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Search Results: 1 - 10 of 395651 matches for " ALEJANDRO CORVALáN R. "
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Biología molecular en Infectología: Parte I: Desarrollo y metodologías
CORVALáN R.,ALEJANDRO;
Revista chilena de infectología , 2002, DOI: 10.4067/S0716-10182002000100003
Abstract: eventhough molecular biology was iniciated at the end of the xix century, the discovery of the structure of dna is considered the beginning of this field. advances during 1960-1970 produced methods and technologies to study microorganisms at molecular level. in particular, the discovery of dna polymerase and the specificity of dna reanaturation are the bases for polymerase chain reaction, transcription mediated amplification, and branched dna methods useful for diagnosis and direct quantitation of infectious agents. finally, the complete genome sequence should ultimately result in new methods for diagnosing and treating infectious diseases
Biología molecular en Infectología: Parte I: Desarrollo y metodologías MOLECULAR BIOLOGY IN INFECTIOUS DISEASES: PART I. DEVELOPMENT AND METHODOLOGIES
ALEJANDRO CORVALáN R.
Revista chilena de infectología , 2002,
Abstract: El origen de la biología molecular se puede rastrear hasta fines del siglo XIX; sin embargo, el descubrimiento de la estructura del ADN se considera como el inicio de esta disciplina. Los avances producidos por la biología molecular en la década del ′60 nos permiten contar hoy con herramientas para el estudio de microorga-nismos a nivel molecular. En particular, el descubrimiento de la ADN polimerasa y las propiedades de hibridación del ADN son algunos de los descubrimientos que aplicados hoy día en la reacción de polimerasa en cadena, la amplificación isotérmica y la hibridación con ADN ramificado, se han transformado en herramientas útiles en el diagnóstico y cuantificación de agentes infecciosos. Finalmente la secuenciación de genomas bacterianos completos permitirá el desarrollo de nuevos métodos para el diagnóstico y tratamiento de enfermedades infecciosas Eventhough Molecular Biology was iniciated at the end of the XIX century, the discovery of the structure of DNA is considered the beginning of this field. Advances during 1960-1970 produced methods and technologies to study microorganisms at molecular level. In particular, the discovery of DNA polymerase and the specificity of DNA reanaturation are the bases for Polymerase Chain Reaction, Transcription Mediated Amplification, and Branched DNA methods useful for diagnosis and direct quantitation of infectious agents. Finally, the complete genome sequence should ultimately result in new methods for diagnosing and treating infectious diseases
Biología molecular en Infectología: Parte II: Diagnóstico molecular de agentes infecciosos
Corvalán R.,Alejandro; Aguayo G.,Francisco; Lévican G.,Jorge; Corvalán V.,Ignacio;
Revista chilena de infectología , 2003, DOI: 10.4067/S0716-10182003000100004
Abstract: the diagnostic applications of the molecular biology in infectious diseases are wide and applicable to any diagnostic problem. in the herpesviridae family, the most used methods are those based on the amplification of dna polymerase gene for the detection of hsv 1 and 2, varicela-zoster, citomegalovirus, epstein barr virus and hhv6 simultaneously. this methodology has been able of detect the co-infection of hsv1 and vzv in samples of cns fluid. in citomegalovirus, molecular methods are used in the monitoring of the reactivation of cmv in immunosuppressed patients and are able to detect viral reactivation within 1 week before symptoms. the molecular methods are also able to identify the epstein-barr virus in a proportion of 8 to 20% of gastric cancer cases harboring a unique strain in spite of the presence multiples strains in the healthy population. these associations between virus and cancer have also been described for the human papilloma virus and esophageal and lung cancer. in bacterial agents, the detection and quantification of bordetella pertussis is another interesting application since it might become a method for rapid diagnosis and predictive of severity in children less than 6 months old. the identification of helicobacter pylori strains in relation to gastric cancer and peptic ulcer disease and the characterization of strains of methicillin resistant staphylococcus aureus are other examples of potential applications of the molecular methods in typing microorganisms. in the diagnosis of respiratory tract infectious agents such as mycobacterium tuberculosis, pneumocystis carinii and atypical agents, the molecular methods allow the diagnosis in non-invasive samples. finally, these new methodologies also contribute to the diagnosis of systemic mycotic agents (candidiasis and aspergillosis) particularly in immunosuppressed patients
Biología molecular en Infectología: Parte II: Diagnóstico molecular de agentes infecciosos Molecular biology in infectious diseases: Part II: Molecular diagnosis of infectious agents
Alejandro Corvalán R.,Francisco Aguayo G.,Jorge Lévican G.,Ignacio Corvalán V.
