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Conjugation of small molecules such as lipids or receptor ligands to anti-cancer drugs has been used to improve their pharmacological properties. In this work, we studied the biological effects of several small-molecule enhancers into a short oligonucleotide made of five floxuridine units. Specifically, we studied adding cholesterol, palmitic acid, polyethyleneglycol (PEG 1000), folic acid and triantennary N-acetylgalactosamine (GalNAc) as potential enhancers of cellular uptake. As expected, all these molecules increased the internalization efficiency with different degrees depending on the cell line. The conjugates showed antiproliferative activity due to their metabolic activation by nuclease degradation generating floxuridine monophosphate. The cytotoxicity and apoptosis assays showed an increase in the anti-cancer activity of the conjugates related to the floxuridine oligomer, but this effect did not correlate with the internalization results. Palmitic and folic acid conjugates provide the highest antiproliferative activity without having the highest internalization results. On the contrary, cholesterol oligomers that were the best-internalized oligomers had poor antiproliferative activity, even worse than the unmodified floxuridine oligomer. Especially relevant is the effect induced by palmitic and folic acid derivatives generating the most active drugs. These results are of special interest for delivering other therapeutic oligonucleotides.
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Apoptosis/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Citotoxinas , Floxuridina , Oligonucleótidos , Citotoxinas/química , Citotoxinas/farmacocinética , Citotoxinas/farmacología , Floxuridina/química , Floxuridina/farmacocinética , Floxuridina/farmacología , Células HeLa , Células Hep G2 , Humanos , Oligonucleótidos/química , Oligonucleótidos/farmacocinética , Oligonucleótidos/farmacologíaRESUMEN
The recent availability of commercial platforms for behavioral analyses in zebrafish larvae based on video-tracking technologies has exponentially increased the number of studies analyzing different behaviors in this model organism to assess neurotoxicity. Among the most commonly used assays in zebrafish larvae are basal locomotor activity (BLA) and visual motor responses (VMRs). However, the effect of different intrinsic and extrinsic factors that can significantly alter the outcome of these assays is still not well understood. In this work, we have analyzed the influence of age (5-8 days post-fertilization), time of day (8:00, 10:00, 12:00, 14:00; 16:00, 18:00, and 20:00 h), and experiment (three experiments performed at different days) on BLA and VMR results (4004 analyses for each behavior) in 143 larvae. The results from both behaviors were adjusted to a random-effects linear regression model using generalized least squares (GLSs), including in the model the effect of the three variables, the second-way interactions between them, and the three-way interaction. The results presented in this manuscript show a specific effect of all three intrinsic factors and their interactions on both behaviors, supporting the view that the most stable time period for performing these behavioral assays is from 10:00 am to 04:00 pm, with some differences depending on the age of the larva and the behavioral test.
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Oilseed crops are greatly extended all over the world. Their high fat content can interfere during pesticide multiresidue analysis through liquid chromatography-tandem mass spectrometry (LC-MS/MS). This work aimed at overcoming this issue by developing and validating two QuEChERS-based methods for LC-MS/MS determination of 42 pesticides in two fatty food matrices: olives and sunflower seeds. Optimization of the extraction method was achieved following a 26-2 fractional factorial design in a highly cost-effective way. Validation of the multi-residue methods demonstrated improved limits of detection, below the established maximum residue levels (MRLs) for almost all compounds, good precision, and trueness, in compliance with SANTE guidelines. Application of these methods to the analysis of real samples from the Iberian Peninsula showed the presence of some pesticides of relevant environmental concern, including four compounds contained in the Pesticide Action Network International list of highly hazardous pesticides, found at levels between 0.03 ng/g and 104 ng/g.
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Helianthus , Olea , Residuos de Plaguicidas , Plaguicidas , Cromatografía Liquida/métodos , Olea/química , Residuos de Plaguicidas/análisis , Plaguicidas/análisis , Semillas/química , Extracción en Fase Sólida , Espectrometría de Masas en Tándem/métodosRESUMEN
The objective of this article is to describe the prevalence of maternal Hepatitis C infection globally and by HIV serostatus. Unlinked anonymous testing on 474,539 samples from newborn babies was carried out, selected through stratified sampling by year and HIV status, in six Spanish Autonomous Regions, from 2003 to 2006. Results were 0.15% for global anti-hepatitis C virus (HCV), 29.69% and 0.10% for HIV(+) and HIV(-) women, respectively. Anti-HCV prevalence rate is low in these regions compared to Hospital cohorts. Although a high prevalence rate in HIV co-infected women is found, it tends to decrease along the period studied.
