Epidermal growth factor receptor and KRAS mutations in Brazilian lung cancer patients

OBJECTIVE: Epidermal growth factor receptor is involved in the pathogenesis of non-small cell lung cancer and has recently emerged as an important target for molecular therapeutics. The KRAS oncogene also plays an important role in the development of lung cancer. The aim of this study was to evaluate the frequency of epidermal growth factor receptor and KRAS mutations in a population of Brazilian patients with non-small cell lung cancer. METHODS: A total of 207 specimens from Brazilian patients with non-small cell lung cancer were analyzed for activating epidermal growth factor receptor and KRAS somatic mutations, and their associations with clinicopathological characteristics (including age, gender, ethnicity, smoking habits, and histological subtype) were examined. RESULTS: We identified 63 cases (30.4%) with epidermal growth factor receptor mutations and 30 cases (14.6%) with KRAS mutations. The most frequent epidermal growth factor receptor mutation we detected was a deletion in exon 19 (60.3%, 38 patients), followed by an L858R amino acid substitution in exon 21 (27%, 17 patients). The most common types of KRAS mutations were found in codon 12. There were no significant differences in epidermal growth factor receptor or KRAS mutations by gender or primary versus metastatic lung cancer. There was a higher prevalence of KRAS mutations in the non-Asian patients. Epidermal growth factor receptor mutations were more prevalent in adenocarcinomas than in non-adenocarcinoma histological types. Being a non-smoker was significantly associated with the prevalence of epidermal growth factor receptor mutations, but the prevalence of KRAS mutations was significantly associated with smoking. CONCLUSIONS: This study is the first to examine the prevalence of epidermal growth factor receptor and KRAS mutations in a Brazilian population sample with non-small cell lung cancer

Differences between CO- and calcium triplet-derived velocity dispersions in spiral galaxies: evidence for central star formation?

We examine the stellar velocity dispersions (sigma) of a sample of 48 galaxies, 35 of which are spirals, from the Palomar nearby galaxy survey. It is known that for ultra-luminous infrared galaxies (ULIRGs) and merger remnants thesigma derived from the near-infrared CO band-heads is smaller than that measured from optical lines, while no discrepancy between these measurements is found for early-type galaxies. No such studies are available for spiral galaxies - the subject of this paper. We used cross-dispersed spectroscopic data obtained with the Gemini Near-Infrared Spectrograph (GNIRS), with spectral coverage from 0.85 to 2.5um, to obtain sigma measurements from the 2.29 $\mu$m CO band-heads (sigma_{CO}), and the 0.85 um calcium triplet (sigma_{CaT}). For the spiral galaxies in the sample, we found that sigma_{CO} is smaller than sigma_{CaT}, with a mean fractional difference of 14.3%. The best fit to the data is given by sigma_{opt} = (46.0+/-18.1) + (0.85+/-0.12)sigma_{CO}. This "sigma discrepancy" may be related to the presence of warm dust, as suggested by a slight correlation between the discrepancy and the infrared luminosity. This is consistent with studies that have found no sigma-discrepancy in dust-poor early-type galaxies, and a much larger discrepancy in dusty merger remnants and ULIRGs. That sigma_{CO}$ is lower than sigma_{opt} may also indicate the presence of a dynamically cold stellar population component. This would agree with the spatial correspondence between low sigma_{CO} and young/intermediate-age stellar populations that has been observed in spatially-resolved spectroscopy of a handful of galaxies.Comment: Published in MNRAS, 446, 282

A close look at the dwarf AGN of NGC 4395 : optical and near-IR integral field spectroscopy

Intermediate-mass black holes (103–105 M⊙) in the centre of dwarf galaxies are believed to be analogous to growing active galactic nuclei (AGNs) in the early Universe. Their characterization can provide insight about the early galaxies. We present optical and near-infrared integral field spectroscopy of the inner ∼50 pc of the dwarf galaxy NGC 4395, known to harbour an AGN. NGC 4395 is an ideal candidate to investigate the nature of dwarf AGN, as it is nearby (d ≈ 4.4 Mpc) enough to allow a close look at its nucleus. The optical data were obtained with the Gemini GMOS-IFU covering the 4500 –7300 Å spectral range at a spatial resolution of 10 pc. The J and K-band spectra were obtained with the Gemini NIFS at spatial resolutions of ∼5 pc. The gas kinematics show a compact, rotation disc component with a projected velocity amplitude of 25 kms−1. We estimate a mass of 7.7 × 105 M⊙ inside a radius of 10 pc. From the Hα broad-line component, we estimate the AGN bolometric luminosity as Lbol=(9.9±1.4)×1040 erg s−1 and a mass MBH=(2.5+1.0−0.8)×105 M⊙ for the central black hole. The mean surface mass densities for the ionized and molecular gas are in the ranges (1–2) M⊙ pc−2 and (1–4) × 10−3 M⊙ pc−2 and the average ratio between ionized and hot molecular gas masses is ∼500. The emission-line flux distributions reveal an elongated structure at 24 pc west of the nucleus, which is blueshifted relative to the systemic velocity of the galaxy by ≈30 kms−1. We speculate that this structure is originated by the accretion of a gas-rich small satellite or by a low-metallicity cosmic clou

Molecular Genetic Variability, Population Structure and Mating System in Tropical Forages

Microsatellite (SSR) markers were developed for the following tropical forage species, using accessions available from the plant genetic resources (PGR) collections held by EMBRAPA (Brazilian Agricultural Research Corporation): Brachiaria brizantha, B. humidicola, Panicum maximum, Paspalum spp., Stylosanthes capitata, S. guianensis, S. macrocephala, Calopogonium mucunoides and Centrosema spp. The markers were used to analyse population structure and genetic diversity, evolution and origin of the genetic variability in the centre of origin, mating systems and genetic resources in EMBRAPA’s germplasm bank. The results shed light on the amount of genetic variation within and between populations, revealed the need in some cases for further plant collection to adequately represent the species in PGR collections, allowed us to assemble core collections (subsets of the total collections) that should contain most of the available diversity and (in the case of the legumes) showed the need to avoid unwanted outcrossing when regenerating conserved material. The data will allow plant breeders to better select accessions for hybrid production, discriminate between genotypes and use marker-assisted selection in breeding programs. Our results will also underpin the construction of genetic maps, mapping of genes of agronomic interest and numerous other studies on genetic variability, population structure, gene flow and reproductive systems for the tropical forage species studied in this work