Molecular epidemiology of enteroviruses from Guatemalan wastewater isolated from human lung fibroblasts.

The Global Specialized Polio Laboratory at CDC supports the Global Poliovirus Laboratory Network with environmental surveillance (ES) to detect the presence of vaccine strain polioviruses, vaccine-derived polioviruses, and wild polioviruses in high-risk countries. Environmental sampling provides valuable supplementary information, particularly in areas with gaps in surveillance of acute flaccid paralysis (AFP) mainly in children less than 15 years. In collaboration with Guatemala's National Health Laboratory (Laboratorio Nacional de Salud Guatemala), monthly sewage collections allowed screening enterovirus (EV) presence without incurring additional costs for sample collection, transport, or concentration. Murine recombinant fibroblast L-cells (L20B) and human rhabdomyosarcoma (RD) cells are used for the isolation of polioviruses following a standard detection algorithm. Though non-polio-Enteroviruses (NPEV) can be isolated, the algorithm is optimized for the detection of polioviruses. To explore if other EV's are present in sewage not found through standard methods, five additional cell lines were piloted in a small-scale experiment, and next-generation sequencing (NGS) was used for the identification of any EV types. Human lung fibroblast cells (HLF) were selected based on their ability to isolate EV-A genus. Sewage concentrates collected between 2020-2021 were isolated in HLF cells and any cytopathic effect positive isolates used for NGS. A large variety of EVs, including echoviruses 1, 3, 6, 7, 11, 13, 18, 19, 25, 29; coxsackievirus A13, B2, and B5, EV-C99, EVB, and polioviruses (Sabin 1 and 3) were identified through genomic typing in NGS. When the EV genotypes were compared by phylogenetic analysis, it showed many EV's were genomically like viruses previously isolated from ES collected in Haiti. Enterovirus occurrence did not follow a seasonality, but more diverse EV types were found in ES collection sites with lower populations. Using the additional cell line in the existing poliovirus ES algorithm may add value by providing data about EV circulation, without additional sample collection or processing. Next-generation sequencing closed gaps in knowledge providing molecular epidemiological information on multiple EV types and full genome sequences of EVs present in wastewater in Guatemala.

Actitudes de los psicólogos costarricenses hacia la aplicación de la psicología en la consulta odontológica / Attitudes of Costa Rican Psychologists Towards the Application of Psychology During the Dentistry Consultation

Resumen Estudio exploratorio-descriptivo sobre un grupo de profesionales costarricenses en psicología acerca de sus actitudes hacia la aplicación de los principios psicológicos en la práctica odontológica. La muestra fue de 377 psicólogos (activos en el Colegio de Profesionales en Psicología de Costa Rica). A partir del cuestionario original diseñado por Gómez y Gómez (2007), el cual fue construido para estimar la necesidad de conformar programas universitarios que integren la psicología y la odontología, se aplicó una adaptación consistente en una encuesta de 10 preguntas autoadministradas de selección simple, la cual se efectuó en línea a través del sistema QuestionPro®. Se pudo evidenciar que existe una actitud positiva ante el enfoque interdisciplinario entre la Odontología y la Psicología; se demostró que un 74% de la muestra sostiene que los aspectos psicosociales son "Bastante importantes" en el marco de la atención odontológica. A pesar de ello, la mayoría (57%) de las personas consultadas indicó que no ha tenido ocasión de aplicar sus conocimientos y experiencia en psicología al contexto odontológico. Asimismo, un 72% de los participantes considera "Bastante importante" que los profesionales en Odontología reciban capacitación básica en el área psicológica para la prevención o contención de ciertos síntomas que puedan incidir en la salud mental. Por otra parte, el 80% de quienes respondieron la encuesta indicaron que las iniciativas interdisciplinarias de colaboración científica (investigación) y aplicada (ejercicio profesional) son "Bastante importantes" para producir beneficios tangibles en la prestación de servicios integrales a los pacientes y el bienestar del personal sanitario.

