Flagellar Motility of Trypanosoma cruzi Epimastigotes

The hemoflagellate Trypanosoma cruzi is the causative agent of American trypanosomiasis. Despite the importance of motility in the parasite life cycle, little is known about T. cruzi motility, and there is no quantitative description of its flagellar beating. Using video microscopy and quantitative vectorial analysis of epimastigote trajectories, we find a forward parasite motility defined by tip-to-base symmetrical flagellar beats. This motion is occasionally interrupted by base-to-tip highly asymmetric beats, which represent the ciliary beat of trypanosomatid flagella. The switch between flagellar and ciliary beating facilitates the parasite's reorientation, which produces a large variability of movement and trajectories that results in different distance ranges traveled by the cells. An analysis of the distance, speed, and rotational angle indicates that epimastigote movement is not completely random, and the phenomenon is highly dependent on the parasite behavior and is characterized by directed and tumbling parasite motion as well as their combination, resulting in the alternation of rectilinear and intricate motility paths

Improved Method for In Vitro Secondary Amastigogenesis of Trypanosoma cruzi: Morphometrical and Molecular Analysis of Intermediate Developmental Forms

Trypanosoma cruzi undergoes a biphasic life cycle that consists of four alternate developmental stages. In vitro conditions to obtain a synchronic transformation and efficient rates of pure intermediate forms (IFs), which are indispensable for further biochemical, biological, and molecular studies, have not been reported. In the present study, we established an improved method to obtain IFs from secondary amastigogenesis. During the transformation kinetics, we observed progressive decreases in the size of the parasite body, undulating membrane and flagellum that were concomitant with nucleus remodeling and kinetoplast displacement. In addition, a gradual reduction in parasite movement and acquisition of the amastigote-specific Ssp4 antigen were observed. Therefore, our results showed that the in vitro conditions used obtained large quantities of highly synchronous and pure IFs that were clearly distinguished by morphometrical and molecular analyses. Obtaining these IFs represents the first step towards an understanding of the molecular mechanisms involved in amastigogenesis

Protocolo de manejo en deshidratación hipernatrémica neonatal

La deshidratación hipernatrémica neonatal (DHN) es una enfermedad grave y se asocia con edema cerebral, hemorragia intracraneal y gangrena. El manejo de estos pacientes es controvertido por las complicaciones que se han reportado si la corrección de la natremia se lleva a cabo rápidamente. Se propone un protocolo para disminuir lentamente el sodio sérico. Metodología: Estudio prospectivo que incluyó a pacientes con Na sérico >150 mEq. Se manejaron con una carga rápida de solución salina y soluciones de rehidratación con 50 mEq de Na/L y glucosa al 5%. Se monitorizó el Na sérico a las 12 y las 24 horas. Resultados: Se ingresaron al estudio 51 pacientes, con una incidencia identificada de 10.2 casos por 1,000 recién nacidos vivos. El promedio de Na en el momento del ingreso fue de 158 mEq/l. El promedio de disminución de Na en las primeras 12 horas fue de 0.53 ± 0.08 mEq/l/h. En las siguientes 12 horas fue de 0.46 ± 0.09 mEq/l/h. No se presentaron alteraciones neurológicas en ningún paciente. Conclusiones: La rehidratación en el neonato con DHN con una o dos cargas de solución salina al 0.9% y el posterior manejo con soluciones con 50 mEq/l de Na y solución glucosada al 5% (“tercio normal”) fueron seguros para descender lentamente los niveles séricos de Na, aproximadamente, a 0.5 mEq/h

The mKate fluorescent protein expressed by Leishmania mexicana modifies the parasite immunopathogenicity in BALB/c mice.

Parasites have been engineered to express fluorescent reporter proteins, yet the impact of red fluorescent proteins on Leishmania infections remains largely unknown. We analysed the infection outcome of Leishmania mexicana parasites engineered for the constitutive expression of mKate protein and evaluated their immunogenicity in BALB/c mice. Infection of BALB/c mice with mKate transfected L. mexicana (Lmex <sup>mKate</sup> ) parasites caused enlarged lesion sizes, leading to ulceration, and containing more parasites, as compared to Lmex <sup>WT</sup> . The mKate protein showed immunogenic properties inducing antibody production against the mKate protein, as well as enhancing antibody production against the parasite. The augmented lesion sizes and ulcers, together with the more elevated antibody production, were related to an enhanced number of TNF-α and IL-1β producing cells in the infected tissues. We conclude that mKate red fluorescent protein is an immunogenic protein, capable of modifying disease evolution of L. mexicana