Development of piscirickettsiosis in Atlantic salmon (Salmo salar L.) smolts after intraperitoneal and cohabitant challenge using an EM90-like isolate: A comparative study.

Piscirickettsiosis, caused by the intracellular Gram-negative bacteria Piscirickettsia salmonis, is at present the most devastating disease in the Chilean salmon industry. The aim of this study was to analyse disease development after challenge with a P. salmonis strain (EM90-like) under a controlled environment by comparing intraperitoneal challenge with cohabitation challenge. The P. salmonis EM90-like isolate was cultured in a liquid medium for the challenge of 400 Atlantic salmon (Salmo salar) smolts. Cumulative mortality was registered, necropsy was performed, and bacterial distribution in the tissues and histopathological changes were analysed. The results revealed a similar progression of the disease for the two different challenge models. Pathological and histopathological changes became more visible during the development of the clinical phase of the disease. Bacterial DNA was identified in all the analysed tissues indicating a systemic infection. Bacterial tropism to visceral organs was demonstrated by real-time quantitative PCR and immunohistochemistry. Better knowledge of disease development during P. salmonis infection may contribute to further development of challenge models that mimic the field situation during piscirickettsiosis outbreaks. The models can be used to develop and test future preventive measures against the disease.

Comparative evaluation of experimental challenge by intraperitoneal injection and cohabitation of Atlantic salmon (Salmo salar L) after vaccination against Piscirickettsia salmonis (EM90-like).

The Chilean aquaculture has been challenged for years by piscirickettsiosis. A common prophylactic measurement to try to reduce the impact from this disease is vaccination, but the development of vaccines that induce satisfactory protection of the fish in the field has so far not been successful. Experimental challenge models are used to test vaccine efficacy. The aim of this study was to evaluate the performance of experimental vaccines after challenge by the two most widely used challenge routes, intraperitoneal injection and cohabitation. A total of 1,120 Atlantic salmon were vaccinated with non-commercial experimental vaccines with increasing amounts of an inactivated Piscirickettsia salmonis EM90-like isolate. Differences in mortality, macroscopic and microscopic pathological changes, bacterial load and immune gene expression were compared after challenge by different routes. The results revealed a similar progression of the diseases after challenge by both routes and no gross differences reflecting the efficacy of the vaccines could be identified. The analysis of the immune genes suggests a possible suppression of the cellular immunity by CD8 T cell and with this stimulation of bacterial survival and replication. Comparative studies of experimental challenge models are valuable with regard to identifying the best model to mimic real-life conditions and vaccines' performance.

[Ameboma: possible therapeutic decisions in an amebiasis-endemic region]. / Ameboma: posibles decisiones terapéuticas en región endémica de amibiasis.

INTRODUCTION: Amebiasis can mimic cecal tumors. Unless this infection is diagnosed in a timely manner, affected individuals may undergo extensive surgery. MATERIAL AND METHODS: We carried out a retrospective analytical study of the therapeutic approach to amebiasis in a second-level hospital in an area of central Mexico with a high prevalence of this infection. Records from 2005-2011 were reviewed. There were 261 cases of amebiasis. Twenty cases were diagnosed by the histopathologist or on the basis of serological results. Sixteen patients underwent surgery due to acute abdomen, and four received medical treatment with metronidazole. Three treatment groups were analyzed: 1. hemicolectomy, 2. appendicectomy and antiamebic therapy, and 3. antiamoebic therapy alone. In the non-surgical group, imaging studies showed improvement with medical therapy. RESULTS: Length of hospital stay was higher in the group undergoing extensive surgery (p < 0.0133). There were no statistically significant differences among the remaining variables. CONCLUSIONS: The incidence of ameboma in our environment is higher (7.6%) than that reported in the literature. We believe that, in endemic regions, ameboma should be ruled out in patients with a cecal mass. As part of the therapeutic approach, patients should be tested for amebiasis or receive antiamebic therapy with monitoring of the mass to avoid extensive resective surgery.