Revista chilena de infectología , 2003,
Abstract: The diagnostic applications of the molecular biology in infectious diseases are wide and applicable to any diagnostic problem. In the Herpesviridae family, the most used methods are those based on the amplification of DNA polymerase gene for the detection of HSV 1 and 2, varicela-zoster, citomegalovirus, Epstein Barr virus and HHV6 simultaneously. This methodology has been able of detect the co-infection of HSV1 and VZV in samples of CNS fluid. In citomegalovirus, molecular methods are used in the monitoring of the reactivation of CMV in immunosuppressed patients and are able to detect viral reactivation within 1 week before symptoms. The molecular methods are also able to identify the Epstein-Barr virus in a proportion of 8 to 20% of gastric cancer cases harboring a unique strain in spite of the presence multiples strains in the healthy population. These associations between virus and cancer have also been described for the human papilloma virus and esophageal and lung cancer. In bacterial agents, the detection and quantification of Bordetella pertussis is another interesting application since it might become a method for rapid diagnosis and predictive of severity in children less than 6 months old. The identification of Helicobacter pylori strains in relation to gastric cancer and peptic ulcer disease and the characterization of strains of methicillin resistant Staphylococcus aureus are other examples of potential applications of the molecular methods in typing microorganisms. In the diagnosis of respiratory tract infectious agents such as Mycobacterium tuberculosis, Pneumocystis carinii and atypical agents, the molecular methods allow the diagnosis in non-invasive samples. Finally, these new methodologies also contribute to the diagnosis of systemic mycotic agents (Candidiasis and Aspergillosis) particularly in immunosuppressed patients
Identificación de Virus Papiloma Humano 16 (vph-16) en carcinoma queratinizante de pulmón IDENTIFICATION OF HUMAN PAPILLOMAVIRUS 16 (HPV 16) IN KERATINIZING LUNG CARCINOMA
Francisco Aguayo G.,Manuel Meneses M.,Alejandro Corvalán R.,María Luisa Mu?oz S.
Revista Chilena de Enfermedades Respiratorias , 2002,
Abstract: El cáncer pulmonar constituye la primera causa de muerte por cáncer en el mundo y la cuarta causa de muerte por cáncer en Chile. El carcinoma escamoso de pulmón representa entre el 35% a 50% de los casos de cáncer pulmonar. Existe fuerte evidencia, aunque aún controversial, respecto de la asociación entre esta forma histológica y la infección por Virus Papiloma Humano (VPH), siendo los genotipos VPH 16 y 18 los que se han asociado a lesiones malignas y premalignas de diversos tejidos epiteliales. Analizamos casos de carcinoma escamoso de pulmón del tipo queratinizante para evaluar la presencia de genotipos de VPH 16 y 18 en Chile. Quince casos con diagnóstico histológico de carcinoma escamoso moderada y altamente diferenciados en tejido incluido en parafina, fueron tratados con xilol y etanol y resuspendidos en proteinasa K durante 48 horas a 56o C para la extracción de ADN. Este se amplificó mediante la reacción de polimerasa en cadena (PCR) usando partidores específicos para VPH genérico, VPH 16, VPH 18 y betaglobina humana como control positivo interno. Los amplificados fueron revelados en geles de polacrilamida y tinción con nitrato de plata. Identificamos la presencia de VPH genérico en 6 (42,2%) de 13 casos amplificables. De estos casos todos correspondieron al genotipo VPH 16 y ninguno correspondió al genotipo VPH 18. La presencia de VPH 16 en la serie analizada indicaría que VPH puede tener algún rol en cáncer pulmonar del tipo escamoso - queratinizante. Es interesante la ausencia de VPH 18 en la serie analizada lo cual podría indicar características epidemiológicas propias en nuestra población. En esta serie analizada, una muestra mostró no corresponder a los genotipos estudiados. Es necesario realizar un estudio más amplio con otros genotipos de VPH y un universo mayor de casos para confirmar estos resultados Lung cancer is the first cause of death by cancer in the world and the fourth cause in Chile. The histological type squamous cell carcinoma represents between 35% to 50% of the cases. Strong evidence exists about the association between this histological type and the human papilloma virus (HPV) infection, being genotypes HPV-16 and 18 those that have an strong association. We analyzed cases of lung squamous cell carcinoma of the keratinizing type to evaluate the presence of HPV 16 and 18 genotypes in Chile. Thirteen cases with histological diagnosis of keratinizing highly or moderately differentiated squamous cell carcinoma were analyzed. Samples were formalin-fixed and paraffin-embedded tissue. DNA was extracted with proteinase K and it
