Claudia Ortega - Academia.edu (original) (raw)

Papers by Claudia Ortega

The American Journal of Medicine, 1966

Analytical and bioanalytical chemistry, 2003

An on-line dysprosium preconcentration and determination system based on the hyphenation of cloud... more An on-line dysprosium preconcentration and determination system based on the hyphenation of cloud point extraction (CPE) to flow injection analysis (FIA) associated with ICP-OES was studied. For the preconcentration of dysprosium, a Dy(III)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex was formed on-line at pH 9.22 in the presence of nonionic micelles of PONPE-7.5. The micellar system containing the complex was thermostated at 30 degrees C in order to promote phase separation, and the surfactant-rich phase was retained in a microcolumn packed with cotton at pH 9.2. The surfactant-rich phase was eluted with 4 mol L(-1) nitric acid at a flow rate of 1.5 mL min(-1), directly in the nebulizer of the plasma. An enhancement factor of 50 was obtained for the preconcentration of 50 mL of sample solution. The detection limit value for the preconcentration of 50 mL of aqueous solution of Dy was 0.03 microg L(-1). The precision for 10 replicate determinations at the 2.0 microg L(-1)Dy ...

Thrombosis Research, 2014

People with cancer are at increased risk of incidental venous thromboembolism (VTE) and PET-CT im... more People with cancer are at increased risk of incidental venous thromboembolism (VTE) and PET-CT imaging is commonly used in this population. However, the prevalence of incidental VTE detected by PET-CT in patients with cancer and its impact on survival are unknown. This retrospective study was approved by the local Institutional Review Board. 1331 consecutive adult patients with cancer who underwent PET-CT examination between 2009 and 2012 were included in the study (mean age: 57 ± 15 years). PET-CT reports were reviewed to identify patients with incidental VTE at the time of examination. Survival rates were assessed with Kaplan-Meier curves. The Cox proportional hazards model was used to determine the association between incidental VTE and overall survival, after controlling for clinical variables. Incidental VTE was detected in 19 patients (1.4%). Patients with genitourinary malignancies, colorectal cancer and lung cancer had the highest rates of incidental VTE at PET-CT. At multivariate analysis, incidental VTE detected by PET-CT was associated with worse overall survival independently of patient age, hospitalization status at time of PET-CT examination, and the presence of metastatic disease (Hazard ratio=2.03; 95% confidence interval=1.08-3.81, p=0.028). Incidental VTE was detected in 1.4% of adult patients with cancer undergoing PET-CT imaging. Diagnosis of incidental VTE at PET-CT imaging was associated with worse overall survival in this population.

Journal of Pharmaceutical and Biomedical Analysis, 2004

Automated preconcentration strategies are needed when analyzing metals in real samples by capilla... more Automated preconcentration strategies are needed when analyzing metals in real samples by capillary electrophoresis (CE) with UV detection. The on-line incorporation of cloud point extraction (CPE) to flow injection analysis (FIA) associated with CE for simultaneously determining dysprosium and iron at ppb levels in urine is presented and evaluated for the first time. The preconcentration step is mediated by micelles of the non-ionic surfactant polyethyleneglycol-mono-p-nonylphenylether (PONPE 7.5) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol. The micellar system containing the complex was loaded into the FIA manifold at a flow rate of 8 mlmin(-1), and the surfactant rich-phase was retained in a microcolumn packed with cotton, at pH 9.2. The surfactant-rich phase was eluted with 50 microl acetonitrile directly into the CE sample vial, allowing to reach an enrichment factor of 200-fold for a 10 ml sample urine. The type and composition of the background electrolytes (BGE) were investigated with respect to separation selectivity, reproducibility and stability. A BGE of 20mM sodium tetraborate buffer containing 13% acetonitrile, pH 9.0 was found to be optimal for the separation of metal chelates. Detection was performed at 585 nm. An enhancement factor of 200 was obtained for the preconcentration of 10 ml of sample solution. The detection limits for the preconcentration of 10 ml of urine were 0.20 microgl(-1) for Dy, and. 0.48 microgl(-1) for Fe. The calibration graphs using the preconcentration system were linear with a correlation coefficient of 0.9989 (Dy) and 0.9976 (Fe) at levels near the detection limits up to at least 500 microgl(-1). The method was successfully applied to the determination of dysprosium and iron in urine for monitoring the elimination of dysprosium-based pharmaceuticals.

