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Dive into the research topics where Amadeo Sáez-Alquézar is active.

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Featured researches published by Amadeo Sáez-Alquézar.


Journal of Gastroenterology | 1996

Spontaneous hepatitis B surface antigen clearance in a long-term follow-up study of patients with chronic type B hepatitis. Lack of correlation with hepatitis C and D virus superinfection

Luiz Caetano da Silva; Carmen Lúcia de Assis Madruga; Flair José Carrilho; João Renato Rebello Pinho; Amadeo Sáez-Alquézar; Carlos Ferreira Santos; Leda Bassit; Claudia C. Barreto; Luís Edmundo Pinto da Fonseca; Venâncio Avancini Ferreira Alves; Regina Maria Cubero Leitão; Regina Suplicy Vianna; Rita Helena Antonelli Cardoso; Alex Vianey Callado França; Luiz Carlos da Costa Gayotto

We investigated the frequency of HBsAg clearance and the possible role of viral superinfection in a long-term follow-up of 184 patients with chronic hepatitis B (CHB). Our subjects were 184 patients with chronic hepatitis B and the follow-up was 12–216 months (mean 66.2±53.7 months). The investigative methods used were: immunoenzymatic assays for HBV, HCV, HDV, and HIV markers; polymerase chain reaction (PCR) for HBV DNA; and liver biopsy and immunoperoxidase. During the follow-up, 20 of the 184 patients cleared serum HBsAg. A comparison of patients with persistent HBsAg (group I) and of those who cleared this marker (group II) showed a significant difference in mortality (P=0.002) between the two groups and a tendency to a more severe exacerbation (flare) in group II (P=0.07). Antibodies to hepatitis C and D virus as well as antibodies to HIV were equally distributed in both groups. Thirteen patients (7.9%) from group I, but none from group II, subsequently developed hepatocellular carcinoma. These results suggest that the frequency of spontaneous clearance of HBsAg during chronic HBV infection is low. No determinant factor for the clearance was found, including the presence of liver cirrhosis. Serum HBV DNA was undetectable by PCR after clearance in 16 out of 17 patients.


Journal of Clinical Microbiology | 2014

Comparative Evaluation of 11 Commercialized Rapid Diagnostic Tests for Detecting Trypanosoma cruzi Antibodies in Serum Banks in Areas of Endemicity and Nonendemicity

Claudia L. Sánchez-Camargo; Pedro Albajar-Viñas; Patricia P. Wilkins; Javier Nieto; David A. Leiby; Luc Paris; Karenina Scollo; Carolina Flórez; Carmen Guzmán-Bracho; Alejandro O. Luquetti; Nidia Calvo; Kenji Tadokoro; Amadeo Sáez-Alquézar; Pedro Pablo Palma; Miguel Martin; Laurence Flevaud

ABSTRACT Chagas disease is one of the main public health issues in Latin America. Increasingly during the past few decades, Trypanosoma cruzi infection has been detected in North America, Europe, and the Western Pacific, mainly as a result of population movement. The limited availability of rapid serological diagnostic tests hinders rapid diagnosis and early treatment in areas of endemicity and nonendemicity. In collaboration with 11 national reference laboratories (NRLs) from different geographical areas, we evaluated the performances of commercialized serological rapid diagnostic tests (RDT) for T. cruzi infection. Eleven commercialized T. cruzi infection RDTs were evaluated on a total of 474 samples extensively tested with at least three different techniques for Chagas disease, maintained at controlled low temperatures, and stored in the serum banks of the 11 NRLs. We measured the sensitivity, specificity, and concordance of each RDT and provided an additional questionnaire to evaluate its ease of use. The selected RDTs in this study were performed under controlled laboratory conditions. Out of the 11 RDTs, we found 8 of them to be useful, with the cassette format favored over the strip. We did not observe significant differences in RDT performances in the different regions. Overall, the performance results were lower than those disclosed by the manufacturers. The results of this evaluation validate the possibility of using RDTs to diagnose Chagas disease, thereby decreasing the time to treatment at a primary health care facility for patients who are willing to be treated. Further studies should be conducted in the laboratory and in the field to confirm these data, expressly to evaluate reproducibility in resource-limited settings, or using whole blood in clinical settings in areas of endemicity and nonendemicity.


