Infección de Rattus rattus por Trypanosoma cruzi como indicador del control vectorial en Arequipa, Perú

Residual insecticide spraying with deltamethrin PM 5% has been a cornerstone strategy used in the Chagas disease Control Program in the region of Arequipa. Nonetheless, Trypanosoma cruzi natural infected synanthropic rodents are not used as an indicator to evaluate interruption of vector transmission. The objective was to determine the natural infection index by T. cruzi in the synanthropic rodent, Rattus rattus, before and after household residual insecticide spraying with deltamethrin PM 5%, as impact indicator for Chagas disease vector control strategies. A quasi-experimental study was performed in the rural locality of Murco (Caylloma, Arequipa), through capture of rodents during household pre-spraying stage and capture of rodents during the post-spraying stage. One xenodiagnosis box was used in each animal containing 10 nymphs III of Triatoma infestans. The rodent’s identified was Rattus rattus and the infection index for the hemoflagellate identified as Trypanosoma cruzi, was 84.2% in the pre-spraying stage and 0% in the post-spraying stage. Furthermore, 50% (2/4) of Mus musculus were positive in the pre-spraying stage. It is concluded that the negativization of R. rattus in the post-spraying stage could indicate a remarkable transmission reduction or interruption of T. cruzi vector transmission in the locality of Murco.Como parte del programa de control de la enfermedad de Chagas en la región Arequipa, se vienen realizando rociados residuales, con deltametrina PM 5%, y entre los criterios para evaluar la interrupción de la transmisión vectorial, no se considera la infección natural de los roedores sinantrópicos por T. cruzi. El objetivo fue determinar el índice de infección natural por T. cruzi en el roedor sinantrópico R. rattus, antes y después del rociado residual de las viviendas con deltametrina PM 5%, como indicador del impacto del control vectorial de la enfermedad de Chagas. Se diseñó un estudio cuasi-experimental, a través de capturas de roedores en la etapa pre-rociado en el intradomicilio y capturas de roedores en la etapa post-rociado, en la localidad rural de Murco (Caylloma, Arequipa). Se les aplicó xenodiagnóstico por animal, con 10 ninfas III de Triatoma infestans. Los roedores fueron identificados como R. rattus y el índice de infección por el hemoflagelado identificado como T. cruzi, en el pre-rociado fue 84,2% y en el post- -rociado fue 0%. Además, en el pre-rociado el 50.0% (2/4) de Mus musculus fueron positivos a T. cruzi. Se concluye que la negativización de R. rattus en el post-rociado, indicaría la notable reducción de la transmisión o la interrupción de la transmisión vectorial de T. cruzi en la localidad de Murco

How much dark matter is there inside early-type galaxies?

We study the luminous mass as a function of the dynamical mass inside the effective radius (r_e) of early-type galaxies (ETGs) to search for differences between these masses. We assume Newtonian dynamics and that any difference between these masses is due to the presence of dark matter. We use several samples of ETGs -ranging from 19 000 to 98 000 objects- from the ninth data release of the Sloan Digital Sky Survey. We perform Monte Carlo (MC) simulations of galaxy samples and compare them with real samples. The main results are: i) MC simulations show that the distribution of the dynamical vs. luminous mass depends on the mass range where the ETGs are distributed (geometric effect). This dependence is caused by selection effects and intrinsic properties of the ETGs. ii) The amount of dark matter inside r_e is approximately 7% +- 22%. iii) This amount of dark matter is lower than the minimum estimate (10%) found in the literature and four times lower than the average (30%) of literature estimates. However, if we consider the associated error, our estimate is of the order of the literature average.Comment: 24 pages, 12 figures. MNRAS accepte

