Draft genome of neotropical Bacillus thuringiensis UFT038 and its potential against lepidopteran soybean pests.

Bacillus thuringiensis (Bt) is known for its Cry and Vip3A pesticidal proteins with high selectivity to target pests. Here, we assessed the potential of a novel neotropical Bt strain (UFT038) against six lepidopteran pests, including two Cry-resistant populations of fall armyworm, Spodoptera frugiperda. We also sequenced and analyzed the genome of Bt UFT038 to identify genes involved in insecticidal activities or encoding other virulence factors. In toxicological bioassays, Bt UFT038 killed and inhibited the neonate growth in a concentration-dependent manner. Bt UFT038 and HD-1 were equally toxic against S. cosmioides, S. frugiperda (S_Bt and R_Cry1 + 2Ab populations), Helicoverpa zea, and H. armigera. However, larval growth inhibition results indicated that Bt UFT038 was more toxic than HD-1 to S. cosmioides, while HD-1 was more active against Chrysodeixis includens. The draft genome of Bt UFT038 showed the cry1Aa8, cry1Ac11, cry1Ia44, cry2Aa9, cry2Ab35, and vip3Af5 genes. Besides this, genes encoding the virulence factors (inhA, plcA, piplC, sph, and chi1-2) and toxins (alo, cytK, hlyIII, hblA-D, and nheA-C) were also identified. Collectively, our findings reveal the potential of the Bt UFT038 strain as a source of insecticidal genes against lepidopteran pests, including S. cosmioides and S. frugiperda.

Pseudomonas aeruginosa and Bacillus cereus Isolated from Brazilian Cerrado Soil Act as Phosphate-Solubilizing Bacteria.

The phosphate-solubilizing microorganism is essential for soil quality and plant development and can serve as an alternative to reduce such Brazilian needs for importing phosphate overseas. Here, we isolated and selected bacteria from Brazilian Cerrado soils capable of solubilize phosphate. We obtained 53 bacteria isolates, of which 23 could solubilize phosphate at a pH of 7.0, 17 could solubilize phosphate at a pH of 6.0, and 8 could solubilize at a pH of 5.5. Using 16S rRNA gene sequences, we identified nine bacteria species clustered in four groups: Bacillus sp., Pseudomonas sp., Priestia sp., and Klebsiella sp. Our results revealed that the UFT01 (P. aeruginosa) and UFT42 (B. cereus) isolates exhibited the best phosphate solubilization performance at all tested pH values. We further recorded higher levels of solubilization and phosphate availability six days after the soil inoculation with P. aeruginosa, and enzymatic analysis of the soil samples revealed that the P. aeruginosa-inoculated samples resulted in four-fold higher enzymatic activities when compared to non-inoculated soils. The B. cereus soil inoculation increased ß-glucosidase activities and resulted in reduced the activities of arylsulfatase. Altogether, our findings demonstrated that P. aeruginosa and B. cereus isolated from Cerrado soils showed high phosphate solubilization potential.

Genomic-proteomic analysis of a novel Bacillus thuringiensis strain: toxicity against two lepidopteran pests, abundance of Cry1Ac5 toxin, and presence of InhA1 virulence factor.

Bacillus thuringiensis (Bt) is a biological alternative to the indiscriminate use of chemical insecticides in agriculture. Due to resistance development on insect pests to Bt crops, isolating novel Bt strains is a strategy for screening new pesticidal proteins or strains containing toxin profile variety that can delay resistance. Besides, the combined genomic and proteomic approaches allow identifying pesticidal proteins and virulence factors accurately. Here, the genome of a novel Bt strain (Bt TOL651) was sequenced, and the proteins from the spore-crystal mixture were identified by proteomic analysis. Toxicity bioassays with the spore-crystal mixture against larvae of Diatraea saccharalis and Anticarsia gemmatalis, key pests of sugarcane and soybean, respectively, were performed. The toxicity of Bt TOL651 varies with the insect; A. gemmatalis (LC50 = 1.45 ng cm-2) is more susceptible than D. saccharalis (LC50 = 73.77 ng cm-2). Phylogenetic analysis of the gyrB gene indicates that TOL651 is related to Bt kenyae strains. The genomic analysis revealed the presence of cry1Aa18, cry1Ac5, cry1Ia44, and cry2Aa9 pesticidal genes. Virulence factor genes such as phospholipases (plcA, piplc), metalloproteases (inhA), hemolysins (cytK, hlyIII, hblA, hblC, hblD), and enterotoxins (nheA, nheB, nheC) were also identified. The combined use of the genomic and proteomic data indicated the expression of Cry1Aa18, Cry1Ac5, and Cry2Aa9 proteins, with Cry1Ac5 being the most abundant. InhA1 also was expressed and may contribute to Bt TOL651 pathogenicity. These results provide Bt TOL651 as a new tool for the biocontrol of lepidopteran pests.

