The American bullfrog Lithobates catesbeianus has been introduced around the world, with invasive populations reported from almost all South American countries. A population of this species was introduced in the Calingasta department of San Juan province, which is an arid environment in western Argentina. This work provides information on the dietary composition of an invasive population of L. catesbeianus, and compares the degree of dietary overlap between adults and juveniles. Stomach contents of 169 bullfrogs (82 adults and 87 juveniles) were analysed. Adults consumed 40 prey taxa and Hymenoptera (Insecta) was the most numerous prey item (41.8%), followed by Araneae (13.6%) and Aeglidae (13.4%). Juveniles consumed 29 prey taxa and Hymenoptera constituted the highest percentage in prey number (77.2%). The trophic overlap niche index at the same level shows a value of 0.64 overlap in dietary community between adults and juveniles of this bullfrog. Aeglidae was volumetrically the most important trophic item (25.4%), followed by Anura (25.02%). Our results showed that cannibalism in bullfrogs is more common than the consumption of native anurans, coinciding with that reported in other populations of introduced bullfrogs. The high similarity in the diets of both size classes and the association between the size of the predator and prey suggest that the impact caused by bullfrogs throughout their ontogeny is high and probably has an impact on their prey. Freshwater crabs are the main items in the diet of Lithobates catesbeianus in other introduced populations and are usually the most conspicuous at our study site. The crabs in freshwater ecosystems are part of the lowest trophic level in the food chain. The major threats to the southern region's freshwater crabs include deforestation, farming and exotic species. Lithobates catesbeianus has a generalist diet and high overlap between adults and juveniles.
El síndrome de Devic, también conocido como trastorno del espectro de la neuromielitis óptica (NMOSD, por sus sigla en inglés), es considerado una enfermedad inflamatoria, desmielinizante y autoinmune del sistema nervioso central que afecta en su mayoría los nervios ópticos, el quiasma óptico y la médula espinal. Si bien en algunos casos se puede simular un cuadro clínico similar a esclerosis múltiple, hoy en día se conocen aspectos imagenológicos, inmunológicos y patológicos que permiten establecer las diferencias entre estas dos entidades. Se presenta el caso de una mujer adulta mayor con antecedente de síndrome de Sjögren en manejo ambulatorio con corticoide y azatioprina, quien ingresa por cuadro clínico de mes y medio de evolución consistente en disestesias de predominio en miembros inferiores, alteración de la marcha y compromiso visual. Ante el compromiso neurológico, se decide realizar imágenes diagnósticas y perfil inmunológico, con reportes de resonancia magnética nuclear cervical y torácica con contraste que evidencian mielitis multifocal por compromiso cervical y torácico a nivel de C4 en T7-T8 con hiperdensidad centromedular sin realce, además de autoanticuerpos séricos dirigidos contra el canal acuaporínico (AQP4) positivos, dando así el diagnóstico de NMOSD. Se inició manejo con pulsos de metilprednisolona concomitantemente con plasmaféresis completando cinco sesiones. Sin embargo, ante la persistencia del cuadro clínico se inició manejo con un agente biológico selectivo que bloquea la actividad de los linfocitos B tipo rituximab con resolución parcial de los síntomas. Se discute, además, la evolución clínica e imagenológica de este caso ejemplar, así como los avances más notables en el diagnóstico y manejo.
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