Virial masses of late-type galaxies from the SDSS DR16

Motivated by the challenges of calculating the dynamical masses of late-type galaxies (LTGs) and the enormous amount of data from the Sloan Digital Sky Survey (SDSS), we calculate virial masses of a sample of approximately 126 000 LTGs from the sixteenth data release of the SDSS. The virial mass estimations were made considering Newtonian mechanics, virial equilibrium and velocity dispersion from stars and gas. The procedure gave as a result seven mass estimations for each galaxy. The calculated masses were calibrated using a sample of spiral galaxies with velocity rotation curves. Considering the results from the calibration, we find that the correlation between virial and dynamical (rotation curve) masses is stronger for high inclination values. Therefore, the calibration relies more on the available data for higher inclination angle galaxies. We also show that if we have a heterogeneous sample of galaxies one must take into consideration the size and colour of these galaxies by using the following variables: Sersic index n, concentration index, and colour of the stars. For relatively smaller and bluer LTGs, the gas velocity dispersion provides a more consistent mass calculation, while for LTGs that are relatively larger and redder the stellar velocity dispersion provides a better correlated mass calculation.Fil: Nigoche Netro, A.. Universidad de Guadalajara; México. Instituto de Astronomía y Meteorologia de la Universidad de Guadalajara; MéxicoFil: De La Fuente, E.. Universidad de Guadalajara; México. University of Tokyo; JapónFil: Diaz, Ruben Joaquin. United States Gemini Office; Estados Unidos. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Agüero, Maria Paz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Kemp, S. N.. Instituto de Astronomía y Meteorologia de la Universidad de Guadalajara; MéxicoFil: Marquez Lugo, R. A.. Instituto de Astronomía y Meteorologia de la Universidad de Guadalajara; MéxicoFil: Lagos, P.. Centro de Astrofísica Da Universidade Do Porto; PortugalFil: Ruelas Mayorga, A.. Universidad Nacional Autónoma de México; MéxicoFil: López Contreras, N. L.. Instituto de Astronomía y Meteorologia de la Universidad de Guadalajara; Méxic

Simultaneous multiwavelength observations of the Low/Hard State of the X-ray transient source SWIFT J1753.5-0127

We report the results of simultaneous multiwavelength observations of the X-ray transient source SWIFT J1753.5-0127 performed with INTEGRAL, RXTE, NTT, REM and VLA on 2005 August 10-12. The source, which underwent an X-ray outburst since 2005 May 30, was observed during the INTEGRAL Target of Opportunity program dedicated to new X-ray novae located in the Galactic Halo. Broad-band spectra and fast timing variability properties of SWIFT J1753.5-0127 are analyzed together with the optical, near infra-red and radio data. We show that the source was significantly detected up to 600 keV with Comptonization parameters and timing properties typical of the so-called Low/Hard State of black hole candidates. We build a spectral energy distribution and we show that SWIFT J1753.5-0127 does not follow the usual radio/X-ray correlation of X-ray binaries in the Low/Hard State. We give estimates of distance and mass. We conclude that SWIFT J1753.5-0127 belongs to the X-ray nova class and that it is likely a black hole candidate transient source of the Galactic Halo which remained in the Low/Hard State during its main outburst. We discuss our results within the context of Comptonization and jet models.Comment: Accepted for publication in ApJ, 25 pages, 4 tables, 11 figures (3 in color

The optical/NIR counterpart of the INTEGRAL obscured source IGR J16318-4848 : a sgB[e] in a HMXB ?

The X-ray source IGR J16318-4848 was the first source discovered by INTEGRAL. The high energy spectrum exhibits such a high column density that the source is undetectable in X-rays below 2 keV. We used the NTT telescope of ESO to obtain optical and near-infrared (NIR) observations. We confirm the already proposed NIR counterpart and for the first time extended detection into optical. We report here photometric measurements in the R, I, J, bands, upper flux limits in the Bb and V bands, lower flux limits in the H and Ks bands. We also obtain NIR spectroscopy, revealing a large number of emission lines, including forbidden iron lines and P-Cygni profiles, and showing a strong similarity with CI Cam, another strongly absorbed source. These data point to a high luminosity, high temperature source, with an intrinsic optical-NIR absorption greater than the interstellar absorption, but two orders of magnitude below the X-ray absorption. We propose that the source is a High Mass X-ray binary (HMXB) at a distance between 0.9 and 6.2 kpc, the optical/NIR counterpart corresponds to the mass donor, which is an early-type star, maybe a sgB[e] star, surrounded by a dense and absorbing circumstellar material. This would make the second HMXB with a sgB[e] star as the mass donor after CI Cam. Such sources may represent a different evolutionary state of X-ray binaries previously undetected with the lower energy space telescopes ; if it is so, a new class of strongly absorbed X-ray binaries is being unveiled by INTEGRAL.Comment: 42 pages, 12 figures, accepted in Ap.