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Infecciones por VIH/inmunología , Seropositividad para VIH , VIH/inmunología , Hepatitis C/epidemiología , Complicaciones Infecciosas del Embarazo/epidemiología , Western Blotting , Ensayo de Inmunoadsorción Enzimática , Femenino , Anticuerpos Anti-VIH/sangre , Infecciones por VIH/complicaciones , Hepatitis C/complicaciones , Humanos , Recién Nacido , Embarazo , Prevalencia , España/epidemiologíaRESUMEN
BACKGROUND: Previous studies have demonstrated the efficacy of treatment for latent tuberculosis infection (TLTBI) in persons infected with the human immunodeficiency virus, but few studies have investigated the operational aspects of implementing TLTBI in the co-infected population.The study objectives were to describe eligibility for TLTBI as well as treatment prescription, initiation and completion in an HIV-infected Spanish cohort and to investigate factors associated with treatment completion. METHODS: Subjects were prospectively identified between 2000 and 2003 at ten HIV hospital-based clinics in Spain. Data were obtained from clinical records. Associations were measured using the odds ratio (OR) and its 95% confidence interval (95% CI). RESULTS: A total of 1242 subjects were recruited and 846 (68.1%) were evaluated for TLTBI. Of these, 181 (21.4%) were eligible for TLTBI either because they were tuberculin skin test (TST) positive (121) or because their TST was negative/unknown but they were known contacts of a TB case or had impaired immunity (60). Of the patients eligible for TLTBI, 122 (67.4%) initiated TLTBI: 99 (81.1%) were treated with isoniazid for 6, 9 or 12 months; and 23 (18.9%) with short-course regimens including rifampin plus isoniazid and/or pyrazinamide. In total, 70 patients (57.4%) completed treatment, 39 (32.0%) defaulted, 7 (5.7%) interrupted treatment due to adverse effects, 2 developed TB, 2 died, and 2 moved away. Treatment completion was associated with having acquired HIV infection through heterosexual sex as compared to intravenous drug use (OR:4.6; 95% CI:1.4-14.7) and with having taken rifampin and pyrazinamide for 2 months as compared to isoniazid for 9 months (OR:8.3; 95% CI:2.7-24.9). CONCLUSIONS: A minority of HIV-infected patients eligible for TLTBI actually starts and completes a course of treatment. Obstacles to successful implementation of this intervention need to be addressed.
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Antituberculosos/uso terapéutico , Infecciones por VIH/complicaciones , Tuberculosis Latente/tratamiento farmacológico , Adulto , Femenino , Humanos , Masculino , Cumplimiento de la Medicación/estadística & datos numéricos , Persona de Mediana Edad , Estudios Prospectivos , España , Resultado del TratamientoRESUMEN
INTRODUCTION: Tuberculin skin testing (TST) for tuberculosis (TB) is recommended for all patients with HIV infection because of the known relationship between these two conditions. In this report we analyze the incidence and variables associated with non-prescription of TST in a cohort of HIV-infected people. PATIENTS AND METHODS: Longitudinal study conducted between 2000 and 2002 at 10 HIV hospital-based clinics. All HIV-infected patients who had not been regularly followed-up previously in dedicated clinics were identified. Data about TST and other variables related to TB were obtained from the clinical records. We calculated the percentage of patients who did not undergo TST and the associated factors, using odds ratios (ORs) and the 95% CI to investigate associations. A multivariate logistic regression analysis was performed. RESULTS: A total of 1242 patients met the inclusion criteria. TST was not performed in 185 patients (17.6% of those eligible). The fact of being an intravenous drug abuser was associated with a higher probability of TST non-prescription (OR: 2.6, 95% CI 1.1-6.5), whereas being unemployed (OR: 0.6, 95% CI 0.3-1.0), having a CD4 cell count >200 (CD4 200-499: OR 0.5, 95% CI 0.3-0.9. CD4> or =500: OR 0.3, 95% CI 0.2-0.6), and contact with persons with TB (OR 0.2, 95% CI 0.1-0.5) were associated with a lower probability. CONCLUSIONS: In this study, the percentage of TST non-prescription was quite high. The results suggest that TST non-prescription in this population is related to the clinicians' expectations regarding the results of the test and the patients' adherence to treatment for latent TB infection.