Potential Action Mechanism and Inhibition Efficacy of Morinda citrifolia Essential Oil and Octanoic Acid against Stagonosporopsis cucurbitacearum Infestations.

The use of plant-based products has been shown to efficiently inhibit fungi-mediated diseases in agricultural crops. Here, we extracted and evaluated the composition of noni, Morinda citrifolia L., essential oil and assessed its activities against Stagonosporopsis cucurbitacearum in Cucumis melo L. Using in silico molecular approaches, potential interactions between the essential oil major components and S. cucurbitacearum tyrosine-tRNA ligase were predicted. Finally, we also measured the potential interference of plant physiology (the stomatal conductance and net photosynthesis) mediated by the application of the M. citrifolia essential oil. Chromatographic analysis revealed that octanoic acid (75.8%), hexanoic acid (12.8%), and isobutyl pent-4-enyl carbonate (3.1%) were the major essential oil compounds. Octanoic acid and noni essential oil, when used as preventive measures, reduce fungal mycelial growth at a concentration of 5 mg/mL without causing significant damage to the treated leaves, which reinforces their efficacies as preventive tools against S. cucurbitacearum. Molecular docking analyses predicted very stable interactions between the major essential oil constituents and S. cucurbitacearum tyrosine-tRNA ligase, suggesting the interference of these plant-based molecules upon enzyme activation. Octanoic acid and M. citrifolia essential oil at concentrations of 20 mg/mL decreased the stomatal conductance and net photosynthesis rate of melon plants, resulting in robust phytotoxicity. Collectively, our findings indicated that despite the phytotoxicity risks at higher concentrations, M. citrifolia essential oil and octanoic acid, have potential as alternative tools for the integrative management of S. cucurbitacearum.

Bayesian Multi-Targets Strategy to Track Apis mellifera Movements at Colony Level.

Interactive movements of bees facilitate the division and organization of collective tasks, notably when they need to face internal or external environmental challenges. Here, we present a Bayesian and computational approach to track the movement of several honey bee, Apis mellifera, workers at colony level. We applied algorithms that combined tracking and Kernel Density Estimation (KDE), allowing measurements of entropy and Probability Distribution Function (PDF) of the motion of tracked organisms. We placed approximately 200 recently emerged and labeled bees inside an experimental colony, which consists of a mated queen, approximately 1000 bees, and a naturally occurring beehive background. Before release, labeled bees were fed for one hour with uncontaminated diets or diets containing a commercial mixture of synthetic fungicides (thiophanate-methyl and chlorothalonil). The colonies were filmed (12 min) at the 1st hour, 5th and 10th days after the bees' release. Our results revealed that the algorithm tracked the labeled bees with great accuracy. Pesticide-contaminated colonies showed anticipated collective activities in peripheral hive areas, far from the brood area, and exhibited reduced swarm entropy and energy values when compared to uncontaminated colonies. Collectively, our approach opens novel possibilities to quantify and predict potential alterations mediated by pollutants (e.g., pesticides) at the bee colony-level.

Acaricide activity of extract and an isolated compound of Lithraea brasiliensis on Rhipicephalus microplus and selectivity actions against a non-target organism.

