Browsing by Author "Tobar Durán, Hugo Eduardo"

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    Chromosomal excision of a new pathogenicity island modulates Salmonella virulence in vivo
    (BENTHAM SCIENCE PUBL LTD, 2013) Tobar Durán, Hugo Eduardo; Salazar Echegarai, Francisco J.; Nieto Pacheco, Pamela Andrea; Palavecino, Christian E.; Sebastian, Vatenlina P.; Riedel Soria, Claudia; Kalergis Parra, Alexis Mikes; Bueno Ramírez, Susan
    Although the excision of unstable pathogenicity islands is a phenomenon that has been described for several virulent bacteria, whether this process directly affects the capacity of these microorganisms to cause disease in their hosts remains unknown. Salmonella enterica serovar Enteritidis (S. Enteritidis) is an enterobacterium that harbors several unstable pathogenicity islands that can excise from the main bacterial chromosome. Here we have evaluated whether excision of one of these pathogenicity islands, denominated as Region of Difference 21 (ROD21), is required for S. Enteritidis to cause disease in the host. By means of genetic targeting of the integrase encoded by the ROD21 we have generated S. Enteritidis strains unable to excise ROD21. The failure to excise ROD21 significantly reduced the capacity to cause a lethal disease and to colonize the spleen and liver of mice, as compared to wild type S. Enteritidis. On the contrary, S. Enteritidis strains overexpressing an excisionase protein increased the frequency of ROD21 excision and showed an improved capacity to cause lethal disease in mice. Accordingly, strains unable to excise ROD21 showed an altered expression of genes located in this pathogenicity island. Our results suggest that the genetic excision of the pathogenicity island ROD21 in S. Enteritidis modulates the capacity of this bacterium to cause disease in mice due to a change in the expression of virulence genes.
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    Conjugal transfer of the pathogenicity island ROD21 in Salmonella enterica serovar enteritidis depends on environmental conditions
    (2014) Salazar Echegarai, Francisco Javier; Tobar Durán, Hugo Eduardo; Nieto Pacheco, Pamela Andrea; Bueno Ramírez, Susan
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    Deletion of a prophage-like element causes attenuation of Salmonella enterica serovar Enteritidis and promotes protective immunity
    (2010) Araya González, Daniela Valentina; Tobar Durán, Hugo Eduardo; Kalergis Parra, Alexis Mikes; Bueno Ramírez, Susan
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    Host immunity during RSV pathogenesis
    (2008) Bueno Ramírez, Susan; González Muñoz, Pablo Alberto; Pacheco, Rodrigo; Leiva Llantén, Eduardo David; Cautivo Reyes, Kelly Margarita; Tobar Durán, Hugo Eduardo; Mora, Jorge E.; Prado, Carolina E.; Zuniga, Juan P.; Jimenez, Jorge; Riedel, Claudia A.; Kalergis Parra, Alexis Mikes
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    New insights about excisable pathogenicity islands in Salmonella and their contribution to virulence
    (2016) Nieto Pacheco, Pamela Andrea; Pardo Roa, Catalina; Salazar Echegarai, Francisco Javier; Tobar Durán, Hugo Eduardo; Coronado Arrázola, Irenice; Riedel, Claudia A.; Kalergis Parra, Alexis Mikes; Bueno Ramírez, Susan
    Pathogenicity islands (PAIs) are regions of the chromosome of pathogenic bacteria that harbor virulence genes, which were probably acquired by lateral gene transfer. Several PAIs can excise from the bacterial chromosome by site-specific recombination and in this review have been denominated "excisable PAIs ". Here, the characteristic of some of the excisable PAIs from Salmonella enterica and the possible role and impact of the excision process on bacterial virulence is discussed. Understanding the role of PAI excision could provide important insights relative to the emergence, evolution and virulence of pathogenic enterobacteria. (C) 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.
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    Plasma insulin-like growth factor-II (IGF-II) and IGF-II/IGF-I ratio in a chilean case of Doege-Potter Syndrome
    (2023) Tobar Durán, Hugo Eduardo; Ibaceta Gómez, Rodrigo Andrés; Figueroa Toledo, Ana María; Quiñones Tobar, Verónica Pilar; Iñiguez, Germán; Salman, Patricio; Serrano Larrea, Valentina Paz; Salinas Fernández, Lorena Del Pilar; Santos Martin, José Luis
    Doege-Potter syndrome is a rare clinical entity characterized by recurrent hypoglycemic events caused by non-pancreatic tumors secreting an incompletely processed high-molecular-weight form of Insulin-like Growth factor-II (IGF-II). To report IGF-II and IGF-I circulating levels in a Chilean case of Doege-Potter syndrome and control individuals, and to identify the high-molecular-weight form of IGF-II. We measured IGF-II and IGF-I plasma levels using enzyme-linked immunoassays (ELISA) in the patient and ten controls. We identified the high-molecular-weight form of IGF-II performed by Western blot. The plasma concentration of IGF-II in the patient was 868.9 ng/mL, which is only slightly > 80th percentile of controls (681,4 ± 212,8 ng/mL; mean ± standard deviation). In contrast, IGF-I plasma concentration in the patient was 17.6 ng/mL, which is notoriously lower than the corresponding levels in controls (109.1 ± 19.1 ng/mL). The IGF-II/IGF-I ratio in the patient was 49.4 (normal value < 10), which is 7.8 times higher compared to the average ratio of controls (6.3 ± 1.5). The high-molecular form of IGF-II presence in samples was confirmed through Western blot.