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Infecciones por VIH/complicaciones , Prueba de Tuberculina/estadística & datos numéricos , Tuberculosis/diagnóstico , Adulto , Estudios de Cohortes , Comorbilidad , Diagnóstico Tardío , Pruebas Diagnósticas de Rutina/estadística & datos numéricos , Emigrantes e Inmigrantes/estadística & datos numéricos , Femenino , Adhesión a Directriz , Infecciones por VIH/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Factores de Riesgo , Conducta Sexual , Factores Socioeconómicos , España/epidemiología , Abuso de Sustancias por Vía Intravenosa/epidemiología , Reacción a la Transfusión , Tuberculosis/complicaciones , Tuberculosis/epidemiología , Adulto JovenRESUMEN
Most previous longitudinal studies of functional magnetic resonance imaging (fMRI) in first-episode psychosis (FEP) using cognitive paradigm task found an increased activation after antipsychotic medications. We designed an emotional auditory paradigm to explore brain activation during emotional and nonemotional word processing. This study aimed to analyze if longitudinal changes in brain fMRI BOLD activation is present in patients vs. healthy controls. A group of FEP patients (n = 34) received clinical assessment and had a fMRI scan at baseline and follow-up (average, 25-month interval). During the fMRI scan, both emotional and nonemotional words were presented as a block design. Results were compared with a pair of healthy control group (n = 13). Patients showed a decreased activation at follow-up fMRI in amygdala (F = 4.69; p = 0.04) and hippocampus (F = 5.03; p = 0.03) compared with controls. Middle frontal gyrus was the only area that showed a substantial increased activation in patients (F = 4.53; p = 0.04). A great heterogeneity in individual activation patterns was also found. These results support the relevance of the type of paradigm in neuroimaging for psychosis. This is, as far as we know, the first longitudinal study with an emotional auditory paradigm in FEP. Our results suggested that the amygdala and hippocampus play a key role in psychotic disease. More studies are needed to understand the heterogeneity of response at individual level.
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BACKGROUND AND OBJECTIVE: Our objectives were to detect asymptomatic cases involved in an outbreak of hepatitis B, to assess the seroprevalence of hepatitis B (HB) in orienteers and to establish recommendations. PATIENTS AND METHOD: One hundred sixteen orienteers who had competed in the categories involved in the previous outbreak as well as a stratified random sample of 166 of the remaining orienteers in other competition categories were included in a cross-sectional serological prevalence study. HB surface antigen (anti-HBs); total antibody to HB core antigen (total anti-HBc); HB surface antigen (Ag HBs); and antibody IgM to HB core antigen (anti-HBcIgM) along with the history of vaccination for hepatitis B were analyzed. The results were weighted. RESULTS: The seroprevalence of HB (total anti-HBc positive) was 6.7% (n=12, 95% CI 0.6-12.9). No case of acute HB or chronic infection was observed. All the serological markers were negative for 61.1% (n=64, 95% CI 46.3-75.6), and 31.5% (n=29, 95% CI 18.2-46.4) had markers of immunity due to vaccination. Among individuals under 25 years of age, 28.4% were unvaccinated, although they were covered by vaccination programs. CONCLUSION: Our results suggest that the seroprevalence of HB among orienteers is not different from the general population in Spain. However, it is necessary to reinforce the vaccination among adolescents and young adults. General recommendations for the prevention of HB were made to orienteering federations.
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Brotes de Enfermedades , Anticuerpos contra la Hepatitis B/sangre , Hepatitis B/sangre , Hepatitis B/epidemiología , Deportes , Adulto , Estudios Transversales , Femenino , Antígenos del Núcleo de la Hepatitis B/inmunología , Humanos , Masculino , Estudios Seroepidemiológicos , España/epidemiología , Adulto JovenRESUMEN
Anti-citrullinated peptide/protein antibodies (ACPAs) are the most specific serological biomarkers for rheumatoid arthritis (RA). They have both diagnostic and prognostic value, and are related to more aggressive joint disease in RA. However, a single biomarker cannot differentiate RA subtypes. So, simultaneous analysis of target citrullinated peptides, using a multiplex array based on chimeric peptides composed of several domains of human proteins, could be useful. In this work, eight chimeric peptides and the corresponding native arginine-containing control peptides were obtained by solid-phase peptide synthesis. The study included RA and psoriatic arthritis (PsA) patients attending the Rheumatology Unit of the Hospital Clinic in Barcelona, as well as healthy blood donors (BD) at the same hospital. Our main aim was to explore the diagnostic value of the novel multiplex array compared to a commercial ELISA-based ACPA assay in a serum-saving way. Using the combination of the eight chimeric peptide antigens in the multiplex array, 61.4% of the RA cohort were positive for 3 or more peptides; while, the healthy BD and PsA cohorts did not show any reactivity with the tested peptides. These results indicate that we have developed a highly specific multiplex assay based of chimeric citrullinated peptides derived from filaggrin, fibrin, vimentin and human enolase proteins for the detection of ACPAs in a serum-saving way.