Rhipicephalus microplus, known as the cattle tick, is a cause of great economic losses for dairy cattle farming because of its high frequency of occurrence and the difficulty in controlling it. This research characterized the chemical profile and evaluated the in vitro toxicity of crude Lithraea brasiliensis extract and its isolated compound against acaricide-resistant and acaricide-susceptible R. microplus strains. Acaricidal activity was evaluated using a larval immersion test and the selectivity against non-target organisms was assessed on Artemia salina assay. The chemical investigation by high-performance liquid chromatography coupled with mass spectrometry (i.e., HPLC-MS) analysis showed the presence of hydrolysable tannins as well as urushiol derivatives. Column chromatography (CC) was carried out on the extract to obtain fractions and an isolated compound. The extract exhibited significant activity against acaricide-resistant (LC50 0.64 mg/mL) and acaricide-susceptible (LC50 0.76 mg/mL) strains of R. microplus larvae. The isolated compound from the extract (urushiol II), exhibited LC50 of 1.11 mg/mL for acaricide-resistant larvae. For acute toxicity in A. salina, the extract showed LC50>100 µg/mL. Thus, our findings represent the first effort to demonstrate the potential of L. brasiliensis extract and urushiol II as potential natural acaricides to replace or to be integrated into the conventional control of R. microplus larvae.

The salivary glands of Brontocoris tabidus (Heteroptera: Pentatomidae): Morphology and secretory cycle.

Brontocoris tabidus (Signoret) (Heteroptera: Pentatomidae) is a zoophytophagous insect used for biological control in agriculture and forest systems because its nymphs and adults feed on insects and plants. The predatory Pentatomidae insert the mouthparts into the prey, releasing saliva to paralysis and kills the insect, as well as digest body parts to be sucked in a preliminary extra-oral digestion. In a short period of time, this insect shows the ability to feed again, suggesting the existence of a constant and abundant secretory cycle in the salivary glands. This study evaluated the morphological, histochemical and ultrastructural changes of the salivary glands of B. tabidus in fed and starved insects. The salivary complex of this predatory bug has a pair of bilobed salivary glands and a pair of tubular accessory salivary glands. The accessory glands have the lumen lined by a thick non-cuticular layer rich in glycoproteins. The secretory cells of the B. tabidus principal salivary glands have constant secretory activity, with each lobe producing different substances. The physiological processes that occur in the salivary gland of B. tabidus indicate that the insect needs to feed constantly, corroborating the potential of this insect to be used in biological control programs.

Disentangling the ecotoxicological selectivity of clove essential oil against aphids and non-target ladybeetles.

The plant-based biopesticides have been proposed as insect pest control tools that seem to be safer for the environment and human health when compared to synthetic conventional molecules. However, such assumptions are generally made without considering the absence of detrimental effects on sublethally-exposed non-target organisms or showing the physiological basis of the selective action of such botanical products. Thus, by using in silico-based and in vivo toxicological approaches, the present investigation aimed to disentangle the ecotoxicological selectivity of clove, Syzygium aromaticum, essential oil against the aphid Rhopalosiphum maidis and the non-target ladybeetle, Coleomegilla maculata. We also investigated whether the sublethal exposure to clove essential oil would affect the locomotory and predatory abilities of C. maculata. We found that the clove essential oil concentration estimated to kill 95% (LC95: 0.17 µL/cm2) of the aphids was lethal to <18% of C. maculata. Indeed, our in silico results reinforced such differential susceptibility, as it predicted that eugenol and ß-caryophyllene (i.e., the clove essential oil major components) bound to three potential molecular targets (i.e., transient receptor potential (TRP) channels, octopamine, and gamma-aminobutyric acid (GABA) receptors) of the aphids but only to the octopamine receptors of the ladybeetles. Additionally, the ladybeetles that were exposure to the clove essential oil exhibited unaffected abilities to locomote and to prey upon R. maidis aphids when compared to unexposed ladybeetles. Thus, by displaying lower toxicity against the ladybeetles, the clove essential oil represents a safer alternative tool to be integrated into programs aiming to manage aphid infestations.

Rethinking biorational insecticides for pest management: unintended effects and consequences.