Vox Sanguinis | 1998

Evaluation of the Performance of Brazilian Blood Banks in Testing for Chagas’ Disease

Amadeo Sáez-Alquézar; Marcia M. Otani; Ester C. Sabino; Gabriela Ribeiro-dos-Santos; Nanci A. Salles; Dalton de Alencar Fischer Chamone

Background and Objectives: Due to the low sensitivity and reproducibility of available tests, in 1989 it became mandatory for all Brazilian blood donors to be screened for Chagas’ disease by at least two serological techniques. In 1994 the Brazilian Ministry of health launched a program to systematically evaluate the quality of serological screening for the detection of blood-transmissible diseases as performed by public blood banks. Methods: A blind panel containing positive samples for blood-transmissible disease was distributed to 57 major public blood banks in four sequential programs. Results: The ELISA test was chosen by the majority of the blood banks. There were 64 (3.7%) false-negative results, 49 produced by banks using indirect hemagglutination. Since most blood banks screened with more than one test for Chagas, only 8 samples were actually missed, of which 3 were by banks using only one test. Conclusion: Our data show a clear improvement in performance of Brazilian blood banks testing for Chagas’ disease.


Vox Sanguinis | 1998

Hepatitis G Virus: Prevalence and Sequence Analysis in Blood Donors of São Paulo, Brazil

Leda Bassit; Bernhard Kleter; Gabriela Ribeiro-dos-Santos; Geert Maertens; Ester C. Sabino; Dalton de Alencar Fischer Chamone; Wim Quint; Amadeo Sáez-Alquézar

Background and objectives: Hepatitis G virus (HGV) is a recently discovered viral agent transmitted by blood, which was firstly identified in patients with acute or chronic liver disease. HGV prevalence in US blood donors was recently found to average 1–2%. We report a much higher HGV frequency among blood donors of São Paulo, Brazil. Materials and methods: 200 serum samples were submitted to RT-PCR using primers directed to the 5′ untranslated region and nonstructural 5A (NS5A) region. PCR products were analyzed by gel electrophoresis and Southern blot hybridization. Results: Of the 200 specimens, 18 (9%; 95% CI 5.4–13.8%) were positive by both sets of primers. Sequence analysis of the NS5A PCR products revealed a homology of 96.3%. Of the 18 HGV-positive symples, only one was positive for anti-HBc and all were anti-HCV- and HCV-RNA-negative. Conclusion: Such a high prevalence of HGV in a nonsymptomatic population suggests that this is a benign agent.


Vox Sanguinis | 1998

Consequences of Nucleic Acid Amplification Testing for Blood Transfusion Centres

A.M. Couroucé; L. Noel; F. Barin; M.H. Elghouzzi; F. Lunel; M.L. North; W. Smilovici; Amadeo Sáez-Alquézar; Marcia M. Otani; Ester C. Sabino; Gabriela Ribeiro-dos-Santos; Nanci A. Salles; Dalton de Alencar Fischer Chamone; K. Koerner; M. Cardoso; T. Dengler; M. Kerowgan; B. Kubanek; E.P. Mauser-Bunschoten; H.L. Zaaijer; A.A.J. van Drimmelen; S. I. De Vries; G. Roosendaal; H. M. van den Berg; P.N. Lelie; Sharon X. Chen; David J. Hammond; John M. Lang; Wytold R. Lebing; J.M. Moulds

This article is also accessible online at: http://BioMedNet.com/karger Blood banks and transfusion centres are faced with the imminent introduction of nucleic acid amplification testing (NAT), or genomic amplification testing of plasma pools used by the plasma industry. The Committee for Proprietary Medicinal Products (CPMP) in Europe requires that all manufactured plasma pools should be tested for HCV RNA by NAT by July 1, 1999. To avoid the destruction of large NAT-reactive plasma pools, the CPMP strongly advises to implement a system for the screening of minipools of plasma by NAT. In future, genomic screening of individual donations for blood-borne viruses is expected to become obligatory. At present, genomic screening of individual donations cannot be routinely performed, and NAT minipool screening (i.e. a pool of plasma of 100 donations) is not (well) standardized, is costly and time-consuming, especially when the individual positive donors from a positive pool have to be sorted out. An especially difficult and ethical question is what should be decided concerning the release of red cell products and especially platelets when minipool screening is implemented. Either these cellular products will be blocked for at least several days, creating shortage and loss of product, or the results of minipool screening tests will not affect these products. This may create different levels of safety and serious ethical problems by informing (or not informing) recipients of these products after a positive result has been obtained. Fourteen experts in the field were asked for their opinion, answers were obtained from 10 of them on the following questions.


