Generation of Organotypic Multicellular Spheres by Magnetic Levitation: Model for the Study of Human Hematopoietic Stem Cells Microenvironment.

BACKGROUND AND OBJECTIVE: The characteristics of human hematopoietic stem cells are conditioned by the microenvironment of the bone marrow, where they interact with other cell populations, such as mesenchymal stem cells and endothelial cells; however, the study of this microenvironment is complex. The objective of this work was to develop a 3D culture system by magnetic levitation that imitates the microenvironment of human HSC. METHODS AND RESULTS: Human bone marrow-mesenchymal stem cells, umbilical cord blood-hematopoietic stem cells and a non-tumoral endothelial cell line (CC2811, LonzaⓇ) were used to develop organotypic multicellular spheres by the magnetic levitation method. We obtained viable structures with an average sphericity index greater than 0.6, an average volume of 0.5 mm3 and a percentage of aggregation greater than 70%. Histological studies of the organotypic multicellular spheres used hematoxylin and eosin stains, and an evaluation of vimentin expression by means of immunohistochemistry demonstrated an organized internal structure without picnotic cells and a high expression of vimentin. The functional capacity of human hematopoietic stem cells after organotypic multicellular spheres culture was evaluated by multipotency tests, and it was demonstrated that 3D structures without exogenous Flt3L are autonomous in the maintenance of multipotency of human hematopoietic stem cells. CONCLUSIONS: We developed organotypic multicellular spheres from normal human cells that mimic the microenvironment of the human hematopoietic stem cells. These structures are the prototype for the development of complex organoids that allow the further study of the biology of normal human stem cells and their potential in regenerative medicine.

Genomas virales fragmentados sugieren contaminación para aguas de consumo humano / Viral genome fragments suggests contamination of human drinking water

Objetivo. Determinar la presencia de rotavirus y norovirus en agua para consumo humano en una localidad de Bogotá. Materiales y métodos. Se recolectaron ocho muestras de agua por semana en ocho lugares diferentes del predio en estudio. Para determinar la presencia del genoma viral, las muestras se ultrafiltraron y se hizo detección viral por medio de la técnica RT-PCR, amplificando un segmento del gen VP6 del rotavirus y un segmento del ORF2 del norovirus. Este estudio se llevó a cabo en una institución universitaria ubicada en una zona periurbana cercana a Bogotá, a 45 km del acueducto que surte de agua al predio. La zona se encuentra rodeada por fincas con ganado lechero, centros comerciales y cuatro cementerios. El agua se recolectó en recipientes de polipropileno. En total, fueron 64 muestras de cinco litros de agua cada una. Resultados. La presencia viral fue de 12,5 %, encontrándose rotavirus en cuatro y norovirus en cuatro de las 64 muestras colectadas. Además de presentar la importancia de la presencia viral en agua para consumo humano, en este documento se discute el significado que tiene el encontrar solo segmentos virales y no la partícula viral completa e infecciosa.

Objective: To determine the presence of rotavirus and norovirus in drinking water in a northern neighborhood in Bogotá, Colombia. Materials and methods: Eight weekly samples of water were collected and ultrafiltered in order to detect the viral genome presence. The technique used for detection of genome segments was RT-PCR. VP6 gene from rotavirus and ORF2 segment from norovirus were selected in order to find the virus in the water. This study was performed in a higher education institution located in a periurban zone near Bogotá, 45 km away from the aqueduct that services the area. The zone is surrounded by dairy cattle farms, malls and four cemeteries. Water was collected in clean polypropylene containers. There were a total of 64 samples of 5 liters of water each. Results: Viral segments were found in 12.5% of the samples. We found rotavirus in four samples and norovirus in another 4. Besides discussing the importance of viral contamination in drinking water, we discussed the meaning of finding only viral segments and not complete and infectious viral particles.

Genomic analysis of two ORF2 segments of new porcine astrovirus isolates and their close relationship with human astroviruses.