Biorational insecticides are composed of natural products, including animals, plants, microbes, and minerals, or are their derivates. The use of biorational products for the management of insect pests has grown intensively in recent years, which has increased their popularity and share on the insecticide global market. Much of these recent increases in the use of biorational insecticides has been derived from the generalized perception that conventional insecticides have undesirable ecological and human health impacts. However, the idea of simply replacing synthetic compounds with biorational insecticides without considering their potential unintended effects can mislead their use and reduce the market life of such pest management tools. A systematic literature survey encompassing over 15 000 scientific manuscripts published between 1945 and 2019 reinforces the bias of focusing on studying the targeted effects while overlooking the potential detrimental effects of biorational products on human health and the environment (e.g. death and negative sublethal effects on pollinators and beneficial arthropods such as parasitoids and predators). Thus, the risks associated with biorational compounds (e.g. control failures, the evolution of resistance, shift in dominance, and outbreaks of secondary or primary pests) need to be revisited and the outcomes of such inquiry could be decisive for their future use in pest management programs. The shortcomings of regulatory processes, knowledge gaps, and the outlook for the use of the biorational products in pest management are discussed. © 2020 Society of Chemical Industry.

Essential oil from Negramina (Siparuna guianensis) plants controls aphids without impairing survival and predatory abilities of non-target ladybeetles.

Plant essential oils are regarded as interesting alternative tools to be integrated into the management of pest insects. However, as they generally consist of mixtures of numerous molecules, the physiological basis for their action is unresolved. Here, we evaluated the effects of essential oil of the Neotropical plant Siparuna guianensis Aubl., commonly known as Negramina, against an important pest insect: the green peach aphid Myzus persicae (Sulzer), and also in two non-target natural enemies: the ladybeetle predators Coleomegilla maculata (DeGeer) and Eriopis connexa (Germar). In addition, we conducted a computational docking analysis for predicting the physical interactions between the two Negramina essential oil major constituents: ß-myrcene and 2-undocanone, and the transient receptor potential (TRP) channels as potential binding receptors in the aphid and ladybeetles. As the most important results, Negramina essential oil caused mortality in M. persicae aphids with an LC95 = 1.08 mg/cm2, and also significantly repelled the aphids at concentrations as low as 0.14 mg/cm2. Our computational docking analysis reinforced such selectivity actions as the Negramina essential oil major compounds (i.e., ß-myrcene and 2-undocanone) bound to the TRP channels of M. persicae but not to ladybeetle-related TRP channels. Interestingly, the exposure to the Negramina essential oil did not affect the predatory abilities of C. maculata but increased the abilities of E. connexa to prey upon M. persicae. Collectively, our findings provided a physiological basis for the insecticidal and selectivity potential of Negramina essential oil, reinforcing its potential as a tool to be used in integrated pest control programs.

Prolonged mosquitocidal activity of Siparuna guianensis essential oil encapsulated in chitosan nanoparticles.

BACKGROUND: The use of synthetic insecticides is one of the most common strategies for controlling disease vectors such as mosquitos. However, their overuse can result in serious risks to human health, to the environment, as well as to the selection of insecticidal resistant insect strains. The development of efficient and eco-friendly insect control is urgent, and essential oils have been presented as potential alternatives to synthetic insecticides. Moreover, nanoencapsulation techniques can enhance their efficiency by protecting from degradation and providing a controlled release rate. RESULTS: We assessed the potential of chitosan nanoparticles in encapsulating Siparuna guianensis essential oil, and maintaining its efficiency and prolonging its activity for the control of Aedes aegypti larvae. The encapsulation was characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), with an encapsulation efficiency ranging from 84.8% to 88.0%. Toxicity studies have demonstrated efficacy against mosquito larvae over 50% for 19 days with 100% mortality during the first week. This persistent action is presumably due to the enhanced contact and slow and maintained release conferred by chitosan nanoparticles. Furthermore, the exposure of aquatic non-target organisms (e.g. embryos and small adult fishes) revealed adequate selectivity of these nanoparticles. CONCLUSIONS: The encapsulation of S. guianensis essential oil in chitosan nanoparticles showed promising potential as a larvicide control alternative and should be considered within strategies for fighting Ae. aegypti.