European Journal of Cancer, 2011

European Journal of Cancer, 2011

Biochemical and Biophysical Research Communications, 2005

A point mutation (G ! C) in the gene promoter for the human nitric oxide synthase (NOS) 2 at posi... more A point mutation (G ! C) in the gene promoter for the human nitric oxide synthase (NOS) 2 at position À954 is associated with protection against severe Plasmodium falciparum malaria in Gabon. Carriers of this mutation show higher basal levels of nitric oxide production than wild type individuals. To obtain information about the possible binding transcription factors, nucleic proteins from the lung carcinoma cell line were enriched by affinity chromatography using DEAE-Sepharose and immobilized oligonucleotides derived from the promoter sequence. A mutational analysis was performed on 30 samples to detect polymorphisms in the NOS2 promoter region that contains important NF-jB sites. Three point mutations were identified in this region. In vitro studies with promoter constructs showed an altered expression of the marker gene depending on the promoter variant used.

The American Journal of Medicine, 1966

Thymomas are neoplasias that begin in the thymus and develop in the anterior mediastinum. They ar... more Thymomas are neoplasias that begin in the thymus and develop in the anterior mediastinum. They are commonly associated with a variety of systemic and autoimmune disorders, such as pure red cell aplasia, hypogammaglobulinaemia, pancytopaenia, collagen diseases, and, most commonly, myasthenia gravis. The presence of inter-current infections, especially diarrhoea and pneumonia, in the presence of lymphocyte B depletion and hypogammaglobulinaemia is known as Good's syndrome and may affect up to 5% of patients with thymoma. While anaemia is present in 50%-86% of patients with Good's syndrome, only 41.9% of cases present pure red cell aplasia. Concomitance of these two conditions has only been rarely studied.

Revista chilena de radiología, 2010

A case report of a patient with treated Non-Hodgkin Lymphoma is presented. In his usual tomograph... more A case report of a patient with treated Non-Hodgkin Lymphoma is presented. In his usual tomographic control patient was requested a PET-CT scan to supplement prior study that showed a metabolically active focus on the left adductor muscle without evident tomographic correlation. Lesion underwent both a soft tissue ultrasound study and a directed biopsy, the latter being positive for secondary infiltration by lymphoma. This case has demonstrated the usefulness of applying complementary techniques in the management of these lesions, mainly of PET-CT scans in the study of unusual sites of spread. This combined medical imaging technique allows accurate lesion localization, which in turn permits performance of a subsequent directed study.

The American Journal of Medicine, 1966

Analytical and bioanalytical chemistry, 2003

An on-line dysprosium preconcentration and determination system based on the hyphenation of cloud... more An on-line dysprosium preconcentration and determination system based on the hyphenation of cloud point extraction (CPE) to flow injection analysis (FIA) associated with ICP-OES was studied. For the preconcentration of dysprosium, a Dy(III)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex was formed on-line at pH 9.22 in the presence of nonionic micelles of PONPE-7.5. The micellar system containing the complex was thermostated at 30 degrees C in order to promote phase separation, and the surfactant-rich phase was retained in a microcolumn packed with cotton at pH 9.2. The surfactant-rich phase was eluted with 4 mol L(-1) nitric acid at a flow rate of 1.5 mL min(-1), directly in the nebulizer of the plasma. An enhancement factor of 50 was obtained for the preconcentration of 50 mL of sample solution. The detection limit value for the preconcentration of 50 mL of aqueous solution of Dy was 0.03 microg L(-1). The precision for 10 replicate determinations at the 2.0 microg L(-1)Dy ...

Thrombosis Research, 2014

People with cancer are at increased risk of incidental venous thromboembolism (VTE) and PET-CT im... more People with cancer are at increased risk of incidental venous thromboembolism (VTE) and PET-CT imaging is commonly used in this population. However, the prevalence of incidental VTE detected by PET-CT in patients with cancer and its impact on survival are unknown. This retrospective study was approved by the local Institutional Review Board. 1331 consecutive adult patients with cancer who underwent PET-CT examination between 2009 and 2012 were included in the study (mean age: 57 ± 15 years). PET-CT reports were reviewed to identify patients with incidental VTE at the time of examination. Survival rates were assessed with Kaplan-Meier curves. The Cox proportional hazards model was used to determine the association between incidental VTE and overall survival, after controlling for clinical variables. Incidental VTE was detected in 19 patients (1.4%). Patients with genitourinary malignancies, colorectal cancer and lung cancer had the highest rates of incidental VTE at PET-CT. At multivariate analysis, incidental VTE detected by PET-CT was associated with worse overall survival independently of patient age, hospitalization status at time of PET-CT examination, and the presence of metastatic disease (Hazard ratio=2.03; 95% confidence interval=1.08-3.81, p=0.028). Incidental VTE was detected in 1.4% of adult patients with cancer undergoing PET-CT imaging. Diagnosis of incidental VTE at PET-CT imaging was associated with worse overall survival in this population.

