Browsing by Author "Riquelme, Erick"

Now showing 1 - 7 of 7
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    A novel adrenocorticotropin receptor mutation alters its structure and function, causing familial glucocorticoid deficiency
    (ENDOCRINE SOC, 2008) Artigas, Rocio A.; Gonzalez, Angel; Riquelme, Erick; Carvajal, Cristian A.; Cattani, Andreina; Martinez Aguayo, Alejandro; Kalergis, Alexis M.; Perez Acle, Tomas; Fardella, Carlos E.
    Context: Familial glucocorticoid deficiency (FGD) is an autosomal recessive disorder characterized by unresponsiveness to ACTH. In this study, two mutations of the ACTH receptor (MC2R) gene are reported in this FGD clinical case.
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    A polymorphic GT short tandem repeat affecting beta-ENaC mRHA expression is associated with low renin essential hypertension
    (OXFORD UNIV PRESS, 2007) Gonzalez, Alexis A.; Carvajal, Cristian A.; Riquelme, Erick; Krall, Paola M.; Munoz, Carlos R.; Mosso, Lorena M.; Kalergis, Alexis M.; Fardella, Carlos E.
    Background: The epithelial sodium channel (ENaC) is a candidate gene associated with the development of essential hypertension. A potentially polymorphic repetitive region (GT dinucleotide short tandem repeat [STR]) was identified in intron 8 of beta-ENaC gene (SCNN I B). The aim of this study was to identify the prevalence and distribution of a polymorphic GT-STR in SCNN1B in Chilean essential hypertensive (EH) patients and to analyze the correlation between the different genotypes with plasma renin activity (PRA) and serum aldosterone (SA), and furthermore, to evaluate the beta-ENaC gene expression in vitro.
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    Analytical detection of immunoglobulin heavy chain gene rearrangements in gastric lymphoid infiltrates by peak area analysis of the melting curve in the LightCycler System
    (ELSEVIER SCIENCE INC, 2007) Retamales, Eduardo; Rodriguez, Luis; Guzman, Leda; Aguayo, Francisco; Palma, Mariana; Backhouse, Claudia; Argandona, Jorge; Riquelme, Erick; Corvalan, Alejandro
    Because it is difficult to differentiate gastric mucosa-associated lymphoid tissue (MALT) lymphoma from chronic gastritis in gastric lymphoid infiltrates, molecular detection of monoclonality through immunoglobulin heavy chain (IgH) gene rearrangements is commonly performed. However, heterogeneity in the performance and results obtained from IgH gene rearrangements has been reported. To improve the accuracy in the diagnosis of gastric lymphoid infiltrates, we developed an analytical approach based on one-peak area analysis of the melting curve in the LightCycler System. Using a training-testing approach, the likelihood ratio method was selected to find a discriminative function of 4.64 in the training set (10 gastric MALT lymphomas and 10 chronic gastritis cases). This discriminative function was validated in the testing set (five gastric MALT lymphomas, six abnormal lymphocytic infiltrates with subsequently demonstrated gastric MALT lymphomas, and six cases of chronic gastritis). All but one case of gastric MALT lymphoma, as well as abnormal lymphocytic infiltrates, clustered under 4.64, and all chronic gastritis cases clustered above 4.64. These results were validated by conventional electrophoreses confirming one or two sharp bands in cases of gastric MALT lymphomas and a smear of multiple bands in cases of chronic gastritis. Analytical detection of IgH gene rearrangement in gastric lymphoid infiltrates by one-peak area analysis correctly distinguishes gastric MALT lymphomas from chronic gastritis, even in cases with diagnosis of abnormal lymphocytic infiltrates.
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    Bone Marrow Stromal Cells Modulate Mouse ENT1 Activity and Protect Leukemia Cells from Cytarabine Induced Apoptosis
    (PUBLIC LIBRARY SCIENCE, 2012) Macanas Pirard, Patricia; Leisewitz, Andrea; Broekhuizen, Richard; Cautivo, Kelly; Barriga, Francisco M.; Leisewitz, Francisco; Gidi, Victoria; Riquelme, Erick; Montecinos, Viviana P.; Swett, Pilar; Besa, Pelayo; Ramirez, Pablo; Ocqueteau, Mauricio; Kalergis, Alexis M.; Holt, Matthew; Rettig, Michael; DiPersio, John F.; Nervi, Bruno
    Background: Despite a high response rate to chemotherapy, the majority of patients with acute myeloid leukemia (AML) are destined to relapse due to residual disease in the bone marrow (BM). The tumor microenvironment is increasingly being recognized as a critical factor in mediating cancer cell survival and drug resistance. In this study, we propose to identify mechanisms involved in the chemoprotection conferred by the BM stroma to leukemia cells.
