Vascular Neonatal Thymus Transplantation in Rabbits.

BACKGROUND: Successful vascular adult thymus transplant has been reported in different animal models but not in rabbits. These animal models are slightly larger than the murine and substantially smaller than the porcine. We describe in rabbits a supermicrosurgical technique for vascular neonatal thymus transplant and provide histologic evidence of tissue viability. METHODS: Newborn (New Zealand, n = 12, 6 female) and adult (New Zealand, n = 12, 6 female) rabbits were used as donors and recipients, respectively. Whole thymuses were extracted from donors and grafted into recipients. Immediate direct vascularization was accomplished by anastomosis to the right common carotid artery and the right external vena cava. At day 14, graft sites were surgically explored, and grafted thymuses were explanted for histologic evaluation. All recipients were followed over 2 weeks for clinical signs of graft-vs-host reaction. RESULTS: The vascular pedicles of the thymus grafts ranged 0.5 to 0.8 mm in vessel diameter. From the 12 transplants, 3 recipients (3/12; 25%) died during the surgical procedure because of blood loss after clamp release. On histology, from the 9 (9/12; 75%) successful at revascularization, none (0/9; 0%) had signs of acute rejection or necrosis, and all (9/9; 100%) evidenced normal cytoarchitecture. No clinical signs of graft-vs-host reaction were evidenced during follow-up. CONCLUSIONS: Vascular neonatal thymus transplant in rabbits is surgically feasible. This technique will enable a novel approach for studying the biology of the thymus.

Cytochrome P450 CYP2B6 genotypes and haplotypes in a Colombian population: identification of novel variant CYP2B6 alleles.

OBJECTIVE: Information on CYP2B6 allele frequencies and detrimental genotypes in mixed human populations is scarce. The aim of this study was to analyze the frequencies and haplotypes of nonsynonymous CYP2B6 single nucleotide polymorphisms (SNPs) in a Colombian population. METHODS: One hundred and fifty-two healthy individuals were analyzed for five nonsynonymous CYP2B6 SNPs, namely rs8192709, rs3745274, rs2279343 rs28399499, and rs3211371. RESULTS: Besides eight known variant alleles, we identified two as yet unknown variant alleles combining, respectively, the SNPs rs3745274 and rs3211371 and rs8192709 and rs3745274. Comparison of Colombian mestizo individuals with other mestizo population indicates statistically significant differences (P<0.001) for the gain-of-function CYP2B6*4 allele and for combined detrimental CYP2B6 alleles. In addition, we observed a low linkage between the SNPs rs3745274 and rs2279343, which are often assumed as linked. CONCLUSION: In conclusion, large interethnic and intraethnic variability exists for CYP2B6 polymorphisms, thus reinforcing the need for tailored genotyping protocols for CYP2B6 testing as a biomarker of drug response.

[Cyclosporine A effect in mice C57BL/6 infected with Encephalitozoon intestinalis]. / Efecto de la ciclosporina A en ratones C57BL/6 infectados con Encephalitozoon intestinalis.

INTRODUCTION: Encephalitozoon intestinalis, a parasite belonging to the phylum Microsporidia, is causes gastrointestinal infections in the immunocompromised host. A suitable pharmacologically immunosuppressed animal model for the study of natural E. intestinalis infection, which can establish the immune components that respond to this parasite, is lacking. OBJECTIVE: To evaluate the effect of immunosuuppression with Cyclosporine A (CsA) in C57BL/ 6 mice on experimental infection with E. intestinalis infection. MATERIALS AND METHODS: Eighty C57BL/6 mice were distributed in four treatment groups: Control, CsA-immunosuppressed mice without infection, immunocompetent and immunossuppressed mice infected with E. intestinalis. Mice were immunosuppressed with a weekly dose of 50 mg/Kg body weight of CsA, during the course of the study. Five mice from each group were sacrificed 2, 3, 4 and 6 weeks post-infection, to obtain blood for antibody testing and stool samples were analyzed to assess excretion of spores. RESULTS: Production of specific IgG antibodies was significantly higher in the immunocompetent group as compared to the immunosuppressed group of experimentally infected mice. In the infected mice, parasites were not observed in any tissues different from the small intestine. However, spore excretion through the stool and duodenal liquid was higher in the group of immunosuppresed infected mice. CONCLUSION: Immunosuppression induced with CsA in the murine model did not allow parasite dissemination and illness progression, but raised kinetics of spore excretion and decreased the production of IgG antibodies.

Efecto de la ciclosporina A en ratones C57BL/6 infectados con encephalitozoon intestinalis / Cyclosporine A effect in mice C57BL/6 infected with Encephalitozoon intestinalis

Introducción. Encephalitozoon intestinalis es un microsporidio parásito del intestino, que puedediseminarse en pacientes inmunocomprometidos. Existen referencias de modelos animales inmunosuprimidos para el estudio de la microsporidiosis utilizando fármacos que producen supresión total de la respuesta inmune; sin embargo, no se han estudiado los efectos deinmunosupresores con acción selectiva sobre los componentes de esta respuesta. Objetivo. Evaluar el efecto de la inmunosupresión con ciclosporina A (CsA) en ratones C57BL/ 6 infectados con E. intestinalis.Materiales y métodos. Se utilizaron 80 ratones C57BL/6 distribuidos en cuatro grupos: infectados, inmunosuprimidos e infectados, inmunosuprimidos no infectados y controles. La inmunosupresión con CsA (50 mg/kg) se realizó vía intraperitoneal durante todo el estudio. En la semanas 2, 3, 4 y 6 posteriores a la infección se obtuvo sangre para determinar los anticuerpos, y materia fecal para evaluar la cinética de excreción de esporas. Además, se extrajeron varios órganos para estudiar la histopatología y observar la posible diseminación del parásito. Resultados. La producción de anticuerpos IgG fue mayor en los ratones inmunocompetentes infectados que en los inmunosuprimidos infectados con E. intestinalis. No se encontró elparásito en órganos diferentes al intestino delgado en los dos grupos infectados. Sin embargo, la excreción de esporas, tanto en heces como en líquido duodenal, fue mayor en el grupo inmunosuprimido infectado. Conclusión. La CsA en el modelo en ratón no indujo la diseminación de E. intestinalis ni la exacerbación de la enfermedad, pero contribuyó al aumento en la cinética de excreción deesporas y la disminución de la producción de anticuerpos IgG en los ratones inmunosuprimidos infectados.