The lacewing Ceraeochrysa caligata as a potential biological agent for controlling the red palm mite Raoiella indica.

BACKGROUND: Compared to chemical control, the use of naturally occurring biological agents to control invasive pests is less threatening to the environment and human health. OBJECTIVES: Here, we assessed the ability of immature stages of the lacewing Ceraeochrysa caligata (Neuroptera: Chrysopidae) to prey upon different developmental stages of the red palm mite Raoiella indica (Acari: Tenuipalpidae), one of the most destructive invasive pests of palm trees in Neotropical regions. METHODS: Increasing densities of three stages of R. indica (eggs, immature stages, and adult females) were offered to C. caligata in coconut leaf arenas. The immature stages of C. caligata were less than 24 h old and were starved before being transferring to the arenas. The amount of prey consumed was recorded 6 h after releasing the C. caligata. RESULTS: Our results indicated that the ability of C. caligata to feed upon R. indica increased with the larval development of the predator. Higher feeding levels and shorter handling times were recorded for the first and second instars of C. caligata when preying upon the eggs and immature stages of R. indica. Furthermore, C. caligata individuals of different stages exhibited differential functional responses according to prey type (i.e., eggs, immatures, or adult females of R. indica). Ceraeochrysa caligata second instar individuals exhibited a sigmoid increase in consumption rate with increasing prey availability (i.e., a type III functional response) when preying upon immature stages of R. indica. However, when preying upon R. indica adult females, C. caligata second instar individuals exhibited a type II functional response (i.e., an increase in consumption rate with increasing prey availability, before reaching a plateau). Predator individuals of the first and third instar stages exhibited a type II functional response for all prey types. CONCLUSIONS: Collectively, our findings demonstrate that C. caligata, especially at the second instar stage, has potential as a tool for ecological management of the red palm mite.

Toxicity to, oviposition and population growth impairments of Callosobruchus maculatus exposed to clove and cinnamon essential oils.

The use of plant essential oils has been shown to efficiently control insect pests of stored beans, significantly reducing the threats associated with synthetic insecticides. Here, we evaluated the potential of applications of essential oils of clove, Syzygium aromaticum L., and cinnamon, Cinnamomum zeylanicum L., to control Callosobruchus maculatus, considered as one of the most cosmopolitan pests of stored beans. Using four combinations of couples (i.e., unexposed couples, exposed females, exposed males, and exposed couples), we also evaluated how sublethal exposure to these essential oils impacted C. maculatus oviposition. Bioassays results revealed that both essential oils exhibited insecticidal activities similar to the synthetic pyrethroid insecticide deltamethrin. Furthermore, oil dosage increments proportionately decreased the growth rate and reduced the losses in bean weight caused by cowpea weevils, and offspring emergence was almost abolished when parents were exposed to the LD20 of each essential oil. Finally, significant oviposition impairments were perceived only in couples where females were exposed (i.e., females exposed and exposed couples) to the LD20 of cinnamon and clove essential oils. Thus, by exhibiting similar insecticidal activities as synthetic insecticides and by significantly affecting the oviposition of sublethally exposed C. maculatus females, the cinnamon and clove essential oils represent valuable tools with potential of integration into the management of C. maculatus infestations.

Diversity and convergence of mechanisms involved in pyrethroid resistance in the stored grain weevils, Sitophilus spp.

Target-site mutations and changes in insect metabolism or behavior are common mechanisms in insecticide-resistant insects. The co-occurrence of such mechanisms in a pest strain is a prominent threat to their management, particularly when alternative compounds are scarce. Pyrethroid resistance among stored grain weevils (i.e., Sitophilus spp.) is an example of a long-standing concern, for which reports of resistance generally focus on a single mechanism in a single species. Here, we investigated pyrethroid resistance in maize and rice weevils (i.e., Sitophilus zeamais and S. oryzae), exploring potential knockdown resistance (kdr) mutations in their sodium channels (primary site for pyrethroid actions) and potential changes in their detoxification and walking processes. Resistance in pyrethroid-resistant rice weevils was associated with the combination of a kdr mutation (L1014F) and increases in walking and detoxification activities, while another kdr mutation (T929I) combined with increases in walking activity were the primary pyrethroid resistance mechanisms in maize weevils. Our results suggest that the selection of pyrethroid-resistant individuals in these weevil species may result from multiple and differential mechanisms because the L1014F mutation was only detected in Latin American rice weevils (e.g., Brazil, Argentina and Uruguay), not in Australian and Turkish rice weevils or Brazilian maize weevils.