Porcine astrovirus (PAstV) has been poorly studied and has been associated mainly with gastroenteritis. Computational analysis has revealed the close relationship of PAstV with astroviruses of humans (HAstV) and cats (FAstV). In this study, 105 and 171 stool specimens were collected from piglets and children under 5 years of age, respectively, in different Colombian regions during a 1-year period. The stool samples were examined for astroviruses by ELISA and RT-PCR; 23.8% and 4% were found to be positive for PAstV and HAstV, respectively. Additional sequence analysis with partial sequences obtained from ORF2 identified at least 2 probable groups of PAstVs and possible recombination events between porcine and human astroviruses. This study provides preliminary evidence of the high presence of PAstVs in pigs and proposes the existence of multiple PAstV types that are evolutionarily closely related to HAstVs.

Molecular analysis of a 348 base-pair segment of open reading frame 2 of human astrovirus. A characterization of Colombian isolates.

We are reporting computational studies of several genotyped strains of astrovirus isolated in Colombia which we have genotyped using the 348-bp segment located between nucleotides 258 and 606 close to the amino terminal region of the complete ORF 2. By biocomputational techniques this 348-bp segment from the different strains was translated into an amino acid sequence. The sequences were aligned and compared in order to build a dendrogram. Our results show that the 348 bp and the 116 amino acid peptides cluster in a very conservative way, showing slight genetic variations between them. This slight sequence variability does not allow us to identify common amino acid substitution patterns shared by all members of each HAstV specific type, thus suggesting that antigenic epitopes are probably located outside the 116 peptide fragment of this capsid protein. These results show that there is little recombination among different regions of the ORF2, thus suggesting that this genotyping method should continue to be useful for serotyping HAstV isolates.

Astrovirus (HAstV)como agente causal de diarrea en niños colombianos: Siete años de estudio / Astrovirus (HAstV)causing diarrea in Colombian children: Seven years of study

Con el objeto de determinar el comportamiento de los Astrovirus como agentes causantes de diarrea en algunas regiones colombianas, se colectaron 1147 muestras de diarrea de niños menores de 5 años que acudieron a los servicios de consulta externa de cuatro centros de salud de regiones de Bogotá, Facatativa,Cartagena y Quibdo durante el periodo comprendido entre 1996 y el año 2002. La determinación de la presencia viral se realizó por medio de pruebas de ELISA encontrando una prevalencia global de 2,8 porciento. De las muestras positivas se seleccionaron 14 a las cuales se les obtuvo su ARN, se realizaron pruebas de RT-PCR y secuenciación de un segmento de 348 pb del ORF 2 del genoma viral para elaborar dendrogramas con el método de Neiborg joining y así, determinar su comportamiento filogenético. Las conclusiones generales de este estudio fueron:que en Colombia los HAstV poseen comportamientos endémicos y que las cepas colombianas no han sufrido cambios evolutivos que les permitan distanciarse de cepas de otros países.

Enfermedad de niemann pick error innato del metabolismo de los lípidos: reporte de caso

Se hace una revisión de la enfermedad de Niemann-Pick que es una alteración innata del metabolismo de los fosfolípidos, la ESPINGOMIELINA, que se acumula en los lisosomas, constituyendo la enfermedad lisosomal, debido a una alteración cualitativa o cuantitativa de la ESZPINGOMIELINASA. La enfermedad es transmitida en forma autosómica recesiva, alterando los diversos órganos, especialmente el sistema nervioso y el fondo de ojo en el cual se observa en la mácula una mancha de color cereza. A continuación se presenta el caso problema en un indígena puro del Cañar-Ecuador (años anteriores se encontró otro caso que fue descrito por su extrema rareza), existe consanguinidad; hepatoesplenomegalia, mancha roja en mácula y células espúmosas en médula ósea. Un hermano falleció con identicas características clínicas.