Abstract Exploratory-descriptive study on a group of Costa Rican professionals in psychology about their attitudes towards the application of psychological principles in dental practice. The sample consisted of 377 psychologists (active in the Association of Psychology Professionals of Costa Rica). From the original questionnaire designed by Gómez and Gómez (2007), which was built to estimate the need to create university programs that integrate psychology and dentistry, an adaptation consisting of a survey of 10 self-administered questions of simple selection was applied, which was carried out online through the QuestionPro® system. It was possible to show that there is a positive attitude towards the interdisciplinary approach between Dentistry and Psychology; it was shown that 74% of the sample maintains that psychosocial aspects are "Quite important" in the context of dental care. Despite this, the majority (57%) of the people consulted indicated that they had not had the opportunity to apply their knowledge and experience as psychologists to the dental context. Likewise, 72% of the participants consider it "Quite important" that dental professionals receive basic training in the psychological area for the prevention or containment of certain symptoms that may affect mental health. On the other hand, 80% of the survey respondents indicated that interdisciplinary initiatives of professional scientific (research) and applied (practice) collaboration are "Quite important" to produce tangible benefits in the provision of comprehensive services to patients and wellbeing of health personnel.

A Trypanosoma cruzi phosphoglycerate kinase isoform with a Per-Arnt-Sim domain acts as a possible sensor for intracellular conditions.

Per-ARNT-Sim (PAS) domains constitute a family of domains present in a wide variety of prokaryotic and eukaryotic organisms. They form part of the structure of various proteins involved in diverse cellular processes. Regulation of enzymatic activity and adaptation to environmental conditions, by binding small ligands, are the main functions attributed to PAS-containing proteins. Recently, genes for a diverse set of proteins with a PAS domain were identified in the genomes of several protists belonging to the group of kinetoplastids, however, until now few of these proteins have been characterized. In this work, we characterize a phosphoglycerate kinase containing a PAS domain present in Trypanosoma cruzi (TcPAS-PGK). This PGK isoform is an active enzyme of 58 kDa with a PAS domain located at its N-terminal end. We identified the protein's localization within glycosomes of the epimastigote form of the parasite by differential centrifugation and selective permeabilization of its membranes with digitonin, as well as in an enriched mitochondrial fraction. Heterologous expression systems were developed for the protein with the N-terminal PAS domain (PAS-PGKc) and without it (PAS-PGKt), and the substrate affinities of both forms of the protein were determined. The enzyme does not exhibit standard Michaelis-Menten kinetics. When evaluating the dependence of the specific activity of the recombinant PAS-PGK on the concentration of its substrates 3-phosphoglycerate (3PGA) and ATP, two peaks of maximal activity were found for the complete enzyme with the PAS domain and a single peak for the enzyme without the domain. Km values measured for 3PGA were 219 ± 26 and 8.8 ± 1.3 µM, and for ATP 291 ± 15 and 38 ± 2.2 µM, for the first peak of PAS-PGKc and for PAS-PGKt, respectively, whereas for the second PAS-PGKc peak values of approximately 1.1-1.2 mM were estimated for both substrates. Both recombinant proteins show inhibition by high concentrations of their substrates, ATP and 3PGA. The presence of hemin and FAD exerts a stimulatory effect on PAS-PGKc, increasing the specific activity by up to 55%. This stimulation is not observed in the absence of the PAS domain. It strongly suggests that the PAS domain has an important function in vivo in T. cruzi in the modulation of the catalytic activity of this PGK isoform. In addition, the PAS-PGK through its PAS and PGK domains could act as a sensor for intracellular conditions in the parasite to adjust its intermediary metabolism.