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Artritis Reumatoide/diagnóstico , Ensayo de Inmunoadsorción Enzimática , Péptidos Cíclicos/química , Proteínas Recombinantes de Fusión/química , Secuencia de Aminoácidos , Anticuerpos Antiproteína Citrulinada/sangre , Anticuerpos Antiproteína Citrulinada/inmunología , Artritis Reumatoide/sangre , Artritis Reumatoide/inmunología , Proteínas Filagrina , Humanos , Péptidos Cíclicos/inmunología , Proteínas Recombinantes de Fusión/inmunologíaRESUMEN
BACKGROUND: Epidemiologic evidence of surgical transmission of sporadic Creutzfeldt-Jakob disease (sCJD) remains controversial. METHODS: From Danish and Swedish registries we selected 167 definite and probable sCJD cases (with onset between 1987 and 2003) and 3,059 controls (835 age-, sex-, and residence-matched, and 2,224 unmatched). Independent of case/control status, surgical histories were obtained from National Hospital Discharge Registries. Surgical procedures were categorized by body system group and lag time to onset of sCJD. Exposure frequencies were compared using logistic regression. RESULTS: A history of any major surgery, conducted >/=20 years before sCJD onset, was more common in cases than both matched (OR = 2.44, 95% CI = 1.46-4.07) and unmatched controls (OR = 2.25, 95% CI = 1.48-3.44). This observation was corroborated by a linear increase in risk per surgical discharge (OR = 1.57, 95% CI = 1.13-2.18; OR = 1.50, 95% CI = 1.18-1.91). Surgery of various body systems, including peripheral vessels, digestive system and spleen, and female genital organs, was significantly associated with increased sCJD risk. CONCLUSIONS: A variety of major surgical procedures constitute a risk factor for sCJD following an incubation period of many years. A considerable number of sCJD cases may originate from health care-related accidental transmission.
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Síndrome de Creutzfeldt-Jakob/epidemiología , Síndrome de Creutzfeldt-Jakob/cirugía , Procedimientos Quirúrgicos Operativos/efectos adversos , Estudios de Casos y Controles , Síndrome de Creutzfeldt-Jakob/mortalidad , Síndrome de Creutzfeldt-Jakob/transmisión , Dinamarca/epidemiología , Femenino , Humanos , Masculino , Enfermedades por Prión/epidemiología , Enfermedades por Prión/cirugía , Valores de Referencia , Sistema de Registros , Procedimientos Quirúrgicos Operativos/estadística & datos numéricos , Análisis de Supervivencia , Suecia/epidemiología , Factores de Tiempo , Reacción a la TransfusiónRESUMEN
We present an off-line cursive word recognition system based completely on neural networks: reading models and models of early visual processing. The first stage (normalization) preprocesses the input image in order to reduce letter position uncertainty; the second stage (feature extraction) is based on the feedforward model of orientation selectivity; the third stage (letter pre-recognition) is based on a convolutional neural network, and the last stage (word recognition) is based on the interactive activation model.
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Algoritmos , Inteligencia Artificial , Procesamiento de Imagen Asistido por Computador/métodos , Redes Neurales de la Computación , Reconocimiento de Normas Patrones Automatizadas/normas , Animales , Escritura Manual , Humanos , Red Nerviosa/fisiología , Reconocimiento Visual de Modelos/fisiología , Lectura , Factores de Tiempo , Corteza Visual/fisiología , Vías Visuales/fisiologíaRESUMEN
Neural Network Language Models (NNLMs) are a successful approach to Natural Language Processing tasks, such as Machine Translation. We introduce in this work a Statistical Machine Translation (SMT) system which fully integrates NNLMs in the decoding stage, breaking the traditional approach based on [Formula: see text]-best list rescoring. The neural net models (both language models (LMs) and translation models) are fully coupled in the decoding stage, allowing to more strongly influence the translation quality. Computational issues were solved by using a novel idea based on memorization and smoothing of the softmax constants to avoid their computation, which introduces a trade-off between LM quality and computational cost. These ideas were studied in a machine translation task with different combinations of neural networks used both as translation models and as target LMs, comparing phrase-based and [Formula: see text]-gram-based systems, showing that the integrated approach seems more promising for [Formula: see text]-gram-based systems, even with nonfull-quality NNLMs.
