Enfermedad Mínima Residual (EMR) en Leucemia Linfoblástica Aguda pediátrica (LLA). Estudio multicéntrico

En las últimas 4 décadas se profundizó el conocimiento en la cinética de la respuesta temprana al tratamiento en pacientes con Leucemia Linfoblástica Aguda (LLA) para predecir riesgo de recaída1. Sin embargo, 20% de los pacientes que inicialmente responden al tratamiento y morfológicamente no presentan blastos en médula ósea, recidivan durante el tratamiento o luego de la finalizar el mismo.Fil: Soria, Rose Mari. Hospital de Niños Dr. Ricardo Gutiérrez; Argentina.Fil: Agriello, Evangelina. Laboratorio de Especialidades Bioquímicas; Argentina.Fil: Agriello, Evangelina. Hospital Interzonal General Dr. José Penna; Argentina.Fil: Agriello, Evangelina. Grupo Argentino de Tratamiento de la Leucemia Aguda; Argentina.Fil: Gutierrez, María. Hospital de Niños Dr. Ricardo Gutiérrez; Argentina.Fil: Gil, Gimena. Hospital de Niños Dr. Ricardo Gutiérrez; Argentina.Fil: Iommi, María Paula. Laboratorio de Especialidades Bioquímicas; Argentina.Fil: Torreguitart, Federico Andrés. Laboratorio de Especialidades Bioquímicas; Argentina.Fil: Caferri, Horacio. Hospital Interzonal General Dr. José Penna; Argentina.Fil: Cédola, Alejandra. Sanatorio San Lucas; Argentina.Fil: Majek, Elena. Hospital de Niños Dr. Héctor Quintana; Argentina.Fil: Hiramatsu, Elizabeth. Hospital Pediátrico del Niño Jesús; Argentina.Fil: Morell, Daniela. Hospital Pediátrico del Niño Jesús; Argentina.Fil: Rizzi, María Laura. Sanatorio Allende; Argentina.Fil: Rodríguez Cuimbra, Silvia. Hospital Pediátrico Juan Pablo II; Argentina.Fil: Gomel De Baraja, María E. Hospital Pediátrico Juan Pablo II; Argentina.Fil: Cabral Castella, Antonia C. Hospital Pediátrico Juan Pablo II; Argentina.Fil: Pistaccio, Luis. Hospital Interzonal de Agudos Especializado en Pediatría Sor María Ludovica; Argentina.Fil: Schuttemberg, Virginia. Hospital Interzonal de Agudos Especializado en Pediatría Sor María Ludovica; Argentina.Fil: Riccieri, Cecilia.Fil: Solari, Liliana. Hospital Nacional Profesor Alejandro Posadas; Argentina.Fil: Solari, Liliana. Grupo Argentino de Tratamiento de la Leucemia Aguda; Argentina.Fil: Riccieri, Cecilia. Hospital Nacional Profesor Alejandro Posadas; Argentina.Fil: Gaillard, María I. Hospital de Niños Dr. Ricardo Gutiérrez; Argentina.Fil: Gaillard, María I. Grupo Argentino de Tratamiento de la Leucemia Aguda; Argentina.Fil: Ferraro, C. Hospital de Niños Dr. Ricardo Gutiérrez; Argentina.Fil: Hernández, M. Clínica Dr. Matera; Argentina.Fil: Drosovsky, C. Sanatorio San Lucas; Argentina.Hematologí

Clonal human fetal ventral mesencephalic dopaminergic neuron precursors for cell therapy research

A major challenge for further development of drug screening procedures, cell replacement therapies and developmental studies is the identification of expandable human stem cells able to generate the cell types needed. We have previously reported the generation of an immortalized polyclonal neural stem cell (NSC) line derived from the human fetal ventral mesencephalon (hVM1). This line has been biochemically, genetically, immunocytochemically and electrophysiologically characterized to document its usefulness as a model system for the generation of A9 dopaminergic neurons (DAn). Long-term in vivo transplantation studies in parkinsonian rats showed that the grafts do not mature evenly. We reasoned that diverse clones in the hVM1 line might have different abilities to differentiate. In the present study, we have analyzed 9 hVM1 clones selected on the basis of their TH generation potential and, based on the number of v-myc copies, v-myc down-regulation after in vitro differentiation, in vivo cell cycle exit, TH+ neuron generation and expression of a neuronal mature marker (hNSE), we selected two clones for further in vivo PD cell replacement studies. The conclusion is that homogeneity and clonality of characterized NSCs allow transplantation of cells with controlled properties, which should help in the design of long-term in vivo experimentsThis work was supported by grants from the Spanish Ministry of Economy and Competitiveness (formerly Science and Innovation; PLE2009-0101, SAF2010-17167), Comunidad Autónoma Madrid (S2011-BMD-2336), Instituto Salud Carlos III (RETICS TerCel, RD06/0010/0009) and European Union (Excell, NMP4-SL-2008-214706). This work was also supported by an institutional grant from Foundation Ramón Areces to the Center of Molecular Biology Severo Ocho

Genome-Wide Analysis of Factors Affecting Transcription Elongation and DNA Repair: A New Role for PAF and Ccr4-Not in Transcription-Coupled Repair