La exposición prenatal a fluoruro induce cambios en la porción coronal de la cripta ósea y altera la erupción dental en crías lactantes / Prenatal fluoride exposure induces changes in the coronal portion of bony crypt and alters dental eruption in suckling rats

La erupción dental es un proceso estrictamente regulado y programado espacial y temporalmente. El objetivo del trabajo fue estudiar el efecto de la exposición prenatal a fluoruro de sodio (NaF) sobre los eventos morfológicos y celulares que ocurren en el hueso supracoronal del primer molar de crías de rata durante la etapa preeruptiva. Se emplearon crías (n=6-8 por grupo) provenientes de madres que bebieron crónicamente agua con diferentes concentraciones de F- en forma de NaF durante la gestación y lactancia: control y NaF (50 mg/L). En cortes histológicos de la mandíbula de crías de 3 y 10 días se analizaron parámetros de histomorfometría estática en la zona supracoronal de la canastilla ósea a la altura del primer molar inferior: volumen óseo trabecular [BV/TV (%)], número de osteoclastos por milímetro (N.Oc/mm) y las variables indirectas: número de trabéculas [Tb.N (1/mm)], espesor [Tb.Th (µm)] y separación trabecular [Tb.Sp (µm)]. En crías de 15 días se midió el grado de erupción [TED (µm)] del primer molar inferior. Los resultados se analizaron con el test "t" de Student considerando diferencias significativas a p<0,05. El análisis histomorfométrico demostró un incremento en el BV/TV (%) del hueso supracoronal (p<0,01) asociado con disminución del N.Oc/mm (p<0,01) en crías de 3 y 10 días expuestas prenatalmente al F-. El grado de erupción dental fue menor en animales expuestos prenatalmente al F- en comparación con los controles (p<0,01). En conclusión, los resultados observados en la mandíbula de crías expuestas durante la etapa prenatal y posnatal temprana al F- sugieren un efecto disruptivo sobre la actividad resortiva necesaria para formación del canal eruptivo. (AU)

Tooth eruption is a tightly regulated and spatially and temporally programmed process. The aim of this study was to examine the effect of prenatal NaF exposure on the morphological and cellular events that occur in the supracoronal area of bony crypt of the first rat molar during the preeruptive stage. Offspring from two groups of rats were used (6-8 per group): Control and 50 mg/L NaF. The treatment was performed during pregnancy and lactation. Suckling pups were euthanized at 3-, 10- and 15-days-old by cervical dislocation. Mandibles were removed and histologically processed to obtain buccolingual sections stained with H&E. In sections of first mandibular molar of 3- and 10-days-old pups, the following static histomorphometric parameters were evaluated: trabecular bone volume [BV/TV (%)] and number of osteoclasts (N.Oc/mm). Also, indirect parameters were obtained: trabecular number [Tb.N (1/mm)], trabecular thickness [Tb.Th (µm)], and trabecular separation [Tb.Sp (µm)]. The degree of tooth eruption [TED (µm)] was determined. Results are expressed as mean ± SE and analyzed by Student t-test. Histomorphometric analysis showed an increase in the BV/TV (%) of the bone crypt of 3- and 10- days-old pups exposed to NaF (p <0.01); this increase was associated with a decrease in the N.Oc/mm (p <0.01). TED of mandibular first molar was lower in prenatal NaF exposed group than in control group (p<0.01). In conclusion, the increased BV/TV and the lower N.Oc observed in the bone crypt of 3- and 10- days-old pups from mothers treated with NaF suggested a disruptive effect triggered by F- on the formation events of the eruptive pathway in the offspring. (AU)