Drug Discovery for Schistosomiasis: Hit and Lead Compounds Identified in a Library of Known Drugs by Medium-Throughput Phenotypic Screening

The flatworm disease schistosomiasis infects over 200 million people with just one drug (praziquantel) available—a concern should drug resistance develop. Present drug discovery approaches for schistosomiasis are slow and not conducive to automation in a high-throughput format. Therefore, we designed a three-component screen workflow that positions the larval (schistosomulum) stage of S. mansoni at its apex followed by screens of adults in culture and, finally, efficacy tests in infected mice. Schistosomula are small enough and available in sufficient numbers to interface with automated liquid handling systems and prosecute thousands of compounds in short time frames. We inaugurated the workflow with a 2,160 compound library that includes known drugs in order to cost effectively ‘re-position’ drugs as new therapies for schistosomiasis and/or identify compounds that could be modified to that end. We identify a variety of ‘hit’ compounds (antibiotics, psychoactives, antiparasitics, etc.) that produce behavioral responses (phenotypes) in schistosomula and adults. Tests in infected mice of the most promising hits identified a number of ‘leads,’ one of which compares reasonably well with praziquantel in killing worms, decreasing egg production by the parasite, and ameliorating disease pathology. Efforts continue to more fully automate the workflow. All screen data are posted online as a drug discovery resource

The Hamburg/ESO R-process Enhanced Star survey (HERES) III. HE 0338-3945 and the formation of the r+s stars

We have derived abundances of 33 elements and upper limits for 6 additional elements for the metal-poor ([Fe/H] = -2.42) turn-off star HE 0338-3945 from high-quality VLT-UVES spectra. The star is heavily enriched, by about a factor of 100 relative to iron and the Sun, in the heavy s-elements (Ba, La, ..). It is also heavily enriched in Eu, which is generally considered an r-element, and in other similar elements. It is less enriched, by about a factor of 10, in the lighter s-elements (Sr, Y and Zr). C is also strongly enhanced and, to a somewhat lesser degree, N and O. These abundance estimates are subject to severe uncertainties due to NLTE and thermal inhomogeneities which are not taken into detailed consideration. However, an interesting result, which is most probably robust in spite of these uncertainties, emerges: the abundances derived for this star are very similar to those of other stars with an overall enhancement of all elements beyond the iron peak. We have defined criteria for this class of stars, r+s stars, and discuss nine different scenarios to explain their origin. None of these explanations is found to be entirely convincing. The most plausible hypotheses involve a binary system in which the primary component goes through its giant branch and asymptotic giant branch phases and produces CNO and s-elements which are dumped onto the observed star. Whether the r-element Eu is produced by supernovae before the star was formed (perhaps triggering the formation of a low-mass binary), by a companion as it explodes as a supernova (possibly triggered by mass transfer), or whether it is possibly produced in a high-neutron-density version of the s-process is still unclear. Several suggestions are made on how to clarify this situation.Comment: Accepted for A&A; 22 pages, 9 figures, 2 tables. Table 2 is in electronic form and available at http://www.astro.uu.se/~karin/table2.dat with description at http://www.astro.uu.se/~karin/jonsellReadMe

RNA Interference in Schistosoma mansoni Schistosomula: Selectivity, Sensitivity and Operation for Larger-Scale Screening

RNA interference (RNAi) is a technique to selectively suppress mRNA of individual genes and, consequently, their cognate proteins. RNAi using double-stranded (ds) RNA has been used to interrogate the function of mainly single genes in the flatworm, Schistosoma mansoni, one of a number of schistosome species causing schistosomiasis. In consideration of large-scale screens to identify candidate drug targets, we examined the selectivity and sensitivity (the degree of suppression) of RNAi for 11 genes produced in different tissues of the parasite: the gut, tegument (surface) and otherwise. We used the schistosomulum stage prepared from infective cercariae larvae which are accessible in large numbers and adaptable to automated screening platforms. We found that RNAi suppresses transcripts selectively, however, the sensitivity of suppression varies (40%–>75%). No obvious changes in the parasite occurred post-RNAi, including after targeting the mRNA of genes that had been computationally predicted to be essential for survival. Additionally, we defined operational parameters to facilitate large-scale RNAi, including choice of culture medium, transfection strategy to deliver dsRNA, dose- and time-dependency, and dosing limits. Finally, using fluorescent probes, we show that the developing gut allows rapid entrance of dsRNA into the parasite to initiate RNAi