RNA polymerases frequently deal with a number of obstacles during transcription elongation that need to be removed for transcription resumption. One important type of hindrance consists of DNA lesions, which are removed by transcription-coupled repair (TC-NER), a specific sub-pathway of nucleotide excision repair. To improve our knowledge of transcription elongation and its coupling to TC-NER, we used the yeast library of non-essential knock-out mutations to screen for genes conferring resistance to the transcription-elongation inhibitor mycophenolic acid and the DNA-damaging agent 4-nitroquinoline-N-oxide. Our data provide evidence that subunits of the SAGA and Ccr4-Not complexes, Mediator, Bre1, Bur2, and Fun12 affect transcription elongation to different extents. Given the dependency of TC-NER on RNA Polymerase II transcription and the fact that the few proteins known to be involved in TC-NER are related to transcription, we performed an in-depth TC-NER analysis of a selection of mutants. We found that mutants of the PAF and Ccr4-Not complexes are impaired in TC-NER. This study provides evidence that PAF and Ccr4-Not are required for efficient TC-NER in yeast, unraveling a novel function for these transcription complexes and opening new perspectives for the understanding of TC-NER and its functional interconnection with transcription elongation

Global population structure and evolution of Bordetella pertussis and their relationship with vaccination.

Bordetella pertussis causes pertussis, a respiratory disease that is most severe for infants. Vaccination was introduced in the 1950s, and in recent years, a resurgence of disease was observed worldwide, with significant mortality in infants. Possible causes for this include the switch from whole-cell vaccines (WCVs) to less effective acellular vaccines (ACVs), waning immunity, and pathogen adaptation. Pathogen adaptation is suggested by antigenic divergence between vaccine strains and circulating strains and by the emergence of strains with increased pertussis toxin production. We applied comparative genomics to a worldwide collection of 343 B. pertussis strains isolated between 1920 and 2010. The global phylogeny showed two deep branches; the largest of these contained 98% of all strains, and its expansion correlated temporally with the first descriptions of pertussis outbreaks in Europe in the 16th century. We found little evidence of recent geographical clustering of the strains within this lineage, suggesting rapid strain flow between countries. We observed that changes in genes encoding proteins implicated in protective immunity that are included in ACVs occurred after the introduction of WCVs but before the switch to ACVs. Furthermore, our analyses consistently suggested that virulence-associated genes and genes coding for surface-exposed proteins were involved in adaptation. However, many of the putative adaptive loci identified have a physiological role, and further studies of these loci may reveal less obvious ways in which B. pertussis and the host interact. This work provides insight into ways in which pathogens may adapt to vaccination and suggests ways to improve pertussis vaccines. IMPORTANCE Whooping cough is mainly caused by Bordetella pertussis, and current vaccines are targeted against this organism. Recently, there have been increasing outbreaks of whooping cough, even where vaccine coverage is high. Analysis of the genomes of 343 B. pertussis isolates from around the world over the last 100 years suggests that the organism has emerged within the last 500 years, consistent with historical records. We show that global transmission of new strains is very rapid and that the worldwide population of B. pertussis is evolving in response to vaccine introduction, potentially enabling vaccine escape

Human natural killer cell maturation defect supports in vivo CD56(bright) to CD56(dim) lineage development.

Two populations of human natural killer (NK) cells can be identified in peripheral blood. The majority are CD3(-)CD56(dim) cells while the minority exhibits a CD3(-)CD56(bright) phenotype. In vitro evidence indicates that CD56(bright) cells are precursors of CD56(dim) cells, but in vivo evidence is lacking. Here, we studied NK cells from a patient that suffered from a melanoma and opportunistic fungal infection during childhood. The patient exhibited a stable phenotype characterized by a reduction in the frequency of peripheral blood CD3(-)CD56(dim) NK cells, accompanied by an overt increase in the frequency and absolute number of CD3(-)CD56(bright) cells. These NK cells exhibited similar expression of perforin, CD57 and CD158, the major activating receptors CD16, NKp46, NKG2D, DNAM-1, and 2B4, as well as the inhibitory receptor CD94/NKG2A, on both CD56(bright) and CD56(dim) NK cells as healthy controls. Also, both NK cell subpopulations produced IFN-γ upon stimulation with cytokines, and CD3(-)CD56(dim) NK cells degranulated in response to cytokines or K562 cells. However, upon stimulation with cytokines, a substantial fraction of CD56(dim) cells failed to up-regulate CD57 and CD158, showed a reduction in the percentage of CD16(+) cells, and CD56(bright) cells did not down-regulate CD62L, suggesting that CD56(dim) cells could not acquire a terminally differentiated phenotype and that CD56(bright) cells exhibit a maturation defect that might result in a potential altered migration pattern. These observations, support the notion that NK cells of this patient display a maturation/activation defect that precludes the generation of mature NK cells at a normal rate accompanied by CD56(dim) NK cells that cannot completely acquire a terminally differentiated phenotype. Thus, our results provide evidence that support the concept that in vivo CD56(bright) NK cells differentiate into CD56(dim) NK cells, and contribute to further understand human NK cell ontogeny