Journal of Pharmaceutical and Biomedical Analysis, 2004

Automated preconcentration strategies are needed when analyzing metals in real samples by capilla... more Automated preconcentration strategies are needed when analyzing metals in real samples by capillary electrophoresis (CE) with UV detection. The on-line incorporation of cloud point extraction (CPE) to flow injection analysis (FIA) associated with CE for simultaneously determining dysprosium and iron at ppb levels in urine is presented and evaluated for the first time. The preconcentration step is mediated by micelles of the non-ionic surfactant polyethyleneglycol-mono-p-nonylphenylether (PONPE 7.5) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol. The micellar system containing the complex was loaded into the FIA manifold at a flow rate of 8 mlmin(-1), and the surfactant rich-phase was retained in a microcolumn packed with cotton, at pH 9.2. The surfactant-rich phase was eluted with 50 microl acetonitrile directly into the CE sample vial, allowing to reach an enrichment factor of 200-fold for a 10 ml sample urine. The type and composition of the background electrolytes (BGE) were investigated with respect to separation selectivity, reproducibility and stability. A BGE of 20mM sodium tetraborate buffer containing 13% acetonitrile, pH 9.0 was found to be optimal for the separation of metal chelates. Detection was performed at 585 nm. An enhancement factor of 200 was obtained for the preconcentration of 10 ml of sample solution. The detection limits for the preconcentration of 10 ml of urine were 0.20 microgl(-1) for Dy, and. 0.48 microgl(-1) for Fe. The calibration graphs using the preconcentration system were linear with a correlation coefficient of 0.9989 (Dy) and 0.9976 (Fe) at levels near the detection limits up to at least 500 microgl(-1). The method was successfully applied to the determination of dysprosium and iron in urine for monitoring the elimination of dysprosium-based pharmaceuticals.

European Journal of Cancer, 2011

European Journal of Cancer, 2011

Biochemical and Biophysical Research Communications, 2005

A point mutation (G ! C) in the gene promoter for the human nitric oxide synthase (NOS) 2 at posi... more A point mutation (G ! C) in the gene promoter for the human nitric oxide synthase (NOS) 2 at position À954 is associated with protection against severe Plasmodium falciparum malaria in Gabon. Carriers of this mutation show higher basal levels of nitric oxide production than wild type individuals. To obtain information about the possible binding transcription factors, nucleic proteins from the lung carcinoma cell line were enriched by affinity chromatography using DEAE-Sepharose and immobilized oligonucleotides derived from the promoter sequence. A mutational analysis was performed on 30 samples to detect polymorphisms in the NOS2 promoter region that contains important NF-jB sites. Three point mutations were identified in this region. In vitro studies with promoter constructs showed an altered expression of the marker gene depending on the promoter variant used.

The American Journal of Medicine, 1966

Thymomas are neoplasias that begin in the thymus and develop in the anterior mediastinum. They ar... more Thymomas are neoplasias that begin in the thymus and develop in the anterior mediastinum. They are commonly associated with a variety of systemic and autoimmune disorders, such as pure red cell aplasia, hypogammaglobulinaemia, pancytopaenia, collagen diseases, and, most commonly, myasthenia gravis. The presence of inter-current infections, especially diarrhoea and pneumonia, in the presence of lymphocyte B depletion and hypogammaglobulinaemia is known as Good's syndrome and may affect up to 5% of patients with thymoma. While anaemia is present in 50%-86% of patients with Good's syndrome, only 41.9% of cases present pure red cell aplasia. Concomitance of these two conditions has only been rarely studied.

Revista chilena de radiología, 2010

A case report of a patient with treated Non-Hodgkin Lymphoma is presented. In his usual tomograph... more A case report of a patient with treated Non-Hodgkin Lymphoma is presented. In his usual tomographic control patient was requested a PET-CT scan to supplement prior study that showed a metabolically active focus on the left adductor muscle without evident tomographic correlation. Lesion underwent both a soft tissue ultrasound study and a directed biopsy, the latter being positive for secondary infiltration by lymphoma. This case has demonstrated the usefulness of applying complementary techniques in the management of these lesions, mainly of PET-CT scans in the study of unusual sites of spread. This combined medical imaging technique allows accurate lesion localization, which in turn permits performance of a subsequent directed study.