Shell-like structures in our cosmic neighbourhood

Signatures of the processes in the early Universe are imprinted in the cosmic web. Some of them may define shell-like structures characterised by typical scales. We search for shell-like structures in the distribution of nearby rich clusters of galaxies drawn from the SDSS DR8. We calculate the distance distributions between rich clusters of galaxies, and groups and clusters of various richness, look for the maxima in the distance distributions, and select candidates of shell-like structures. We analyse the space distribution of groups and clusters forming shell walls. We find six possible candidates of shell-like structures, in which galaxy clusters have maxima in the distance distribution to other galaxy groups and clusters at the distance of about 120 Mpc/h. The rich galaxy cluster A1795, the central cluster of the Bootes supercluster, has the highest maximum in the distance distribution of other groups and clusters around them at the distance of about 120 Mpc/h among our rich cluster sample, and another maximum at the distance of about 240 Mpc/h. The structures of galaxy systems causing the maxima at 120 Mpc/h form an almost complete shell of galaxy groups, clusters and superclusters. The richest systems in the nearby universe, the Sloan Great Wall, the Corona Borealis supercluster and the Ursa Major supercluster are among them. The probability that we obtain maxima like this from random distributions is lower than 0.001. Our results confirm that shell-like structures can be found in the distribution of nearby galaxies and their systems. The radii of the possible shells are larger than expected for a BAO shell (approximately 109 Mpc/h versus approximately 120 Mpc/h), and they are determined by very rich galaxy clusters and superclusters with high density contrast while BAO shells are barely seen in the galaxy distribution. We discuss possible consequences of these differences.Comment: Comments: 9 pages, 10 figures, Astronomy and Astrophysics, in pres

Influencia de las condiciones experimentales en la determinación de S, Cl, Br y I en agua por espectrometría de masas de alta resolución (HR-ICP-MS)

A systematic study was undertaken to optimize a method to determine S, Cl, Br and I in water by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). The sample composition and preparation conditions (the total dissolved solids -TDS-, the total organic compounds -TOC- and the addition of nitric acid) were evaluated to assess the sample matrix influence. Furthermore, the effect of instrumental parameters (carrier gas flow rate, sample flow rate, radiofrequency -RF- power and analyzer resolution) was also studied to minimize the contribution of polyatomic species, and to establish the required resolution. Low, medium or high resolutions were compared in terms of background level and sensitivity. After optimization, a multivariate robustness test was carried out by means of a Placket-Burman design. This method was applied to samples of the Llobregat and Ter rivers which are used for the drinking water system of the Metropolitan Area of Barcelona (~4.5 million inhabitants), Catalonia, northeast Spain.Este estudio fue financiado a través del Proyecto QUECA del Ministerio de Economía y Competitividad de España (CGL2011-23307) y el Proyecto PICT-2013-1259 (FONCyT, Argentina). Los análisis se realizaron en el Laboratorio de Geoquímica labGEOTOP en el ICTJA CSIC, infraestructura cofinanciada por FEDER-UE(Ref. CSIC08-4E-001).Peer Reviewe

Ventajas y desventajas de la aplicación de la técnica de HR-ICP-MS al análisis inorgánico de aguas en terrenos volcánicos

