Differential cell line susceptibility to the emerging Zika virus: implications for disease pathogenesis, non-vector-borne human transmission and animal reservoirs

published_or_final_versio

Unveiling a novel transient druggable pocket in BACE-1 through molecular simulations: conformational analysis and binding mode of multisite inhibitors

The critical role of BACE-1 in the formation of neurotoxic ß-amyloid peptides in the brain makes it an attractive target for an efficacious treatment of Alzheimer’s disease. However, the development of clinically useful BACE-1 inhibitors has proven to be extremely challeng- ing. In this study we examine the binding mode of a novel potent inhibitor (compound 1, with IC50 80 nM) designed by synergistic combination of two fragments—huprine and rhein— that individually are endowed with very low activity against BACE-1. Examination of crystal structures reveals no appropriate binding site large enough to accommodate 1. Therefore we have examined the conformational flexibility of BACE-1 through extended molecular dynamics simulations, paying attention to the highly flexible region shaped by loops 8–14, 154–169 and 307–318. The analysis of the protein dynamics, together with studies of pocket druggability, has allowed us to detect the transient formation of a secondary binding site, which contains Arg307 as a key residue for the interaction with small molecules, at the edge of the catalytic cleft. The formation of this druggable “floppy” pocket would enable the bind- ing of multisite inhibitors targeting both catalytic and secondary sites. Molecular dynamics simulations of BACE-1 bound to huprine-rhein hybrid compounds support the feasibility of this hypothesis. The results provide a basis to explain the high inhibitory potency of the two enantiomeric forms of 1, together with the large dependence on the length of the oligo- methylenic linker. Furthermore, the multisite hypothesis has allowed us to rationalize the inhibitory potency of a series of tacrine-chromene hybrid compounds, specifically regarding the apparent lack of sensitivity of the inhibition constant to the chemical modifications intro- duced in the chromene unit. Overall, these findings pave the way for the exploration of novel functionalities in the design of optimized BACE-1 multisite inhibitors

Complete Genome Sequence of Francisella tularensis Subspecies holarctica FTNF002-00

Francisella tularensis subspecies holarctica FTNF002-00 strain was originally obtained from the first known clinical case of bacteremic F. tularensis pneumonia in Southern Europe isolated from an immunocompetent individual. The FTNF002-00 complete genome contains the RD23 deletion and represents a type strain for a clonal population from the first epidemic tularemia outbreak in Spain between 1997–1998. Here, we present the complete sequence analysis of the FTNF002-00 genome. The complete genome sequence of FTNF002-00 revealed several large as well as small genomic differences with respect to two other published complete genome sequences of F. tularensis subsp. holarctica strains, LVS and OSU18. The FTNF002-00 genome shares >99.9% sequence similarity with LVS and OSU18, and is also ∼5 MB smaller by comparison. The overall organization of the FTNF002-00 genome is remarkably identical to those of LVS and OSU18, except for a single 3.9 kb inversion in FTNF002-00. Twelve regions of difference ranging from 0.1–1.5 kb and forty-two small insertions and deletions were identified in a comparative analysis of FTNF002-00, LVS, and OSU18 genomes. Two small deletions appear to inactivate two genes in FTNF002-00 causing them to become pseudogenes; the intact genes encode a protein of unknown function and a drug:H+ antiporter. In addition, we identified ninety-nine proteins in FTNF002-00 containing amino acid mutations compared to LVS and OSU18. Several non-conserved amino acid replacements were identified, one of which occurs in the virulence-associated intracellular growth locus subunit D protein. Many of these changes in FTNF002-00 are likely the consequence of direct selection that increases the fitness of this subsp. holarctica clone within its endemic population. Our complete genome sequence analyses lay the foundation for experimental testing of these possibilities

Características diferenciales sanitarias y toxicológicas de drogodependientes en tratamiento y consumo activo

Objetivo. Describir y comparar las características demográficas, toxicológicas y sanitarias de un colectivo de drogodependientes que se encuentra en consumo activo y en diferentes modalidades terapéuticas. Analizar las intervenciones realizadas con estos diferentes colectivos. Diseño. Estudio descriptivo. Emplazamiento. Usuarios que han acudido a la asociación ACLAD de Valladolid. Pacientes. Un total de 1.224 drogodependientes. Mediciones. Revisión de las historias clínicas de los usuarios atendidos en un centro de tratamiento y en un programa de reducción de daños durante un período de 30 meses. Se registran diferentes variables demográficas, toxicológicas y clínicas, se efectúa la comparación entre programas y se valora la evolución de los pacientes. Resultados. Se estudian 1.224 pacientes. Un tercio presenta infección por el virus de la inmunodeficiencia humana; el 63%, marcadores de una hepatitis A pasada, el 48%, marcadores de hepatitis B, y el 68,5% de hepatitis C. En el 39,1% es positiva la prueba de Mantoux. Se observan diferencias en la prevalencia de infecciones entre los usuarios en consumo activo y los usuarios en tratamiento, entre los drogodependientes en diferentes modalidades terapéuticas y en el período del estudio. Conclusiones. Existen claras diferencias en las características demográficas, toxicológicas y sanitarias de los usuarios incluidos en el estudio. Los usuarios que no están en tratamiento de rehabilitación son los que peores condiciones sanitarias tienen. Éstos son los menos estudiados por nuestra parte. En estos años de seguimiento se detecta una leve mejoría de estas condiciones y también una tendencia a la mejora de nuestra intervención