Conocimiento del cáncer de mama en estudiantes de enfermería

Objetivo: Este estudio evaluó el conocimiento acerca del cáncer de mama en estudiantes de Enfermería de universidades de la ciudad de Chillán. Material y método: Estudio descriptivo, transversal en estudiantes de Enfermería de tercer y cuarto año, correspondientes a tres universidades de Chillán, Chile. La muestra estuvo conformada por 187 estudiantes, a quienes se les aplicó una encuesta sobre conocimiento respecto del cáncer de mama. Resultados: La mayoría de los estudiantes presentó conocimiento para distinguir signos síntomas, tratamientos y diagnósticos sobre el cáncer de mama como futuros profesionales de la salud. Con respecto a los factores de riesgo y protectores relacionados al cáncer de mama, se observó una dificultad para reconocerlos. Respecto a la realización de la mamografía, el 80,7% indicó que se debía realizar antes de los 30 años, sin embargo, de acuerdo a las guías clínicas, ésta se debe realizar después de los 50 años cuando no existen antecedentes familiares. Conclusión: Los estudiantes manifiestan adquisición de conocimientos respecto de la guía clínica, pero con dificultad para identificar factores de riesgo, protectores, e información específica respecto del tratamiento. Es necesario fortalecer la educación acerca de la prevención de cáncer de mama en los programas de estudio del área de la salud y promover la promoción de la salud.

Objective: This study assessed the knowledge about breast cancer among Nursing students from universities in the city of Chillán (Chile). Materials and methods: Descriptive, cross-sectional study carried out with third and fourth-year Nursing students from three universities of Chillan. The sample consisted of 187 students, who answered a survey related to their knowledge about breast cancer. Results: Most of the students demonstrated sufficient knowledge to distinguish signs and symptoms, treatments, and diagnoses of breast cancer as prospective healthcare practitioners. Difficulties regarding recognition of risk and protective factors related to breast cancer were observed. In relation to mammography tests, 80.7% indicated that they are performed before the age of 30. According to clinical guidelines, however, they should be performed after the age of 50, when there is no family history related to the disease. Conclusion: Students report knowledge of clinical guidelines, though it is difficult for them to identify risk and protective factors as well as specific treatment information. It is thus necessary to improve the level of education related to the prevention of breast cancer in study programs and encourage health promotion.

Objetivo: Este estudo avaliou o conhecimento sobre o câncer de mama em estudantes de Enfermagem das universidades da cidade de Chillán. Métodos: Estudo descritivo, transversal em estudantes de Enfermagem do terceiro e quarto ano, correspondente a três universidades em Chillán, Chile. A amostra foi composta por 187 estudantes que receberam um questionário sobre o conhecimento sobre o câncer de mama. Resultados: A maioria dos estudantes apresentou conhecimentos para distinguir os sinais, sintomas, tratamentos e diagnósticos sobre câncer de mama como profissionais da saúde. No entanto, os estudantes mostraram dificuldade em reconhecer exatamente quais eram os fatores de risco e fatores de proteção relacionados ao câncer de mama. Em relação à mamografia, 80,7% indicaram que o exame devia ser feito antes dos 30 anos, porem as guias clínicas indicam que deve ser feito após 50 anos, quando não há história familiar. Conclusão: Os alunos manifestam a aquisição de conhecimento em relação à diretriz clínica, mas com dificuldade em identificar fatores de risco, protetores e informações específicas sobre o tratamento. É necessário fortalecer a educação sobre a prevenção do câncer de mama nos programas de estudo da área da saúde e promover a promoção da saúde.

A healthy HLA-matched baby born by using a combination of aCGH and Karyomapping: the first latin american case.

PGD for HLA typing is a procedure that can be performed when an affected child requires a transplant to treat a non-hereditary disorder related to the hematopoietic and/or immune system. Hematopoietic stem cell transplantation from an HLA-identical donor provides the best treatment option. Three conventional ovarian stimulation procedures for IVF were performed in a couple with a 10-year-old child diagnosed with T-cell acute lymphoblastic leukemia of high risk. Trophectoderm biopsy and aCGH examination were performed on 15 blastocysts, three on the first IVF procedure, four on the second cycle, and eight on the third. Three euploid blastocysts HLA-compatible with the genome of the affected child were identified. One euploid blastocyst HLA-compatible with the affected child was warmed and transferred, resulting in an HLA-matched live birth. In conclusion, combined aCGH for aneuploidy screening and Karyomapping may be performed in a single biopsy procedure.