La técnica de ICP-MS ha supuesto un gran avance en el análisis de aguas en los últimos decenios tal y como recogen las normativas al respecto en Europa, Estados Unidos, etc., habiéndose convertido en una técnica de referencia particularmente en el tema de calidad del agua. La alta resolución aplicada a la ICP-MS reduce considerablemente las interferencias y su combinación con detectores aptos para concentraciones mayoritarias hace que se disponga de una herramienta analítica muy competitiva que permite determinar simultáneamente elementos mayoritarios y trazas, incluidos halógenos (Cl, Br, I), y además relaciones isotópicas (ej., Li y B). Estos aproximadamente 60 parámetros geoquímicos permiten una caracterización exhaustiva de las aguas para temas de calidad y también ayudan a discernir más fácilmente el origen y el tránsito de las aguas a través de diferentes terrenos volcánicos. Por otra parte, la HR-ICP-MS es de gran aplicación a la determinación de los aportes geoquímicos volcanogénicos a los balances biogeoquímicos regionales, como por ejemplo de los materiales piroclásticos, a través del análisis de lixiviados procedentes de la simulación de la interacción del agua con estos productos eruptivos. En este trabajo se exponen los pros y contras de la aplicación de la HR-ICP-MS a aguas en problemáticas volcanogénicas a través de diferentes ejemplos (Islandia, Argentina, Chile, etc.). Agradecemos la asistencia del Servicio labGEOTOP (infraestructura cofinanciada por FEDER-UE, Ref. CSIC08-4E-001) del ICTJA-CSIC. La financiación fue proporcionada por QUECA (MINECO, CGL2011-23307). Este estudio se llevó a cabo en el marco del Grupo Reconocido GEOPAM (2014 SGR 869).La financiación fue proporcionada por QUECA (MINECO, CGL2011-23307). Este estudio se llevó a cabo en el marco del Grupo Reconocido GEOPAM (2014 SGR 869).Peer Reviewe

Arsenic Biotransformation as a Cancer Promoting Factor by Inducing DNA Damage and Disruption of Repair Mechanisms

Chronic exposure to arsenic in drinking water poses a major global health concern. Populations exposed to high concentrations of arsenic-contaminated drinking water suffer serious health consequences, including alarming cancer incidence and death rates. Arsenic is biotransformed through sequential addition of methyl groups, acquired from s-adenosylmethionine (SAM). Metabolism of arsenic generates a variety of genotoxic and cytotoxic species, damaging DNA directly and indirectly, through the generation of reactive oxidative species and induction of DNA adducts, strand breaks and cross links, and inhibition of the DNA repair process itself. Since SAM is the methyl group donor used by DNA methyltransferases to maintain normal epigenetic patterns in all human cells, arsenic is also postulated to affect maintenance of normal DNA methylation patterns, chromatin structure, and genomic stability. The biological processes underlying the cancer promoting factors of arsenic metabolism, related to DNA damage and repair, will be discussed here

Bilateral Internuclear Ophthalmoplegia in a Patient with Devic's Neuromyelitis Optica

An unusual presentation of Devic's neuromyelitis optica (NMO) disease associated with bilateral internuclear ophthalmoplegia (INO) is described. A 32-year-old pregnant patient was diagnosed with NMO. First symptoms were headache and sudden visual loss in her right eye (RE). Eighteen months ago, she reported other neurologic symptoms such as paresthesia. Based on her visual field, fundoscopy and Ishihara test, she was diagnosed with retrobulbar neuritis of the RE. After delivery, new neurologic symptoms resembling transverse myelitis appeared. She was treated with methylprednisolone and plasmapheresis, which improved her visual acuity; however, a sudden bilateral INO appeared, with adduction defect and nystagmus with abduction in both eyes. No improvement was obtained after treatment with azathioprine and rituximab. Paresis of the legs and the right arm persisted, but double vision and OIN gradually disappeared. At the end, the patient had a residual exophoria in the RE and nystagmus with abduction in the left eye. Prevalence of NMO is lower than one case per one million inhabitants, and it is not likely to affect the encephalic trunk; furthermore, bilateral INO in NMO is rare. Two major criteria and at least two of the three minor ones are required to confirm a NMO diagnosis, and our patient fulfilled these diagnosis criteria

Arsenic Exposure and the Induction of Human Cancers

Arsenic is a metalloid, that is, considered to be a human carcinogen. Millions of individuals worldwide are chronically exposed through drinking water, with consequences ranging from acute toxicities to development of malignancies, such as skin and lung cancer. Despite well-known arsenic-related health effects, the molecular mechanisms involved are not fully understood; however, the arsenic biotransformation process, which includes methylation changes, is thought to play a key role. This paper explores the relationship of arsenic exposure with cancer development and summarizes current knowledge of the potential mechanisms that may contribute to the neoplastic processes observed in arsenic exposed human populations

SWI/SNF regulates a transcriptional programme that induces senescence to prevent liver cancer