Revista Do Instituto De Medicina Tropical De Sao Paulo | 1986

Treatment of patients with Schistosomiasis mansoni: a double blind clinical trial comparing praziquantel with oxamniquine

Luiz Caetano da Silva; José Murilo Robilotta Zeitune; Lucia Maria F. Rosa-Eid; Dirce Mary Correia Lima; Rita H. Antonelli; Carlos Henrique Christo; Amadeo Sáez-Alquézar; Adriany de Castro Carboni

A double-blind clinical trial involving 120 patients with chronic schistosomiasis was carried out to compare the tolerability and efficacy of praziquantel and oxamniquine. The patients were randomly allocated into two groups. One was treated with praziquantel, 55 mg/kg of body weight CBWT), and the other one with oxamniquine, 15mg/kg bwt, administered in a single oral dose. The diagnosis and the parasitological follow-up was based on stool examinations by quantitative Kato-Katz method and on rectal biopsies. Side-effects — mainly dizziness, sleepness, abdominal distress, headache, nausea and diarrhea — were observed in 87% of the cases. Their incidence, intensity and duration were similar for both drugs but abdominal pain was significantly more frequent after praziquantel intake and severe dizziness was more commonly reported after oxamniquine. A significant increase of alanine-aminotransferase and y-glutamyltransferase was found with the latter drug and of total bilirubin with the former one. A total of 48 patients treated with praziquantel and 46 with oxamniquine completed with negative findings the required three post-treatment parasitological controls — three slides of each stool sample on the first, third and sixth month. The achieved cure rates were 79.2% and 84.8%, respectively, a difference without statistical significance. The non-cured cases showed a mean reduction in the number of eggs per gram of feces of 93.5% after praziquantel and of 84.1% after oxamniquine. This diference also was not significant. Five patients retreated with praziquantel were cured but only one out of three treated a second time with oxamniquine. These findings show that both drugs — despite their different chemical structures, pharmacological properties and mechanisms-of-action — induce similar side-effects as well as a comparable therapeutical efficacy, in agreement with the results reported from analogous investigations.


Revista Do Instituto De Medicina Tropical De Sao Paulo | 1999

Chronic hepatitis C virus infections in brazilian patients: association with genotypes, clinical parameters and response to long term alpha interferon therapy

Leda Bassit; Luiz Caetano da Silva; Gabriela Ribeiro-dos-Santos; Geert Maertens; Flair José Carrilho; Luís Edmundo Pinto da Fonseca; Venâncio Avancini Ferreira Alves; Luis Gayotto; Analice N. Pereira; Kioko Takei; Dalton de Alencar Fischer Chamone; Amadeo Sáez-Alquézar

The present study assessed the clinical significance of hepatitis C virus (HCV) genotypes and their influence on response to long term recombinant-interferon-alpha (r-IFN-alpha) therapy in Brazilian patients. One hundred and thirty samples from patients previously genotyped for the HCV and with histologically confirmed chronic hepatitis C (CH-C) were evaluated for clinical and epidemiological parameters (sex, age, time of HCV infection and transmission routes). No difference in disease activity, sex, age or mode and time of transmission were seen among patients infected with HCV types 1, 2 or 3. One hundred and thirteen of them were treated with 3 million units of r-IFN-alpha, 3 times a week for 12 months. Initial response (IR) was significantly better in patients with genotype 2 (100%) and 3 (46%) infections than in patients with genotype 1 (29%) (p < 0. 005). Among subtypes, difference in IR was observed between 1b and 2 (p < 0.005), and between 1b and 3a (p < 0.05). Sustained response (SR) was observed in 12% for (sub)type 1a, 13% for 1b, 19% for 3a, and 40% for type 2; significant differences were found between 1b and 2 (p < 0.001), and between 1b and 3a (p < 0.05). Moreover, presence of cirrhosis was significantly associated with non response and response with relapse (p < 0.05). In conclusion, non-1 HCV genotype and lack of histological diagnosis of cirrhosis were the only baseline features associated with sustained response to treatment. These data indicate that HCV genotyping may have prognostic relevance in the responsiveness to r-IFN-alpha therapy in Brazilian patients with chronic HCV infection, as seen in other reports worldwide.


