CGG-repeat length threshold for FMR1 RNA pathogenesis in a cellular model for FXTAS.

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder that affects carriers of premutation alleles (55-200 CGG repeats) of the fragile X mental retardation 1 (FMR1) gene. The presence of elevated levels of expanded mRNA found in premutation carriers is believed to be the basis for the pathogenesis in FXTAS, but the exact mechanisms by which the mRNA causes toxicity are not known. In particular, it is not clear whether there is a threshold for a CGG-repeat number below which no cellular dysregulation occurs, or whether toxicity depends on mRNA concentration. We have developed a doxycycline-inducible episomal system that allows us to study separately the effects of CGG-repeat number and mRNA concentration (at fixed CGG-repeat length) in neuroblastoma-derived SK cells. Our findings show that there is a CGG-repeat size threshold for toxicity that lies between 62 and 95 CGG repeats. Interestingly, for repeat sizes of 95 CGG and above, there is a clear negative correlation between mRNA concentration and cell viability. Taken together, our results provide evidence for an RNA-toxicity model with primary dependence on CGG-repeat size and secondary dependence on mRNA concentration, thus formally ruling out any simple titration model that operates in the absence of either protein-binding cooperativity or some form of length-dependent RNA structural transition.

Deoxycytidyl-deoxyguanosine oligonucleotide classes A, B, and C induce distinct cytokine gene expression patterns in rhesus monkey peripheral blood mononuclear cells and distinct alpha interferon responses in TLR9-expressing rhesus monkey plasmacytoid dendritic cells.

To determine if deoxycytidyl-deoxyguanosine oligonucleotides (CpG ODN) can be used effectively as nonspecific inducers of innate immune defenses for preventative or therapeutic interventions in infectious disease models for nonhuman primates, the present study evaluated the response of rhesus monkey peripheral blood mononuclear cells to three different synthetic CpG ODN classes by defining the cytokine gene expression patterns and by characterizing IFN-alpha/beta responses. Depending on the type and dose of CpG ODN used for stimulation, distinct gene expression patterns were induced. CpG ODN class A (CpG-A ODN) and CpG-C ODN, but not CpG-B ODN, were potent inducers of alpha interferon (IFN-alpha), and this response was due to IFN-alpha production by TLR9-positive plasmacytoid dendritic cells. Importantly, there was a dose-dependent increase in IFN-alpha responses to CpG-A ODN but a dose-dependent decrease in IFN-alpha responses by CpG-B ODN. The most sustained IFN-alpha response was induced by CpG-A ODN and was associated with a stronger induction of interferon regulatory factor 7 and the induction of several interferon-stimulated genes. In contrast, and independent of the dose, CpG-B ODN were the weakest inducers of IFN-alpha but the most potent inducers of proinflammatory cytokines. CpG-C ODN induced cytokine gene expression patterns that were intermediate between those of CpG-A and CpG-B ODN. Thus, the different types of CpG ODN induce different post-TLR9 signaling pathways that result in distinct cytokine gene expression patterns. Based on these findings, A and C class CpG ODN, but not B class CpG ODN, may be particularly suited for use as therapeutic or prophylactic antiviral interventions.

Diagnóstico etiológico en neumonía con derrame a traves del método de coaglutinación bacteriana / Etiological diagnosis in pneumonia with effusion by the bacterial coagglutination test

Se estudiaron prospectivamente 33 pacientes pediátricos que presentaron Neumonía con derrame pleural en el lapso comprendido entre Marzo 1986-junio 1987. Al líquido pleural obtenido se le practicó la prueba de coaglutinación bacteriana (Phadebact (R) CFS-Pharmacía) y cultivo. Se utilizó la primera prueba con la finalidad de obtener un diagnóstico etiológico rápido y compararlo a su vez con el 2§ método. La prueba de coaglutinación bacteriana reportó 54,6% de positividad, 42,42% correspondieron a Neumococo, 12,12% a Hemófilus influenza y 45,45% resultaron negativos. La comparación etiológica por cultivo del líquido pleural fue 72%. El Estreptococo neumoniae fue el germen más aislado (48,48%); seguido por Hemófilus influenza (15,14%) y el Estafilococo aureus (9,18%). Al comparar los resultados de ambos métodos observamos que fueron coincidentes en el 81,25% de los casos para Neumococo y en el 80% para el Hemófilus influenza. La prueba de coaglutinación bacteriana es de gran utilidad porque además de un diagnóstico etiológico orientado, es de fácil realización e interpretación, facilitando la escogencia de la antibioticoterapia