Morbilidad de la enfermedad de Chagas en fase cronica en Colombia. Deteccion de pacientes chagasicos con cardiopatia en un area endemica del departamento de Boyaca / Morbidity of Chagas's disease in chronic phase on Colombia

Introducción: en Colombia se estima que existen 1.200.000 personas infectadas con T. cruzi. Los estudios publicados sobre cardiomiopatía chagásica en Colombia han sido usualmente descritos en hospitales de tercer nivel. Objetivo: caracterizar desde el punto de vista clínico y electrocardiográfico la cardiomiopatía chagásica crónica en centros de atención primaria en un área endémica. Diseño del estudio: estudio descriptivo, seccional de morbilidad en población chagásica y no chagásica no seleccionadas. Lugar del estudio: municipios de San Eduardo, Zetaquira y Campohermoso, Boyacá. Pacientes: 405 individuos. Mediciones: se consideraron: edad, sexo, escolaridad, antecedentes, síntomas y signos físicos y hallazgos electrocardiográfícos. Se practicaron serologías por test de ELISA e IFI. Se estableció como seropositivo aquel paciente con positividad en las dos pruebas y seronegativo aquél con resultado negativo en las dos técnicas. Análisis estadístico: se calcularon promedios y proporciones de las distintas variables para los dos grupos de acuerdo con el nivel de medición y se establecieron las diferencias de proporciones entre ellos, tomando un nivel de significación del 0.5 por ciento. Resultados: 405 individuos, 205 seropositivos y 200 seronegativos (control). Edad promedio 45 años, 58 por ciento del sexo femenino para ambos grupos. El 80 por ciento del total de los dos grupos no alcanzó un nivel de escolaridad mayor al de primaria completa. Los hallazgos significativos a favor del grupo de seropositivos fueron: contacto con triatominios (p.-O.OOOl), Chagas en hermanos (p :0.01), muerte súbita en hermanos (p:0.04), sensación de palpitaciones (p:0.05), presíncope (p:0.005), angina (p:0.03), insuficiencia mitral (p:0.004), bloqueo de rama derecha (p:0.01), bloqueo bifascicular (p :0.007) y trastornos de la repolarización (p;0.008). Conclusiones: los hallazgos observados en el grupo de pacientes seropositivos con diagnóstico de cardiomiopatía de Chagas, corresponden a estadios clínicos I y II de la enfermedad. La edad media, el predominio en el sexo femenino, el pobre nivel de escolaridad, los antecedentes personales y familiares, son de resaltar por su impacto socio-económico

Cardiomiopatia de Chagas / Chagas cardiomyopathy

Objetivo: realizar una revisión actualizada sobre la cardiomiopatía de Chagas. Fuente de datos: se efectuó una búsqueda en las bases de datos Medline, Lilacs y Sibra en los siguientes aspectos: reseña histórica, patogenia, fisiopatología, definición de caso, espectro del compromiso cardíaco, experiencia institucional y de otros investigadores en el país y finalmente las bases y enfoque actual del tratamiento etiológico. Selección del estudio: se estudiaron 79 trabajos que informaban sobre las tópicos relacionados con el tema. Extracción de datos: los artículos se clasificaron según se trataran de revisiones, artículos originales o informes de casos. Recopilamos y analizamos los artículos originales y luego elaboramos la revisión, el resumen y las conclusiones. Síntesis de datos y conclusiones: los estudios demuestran que la cardiomiopatía de Chagas es la causa más frecuente de cardiomiopatía en América Latina con una variable forma de presentación y un importante impacto sobre la morbimortalidad. Se resalta el aparente papel del T. cruzi en la patogenia de la fase crónica de la enfermedad, el cual es detectado por técnicas de PCR hasta en 63 por ciento de los casos. Se presenta la propuesta de tratamiento etiológico de la enfermedad publicada por la OPS y la OMS.