Mosaic embryo transfer after oocyte in vitro maturation in combination with non-invasive prenatal testing (NIPT)-first report of a euploid live birth.

PURPOSES: The purpose of this study is to describe a healthy life birth after a mosaic embryo transfer in oocyte in vitro maturation (IVM). METHODS: Patient received minimal stimulation, starting on day 3 after menstrual period. No hCG trigger was administered. Oocyte retrieval was performed and oocytes were matured for 30 h. After denuding, mature oocytes were inseminated by ICSI. Embryos were cultured until blastocyst stage and biopsied. RESULTS: One euploid embryo after array comprehensive genome hybridization (aCGH) was diagnostic. However, the next-generation sequencing (NGS) re-analysis showed that embryo was a mosaic for chromosome 13 and 21. Nevertheless, pregnancy ultrasound scans and non-invasive prenatal test (NIPT-Verifi-Illumina) indicated a normal fetus development. Finally, a healthy baby was born after 38 weeks. Its weight was 4480 g, head circumference 36 cm, and total length of 51 cm. To confirm that the baby was chromosomically normal, an NGS test was performed in buccal cells, a normal profile was obtained. CONCLUSIONS: Our finding confirmed that mosaic embryo transfer would bring a healthy offspring.

Monitoring program for mammals in a protected area of Colombia / Programa de monitoreo de mamíferos en un área protegida de colombia / Programa de monitoração de mamíferos em uma área protegida em Colômbia

Abstract Between the second semester of 2009 and the first semester of 2011, camera traps were set up in conserved and disturbed habitats in the Otun Quimbaya Flora and Fauna Sanctuary. From a sampling effort of 2,066 camera-days, 673 photographs of 157 independent events were obtained for eight species of wild mammals and a domestic one. Their activity patterns were mainly nocturnal even for those species reported as diurnal. The impact of human interference and exotic species was evident for two species: Tapiruspinchaque and Cerdocyon thous. The former was observed below its altitudinal range with activity patterns mainly crepuscular and nocturnal. The second was observed in the same habitats where domestic dogs were found, with activity patterns mainly crepuscular and nocturnal. These findings suggest that both species have altered their activity patterns. Actions must be focused on decreasing the interaction of these mammals with humans and domestic dogs.

Resumen La información sobre los mamíferos de mediano y gran tamaño que habitan áreas protegidas en Colombia es cada vez más necesaria para impulsar acciones tendientes a su protección. La identificación completa de estas especies, sus números y sus patrones de actividad son esenciales en programas de monitoreo, especialmente por las relaciones entre estos animales y las dinámicas antropogénicas. El presente estudio se llevó a cabo en el Santuario de Flora y Fauna Otún-Quimbaya (Colombia). Entre el segundo semestre de 2009 y el primer semestre de 2011, se colocaron trampas cámara en áreas conservadas y perturbadas del Santuario de Flora y Fauna Otún-Quimbaya. Con un esfuerzo de muestreo de 2066 días-cámara se obtuvieron 673 fotografías de 157 eventos independientes para 8 especies silvestres y una doméstica. Los patrones de actividad observados fueron principalmente nocturnos, incluso para especies reportadas como diurnas. El impacto de la interferencia humana y de las especies exóticas fue evidente en 2 especies: Tapirus pinchaque y Cerdocyon thous. La primera fue observada por debajo de su rango altitudinal con patrones de actividad principalmente crepusculares y nocturnos. La segunda se observó en los mismos hábitats donde se encontraron los perros domésticos, con patrones de actividad principalmente crepusculares y nocturnos. Estos hallazgos sugieren que ambas especies han alterado sus patrones de actividad. Es necesario enfocar acciones en la disminución de la interacción de estos mamíferos con los humanos y con perros domésticos.

