Origin of supermassive black holes: predictions for the black hole population

The presence of supermassive black holes at redshift z > 6 raises some questions about their formation and growth in the early universe. Due to the construction of new telescopes like the ELT to observe and detect SMBHs, it will be useful to derive theoretical estimates for the population and to compare observations and model predictions in the future. In consequence our main goal is to estimate the population of SMBHs using a semi-analytic code known as Galacticus which is a code for the formation and evolution of galaxies where we are about to include different scenarios for SMBHs formation indicating the initial mass of the black hole seed, its formation conditions and recipes for the evolution of the components of the galaxies. We found that the principal mechanism of growing SMBHs is is via galaxy mergers and accretion of matter. For the comparison of our results with observations, we calculate the radius of influence of the black hole to estimate which part of the population could be detected, leading to relations similar to the observed ones.Comment: 3 pages, 3 figure

CONGENITAL INFECTION OF PROTOZOA: HISTOPATHOLOGICAL AND HISTOCHEMICAL ANALYSIS OF HUMAN CHORIONIC VILLI EXPLANTS INFECTED EX VIVO WITH TRYPANOSOMA CRUZI AND TOXOPLASMA GONDII

Univ Talca, Talca, Vii Region, Chile. Droguett, D (Droguett, Daniel

Trypanasoma cruzi induces cellular proliferation in the trophoblastic cell line bewo

Droguett, D (Droguett, Daniel)[ 1,2 ]. [ 1 ] Univ Chile, Fac Med, Inst Biomed Sci, Santiago 7, Chile [ 2 ] Univ Talca, Fac Ciencias Salud, Talca, ChileChagas’ disease is caused by the haemophlagelated protozoan Trypanosoma cruzi (T. cruzi), which is able to cross the placental barrier and infect both the placenta and fetus. In ex vivo infected human chorionic villi, a low concentration of parasite induces activation of the Mitogen Activated Protein Kinase (MAPK) ERK1/2 signaling pathway, which plays an important role in cellular proliferation and differentiation. In order to determine whether the parasite is able to induce cellular proliferation in the trophoblast, BeWo cells were incubated in presence and absence of T. cruzi trypomastigotes (Y strain) (ratio parasite/BeWo cells 1:10) and in presence and absence of FBS for 2, 6, 12 and 24 hours. DNA synthesis was assayed by bromodeoxyuridine (BrdU) incorporation and determined by spectrometry and immunocytochemistry. Mitotic index was determined in DAPI stained samples and cell growth by detection of Nucleolar organizer regions (NORs) using silver staining (AgNORs). Parasites inside cells were identified by their nuclear and kinetoplast morphology. At least 500 cells were counted in each condition and analyzed using the MATLAB software; the statistical significance was analyzed by ANOVA followed by the Dunnetts post-test. The low concentration of T. cruzi used (mimicking women with chronic Chagas disease) induces a significant increase of BrdU incorporation into DNA and in the number of mitosis and of NORs in BeWo cells. We conclude that T. cruzi induces cell proliferation in the trophoblast; this process may form part of a “local placental antiparasite” defense mechanism. Financed by FONDECYT Projects Nº1120230 (UK), Nº 1130189 (JM), Nº1130113 (NG), 1120579 (SH). Support of CONICYT-PBCT Anillo ACT 112 and ICM (P09-015-F), Chile is also acknowledged

Effectiveness of sampling methods employed for Acanthamoeba keratitis diagnosis by culture

© 2018, Springer Nature B.V.Purpose: This retrospective, observational study was designed to evaluate the effectiveness of the sampling methods commonly used for the collection of corneal scrapes for the diagnosis of Acanthamoeba keratitis (AK) by culture, in terms of their ability to provide a positive result. Methods: A total of 553 samples from 380 patients with suspected AK received at the Parasitology Section of the Public Health Institute of Chile, between January 2005 and December 2015, were evaluated. A logistic regression model was used to determine the correlation between the culture outcome (positive or negative) and the method for sample collection. The year of sample collection was also included in the analysis as a confounding variable. Results: Three hundred and sixty-five samples (27%) from 122 patients (32.1%) were positive by culture. The distribution of sample types was as follows: 142 corneal scrapes collected using a modified bezel needle (a novel method develope

Trypanosoma cruzi induces trophoblast differentiation: A potential local antiparasitic mechanism of the human placenta?

Copyright © 2014 Elsevier Ltd. All rights reserved.Introduction: The congenital transmission of Trypanosoma cruzi (T. cruzi) is responsible for one-third of new Chagas disease cases each year. During congenital transmission, the parasite breaks down the placental barrier formed by the trophoblast, basal laminae and villous stroma. The observation that only 5% of infected mothers transmit the parasite to the fetus implies that the placenta may impair parasite transmission. The trophoblast undergoes continuous epithelial turnover, which is considered part of innate immunity. Therefore, we propose that T. cruzi induces differentiation in the trophoblast as part of a local antiparasitic mechanism of the placenta. Methods: We analyzed β-human chorionic gonadotropin (β-hCG) and syncytin protein expression in HPCVE and BeWo cells using immunofluorescence and western blotting. Additionally, b-hCG secretion into the culture medium was measured by ELISA. We assessed the differentiation of troph

Effectiveness of sampling methods employed for Acanthamoeba keratitis diagnosis by culture

© 2018, Springer Nature B.V.Purpose: This retrospective, observational study was designed to evaluate the effectiveness of the sampling methods commonly used for the collection of corneal scrapes for the diagnosis of Acanthamoeba keratitis (AK) by culture, in terms of their ability to provide a positive result. Methods: A total of 553 samples from 380 patients with suspected AK received at the Parasitology Section of the Public Health Institute of Chile, between January 2005 and December 2015, were evaluated. A logistic regression model was used to determine the correlation between the culture outcome (positive or negative) and the method for sample collection. The year of sample collection was also included in the analysis as a confounding variable. Results: Three hundred and sixty-five samples (27%) from 122 patients (32.1%) were positive by culture. The distribution of sample types was as follows: 142 corneal scrapes collected using a modified bezel needle (a novel method develope