Revista Panamericana De Salud Publica-pan American Journal of Public Health | 2003

Programas de control externo de la calidad en serología desarrollados en América Latina con el apoyo de la OPS entre 1997 y 2000

Amadeo Sáez-Alquézar; Marcia M. Otani; Ester C. Sabino; Nanci A. Salles; Dalton de Alencar Fischer Chamone

OBJETIVOS: Con el apoyo de la Organizacion Panamericana de la Salud (OPS), desarrollamos entre 1997 y 2000 cinco programas de control externo de la calidad en serologia (PCECS) en los que participaron entre 13 y 21 bancos de sangre de 11 a 16 paises de America Latina. El objetivo fue evaluar el desempeno de los bancos de sangre con respecto al tamizaje serologico realizado en donantes de sangre. METODOS: Como herramienta de trabajo utilizamos conjuntos de 24 muestras de sueros anonimos con reactividades variables para los parametros de uso obligatorio en el tamizaje serologico de donantes de sangre en Brasil. En cada PCECS enviamos un multipanel a cada institucion participante para que lo procesara en las mismas condiciones de su rutina de tamizaje. Cada participante recibio la clave del multipanel para autoevaluacion, despues de haber devuelto los resultados obtenidos en su laboratorio. Se mantuvo siempre la mas estricta confidencialidad sobre los resultados obtenidos individualmente. Al terminar de cada programa, el Centro Organizador (Superintendencia de Serologia de la Fundacao Pro-Sangue/Hemocentro de Sao Paulo) elaboro un informe final que contenia toda la informacion obtenida en el programa y que fue enviado a los participantes. RESULTADOS: En el analisis de los cinco PCECS se observo falta de homogeneidad entre los paises con respecto a las estrategias y a los parametros utilizados en el tamizaje de donantes de sangre. Pocos laboratorios practicaron el tamizaje de los virus linfotropico de celulas T humanas (HTLV) (17%, 27%, 35%, 39% y 45%, respectivamente y en orden creciente para los cinco PCECS) y de anticuerpos contra el antigeno nuclear del virus de la hepatitis B (anti-HBc) (42%, 27%, 39%, 50% y 60%). Tambien se observaron diferencias importantes en cuanto a las pruebas o combinaciones de pruebas utilizadas, lo cual puede dificultar el estudio comparativo de los tipos de tamizaje. El numero total de resultados positivos falsos oscilo alrededor del 2%, correspondiendo el mayor valor al tamizaje de anticuerpos contra el virus de la hepatatis C (anti-VHC) (4,6%) y el menor a anti-Trypanosoma cruzi (0,4%). CONCLUSIONES: Los resultados obtenidos en este trabajo demuestran la necesidad de continuar las acciones de la OPS en America Latina para reforzar los procedimientos de tamizaje serologico en bancos de sangre, incluso los PCECS, hasta que se consiga una uniformidad de procedimientos en la Region de las Americas.


Revista Panamericana De Salud Publica-pan American Journal of Public Health | 2003

Resultados de un programa de control de calidad externo del tamizaje serológico de anticuerpos contra Trypanosoma cruzi en donantes de sangre de Brasil

Amadeo Sáez-Alquézar; Márcia Murta; Waldelania Pereira Marques; Guilherme Rodrigues da Silva