Resumen Entre o segundo semestre de 2009 e o primeiro semestre de 2011, câmeras foram armadas em habitats conservados e perturbados no Santuário de Flora e Fauna Otún Quimbaya. A partir de uma amostragem de 2066 dias de instalação da câmera, foram obtidas 673 fotografias de 157 eventos independentes para oito espécies de mamíferos selvagens e uma espécie doméstica. Os padrões de atividade observados eram principalmente noturnos, inclusive para espécies reportadas como diurnas. O impacto da interferência humana e de espécies exóticas foi observado para duas espécies: Tapirus pinchaque e Cerdocyon thous. A primeira foi observada abaixo de seu intervalo de altitude com padrões de atividade majoritariamente crepuscular e noturno. A segunda espécie foi observada nos mesmos habitats em que espécies de cachorros domésticos foram observados, com padrões de atividade majoritariamente crepuscular e noturno. Estes resultados sugerem que ambas as espécies alteraram seus comportamentos padrão. Ações devem ser focalizadas para reduzir a interação de estes mamíferos com os humanos e cães domésticos.

Effect of transfection and co-incubation of bovine sperm with exogenous DNA on sperm quality and functional parameters for its use in sperm-mediated gene transfer.

Sperm-mediated gene transfer (SMGT) is based on the capacity of sperm to bind exogenous DNA and transfer it into the oocyte during fertilization. In bovines, the progress of this technology has been slow due to the poor reproducibility and efficiency of the production of transgenic embryos. The aim of the present study was to evaluate the effects of different sperm transfection systems on the quality and functional parameters of sperm. Additionally, the ability of sperm to bind and incorporate exogenous DNA was assessed. These analyses were carried out by flow cytometry and confocal fluorescence microscopy, and motility parameters were also evaluated by computer-assisted sperm analysis (CASA). Transfection was carried out using complexes of plasmid DNA with Lipofectamine, SuperFect and TurboFect for 0.5, 1, 2 or 4 h. The results showed that all of the transfection treatments promoted sperm binding and incorporation of exogenous DNA, similar to sperm incorporation of DNA alone, without affecting the viability. Nevertheless, the treatments and incubation times significantly affected the motility parameters, although no effect on the integrity of DNA or the levels of reactive oxygen species (ROS) was observed. Additionally, we observed that transfection using SuperFect and TurboFect negatively affected the acrosome integrity, and TurboFect affected the mitochondrial membrane potential of sperm. In conclusion, we demonstrated binding and incorporation of exogenous DNA by sperm after transfection and confirmed the capacity of sperm to spontaneously incorporate exogenous DNA. These findings will allow the establishment of the most appropriate method [intracytoplasmic sperm injection (ICSI) or in vitro fertilization (IVF)] of generating transgenic embryos via SMGT based on the fertilization capacity of transfected sperm.

Intoxicación con anís de estrella en niños menores de 12 meses, en el Hospital Nacional de Niños Doctor Carlos Sáenz Herrera durante el periodo 2001-2005 / Star anise intoxication in children less than 12 months old, at the National Children´s Hospital Doctor Carlos Sáenz Herrera during the period 2001-2005