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    Frequent epigenetic inactivation of chromosome 3p candidate tumor suppressor genes in gallbladder carcinoma
    (ELSEVIER IRELAND LTD, 2007) Riquelme, Erick; Tang, Moying; Baez, Sergio; Diaz, Alfonso; Pruyas, Martha; Wistuba, Ignacio I.; Corvalan, Alejandro
    Gallbladder carcinoma (GBC) is a highly malignant neoplasm that represents the leading cause of death for cancer in Chilean females. There is limited information about the molecular abnormalities involved in its pathogenesis. We have identified a number of molecular changes in GBC, including frequent allelic losses at chromosome 3p regions. Four distinct 3p sites (3p12, 3p14.2, 3p21.3 and 3p22-24) with frequent and early allelic losses in the sequential pathogenesis of this neoplasm have been detected. We investigated epigenetic and genetic abnormalities in GBC affecting 6 candidate tumor suppressor genes (TSG) located in chromosome 3p, including DUTT1 (3p12), FHIT(3p14.2), BLU, RASSF1A, SEMA3B and hMLH1 (3p21.3). DNA extracted from frozen tissue obtained from 50 surgical resected GBCs was examined for gene promoter methylation using MSP (methylation-specific PCR) technique after bisulfite treatment in all 6 genes. In addition, we performed PCR-based mutation examination using SSCP in FHIT and RASSF1A genes and loss of heterozygosity (LOH) analysis using microdissected tissue in a subset of tumors for the 3p21.3 region with 8 microsatellite markers. A very high frequency of GBC methylation was detected in SEMA3B (46/50, 92%) and FHIT (33/50, 66%), inter-mediate incidences in BLU (13/50, 26%) and DUTT1 (11/50, 22%) and very low frequencies in RASSF1A (4/50, 8%) and hMLH1 (2/50, 4%). Allelic loss at 3p21.3 was found in nearly half of the GBCs examined. We conclude that epigenetic inactivation by abnormal promoter methylation is a frequent event in chromosome 3p candidate TSGs in GBC pathogenesis, especially affecting genes SEMA3B (3p21.3) and FHIT (3p 14.2). (c) 2006 Elsevier Ireland Ltd. All rights reserved.
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    Mismatch repair expression in testicular cancer predicts recurrence and survival
    (WILEY-LISS, 2008) Velasco, Alfredo; Corvalan, Alejandro; Wistuba, Ignacio I.; Riquelme, Erick; Chuaqui, Rodrigo; Majerson, Alejandro; Leach, Fredrick S.
    We investigated mismatch repair (MMR) gene expression in testicular cancer as a molecular marker for clinical outcome (recurrence, response to chemotherapy and death) using protein expression and specific genetic alterations associated with the presence or absence of MMR activity. One hundred sixty-two cases of paraffin-embedded testis cancer specimens were subjected to immunohistochemical analysis using monoclonal antibody for MLH1 and MSH2 MMR proteins and genetic analysis using specific polymorphic markers. The degree of MMR immunoreactivity and genetic instability in the form of loss of heterozygosity (LOH) and/or microsatellite instability (MSI) were determined by comparing matched normal and tumor tissue. The degree of immunohistochemical staining for MMR expression was associated with a shorter time to tumor recurrence, resistance to chemotherapy and death. Furthermore, clinical relapse and cancer specific death was also associated with tumors exhibiting a high degree of MSI, p = 0.01 and 0.04, respectively. In contrast, LOH was not associated with recurrence, resistance to chemotherapy or death. Therefore, MMR expression defines testis cancers with distinct molecular properties and clinical behavior, such that tumors with decreased MMR immunostaining and/or increased frequency of MSI have a shorter time to recurrence and death despite chemotherapy. (c) 2007 Wiley-Liss, Inc.
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    Mismatch repair expression in testicular cancer predicts recurrence and survival
    (2008) Velasco Palma, Alfredo Alejandro; Corvalán Rodríguez, Alejandro; Wistuba, Ignacio I.; Riquelme, Erick; Chuaqui, Rodrigo; Majerson Grinberg, Alejandro; Leach, Fredrick S.
    We investigated mismatch repair (MMR) gene expression in testicular cancer as a molecular marker for clinical outcome (recurrence, response to chemotherapy and death) using protein expression and specific genetic alterations associated with the presence or absence of MMR activity. One hundred sixty-two cases of paraffin-embedded testis cancer specimens were subjected to immunohistochemical analysis using monoclonal antibody for MLH1 and MSH2 MMR proteins and genetic analysis using specific polymorphic markers. The degree of MMR immunoreactivity and genetic instability in the form of loss of heterozygosity (LOH) and/or microsatellite instability (MSI) were determined by comparing matched normal and tumor tissue. The degree of immunohistochemical staining for MMR expression was associated with a shorter time to tumor recurrence, resistance to chemotherapy and death. Furthermore, clinical relapse and cancer specific death was also associated with tumors exhibiting a high degree of MSI, p = 0.01 and 0.04, respectively. In contrast, LOH was not associated with recurrence, resistance to chemotherapy or death. Therefore, MMR expression defines testis cancers with distinct molecular properties and clinical behavior, such that tumors with decreased MMR immunostaining and/or increased frequency of MSI have a shorter time to recurrence and death despite chemotherapy. (c) 2007 Wiley-Liss, Inc.