OBJETIVOS: A partir de 1995 en Brasil se iniciaron programas de control de calidad externo de laboratorios de serologia (PCCES) abiertos a la participacion de laboratorios de bancos de sangre publicos y privados. Estos programas se han puesto en practica tres veces al ano desde 1995 y cuentan con la participacion de mas de 100 entidades. El objetivo de este trabajo es analizar los resultados de los ocho ultimos programas de evaluacion del tamizaje serologico para la enfermedad de Chagas, que se realizaron entre abril de 1999 y agosto de 2001. METODOS: Participaron en los ocho programas laboratorios de serologia de instituciones publicas y privadas. El numero de laboratorios participantes que entrego los resultados en cada uno de los ocho PCCES fue de 94, 90, 85, 94, 100, 103, 102 y 116, respectivamente. Al inicio de cada PCCES se envio un panel enmascarado a cada institucion participante, con un plazo de 60 dias para informar los resultados del procesamiento de las muestras. Se utilizaron pruebas de inmunoadsorcion enzimatica (ELISA), inmunofluorescencia indirecta (IFI) y hemaglutinacion indirecta (HAI). Posteriormente, cada institucion recibio del centro organizador (PANEL) la clave con los resultados correctos para su autoevaluacion. Los paneles estaban compuestos por 24 muestras de sueros con diferentes reactividades a los marcadores obligatorios en el tamizaje serologico de donantes de sangre en Brasil, incluido el de muestras negativas. RESULTADOS: La tecnica de ELISA fue la mas utilizada en el tamizaje (92%-98%). La estrategia de tamizaje mas usada por los laboratorios participantes fue la combinacion de una prueba de ELISA y una de HAI (58%-83%). La mayoria de los laboratorios participantes obtuvieron resultados correctos en los diferentes programas sin resultados negativos falsos (83,6%-98,1%). De las 5 406 muestras de suero positivas a anti-Trypanosoma cruzi que hubo en los ocho programas, 85 (1,6%) fueron notificadas de negativas por 58 laboratorios, pero solamente 14 de ellos dejaron de identificar una o mas muestras positivas por no conseguir detectarlas por medio de ninguna de las pruebas de tamizaje utilizadas. No se observo ninguna diferencia significativa entre bancos en los ocho programas (P = 0,5936). No se observo asociacion entre los resultados negativos falsos y una muestra o sistema diagnostico en particular. La tecnica de HAI presento el mayor numero de resultados negativos falsos (0,7%-7,9%). De los 32 855 resultados obtenidos en muestras de sueros negativas a anti-T. cruzi en los ocho programas, 106 (0,32%) fueron notificados como resultados positivos falsos. Entre 1% y 16% de los laboratorios participantes obtuvieron un resultado positivo falso por programa y entre 0% y 4% notifico mas de un resultado positivo falso. La proporcion de resultados negativos falsos muestra una tendencia descendente despues de 1995. CONCLUSIONES: Los resultados obtenidos en este trabajo apuntan hacia una tendencia desecendente en la proporcion de resultados negativos falsos. Al mismo tiempo se observo que la tecnica de HAI continua arrojando el mayor numero de resultados negativos falsos. Se sugiere darle preferencia a la tecnica ELISA para el tamizaje de donantes de sangre.


Vox Sanguinis | 1998

Statement from the Consensus Conference on Anti-D Prophylaxis

Yvonne Hari; Edith von Allmen; Gabriela M. Boss; Abdelbaky Naiem; Matthias Gittermann; Urs E. Nydegger; R.R.A. Coombs; Leda Bassit; Bernhard Kleter; Gabriela Ribeiro-dos-Santos; Geert Maertens; Ester C. Sabino; Dalton de Alencar Fischer Chamone; Wim Quint; Amadeo Sáez-Alquézar; D. Janvier; S. Veaux; M. Benbunan; D. Roelcke; H. Hack; H. Kreft; H.J. Gross; Milcho Mincheff; Dmitri Loukinov; Serguei Zoubak; Michael Hammett; Harold T. Meryman; Dan J. Vick; John C. Byrd; Connie L. Beal

This article is also accessible online at: http://BioMedNet.com/karger Dr. S. Urbaniak Royal College of Physicians of Edinburgh 9 Queen Street Edinburgh EH2 1JQ UK At a conference convened by the Royal College of Physicians of Edinburgh and the Royal College of Obstetricians and Gynaecologists, a consensus panel considered specific issues relating to anti-D prophylaxis in the UK. This statement is based on presentations given at the meeting, published research and expert opinion. The panel reached the following conclusions:

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Nanci A. Salles

Systems Research Institute

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Hoel Sette

University of São Paulo

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L.C. da Silva

University of São Paulo

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Leda Bassit

University of São Paulo

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