AMBIENTE ESTRUCTURAL DE LOS DEPÓSITOS AURÍFEROS DE LA SERRANÍA DE SAN LUCAS (BOLÍVAR, COLOMBIA)

La Serranía de San Lucas corresponde a la porción más al norte de la Cordillera Central colombiana. Geológicamente está comprendida por tres unidades mayores: (1) basamento metamórfico compuesto por gneises y, secundariamente, por migmatitas, anfibolitas y granulitas; (2) dioritas y granodioritas, pertenecientes a un cuerpo de dimensiones batolíticas que intruye las rocas metamórficas; y (3) rocas volcanosedimentarias, en contacto estratigráfico con rocas metamórficas, compuestas principalmente por ignimbritas, brechas volcánicas, lavas intermedias a ácidas, bombas y flujos de ceniza y lapilli, intercaladas con capas de chert.   En adición a estas unidades se encuentran vetas de alto contenido aurífero que cortan a las unidades anteriores y que constituyen uno de los factores de mayor interés en la región. Estas vetas se caracterizan principalmente por: (1) ocurrencia sistemática con controles estructurales y relación de corte con relación a las unidades litológicas encajantes (basamento cristalino y cobertera), (2) ambientes de formación/deformación asociados a procesos transtensionales en regímenes frágil y/o frágil-dúctil, y (3) geometrías compatibles con deformación progresiva asociada a procesos tectónicos regionales.   Las principales vetas están controladas por sistemas de diaclasasfallas preexistentes o precursoras, de direcciones N5-20 ºE y N55-70 ºE, que en el momento de la generación de las estructuras filonianas presentaban orientación favorable para la apertura/relleno por parte de los fluidos mineralizantes. El primer sistema, pertenece al dominio estructural NNE (contemporáneo con la formación de las estructuras vetiformes extensionales) es representativo de depósitos filonianos tipo La Gloria, y el segundo, perteneciente al dominio NWW (o de dislocación, contemporáneo a tardío con respecto a les estructuras cizallantes extensionales) representa los depósitos tipo La Mariana, que a su vez se caracterizan por reactivación asociada a cizallamiento de respaldos.   Los dominios vetiformes definidos, fueron subsecuentemente afectados por procesos de dislocación tectónica, con componente de rumbo (sinestrolateral) y buzamiento (extensional), representados por las estructuras y lineamientos NW-SE

Whole-genome sequencing identifies recurrent mutations in chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL), the most frequent leukaemia in adults in Western countries, is a heterogeneous disease with variable clinical presentation and evolution. Two major molecular subtypes can be distinguished, characterized respectively by a high or low number of somatic hypermutations in the variable region of immunoglobulin genes. The molecular changes leading to the pathogenesis of the disease are still poorly understood. Here we performed whole-genome sequencing of four cases of CLL and identified 46 somatic mutations that potentially affect gene function. Further analysis of these mutations in 363 patients with CLL identified four genes that are recurrently mutated: notch 1 (NOTCH1), exportin 1 (XPO1), myeloid differentiation primary response gene 88 (MYD88) and kelch-like 6 (KLHL6). Mutations in MYD88 and KLHL6 are predominant in cases of CLL with mutated immunoglobulin genes, whereas NOTCH1 and XPO1 mutations are mainly detected in patients with unmutated immunoglobulins. The patterns of somatic mutation, supported by functional and clinical analyses, strongly indicate that the recurrent NOTCH1, MYD88 and XPO1 mutations are oncogenic changes that contribute to the clinical evolution of the disease. To our knowledge, this is the first comprehensive analysis of CLL combining whole-genome sequencing with clinical characteristics and clinical outcomes. It highlights the usefulness of this approach for the identification of clinically relevant mutations in cancer

The role of Streptococcus pneumoniae in community-acquired pneumonia among adults in Europe:a meta-analysis

<p>The primary objective of this meta-analysis was to estimate the prevalence of adult community-acquired pneumonia (CAP) caused by Streptococcus pneumoniae in Europe, adjusted for possible independent covariates. Two reviewers conducted a systematic literature search using PubMed on English-language articles that involved human subjects with CAP during the period from January 1990 to November 2011 across European countries. A mixed-effects meta-regression model was developed and populated with 24,410 patients obtained from 77 articles that met the inclusion criteria. The model showed that the observed prevalence of S. pneumoniae in CAP significantly varies between European regions, even after adjusting for explanatory covariates, including patient characteristics, diagnostic tests, antibiotic resistance, and health-care setting. The probability of detecting S. pneumoniae was substantially higher in studies that performed more frequently a diagnostic polymerase chain reaction assay compared to all the other diagnostic tests included. Furthermore, S. pneumoniae was more likely to be confirmed as the cause of a CAP in studies with intensive care unit patients as compared to those with hospital- or community-treated patients. This study provides estimates of the average observed prevalence of S. pneumoniae, which could be used for projecting the health and economic benefits of pneumococcal immunization.</p>