Cardiomiopatia chagasica cronica: relacion entre severidad y presencia de Trypanosoma cruzi circulante detectado por la reaccion en cadena de la polimerasa / Chronic chagasic cardiomiopathy

Introducción: en la enfermedad de Chagas, con los métodos parasitológicos convencionales sólo se detecta un número reducido de parásitos en los individuos infectados crónicamente lo que ha conducido a la teoría que sugiere que los hallazgos clínicos y anatomopatológicos pueden ser primariamente autoinmunes en su origen. Objetivo: establecer si la detección de antígenos de T. cruzi circulantes por la reacción en cadena de la polimerasa (PCR) en pacientes con diagnóstico de cardiomiopatía chagásica crónica (criterios OMS) puede relacionarse con la severidad de la enfermedad. Métodos: evaluación clínica y paraclínica (electrocardiograma de rutina, radiografía de tórax, ecocardiograma doppler color, test de Holter de 24 horas y/o estudio electrofisiológico) asociada a la realización de una prueba de PCR efectuada en sangre y suero. La severidad en la cardiomiopatía fue definida por la presencia de uno o más de los siguientes hallazgos: disfunción ventricular izquierda (<40 por ciento), disfunción del nodo sinusal, bloqueo auriculoventricular completo y taquicardia ventricular sostenida. Tipo de estudio: observacional analítico de corte transversal. Análisis estadístico: se comparó la prevalencia de los hallazgos definidos como severidad de la cardiomiopatía entre los pacientes con y sin detección de antígenos circulantes por PCR. Se calcularon los riesgos relativos con intervalos de confianza del 95 por ciento. El valor de p considerado como estadísticamente significativo fue de ¿0.05. Resultados: se estudiaron 64 pacientes, 29 hombres y 35 mujeres , edad media 55.5 ±13 años. En 34 de los 64 pacientes (55 por ciento) se encontraron antígenos de T. cruzi circulantes por PCR. No se observó una diferencia estadísticamente significativa con relación a la edad, el género, ni con la severidad de la cardiomiopatía entre el grupo de pacientes con antígenos de T. cruzi circulantes comparado con el grupo en el que este hallazgo no fue encontrado. Conclusión: Se detectó una infección activa o la presencia de antígenos circulantes de T. cruzi por la PCR en el 55 por ciento de los pacientes con diagnóstico de cardiomiopatía chagásica crónica. No se encontró ninguna relación entre la presencia de antígenos de T. cruzi circulantes y la severidad de la cardiomiopatía en esta población. Otros mecanismos posiblemente de tipo autoinmune pueden estar relacionados con la severidad de la cardiomiopatía en estos casos.

Sincope neurocardiogenico: relacion con la edad genero y tipo de respuesta en la prueba de la mesa basculante / Neurocardiogenic syncope