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Procesamiento de Lenguaje Natural , Redes Neurales de la Computación , Traducción , Humanos , Modelos Estadísticos , VocabularioRESUMEN
This paper presents a new method to reduce the computational cost when using Neural Networks as Language Models, during recognition, in some particular scenarios. It is based on a Neural Network that considers input contexts of different length in order to ease the use of a fallback mechanism together with the precomputation of softmax normalization constants for these inputs. The proposed approach is empirically validated, showing their capability to emulate lower order N-grams with a single Neural Network. A machine translation task shows that the proposed model constitutes a good solution to the normalization cost of the output softmax layer of Neural Networks, for some practical cases, without a significant impact in performance while improving the system speed.
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Procesamiento de Lenguaje Natural , Redes Neurales de la Computación , Procesos EstocásticosRESUMEN
The present work investigates the occurrence of 22 drugs of abuse (DAs) and metabolites in surface water from four Spanish River basins: Llobregat, Ebro, Jucar and Guadalquivir. To this end, samples were collected from 77 selected sites in two sampling campaigns conducted in 2010 and 2011. Analyses were performed by means of on-line solid phase extraction-liquid chromatography-electrospray-tandem mass spectrometry (on-line SPE-LC-ESI-MS/MS). Cocaine, its metabolite benzoylecgonine, ephedrine, MDMA (ecstasy), and methadone and its metabolite EDDP were the most ubiquitous compounds, being present in more than 50% of the samples. Overall, DAs were present at low ng/L levels, showing comparatively higher concentrations in small tributary rivers impacted by wastewater treatment plant effluents. The results obtained did not show a clear relationship between the concentrations of DAs and the hydrological conditions of the river basins. Differences in the occurrence of DAs between river basins were observed, but only for MDMA this finding could be confirmed in both sampling campaigns. These results overall suggest similar drugs consumption in the studied areas. Estimation of potential ecotoxicological effects using Hazard Quotient (HQ) ratios and a concentration addition model showed that in four samples the presence of DAs could represent certain risk to aquatic organisms.
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Drogas Ilícitas/análisis , Contaminantes Químicos del Agua/análisis , Cocaína/análogos & derivados , Cocaína/química , Monitoreo del Ambiente , Efedrina/química , Geografía , Metadona/química , N-Metil-3,4-metilenodioxianfetamina/química , Pirrolidinas/química , Medición de Riesgo , Ríos , España , Análisis Espacio-Temporal , Agua/químicaRESUMEN
This paper proposes the use of hybrid Hidden Markov Model (HMM)/Artificial Neural Network (ANN) models for recognizing unconstrained offline handwritten texts. The structural part of the optical models has been modeled with Markov chains, and a Multilayer Perceptron is used to estimate the emission probabilities. This paper also presents new techniques to remove slope and slant from handwritten text and to normalize the size of text images with supervised learning methods. Slope correction and size normalization are achieved by classifying local extrema of text contours with Multilayer Perceptrons. Slant is also removed in a nonuniform way by using Artificial Neural Networks. Experiments have been conducted on offline handwritten text lines from the IAM database, and the recognition rates achieved, in comparison to the ones reported in the literature, are among the best for the same task.
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Algoritmos , Procesamiento Automatizado de Datos/métodos , Escritura Manual , Reconocimiento de Normas Patrones Automatizadas/métodos , Humanos , Cadenas de Markov , Lectura , Reproducibilidad de los ResultadosRESUMEN
A set of topological descriptors has been used to discriminate between antibacterial and nonantibacterial drugs. Topological descriptors are simple integers calculated from the molecular structure represented in SMILES format. The methods used for antibacterial activity discrimination were linear discriminant analysis (LDA) and artificial neural networks of a multilayer perceptron (MLP) type. The following plot frequency distribution diagrams were used: a function of the number of drugs within a value interval of the discriminant function and the output value of the neural network versus these values. Pharmacological distribution diagrams (PDD) were used as a visualizing technique for the identification of antibacterial agents. The results confirmed the discriminative capacity of the topological descriptors proposed. The combined use of LDA and MLP in the guided search and the selection of new structures with theoretical antibacterial activity proved highly effective, as shown by the in vitro activity and toxicity assays conducted.
