Abstract The purpose of this work was to develop a mathematical model able to simúlate the continuous casting process of IF steel (Interstitial Free).and to determine the optimum operating conditions. The model formulation involves the momentum equations of liquid and solidified materials coupled with the temperature evolution of the slab. The differential equations and boundary conditions are numerically solved using the finite volume technique with appropriated boundary conditions for each región of the casting machine. The model predictions were compared with industrial data for conventional continuous casting conditions and extended to IF steel.

El objetivo del trabajo fue desarrollar un modelo matemático capaz de simular el proceso convencional de colada continua de aceros IF (Interstitial Free), y determinar las condiciones operacionales óptimas. La formulación del modelo incluye las ecuaciones de momento lineal de materiales líquidos y solidificados junto con la evolución térmica de la plancha. Las ecuaciones diferenciales y las condiciones de contorno son resueltas numéricamente mediante volúmenes finitos. Ciertas condiciones de contorno como el flujo de calor para el enfriamiento en cada región, además de la resistencia al flujo de la capa de fundente y las oscilaciones en la región del molde, son especificadas. Las predicciones del modelo fueron comparadas con datos industriales para las condiciones de las coladas continuas convencionales y extendidas a aceros IF.

We report the identification to the species level of a microsporidian isolated from the bronchoalveolar lavage of an AIDS patient in Spain. Characterization of the isolate was performed by: 1) morphological methods using optical and electron microscopy; 2) immunological methods such as immunofluorescence assay (IIF) and immunoblot (WB) using specific antiserum and, 3) polymerase chain reaction (PCR) using species-specific primers designed on the coding region of the small subunit of the ribosomal RNA gene. Ultrastructural features allowed the identification of the isolate as belonging to the Encephalitozoon genus. Species identification as Encephalitozoon hellem was achieved by IIF and WB using polyc lonal rabbit serum anti-E. hellem (CDC:0291:V213), as well as, by PCR using EHELF/EHELR species-specific primers. The isolate has been named EHVS-96 and has been maintained for 3 years in Vero-E6 monolayers. This is the first isolation in culture and characterization of E. hellem in Spain.

Comunicamos la identificación, a nivel de especie, de un microsporidio aislado en cultivo celular a partir de un lavado broncoalveolar de un paciente con Sida y neumonía. La caracterización del aislado se realizó mediante: 1) estudio morfológico utilizando métodos de microscopía óptica y electrónica, 2) estudio inmunológico con antisueros específicos, inmunofluorescencia indirecta (IFI) e inmunoblot (WB) y 3) estudio molecular tras reacción en cadena de la polimerasa (PCR) con iniciadores especie-específicos diseñados a partir de la región que codifica la subunidad menor del ARN ribosomal. Las características ultraestructurales del aislado permitieron su identificación en el género Encephalitozoon. La identificación específica del microsporidio como Encephalito-zoon hellem se realizó mediante IFI y WB, empleando suero policlonal de conejo anti-E. hellem (CDC:0291:V213), y mediante la amplificación por PCR del fragmento diagnóstico utilizando el par de iniciadores EHELF/EHELR específicos para esta especie. El aislado ha sido denominado EHVS-96 y se mantiene en cultivo continuo en células Vero-E6. Este es el primer aislamiento en cultivo y caracterización de E. hellem en España.

Enterocytozoon bieneusi é o mais comum microsporídio agente de infecções gastrointestinais que ocorre predominantemente em pessoas com AIDS. Em todo o mundo os microsporídios são reconhecidos como importantes patógenos oportunistas, entretanto poucos casos já foram diagnosticados no Brasil, provavelmente devido ao pouco conhecimento do quadro clínico que os agentes produzem ou a dificuldades no diagnóstico laboratorial. No presente trabalho relatamos o caso de um paciente brasileiro HIV-positivo acompanhado durante 3 anos, em que foram detectados esporos de microsporídios nas fezes, identificados como Enterocytozoon bieneusi por microscopia eletrônica e PCR. O paciente apresentava diarréia crônica, contagem de linfócitos CD4 abaixo de 100/mm3 e fez uso de albendazol em diferentes ocasiões com melhora transitória da diarréia, que reaparecia logo que a droga era suspensa. Entretanto, o paciente apresentou um grande período sem diarréia e com ganho ponderal de até 18 Kg quando foi prescrito como terapêutica antiretroviral uma combinação de nucleosídios e inibidores de protease.

Enterocytozoon bieneusi is the most prevalent microsporidian parasite that causes gastrointestinal infection in persons with AIDS. Microsporidia are increasingly recognized as important opportunistic pathogens all over the world but in Brazil only few cases have been reported due either to the non awareness of the clinical presentation of the disease or to difficulties in the laboratory diagnosis. We report a 3-year follow-up of a Brazilian HIV-positive patient in whom microsporidial spores were detected in stools and were identified as E. bieneusi using electron microscopy and PCR. The patient presented with chronic diarrhea, CD4 T-lymphocytes count below 100/mm3 and microsporidial spores were consistently detected in stools. Albendazole was given to the patient in several occasions with transient relief of the diarrhea, which reappeared as soon as the drug was discontinued. Nevertheless, a diarrhea-free period with weight gain up to 18 Kg occurred when a combination of nucleoside and protease inhibitors was initiated as part of the antiviral treatment.