Importance of a Rapid and Accurate Diagnosis in Strongyloides Stercoralis and Human T-Lymphotropic Virus 1 Co-infection: A Case Report and Review of the Literature

Strongyloides (S.) stercoralis and Human T-Lymphotropic Virus 1 (HTLV-1) share some endemic regions such as Japan, Jamaica, and South America and are mostly diagnosed elsewhere in immigrants from endemic areas. This co-infection has not been documented in Argentina although both pathogens are endemic in the Northwest. We present a case of S. stercoralis and HTLV-1 co-infection with an initial presentation due to gastrointestinal symptoms which presented neither eosinophilia nor the presence of larvae in stool samples in a non-endemic area for these infections. A young Peruvian woman living in Buenos Aires attended several emergency rooms and finally ended up admitted in a gastroenterology ward due to incoercible vomiting, diarrhea, abdominal pain, fever, and weight loss. Gastrointestinal symptoms started 3 months before she returned to Argentina from a trip to Peru. She presented malnutrition and abdominal distension parameters. HIV-1 and other immunodeficiencies were discarded. The serial coproparasitological test was negative. Computed tomography showed diffuse thickening of duodenal and jejunal walls. At the beginning, vasculitis was suspected and corticosteroid therapy was initiated. The patient worsened rapidly. Skin, new enteral biopsies, and a new set of coproparasitological samples revealed S. stercoralis. Then, HTLV-1 was suspected and infection was confirmed. Ivermectin and albendazole were administrated, until the stool sample remained negative for 2 weeks. Larvae were not observed in fresh stool, Ritchie method, and agar culture 1 week post-treatment. Although she required initial support with parenteral nutrition due to oral intolerance she slowly progressed favorably. It has been highly recommended to include a rapid and sensitive PCR strategy in the algorithm to confirm Strongyloides infection, which has demonstrated to improve early diagnosis in patients at-risk of disseminated strongyloidiasis.Fil: Quintero, Olga. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Berini, Carolina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Waldbaum, Carlos. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Avagnina, Alejandra. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Juarez, María. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Repetto, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones en Microbiología y Parasitología Médica. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones en Microbiología y Parasitología Médica; ArgentinaFil: Sorda, Juan. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Biglione, Mirna Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; Argentin

Correlation between PD-L1 expression (clones 28-8 and SP263) and histopathology in lung adenocarcinoma

Lung cancer is the leading cause of cancer-related death worldwide. Recent advances in the management of non-small cell carcinoma are focused on the discovery of targeted therapies and novel immunotherapy strategies for patients with advanced disease. Treatment with anti PD-(L)1 immune checkpoint inhibitors requires the development of predictive biomarkers to select those patients that can most benefit from these therapies. Several immunohistochemical biomarkers have been developed in different technological platforms. However, the most useful and accessible for the daily clinical practice need to be selected. The objective of this study was to compare PD-L1 expression by automated immunohistochemistry in lung adenocarcinoma (ADC) FFPE samples with clones 28-8 and SP263 performed with the BenchMark GX automated staining instrument. To further determine interobserver agreement between two pathologists, and to correlate the results with histologic and pathology variables. FFPE tissue from 40 samples obtained from patients with lung ADC were reviewed retrospectively. Among all studied specimens, 53% of samples presented <1% of positive tumor cells with the 28-8 clone and 50% had <1% of PD-L1 expression in tumor cells with the SP263 clone; PD-L1 expression between ≥1 and <5% was observed in 18% and 24%; ≥5 and <50% PD-L1 expression in 18% and 21%; and ≥50% PD-L1 expression in 11% and 5% of samples, respectively. Similar results between antibodies were observed in 84% of cases for each of the four PD-L1 cutoff groups (Pearson's score 0.90, p < 0.00001). The interobserver degree of agreement calculated with Kappa was 0.75 (95%CI: 0.57–0.93), z = 7.08; p < 0.001. Lepidic, acinar and mucinous patterns had predominantly <1% PD-L1 expression, and the solid pattern subtype had high levels of PD-L1 staining using both clones. PD-L1 expression in less than 1% of tumor cells was similar in stages I/II compared to III/IV. No significant differences were observed in PD-L1 staining and quantification pattern between IHC antibodies 28-8 and SP263.Fil: García, Alejandro. Centro de Educación Médica e Investigaciones Clínicas "Norberto Quirno"; ArgentinaFil: Recondo, Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; ArgentinaFil: Greco, Martín. Centro de Educación Médica e Investigaciones Clínicas "Norberto Quirno"; ArgentinaFil: de la Vega, Máximo. Centro de Educación Médica e Investigaciones Clínicas "Norberto Quirno"; ArgentinaFil: Perazzo, Florencia. Centro de Educación Médica e Investigaciones Clínicas "Norberto Quirno"; ArgentinaFil: Avagnina, Alejandra. Centro de Educación Médica e Investigaciones Clínicas "Norberto Quirno"; ArgentinaFil: Denninghoff, Valeria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentin

Clinical-pathological features and gene profile in colorectal cancer

El cáncer colorectal es el tercer cáncer más frecuente en hombres y el segundo más frecuente en mujeres, con una incidencia mundial aproximada de 1.2 millones de casos nuevos por año. El objetivo primario es estudiar la relación existente entre las características clínico-histológicas de individuos con cáncer colorectal y el estado mutacional de los codones 12 y 13 del gen KRAS (7 mutaciones validadas), con el fin de hallar un marcador histopatológico para los tumores mutados. El objetivo secundario es determinar cuantos pacientes tienen mutaciones adicionales en los codones 15 y 61 del gen KRAS y 600 del gen BRAF que podrían modificar el fenotipo tumoral. Fueron seleccionados 60 individuos con cáncer colorrectal (30 wild-type y 30 con mutaciones validadas en los codones 12 y 13 del gen KRAS). Se amplificaron y secuenciaron del gen KRAS los exones 2 y 3, y del gen BRAF el exón 15. La información recolectada se examinó mediante un análisis descriptivo, análisis univariado y/ó análisis multivariado según correspondiese. En conclusión, no se encontró relación entre las características clínico-histológicas de los tumores de individuos con diagnostico de cáncer colorectal y el estado mutacional de los codones 12 y 13 del gen KRAS. No hallamos un marcador histopatológico para los tumores mutados resulta interesante considerar el estudio del codón 600 del gen BRAF.Colorectal cancer is the third most frequent cancer in men and the second most frequent in women, with a worldwide incidence of approximately 1.2 million new cases per year. Our primary objective was to study the relationship between clinical and histological features of individuals with colorectal cancer and the mutational status of codons 12 and 13 of the KRAS gene (7 validated mutations), in order to find a histopathological marker to mutated tumors. The secondary objective was to determine how many patients had additional mutations in codons 15 and 61 of the KRAS gene, and codon 600 of the BRAF gene, which could modify the tumor phenotype. Sixty individuals with colorectal cancer (30 wild-type subjects and 30 with validated mutations in codons 12 and 13 of the KRAS gene) were selected. Exons 2 and 3 of the KRAS gene, and exon 15 of the BRAF gene were amplified and sequenced. The data collected were reviewed by a descriptive, univariate and/or multivariate analysis, as appropriate. In conclusion, no relation was found between clinical and histological features of individuals with colorectal cancer and their mutational status for codons 12 and 13 of the KRAS gene. This suggests that those easily available data do not allow predicting the response to anti-EGFR therapy. In patients with advanced colorectal adenocarcinomas and KRAS wild-type status, further study of codon 600 of the BRAF gene could be required.Fil: Perazzo, Florencia. Centro de Educación Médica e Investigaciones Clínicas; ArgentinaFil: Piaggio, Fernando. Centro de Educación Médica e Investigaciones Clínicas; ArgentinaFil: Krupitzki, Hugo Bernardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Centro de Educación Médica e Investigaciones Clínicas; ArgentinaFil: Garcia, Alejandro Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Centro de Educación Médica e Investigaciones Clínicas; ArgentinaFil: Avagnina, Alejandra. Centro de Educación Médica e Investigaciones Clínicas; ArgentinaFil: Elsner, Boris. Centro de Educación Médica e Investigaciones Clínicas; ArgentinaFil: Denninghoff, Valeria Cecilia. Centro de Educación Médica e Investigaciones Clínicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Variable Number Tandem Repeats in the promoter region of prostacyclin synthase gene in choline deficient rats.