Tradicionalmente se considera que el síncope neurocardiogénico (SNC) es una causa común de síncope en especial en mujeres jóvenes. En pacientes con síncope de causa no explicada la prueba de la mesa basculante (PMB) es considerada como una herramienta útil para identificar el diagnóstico de SNC. El propósito de este estudio es 1. Determinar la prevalencia de la positividad del SNC en pacientes con síncope de causa no establecida y su relación con la edad y el género. 2. Establecer si la edad tiene una relación con el tipo de respuesta vasovagal en la PMB. Métodos. Se realizó un estudio descriptivo de corte transversal. Se incluyeron pacientes referidos a nuestro centro para una PMB por síncope inexplicado entre septiembre de 1991 y mayo de 1999. Los sujetos fueron divididos en grupos etéreos: < 18 años (grupo 1), entre 19 y 64 años (grupo 2) y > 65 años (grupo 3). La positividad de la PMB fue definida por la presencia de síncope o presíncope asociados a disminución de la presión arterial sistólica (TAS) <- 70 mm con o sin disminución de la frecuencia cardíaca (FC). El tipo de respuesta fue clasificada como vasodepresora: TAS < 70 mmHg y C > 70 Ipm, mixta: TAS < mmHg y FC entre 50-70 Ipm y cardioinhibitoria: TAS < 70 mmHg y FC > 70 Ipm y/o pausas sinusales > 3 segundos. Resultados. Del grupo total de 1.006 individuos, en 405 pacientes se observó una respuesta positiva a la PMB (40.3 por ciento) con edad media de 38.9121 años (4 a 89 años). Un 39 por ciento de los pacientes del grupo 3 tenían antecedentes de hipertensión arterial, un 8.4 por ciento en el grupo 2 y ninguno en el grupo 1. Por grupos etéreos la PMB fue positiva en el 48 por ciento de los pacientes en el grupo 1, en el 40.1 por ciento en el grupo 2 y finalmente en el 28.6 por ciento en el grupo3. Con relación a la edad y el sexo, tan sólo se observó una diferencia limítrofe a favor de las mujeres en el grupo 3 (34.9 por ciento vs 22.4 por ciento, p:0.05). Con respecto al tipo de respuesta, la vasodepresora fue la más frecuente en todos los grupos en especial en los mayores de 65 años (grupo 1: 51.5 por ciento, grupo 2: 62.4 por ciento, grupo 3:78.3 por ciento...

Taquicardia ventricular fascicular verapamil sensible / Fascicular ventricular tachycardia verapamil sensitive

La taquicardia ventricular fascicular es una forma infrecuente de taquicardia sensible al verapamil, usualmente observada en hombres jóvenes sin cardiopatía asociada. Presentamos nuestra experiencia en 8 pacientes, 6 hombres, 2 mujeres con edad media de 24 ñ 14 años y síntomas de 39 ñ 57 meses (rango: 6 a 180 meses) de evolución consistentes en palpitaciones paroxísticas en 6 casos y en falla cardíaca por taquicardia incesante en 2. Las características electrocardiográficas en taquicardia consistieron en: morfología de bloqueo de rama derecha, eje izquierdo -93º ñ 22º (rango: -40" a -110º), frecuencia cardíaca media de 156 ñ 32 Ipm (rango: 133 a 252 Ipm), duración media del QRS de 127 ñ 7 ms (rango 115 a 140 ms), intervalo RS medio en el plano horizontal de 76 ñ 7 ms (rango 70 a 80 ms). En 6 pacientes se observó disociación aurículo-ventricular (75 por ciento). En cada caso la sensibilidad al verapamil fue demostrada. La fracción de eyección media del ventrículo izquierdo fue de 49 ñ 16 por ciento. En todos los casos el sitio de origen de la taquicardia fue localizado en el septum apical e inferior del ventrículo izquierdo donde se registro por mapeo endocárdico un potencial presistólico de Purkinje en 6 pacientes (75 por ciento). Los 8 pacientes fueron sometidos a ablación con energía de radiofrecuencia con resultado exitoso (100 por ciento). En un seguimiento de 22 ñ 14 meses todos los pacientes permanecen asintomáticos. En los dos casos con compromiso significativo de la función ventricular izquierda ésta retorno a valores normales luego de seis meses de la ablación

Sindrome de Brugada. Presentacion de un caso / Brugada's syndrome. Two cases

El síndrome de bloqueo de rama derecha y elevación del segmento ST de VI a V3 y muerte súbita en pacientes con corazón normal es una nueva entidad. La enfermedad está genéticamente determinada y es diferente del síndrome de QT largo y de la displasia arritmogénica del ventrículo derecho. El electrocardiograma es un marcador de muerte súbita en pacientes sintomáticos y en individuos asintomáticos. La incidencia de muerte súbita es alta y sólo puede ser prevenida con el implante de un cardiodestibrilador. Presentamos dos casos que ilustran el diagnóstico y manejo del síndrome de Brugada