Objetivo: Siendo el uso de anís de estrella nocivo en muchos casos es importante obtener los datos correspondientes a nuestro país para convertirlo en un tema de interés público y lograr, en base a evidencia clara, la intervención del Ministerio de Salud y poder evitar la venta libre de este producto que se utiliza popularmente sin ninguna restricción. La idea principal de obtener estos datos locales es divulgar la información a padres de familia y comunidad médica en relación al uso del anís de estrella y sus efectos secundarios enfatizando el adecuado manejo del cólico del lactante, así como de las madres durante la lactancia. Métodos: Es un estudio retrospectivo y descriptivo, en el cual se revisará la presentación clínica y la epidemiología de la toxicidad por anís de estrella en niños menores de 12 meses, que fueron hospitalizados en el Hospital Nacional de Niños Dr. Carlos Sáenz Herrera, durante el período comprendido del 1 de Enero 2001 al 31 de diciembre 2005. Los pacientes se reclutaron utilizando la base de Documentos Médicos y Estadística del HNN y los registros del Centro Nacional de Intoxicaciones en el periodo descrito. Resultados: Durante el periodo de estudio se reportaron como ingresos 68 casos de intoxicación por anís de estrella, de los cuales solo 47 fueron incluidos. El 53.2 por ciento eran mujeres. La edad promedio fue de 34.4 días, rango 3-111 días, de ellos el 91.5 por ciento eran recién nacidos de termino. Los síntomas gastrointestinales se presentaban previo a la intoxicación fueron distensión abdominal en un 61.7 por ciento y vómitos en un 14.8 por ciento. Un 91.5 por ciento se intoxicaron por la ingestión del te y un 4.25 por ciento por lactancia materna. La causa más frecuente por la que se utilizó el te fue por cólicos, 57.4 por ciento, con una exposición a una dosis leve en el 53 por ciento de los niños, menos de 5 estrellas. La estancia hospitalaria promedio fue de 2 días. Entre los síntomas y signos más comunes presentes en los casos estudiados se encuentran los de índole neurológica, como: la irritabilidad en un 97.8 por ciento, seguida por espasticidad en 70 por ciento, desviación de mirada 57.4 por ciento, hiperreflexia 49 por ciento, pobre succión 44.7 por ciento, movimientos oculogiros 36 por ciento y convulsiones 32 por ciento entre otros. De la sintomatología gastrointestinal, la distensión abdominal se presento en un 40.4 por ciento y los vómitos en el 55.3 por ciento. Conclusiones: La mayoría de los casos ocurren el lactantes de termino menores de 2 meses, en los cuales el te fue administrado por síntomas gastrointestinales, presentando manifestaciones neurológicas a pesar de una exposición leve al tóxico. Se debe instar al Ministerio de Salud a una adecuada comercialización de dicho producto, y a los médicos sobre una adecuada educación e información a la población general sobre los posibles efectos adversos y consecuencias de una intoxicación con anís de estrella.

Effect of letrozole at 2.5 mg or 5.0 mg/day on ovarian stimulation with gonadotropins in women undergoing intrauterine insemination.

OBJECTIVE: To determine the effect of combined therapy of letrozole (2.5 mg or 5.0 mg) with recombinant follicle-stimulating hormone (FSH) in comparison with the administration of recombinant FSH alone in an intrauterine insemination (IUI) program. DESIGN: Retrospective study. SETTING: Assisted fertilization program in a specialized infertility center. PATIENT(S): 110 women undergoing IUI and gonadotropin therapy. INTERVENTION(S): Recombinant FSH alone administered from day 3 or combined with letrozole, 2.5 or 5.0 mg/day, on days 3 to 7, and gonadotropins starting on day 7 of the menstrual cycle. Transvaginal ultrasound examinations were done until the dominant follicle reached 18 mm in diameter. Ovulation was triggered with 10,000 IU of human chorionic gonadotropin (hCG), and IUI performed 30 to 40 hours later. MAIN OUTCOME MEASURE(S): Recombinant FSH dose required, number of follicles greater than 14 mm and 18 mm, endometrial thickness, pregnancy rates, miscarriages, and characteristics of newborns. RESULT(S): Women treated with FSH and 5.0 mg/day of letrozole required a lower dose of FSH than the group cotreated with 2.5 mg/day of letrozole or with FSH alone. Throughout most of the follicular phase, the endometrial thickness was statistically significantly less in both letrozole cotreatment groups compared with the FSH control group. By the day of hCG administration, the endometrial thickness was comparable among all the groups. The pregnancy rates were the same with recombinant FSH alone or combined with letrozole. CONCLUSION(S): In terms of cost-effectiveness, 5.0 mg/day of letrozole is more effective than the 2.5 mg/day in cotreatment with no adverse effect on pregnancy rate or outcome.