Ameboma: posibles decisiones terapéuticas en región endémica de amibiasis / Ameboma: possible therapeutic decisions in an amebiasis-endemic region

INTRODUCCIÓN: El ameboma como manifestación de enfermedad amibiana puede imitar un tumor cecal, por ende si no se realiza oportunamente dicho diagnóstico, se puede someter a pacientes a procedimientos quirúrgicos extensos. MATERIAL Y MÉTODOS: Realizamos un estudio retrospectivo analítico en relación con el abordaje terapéutico del ameboma en un hospital de segundo nivel del centro de México, zona de alta prevalencia de amebiasis, desde enero de 2005 hasta diciembre de 2011. Identificamos 261 casos de infección amibiana, identificamos 20 casos de ameboma diagnosticados por histopatología o bien serología. Se intervino quirúrgicamente a 16 pacientes por presentar datos de abdomen agudo y 4 recibieron tratamiento médico con metronidazol. Analizamos 3 tipos de tratamiento: 1. Hemicolectomía con antiamebiano, 2. Apendicectomía con antiamebiano y 3. Solo antiamebiano. En el grupo no quirúrgico se dio seguimiento con características en imagen de acuerdo a la mejoría al tratamiento médico. RESULTADOS: Se encontró una mayor estancia hospitalaria en el primer grupo (p < 0,0133) que corresponde al tratamiento quirúrgico extenso. No hubo diferencia estadísticamente significativa para el resto de las variables. CONCLUSIONES: El ameboma en nuestro medio tiene una alta incidencia (7,6%), mayor a la reportada en la literatura. Consideramos que en regiones endémicas, el ameboma debe ser descartado en un escenario de masa cecal y los pacientes deben ser estudiados para confirmar amebiasis y recibir tratamiento antiamebiano aunado a la vigilancia estrecha de dicha masa y de ésta manera evitar cirugías extensas

INTRODUCTION: Amebiasis can mimic cecal tumors. Unless this infection is diagnosed in a timely manner, affected individuals may undergo extensive surgery. MATERIAL AND METHODS: We carried out a retrospective analytical study of the therapeutic approach to amebiasis in a second-level hospital in an area of central Mexico with a high prevalence of this infection. Records from 2005-2011 were reviewed. There were 261 cases of amebiasis. Twenty cases were diagnosed by the histopathologist or on the basis of serological results. Sixteen patients underwent surgery due to acute abdomen, and four received medical treatment with metronidazole. Three treatment groups were analyzed: 1. hemicolectomy, 2. appendicectomy and antiamebic therapy, and 3. antiamoebic therapy alone. In the non-surgical group, imaging studies showed improvement with medical therapy. RESULTS: Length of hospital stay was higher in the group undergoing extensive surgery (p < 0.0133). There were no statistically significant differences among the remaining variables. CONCLUSIONS:The incidence of ameboma in our environment is higher (7.6%) than that reported in the literature. We believe that, in endemic regions, ameboma should be ruled out in patients with a cecal mass. As part of the therapeutic approach, patients should be tested for amebiasis or receive antiamebic therapy with monitoring of the mass to avoid extensive resective surgery

Recurrent DNA inversion rearrangements in the human genome.

Several lines of evidence suggest that reiterated sequences in the human genome are targets for nonallelic homologous recombination (NAHR), which facilitates genomic rearrangements. We have used a PCR-based approach to identify breakpoint regions of rearranged structures in the human genome. In particular, we have identified intrachromosomal identical repeats that are located in reverse orientation, which may lead to chromosomal inversions. A bioinformatic workflow pathway to select appropriate regions for analysis was developed. Three such regions overlapping with known human genes, located on chromosomes 3, 15, and 19, were analyzed. The relative proportion of wild-type to rearranged structures was determined in DNA samples from blood obtained from different, unrelated individuals. The results obtained indicate that recurrent genomic rearrangements occur at relatively high frequency in somatic cells. Interestingly, the rearrangements studied were significantly more abundant in adults than in newborn individuals, suggesting that such DNA rearrangements might start to appear during embryogenesis or fetal life and continue to accumulate after birth. The relevance of our results in regard to human genomic variation is discussed.