Gastric MALT lymphoma: clinical characteristics and prevalence of H. pylori infection in a series of 37 cases Linfoma MALT gástrico: características clínicas y prevalencia de la infección por H. pylori en una serie de 37 casos

Objective: to perform a retrospective review of the clinical characteristics and prevalence of H. pylori infection in patients with gastric MALT lymphoma diagnosed in our hospital during the last 15 years. Methods: patients with gastric MALT lymphoma diagnosed in our hospital during the last 15 years were retrospectively included. Demographic, clinic, analytic, endoscopic, and histological variables were reviewed. The extension study, the staging classification, and the presence of H. pylori infection were assessed. Results: thirty-seven patients with gastric MALT lymphoma were identified. Mean age was 61 years, with 62% of males. The most common presentation symptom was dyspepsia (76%), followed by digestive bleeding (11%) and constitutional syndrome (8%). At endoscopy, erosive lesions were identified in 41%, and proliferative or exophytic lesions in 43%. Most lymphomas were classified as low-grade (68%). The stage distribution was EI for 56%, EII for 13%, EIII for 3%, and EIV for 28%. The prevalence of H. pylori infection (histology in all cases, rapid urease test in 19%, and 13C-urea breath test in 24%) was 46%. When only low-grade lymphomas in stage EI were considered, H. pylori prevalence increased to 55%. When H. pylori infection was evaluated by 13C-urea breath testing (in addition to histology), the prevalence of H. pylori infection increased to 78%. Conclusions: it is probable that the reduced H. pylori prevalence found in some studies, as in ours, could be explained by false-negative results obtained when only one diagnostic method was used. Therefore, at least two (invasive) diagnostic methods should be performed. Furthermore, the performance of a non-invasive diagnostic method (such as a 13C-urea breath test) before the exclusion of H. pylori infection should be considered.Objetivo: revisar retrospectivamente las características clínicas y la prevalencia de infección por H. pylori en los pacientes con linfoma MALT gástrico diagnosticados en nuestro hospital durante los últimos 15 años. Métodos: se identificaron retrospectivamente todos los pacientes diagnosticados de linfoma MALT gástrico en nuestro centro en los últimos 15 años. Se revisaron las variables demográficas, clínicas, analíticas, endoscópicas, histológicas, el estudio de extensión, la estadificación y la infección por H. pylori. Resultados: se identificaron 37 pacientes con linfoma MALT gástrico, con una edad media de 61 años, el 62% varones. El síntoma de presentación más frecuente fue la dispepsia (76%), seguido de la hemorragia digestiva alta (11%) y el síndrome constitucional (8%). Durante la endoscopia se identificaron lesiones erosivas en el 41% y proliferativas/exofíticas en el 43%. La mayoría de los linfomas fueron de bajo grado (68%). Estadificación: EI (56%), EII (13%), EIII (3%) y EIV (28%). La prevalencia de H. pylori (histología en todos los casos, test rápido de la ureasa en el 19% y prueba del aliento con 13C-urea en el 24%) fue del 46%. Cuando únicamente se consideraron los linfomas de bajo grado en estadio EI, la prevalencia de H. pylori ascendió al 55%. Cuando la presencia de H. pylori se valoró mediante la prueba del aliento (además de la histología), la prevalencia de infección ascendió al 78%. Conclusiones: es probable que la reducida prevalencia de infección por H. pylori encontrada en algunos estudios, como el nuestro, sea debida a resultados falsos negativos obtenidos al utilizar un sólo test diagnóstico, por lo que se sugiere el empleo de al menos dos, e incluso añadir un método diagnóstico "no invasivo' como la prueba del aliento con 13C-urea antes de excluir definitivamente la infección por H. pylori

Inbreeding and testicular abnormalities in a bottlenecked population of koalas (Phascolarctos cinereus)

Habitat destruction and fragmentation, interactions with introduced species or the relocation of animals to form new populations for conservation purposes may result in a multiplication of population bottlenecks. Examples are the translocations of koalas to French Island and its derivative Kangaroo Island population, with both populations established as insurance policies against koala extinction. In terms of population size, these conservation programs were success stories. However, the genetic story could be different. We conducted a genetic investigation of French and Kangaroo Island koalas by using 15 microsatellite markers, 11 of which are described here for the first time. The results confirm very low genetic diversity. French Island koalas have 3.8 alleles per locus and Kangaroo Island koalas 2.4. The present study found a 19% incidence of testicular abnormality in kangaroo Island animals. Internal relatedness, an individual inbreeding coefficient, was not significantly different in koalas with testicular abnormalities from that in other males, suggesting the condition is not related to recent inbreeding. It could instead result from an unfortunate selection of founder individuals carrying alleles for testicular abnormalities, followed by a subsequent increase in these alleles&rsquo; frequencies through genetic drift and small population-related inefficiency of selection. Given the low diversity and possible high prevalence of deleterious alleles, the genetic viability of the population remains uncertain, despite its exponential growth so far. This stands as a warning to other introductions for conservation reasons.<br /