Weanling Sprague-Dawley rats were fed on a choline-deficient diet with hydrogenated vegetable oil and corn oil as lipids develop acute renal failure. Pathogenesis of the latter is controversial and an ischemic mechanism has been proposed. Arachidonic acid derivatives are involved in the regulation of vascular tonus. Vasospasm could be due to an increase in tromboxane A2-mediated vasoconstriction or to a decrease in prostacyclin-induced vasodilatation. Enzymes involved in the synthesis of both compounds are tromboxane A2- and prostacyclin-synthase respectively. The aim of this study was to identify the variable number tandem repeats (VNTR) in the promoter region of prostacyclin synthase gene and verify if there exists a relationship between the occurrence of VNTR in those choline-deficient rats which die because of acute renal failure and those which do not. We verified the presence of the VNTR in the prostacyclin synthase rat gene, but we did not find any difference in the molecular weight of the alleles between experimental and control rats. Renal reparation of the acute kidney injury due to choline deficiency in some rats is not related with differences in VNTR in the promoter region of the prostacyclin synthase gene. Weanling Sprague-Dawley rats fed a choline-deficient diet with hydrogenated vegetable oil and corn oil as lipids develop acute renal failure. Its pathogenesis is controversial. The ischemic mechanism has been proposed. Derivatives from arachidonic acid are involved in the regulation of vascular tone. Vasospasm could be due to an increase in vasoconstriction mediated by tromboxane A2 or a decrease in vasodilatation by prostacyclin. Enzymes involved in the synthesis of them are tromboxane A2 and prostacyclin synthase respectively. The aim of this study is to identify the variable number tandem repeats (VNTR) in the promoter region of prostacyclin synthase gene and verify if there exists a relationship between the VNTR and those rats which dye as a consequence of acute renal failure due to choline deficiency and those which do not die. The VNTR presence was detected by molecular methods. We verified the presence of the VNTR in the prostacyclin synthase rat gene. We did not find difference in the molecular weight of the alleles between experimental and control rats. Renal reparation of the acute kidney injury due to choline deficiency in Sprague-Dawley rats is not related with differences in prostacyclin synthase VNTR, in the promoter region of this gene.Fil: Denninghoff, Valeria Cecilia. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Patología. Centro de Patología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Ossani, Georgina Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Patología. Centro de Patología Experimental; ArgentinaFil: Uceda, Ana Margarita. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Patología. Centro de Patología Experimental; ArgentinaFil: Avagnina Iribarren, Maria Alejandra. Centro de Educaciones Médicas e Investigación Clínica "Norberto Quirno"; ArgentinaFil: Elsner, Boris. Centro de Educaciones Médicas e Investigación Clínica "Norberto Quirno"; ArgentinaFil: Monserrat, Alberto Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Patología. Centro de Patología Experimental; Argentin

Distribución de subtipos moleculares de adenocarcinoma de pulmón y resultados clínicos en un centro de Argentina

La prevalencia de alteraciones en oncogenes en adenocarcinoma de pulmón varía en nuestra región. El objetivo fue describir la prevalencia de mutaciones en KRAS, BRAF y EGFR y las translocaciones de ALK en pacientes con adenocarcinoma de pulmón y estudiar la supervivencia de acuerdo a subtipos moleculares. Se incluyeron pacientes con biopsias adecuadas para el estudio. Se evaluó el estado mutacional de KRAS, BRAF y EGFR por secuenciación con la técnica de Sanger. Las translocaciones de ALK se estudiaron por hibridación in situ por fluorescencia (FISH) e inmunohistoquimica (IHQ) contra ALK (clones D5F3 y 5A4). De 118 pacientes evaluados, se incluyeron 84 (72%) con análisis molecular completo. Se detectaron mutaciones de KRAS en 16 muestras (19%), EGFR en 11 (13%), y BRAF en 1 muestra (1%). Se detectaron rearreglos de ALK en 3 muestras (4%). La mediana de seguimiento de los pacientes fue de 42.4 [rango intercuatilo (RIC): 27.0-64.2] meses. Globalmente, la mediana de supervivencia en la población fue 10.3 [RIC: 5.6-20.2] meses y fue de 10.8 [RIC: 6.0 20.3] meses en pacientes sin alteraciones moleculares detectables. La mediana de supervivencia de los pacientes con mutación en KRAS fue de 9.6 [RIC: 3.7-16.1] meses (HR: 1.08; p = 0.82) y 32.5 [RIC: 19.6-38.4] meses en el grupo con rearreglos de ALK o mutaciones en EGFR tratados con inhibidores de tirosina quinasa (HR: 0.27; p = 0.03). En conclusión, la prevalencia de alteraciones moleculares en nuestra población fue similar a otros países occidentales.The prevalence of relevant oncogenic drivers in lung adenocarcinoma varies in our region and data on clinical outcomes is scarce. The objective of the study was to describe the prevalence of KRAS, BRAF and EGFR mutations and ALK translocations in patients with advanced lung adenocarcinoma, and to depict the clinical outcome according to treatment strategies. Patients with adequate tumor biopsy sampling were included. KRAS, BRAF and EGFR mutations were studied by Sanger sequencing. ALK translocations were studied by fluorescent in situ hybridization (FISH) and immunohistochemistry (IH) with antibodies against ALK with clones D5F3 and 5A4. Informed consent was signed by 118 patients and 84 (72%) with complete molecular analysis were included. KRAS mutations were detected in 16 samples (19%), EGFR in 11 (13%), 9 of them conferring sensitivity to EGFR inhibitors, and BRAF mutations in 1 (1%). ALK translocations were detected in 3 samples (4%). Median follow-up was 42.4 [interquartile range (IQR): 27.0-64.2] months. Globally, median overall survival was 10.3 [IQR: 5.6-20.2] months. Median survival was 10.8 [IQR: 6.0-20.3] months in the group of patients without detectable molecular alteration, 9.6 [IQR: 3.7-16.1] months in KRAS mutant population (HR: 1.08; p = 0.82) and 32.5 [IQR: 19.6-38.4] months in patients with ALK translocations or sensitizing EGFR mutated tumors treated with tyrosine kinase inhibitors (HR: 0.27; p = 0.03). In conclusion, the prevalence of molecular alterations and outcomes in our population is similar to that reported in other studies in Western countries.Fil: Recondo, Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; ArgentinaFil: Denninghoff, Valeria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; ArgentinaFil: Cuello, Maria T.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; ArgentinaFil: Lorente, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; ArgentinaFil: Greco, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; ArgentinaFil: de la Vega, Máximo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; ArgentinaFil: Avagnina, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; ArgentinaFil: Recondo, Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentin

The Pan-Caspase Inhibitor Emricasan (IDN-6556) decreases liver injury and fibrosis in a murine model of non-alcoholic steatohepatitis

BACKGROUND & AIMS: Hepatocyte apoptosis, the hallmark of non-alcoholic steatohepatitis (NASH) contributes to liver injury and fibrosis. Although, both the intrinsic and extrinsic apoptotic pathways are involved in the pathogenesis of NASH, the final common step of apoptosis is executed by a family of cysteine-proteases termed caspases. Thus, our aim was to ascertain if administration of Emricasan, a pan-caspase inhibitor, ameliorates liver injury and fibrosis in a murine model of NASH. METHODS: C57/BL6J-mice were fed regular chow or high fat diet (HFD) for 20 weeks. All mice were treated with vehicle or Emricasan. RESULTS: Mice fed a HFD diet demonstrate a five-fold increase in hepatocyte apoptosis by the TUNEL assay and a 1.5-fold and 1.3-fold increase in caspase-3 and-8 activities respectively; this increase in apoptosis was substantially attenuated in mice fed a HFD treated with Emricasan (HFD-Em). Likewise, liver injury and inflammation were reduced in mice fed HFD-Em as compare to HFD by measuring serum aspartate aminotransferase and alanine aminotransferase levels, NAS histological score and IL 1-β, TNF-α, monocyte chemoattractant protein (MCP-1) and C-X-C chemokine ligand-2 (CXCL2) quantitative reverse-transcription polymerase chain reaction (qPCR). These differences could not be attributed to differences in hepatic steatosis as liver triglycerides content were similar in both HFD groups. Hepatic fibrosis was reduced by Emricasan in HFD animals by decreasing αSMA (a marker for hepatic stellate cell activation), fibrosis score, Sirius red staining, hydroxyproline liver content and profibrogenic cytokines by qPCR. CONCLUSION: In conclusion, these data demonstrate that in a murine model of NASH, liver injury and fibrosis are suppressed by inhibiting hepatocytes apoptosis and suggests that Emricasan may be an attractive antifibrotic therapy in NASH.Fil: Barreyro, Fernando Javier. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Departamento de Microbiología; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Holod, Silvia. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; ArgentinaFil: Finocchietto, Paola Vanesa. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; ArgentinaFil: Camino, Alejandra M.. DIM Clínica Privada; ArgentinaFil: Aquino, Jorge Benjamin. Universidad Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Avagnina, Alejandra. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Carreras, Maria Cecilia. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Poderoso, Juan José. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gores, Gregory J.. Mayo Clinic College of Medicine; Estados Unido

Diagnosis of an adenocarcinoma of Müllerian origin made as a result of its metastasis in the mouth floor

Metastases derived from primary tumours distant to the oral and maxillofacial region account for only 1% of all malignancies at that location, usually with a poor prognosis. In women, the primary tumours that most frequently metastasise to the oral cavity are breast adenocarcinomas affecting the jawbones and soft tissues (41% and 24%, respectively), followed by adrenal glands and female genital organs to the jawbones (8%), and female genital organs to the soft tissues (15%). Metastatic tumours of the mouth are a challenging diagnosis because of their exceptional occurrence. We report on the case of an 83-year-old woman who consulted for a bleeding ulcerated tumour on the floor of the mouth. A biopsy-confirmed metastasis of an adenocarcinoma of Müllerian origin. The oral lesion was the first sign of undetected cancer. The patient agreed to surgical resection and was further referred to palliative care for her symptoms.Fil: Gandolfo, Mariana Silvia. Universidad de Buenos Aires. Facultad de Odontología; ArgentinaFil: Denninghoff, Valeria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Odontología; ArgentinaFil: Avagnina, Alejandra. Centro de Educación Médica e Investigaciones Clínicas "Norberto Quirno"; ArgentinaFil: Adler, Lidia Isabel. Universidad de Buenos Aires. Facultad de Odontología; Argentin