by repeated oral exposure to a combination of fixed doses of YTX and OA (1 mg YTX/kg and 0.185 mg OA/kg, daily for 7 days) was investigated in mice, in comparison to that of each toxin alone. No mortality, signs of toxicity, diarrhea or hematological changes was induced by the toxins co-administration or by the single toxins. Light microscopy revealed changes at gastric level (multifocal subacute inflammation, erosions and epithelial hyperplasia) in 2/5 mice co-administered with the toxins. In animals dosed only with OA, epithelial hyperplasia of forestomach and slight focal subacute inflammation of its submucosa were noted. No changes were induced by the treatment with YTX. Ultrastructural analysis of the heart revealed some cardiomyocytes with "loose packing" of myofibrils and aggregated rounded mitochondria in mice co-administered with the toxins or with YTX; OA-treated mice showed only occasional mitochondrial assemblage and dilated sarcomeres. Thus, the combined oral doses of YTX (1 mg/kg/day) and OA (0.185 mg/kg/day) did not exert cumulative or additive toxic effects in mice, in comparison to the single toxins.
Asunto(s)
Toxinas Marinas/toxicidad , Ácido Ocadaico/toxicidad , Oxocinas/toxicidad , Animales , Femenino , Corazón/efectos de los fármacos , Toxinas Marinas/administración & dosificación , Ratones , Ratones Endogámicos , Venenos de Moluscos , Miocardio/ultraestructura , Ácido Ocadaico/administración & dosificación , Oxocinas/administración & dosificación , Pruebas de Toxicidad , Transaminasas/sangreRESUMEN
For many years, the presence of yessotoxins (YTXs) in shellfish has contributed to the outcome of the traditional mouse bioassay and has on many occasions caused closure of shellfisheries. Since YTXs do not appear to cause diarrhoea in man and exert low oral toxicity in animal experiments, it has been suggested that they should be removed from regulation. Before doing so, it is important to determine whether the oral toxicity of YTXs is enhanced when present together with shellfish toxins known to cause damage to the gastrointestinal tract. Consequently, mice were given high doses of YTX, at 1 or 5 mg/kg body weight, either alone or together with azaspiracid-1 (AZA1) at 200 µg/kg. The latter has been shown to induce damage to the small intestine at this level. The combined exposure caused no clinical effects, and no pathological changes were observed in internal organs. These results correspond well with the very low levels of YTX detected in internal organs by means of LC-MS/MS and ELISA after dosing. Indeed, the very low absorption of YTX when given alone remained largely unchanged when YTX was administered in combination with AZA1. Thus, the oral toxicity of YTX is not enhanced in the presence of sub-lethal levels of AZA1.