Oncogene-induced senescence (OIS) is a potent tumour suppressor mechanism. To identify senescence regulators relevant to cancer, we screened an shRNA library targeting genes deleted in hepatocellular carcinoma (HCC). Here, we describe how knockdown of the SWI/SNF component ARID1B prevents OIS and cooperates with RAS to induce liver tumours. ARID1B controls p16INK4a and p21CIP1a transcription but also regulates DNA damage, oxidative stress and p53 induction, suggesting that SWI/SNF uses additional mechanisms to regulate senescence. To systematically identify SWI/SNF targets regulating senescence, we carried out a focused shRNA screen. We discovered several new senescence regulators including ENTPD7, an enzyme that hydrolyses nucleotides. ENTPD7 affects oxidative stress, DNA damage and senescence. Importantly, expression of ENTPD7 or inhibition of nucleotide synthesis in ARID1B-depleted cells results in re-establishment of senescence. Our results identify novel mechanisms by which epigenetic regulators can affect tumor progression and suggest that pro-senescence therapies could be employed against SWI/SNF-mutated cancers

Raman threshold for nth-order cascade Raman amplification

We study theoretically and experimentally Raman threshold for 1, 2, ... , n orders Stokes in a free running configuration. Using alternative way to solve the differential coupled equations that describe the stimulate Raman scattering, we find simple mathematical expressions that allow calculating the necessary pumping power to obtain Raman threshold for nth-order Stokes and the maximum output power available in each Stokes. The theoretical calculations coincide with the results obtained experimentally

The effect of age on the acquisition and selection of cancer driver mutations in sun-exposed normal skin

BACKGROUND: The accumulation of somatic mutations contributes to ageing and cancer. Sunlight is the principal aetiological factor associated with skin cancer development. However, genetic and phenotypic factors also contribute to skin cancer risk. This study aimed at exploring the role of photoaging, as well as other well-known epidemiological risk factors, in the accumulation of somatic mutations in cancer-free human epidermis. MATERIAL AND METHODS: We deeply sequenced 46 genes in normal skin biopsies from 127 healthy donors, from which phenotypic data (including age, pigmentation-related genotype and phenotype) and sun exposure habits were collected. We determined the somatic mutational burden, mutational signatures, clonal selection and frequency of driver mutations in all samples. RESULTS: Our results reveal an exponential accumulation of UV-related somatic mutations with age, matching skin cancer incidence. The increase of mutational burden is in turn modified by an individual's skin phototype. Somatic mutations preferentially accumulated in cutaneous squamous cell carcinoma (cSCC) cancer genes and clonally expanded with age, with distinct mutational processes underpinning different age groups. Our results suggest loss of fidelity in transcription-coupled repair later in life. CONCLUSION: Our findings reveal that aging is not only associated with an exponential increase in the number of somatic mutations accumulated in normal epidermis, but also with selection and expansion of cancer-associated mutations. Aged, sun-exposed normal skin is thus an extended mosaic of multiple clones with driver mutations, poised for the acquisition of transforming events

Charge Pair Interactions in Transmembrane Helices and Turn Propensity of the Connecting Sequence Promote Helical Hairpin Insertion

α-Helical hairpins, consisting of a pair of closely spaced transmembrane (TM) helices that are connected by a short interfacial turn, are the simplest structural motifs found in multi-spanning membrane proteins. In naturally occurring hairpins, the presence of polar residues is common and predicted to complicate membrane insertion. We postulate that the pre-packing process offsets any energetic cost of allocating polar and charged residues within the hydrophobic environment of biological membranes. Consistent with this idea, we provide here experimental evidence demonstrating that helical hairpin insertion into biological membranes can be driven by electrostatic interactions between closely separated, poorly hydrophobic sequences. Additionally, we observe that the integral hairpin can be stabilized by a short loop heavily populated by turn-promoting residues. We conclude that the combined effect of TM¿TM electrostatic interactions and tight turns plays an important role in generating the functional architecture of membrane proteins and propose that helical hairpin motifs can be acquired within the context of the Sec61 translocon at the early stages of membrane protein biosynthesis. Taken together, these data further underline the potential complexities involved in accurately predicting TM domains from primary structures