Características clínico-moleculares del cáncer gástrico cardial asociado al virus Epstein Barr Clinical and molecular features of cardial gastric cancer associated to Epstein Barr virus
Alejandro Corvalán R,Suminori Akiba,María Teresa Valenzuela B,Miguel Angel Cumsille G
Revista médica de Chile , 2005,
Abstract: Background: Mortality caused by cardial gastric cancer in Chile, is increasing. Previously we demonstrated an association between Epstein Barr virus and this specific location of gastric cancer. Aim: To perform a clinical and molecular characterization of cardial gastric cancer associated to Epstein Barr virus. Material and methods: Epstein Barr virus was identified in 93 cardial gastric tumors, by in situ hybridization. Clinical and pathological features, survival and expression of p53 and c-erbB2 were compared between tumors with or without the presence of the virus. Results: Twenty two (23.6%) tumors expressed Epstein Barr virus. No difference in sex or age of patients with tumors positive or negative for the virus was observed. Epstein Barr positive tumors had a tendency to have a higher frequency of Bormann III endoscopic appearance and a lower frequency of p53 accumulation (p=0.06). Five years survival was 67% and 42% of tumors positive and negative for the presence of the virus, respectively (p=0.57). Conclusions: Our results, although not significant, show a tendency towards unique characteristics of cardial gastric tumors associated to Epstein Barr
Perfiles de expresión génica en decisiones terapéuticas en cáncer de mama
Corvalán,Alejandro;
Revista médica de Chile , 2007, DOI: 10.4067/S0034-98872007000200016
Abstract: in the early stages of breast cancer, surgery and radiotherapy arrest the local and regional disease. however 30% of patients will die as a consequence of tumor dissemination. parameters with a relative predictive value are used to assess candidates to adjuvant therapy. genomic analysis methods (cdna microarray) identified a gene expression profile of greater aggressiveness in breast cancer. this knowledge generated the project "translating molecular knowledge into early breast cancer management" of the breast international group (big). this is a consortium of 32 research groups in which chile participates through the chilean cooperative oncological research group (gocchi). the project consists in three protocols. in the first, denomimated mindact (microarray for node negative disease may avoid chemotherapy), 8000 women will be evaluated by gene expression profile and clinical pathological criteria to decide adjuvant therapy. since a group of patients will not receive therapy, solely based on gene expression profile, gocchi is preparing a follow up protocol based on the expression of 22 genes. mindact is the first prospective effort to evaluate gene expression profiles in clinical practice. our participation in this protocol, installs us in the first line of worlwide oncological investigation
Perfiles de expresión génica en decisiones terapéuticas en cáncer de mama Gene expression profiles for therapeutic decisions in breast cancer
Alejandro Corvalán
Revista médica de Chile , 2007,
