Accuracy of CD64 expression on neutrophils and monocytes in bacterial infection diagnosis at pediatric intensive care admission.

The CD64 receptor has been described as an interesting bacterial infection biomarker. Its expression has not been studied in previously healthy children admitted to pediatric critical care unit (PICU). Our objective was firstly to describe the CD64 expression and secondly study its diagnostic accuracy to discriminate bacterial versus viral infection in this children. We made a prospective double-blind observational study (March 2016-February 2018). A flow cytometry (FC) was done from peripheral blood at PICU admission. We studied the percentage of CD64+ neutrophils and the CD64 mean fluorescence intensity (MFI) on neutrophils (nCD64) and monocytes (mCD64). Statistical analyses were performed with non-parametric tests (p < 0.05). Twenty children in the bacterial infection group (BIG) and 25 in the viral infection group (VIG). Children in BIG showed higher values of CD64+ neutrophils (p = 0.000), nCD64 (p = 0.001), and mCD64 (p = 0.003). In addition, CD64+ neutrophils and nCD64 expression have positive correlation with procalcitonin and C reactive protein. The nCD64 area under the curve (AUC) was 0.83 (p = 0.000). The %CD64+ neutrophils showed an AUC of 0.828 (p = 0.000). The mCD64 AUC was 0.83 (p = 0.003). The nCD64 and %CD64+ neutrophils also showed higher combined values of sensitivity (74%) and specificity (90%) than all classical biomarkers.In our series CD64 expression allows to discriminate between bacterial and viral infection at PICU admission. Future studies should confirm this and be focused in the study of CD64 correlation with clinical data and its utility as an evolution biomarker in critical care children.

[Establishment of a preclinical neuroblastoma model in immunocompetent mice]. / Establecimiento de un modelo preclínico de neuroblastoma en ratones inmunocompetentes.

AIM: To develop a NB animal model which makes possible studies related to tumor immunity. MATERIALS AND METHODS: Two types of NB cells were used. Cell line 36769 was derived from TH-MYCN+ mouse in which overexpression of the MYCN gene is governed by rat tyrosine hydroxylase promotor. Cell line 4040 was derived from TH-MYCN/ALK mice, which in addition express an activating mutation of ALK gene. For each cell type, 1x106 neurospheres were implanted in 129/SVJ mice (with the same genetic background as donors, n=8), via orthotopic injection in the left suprarenal gland by intraperitoneal approach, through a transverse supraumbilical laparotomy. Daily postsurgical clinical follow-up of the animals was done until they were sacrificed at four weeks. The tumor presence was macroscopically confirmed. The tumoral sample was excised and was processed for cellular immunity and molecular tolerance mediator's studies. The existence of metastasis was investigated by flow cytometry in the spleen, bone marrow and peripheral blood. RESULTS: 1) Orthotopic Neuroblastoma was generated in all the transplanted mice. 2) The tumors were infiltrated by several immune subpopulations, with effector, regulatory and suppressor inmunophenotype. This was similar to the inmunophenotype described in human NB. Furthermore, the molecular mediators of the environment point to a state of protumoral tolerance. CONCLUSION: The orthotopic implantation of NB neurospheres in syngeneic mice has allowed us to generate a NB model in which it has been possible to study the tumor immunity.

OBJETTIVO: Desarrollar un modelo animal de neuroblastoma (NB) que posibilite estudios relacionados con la inmunidad tumoral. MATERIAL Y METODOS: Se utilizaron dos tipos de células NB. La línea 36769 procedía del ratón TH-MYCN+ en el que la sobreexpresión del gen MYCN está gobernada por el promotor de la tirosín hidroxilasa de rata. La línea 4040 procedía de ratones TH-MYCN+/ALK+, que además expresan una mutación activadora del gen ALK. De cada tipo celular se implantaron 1x106 neurosferas en ratones 129/SVJ (mismo fondo genetico que los donantes, n=8), mediante inyección ortotópica en glándula suprarrenal izquierda por abordaje intraperitoneal, a través de laparotomía transversa supraumbilical. Se realizó seguimiento clínico diario postquirúrgico de los animales hasta su sacrificio a las 4 semanas. La presencia de tumor se confirmó macroscópicamente. La pieza tumoral se extirpó y se procesó para estudios de inmunidad celular y mediadores moleculares de tolerancia. Se investigó la existencia de metástasis por citometría de flujo en bazo, médula ósea y sangre periférica. RESULTADOS: 1) En todos los ratones trasplantados se generó NB ortotópico. 2) La pieza tumoral se encontró infiltrada por diversas subpoblaciones inmunes, con inmunofenotipo efector, regulador y supresor, similar a la situación descrita en los NB humanos. Además, los mediadores moleculares del microambiente apuntan a un estado de tolerancia protumoral. CONCLUSIONES: La implantación ortotópica de neurosferas NB en ratones singénicos nos ha permitido generar un modelo de NB en el que ha sido posible estudiar la inmunidad tumoral.

Novel processing in a mammalian nuclear 28S pre-rRNA: tissue-specific elimination of an 'intron' bearing a hidden break site.

Splitting and apparent splicing of ribosomal RNA, both previously unknown in vertebrates, were found in rodents of the genus Ctenomys. Instead of being formed by a single molecule of 4.4 kb, 28S rRNA is split in two molecules of 2.6 and 1.8 kb. A hidden break, mapping within a 106 bp 'intron' located in the D6 divergent region, is expressed in mature ribosomes of liver, lung, heart and spleen, as well as in primary fibroblast cultures. Testis-specific processing eliminates the intron and concomitantly the break site, producing non-split 28S rRNA molecules exclusively in this organ. The intron is flanked by two 9 bp direct repeats, revealing the acquisition by insertion of a novel rRNA processing strategy in the evolution of higher organisms.