Browsing by Author "Pena, Alfredo"

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    Inverse correlation between allergy markers and Helicobacter pylori infection in children is associated with elevated levels of TGF-beta
    (LIPPINCOTT WILLIAMS & WILKINS, 2011) Serrano, Carolina A.; Talesnik, Eduardo; Pena, Alfredo; Rollan, Antonio; Duarte, Ignacio; Torres, Javiera; Majerson, Daniela; Einisman, Helly; Viviani, Paola; Harris, Paul R.
    Objectives We evaluated allergy/hypersensitivity clinical markers and their correlation with Helicobactor pylori infection in children and adults to analyze how early acquisition of H. pylori could modulate allergic disorder expression.
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    Relationship between Helicobacter pylori virulence factors and regulatory cytokines as predictors of clinical outcome
    (2007) Serrano, Carolina; Diaz, Maria Ines; Valdivia, Alejandra; Godoy, Alex; Pena, Alfredo; Rollan, Antonio; Kirberg, Arturo; Hebel, Eduardo; Fierro, Jaqueline; Klapp, Gabriela; Venegas, Alejandro; Harris, Paul R.
    Helicobacter pylori infection is highly prevalent in Chile (73%). Usually a minority of infected patients develops complications such as ulcers and gastric cancer that have been associated with the presence of virulence factors (cagA, vacA) and host T helper response (Th1/Th2). Our aim was to evaluate the relationship between strain virulence and host immune response, using a multiple regression approach for the development of a model based on data collected from H. pylori infected patients in Chile. We analyzed levels of selected cytokines determined by ELISA (interleukin (IL)-12, IL-10, interferon (IFN)-gamma and IL-4) and the presence of cagA and vacA alleles polymorphisms determined by PCR in antral biopsies of 41 patients referred to endoscopy. By multiple regression analysis we established a correlation between bacterial and host factors using clinical outcome (gastritis and duodenal ulcer) as dependent variables. The selected model was described by: clinical outcome = 0.867491 (cagA) + 0.0131847 (IL-12/IL-10) + 0.0103503 (IFN-gamma/IL-4) and it was able to explain over 90% of clinical outcomes observations (R-2=96.4). This model considers that clinical outcomes are better explained by the interaction of host immune factors and strain virulence as a complex and interdependent mechanism. (c) 2007 Elsevier Masson SAS. All rights reserved.
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    Rotavirus genotypes in children with gastroenteritis assisted in two public hospitals from Chile: viral strains circulating in a country without a universal vaccination against rotavirus
    (SOC CHILENA INFECTOLOGIA, 2012) Lucero, Yalda; Mamani, Nora; Cortes, Hector; Pena, Alfredo; Vergara, Rodrigo; O'Ryan, Miguel
    Background: Rotavirus is the main cause of severe gastroenteritis (GE) in children. Two vaccines currently available have proven efficacy against the predominant genotypes. Rotavirus genotypes vary both geographically and/or temporally. Genotype surveillance is important to monitor trends associated or not with vaccine use. Aim: To update information on rotavirus genotypes circulating in two main cities of Chile. Methodology: Between May 2009-March 2010, children < 5y of age receiving medical care for GE in two large hospitals were recruited; none of these children had received rotavirus vaccine previously. Epidemiological information was recorded in an ad-hoc form and stool samples were collected for rotavinis detection by a commercial ELISA. Genotyping was performed by semi-nested RT-PCR. Results: A total of 296/967 samples (31%) were positive for rotavirus, with a peak in November/December mostly in children 7-24 months old (67%). G9P[8] was the predominant genotype (76%), followed for G1P[8] (6%) and G2P[4] (6%) in both cities. Conclusions: Rotavirus caused one third of GE requiring emergency room care and/or hospitalization, mostly in children within an age range susceptible to benefit from rotavirus vaccines. G9P[8], a genotype against which rotavirus vaccines have demonstrated high efficacy, was by far the most frequent rotavirus variant. Continued surveillance in Chile is crucial for providing background information on disease burden and strain diversity before the introduction of rotavirus vaccines.