Abstract: In the early stages of breast cancer, surgery and radiotherapy arrest the local and regional disease. However 30% of patients will die as a consequence of tumor dissemination. Parameters with a relative predictive value are used to assess candidates to adjuvant therapy. Genomic analysis methods (cDNA microarray) identified a gene expression profile of greater aggressiveness in breast cancer. This knowledge generated the project "Translating Molecular Knowledge Into Early Breast Cancer Management" of the Breast International Group (BIG). This is a consortium of 32 research groups in which Chile participates through the Chilean Cooperative Oncological Research Group (GOCCHI). The project consists in three protocols. In the first, denomimated MINDACT (Microarray for Node Negative Disease may Avoid Chemotherapy), 8000 women will be evaluated by gene expression profile and clinical pathological criteria to decide adjuvant therapy. Since a group of patients will not receive therapy, solely based on gene expression profile, GOCCHI is preparing a follow up protocol based on the expression of 22 genes. MINDACT is the first prospective effort to evaluate gene expression profiles in clinical practice. Our participation in this protocol, installs us in the first line of worlwide oncological investigation
Rol patogénico del gen supresor de tumores PTEN en cáncer ovárico asociado a endometriosis
Castiblanco G,Adriana; Pires N,Yumay; Wistuba O,Ignacio; Riquelme S,Erick; Andrade M,Leonardo; Corvalán R,Alejandro;
Revista médica de Chile , 2006, DOI: 10.4067/S0034-98872006000300001
Abstract: background: endometrioid carcinoma and clear cell carcinoma of the ovary are associated to endometriosis. somatic mutations of pten (10q23.3) are present in endometrial endometrioid carcinoma. therefore, these mutations could be also present in ovarian tumors. molecular studies show that solitary endometriotic cysts are monoclonal, have aneuploid dna, have a loss of 9p,11q and 22q heterozygosity (loh) and a higher cellular proliferation index of the epithelial component. aim: to determine the cellular proliferation index using ki 67, the immunohistochemical expression of pten and loh in patients with ovarian endometriosis without atypia (en), ovarian endometriosis with atypia (ea) and endometriosis with adjacent ovarian carcinoma (et). material and methods: paraffin embedded samples of 37 endometrioid and clear cell carcinomas of the ovary (cc/ce), 15 solitary ovarian en and 15 ovarian ea, were studied. expression of ki 67 and pten was measured by immunohistochemistry. loh of 10q23.3 locus was measured by polymerase chain reaction. results: ki 67 was 5.5 and 2.3% in ea and en, respectively (p <0.005). there was a histological correlation between ea and a higher cellular proliferation index. pten was negative in 5 of 15 en, 9 of 15 ea and 30 of 37 ce/cc. there was a correlation between loh and loss of pten protein in en, ea and et (60%). conclusions: negative expression on pten in en; ea; et and ce/cc is a manifestation of the inactivation of this gene. the mechanisms that cause this inactivation, must be elucidated
La convergencia de las regiones chilenas, 1960-2009
Corvalán,Alejandro; Pezo,Danilo;
Lecturas de Economía , 2012,
Abstract: in this paper we analyze fifty years of economic convergence for the regions of chile, in a context of radical political changes associated with deep economic transformations. for the analysis of convergence of gdp per capita, the sub-periods 1960-1973, 1973-1989 and 1989-2009 were considered, while the sub-periods 1976-1989 and 1989-2009 were considered for the variable productivity. the analysis was carried out using the definitions of absolute β convergence and σ convergence, and using cross-section and panel data. the panel estimates suggest a process of β convergence for the entire period 1960-2009, 55 years to reduce half of the gap. however, the σ-convergence analysis shows a reduction of dispersion in the fifty years, with a decelerating tendency since 1990. in addition, the distributions of annual productivity and gdp were estimated using kernel functions. these distributions show persistent regional inequality, especially since 1985 when the phenomenon of bimodality (i.e., a gap between certain regions with higher income levels and those with lower levels) emerges. these results indicate slow adjustment to changes in regional economies and low market effectiveness in solving regional disparities. as a consequence, the convergence of chilean regions is an unresolved issue in public policy in chile.
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