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Antibacterianos/química , Redes Neurales de la Computación , Antibacterianos/farmacología , Análisis Discriminante , Pruebas de Sensibilidad MicrobianaRESUMEN
A set of topological and structural descriptors has been used to discriminate general pharmacological activity. To that end, we selected a group of molecules with proven pharmacological activity including different therapeutic categories, and another molecule group without any activity. As a method for pharmacological activity discrimination, an artificial neural network was used, dividing molecules into active and inactive, to train the network and externally validate it. The following plot frequency distribution diagrams were used: a function of the number of drugs within a value interval, and the output value of the neural network versus these values. Pharmacological distribution diagrams (PDD) were used as a visualizing technique for the identification of drug and nondrug molecules. The results confirmed the discriminative capacity of the topological descriptors proposed.
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Redes Neurales de la Computación , Preparaciones Farmacéuticas/química , Farmacología/métodos , Presentación de Datos , Relación Estructura-ActividadRESUMEN
Fundamento y objetivo: Detectar casos asintomáticos relacionados con un brote, valorar la seroprevalencia de hepatitis B (HB) en deportistas de orientación y establecer recomendaciones. Pacientes y método: Se realizó un estudio transversal de seroprevalencia entre 116 deportistas de orientación que habían competido en las categorías implicadas en un brote previo y una muestra estratificada de 166 corredores del resto de otras categorías de competición. Se analizaron marcadores de HB: antígeno de superficie del virus de la HB (VHB) (HBsAg), anticuerpo contra el antígeno core del VHB (anti-HBc), anticuerpos contra el HBsAg, anti-HBc tipo inmunoglobina M y antecedentes de vacunación. Los resultados se expresan utilizando pesos ponderados. Resultados: La seroprevalencia de HB (anti-HBc positivos) fue del 6,7% (n=12; intervalo de confianza [IC] del 95%: 0,6 a 12,9). No se observó ningún caso de HB aguda o crónica. Todos los marcadores fueron negativos para el 61,1% (n=64; IC del 95%: 46,3 a 75,6), y el 32,3% (n=29; IC del 95%: 18,2 a 46,4) tenía marcadores de inmunidad por vacunación. Entre los sujetos menores de 25 años, el 28,4% estaba sin vacunar a pesar de que entraban en el calendario vacunal. Conclusiones: Los resultados muestran que la seroprevalencia de HB entre deportistas de orientación no difiere de la población general. Sin embargo, es necesario reforzar la vacunación entre adolescentes y adultos jóvenes. Se dan recomendaciones generales para la prevención de HB a las federaciones de orientación (AU)
Background and objective: Our objectives were to detect asymptomatic cases involved in an outbreak of hepatitis B, to assess the seroprevalence of hepatitis B (HB) in orienteers and to establish recommendations. Patients and method: One hundred sixteen orienteers who had competed in the categories involved in the previous outbreak as well as a stratified random sample of 166 of the remaining orienteers in other competition categories were included in a cross-sectional serological prevalence study. HB surface antigen (anti-HBs); total antibody to HB core antigen (total anti-HBc); HB surface antigen (Ag HBs); and antibody IgM to HB core antigen (anti-HBcIgM) along with the history of vaccination for hepatitis B were analyzed. The results were weighted. Results: The seroprevalence of HB (total anti-HBc positive) was 6.7% (n=12, 95%CI 0.6-12.9). No case of acute HB or chronic infection was observed. All the serological markers were negative for 61.1% (n=64, 95%CI 46.3-75.6), and 31.5% (n=29, 95%CI 18.2-46.4) had markers of immunity due to vaccination. Among individuals under 25 years of age, 28.4% were unvaccinated, although they were covered by vaccination programs. Conclusion: Our results suggest that the seroprevalence of HB among orienteers is not different from the general population in Spain. However, it is necessary to reinforce the vaccination among adolescents and young adults. General recommendations for the prevention of HB were made to orienteering federations (AU)