A model for preservation of thymocyte-depleted thymus

DiGeorge syndrome is a disorder caused by a microdeletion on the long arm of chromosome 22. Approximately 1% of patients diagnosed with DiGeorge syndrome may have an absence of a functional thymus, which characterizes the complete form of the syndrome. These patients require urgent treatment to reconstitute T cell immunity. Thymus transplantation is a promising investigational procedure for reconstitution of thymic function in infants with congenital athymia. Here, we demonstrate a possible optimization of the preparation of thymus slices for transplantation through prior depletion of thymocytes and leukocyte cell lineages followed by cryopreservation with cryoprotective media (5% dextran FP 40, 5% Me2SO, and 5% FBS) while preserving tissue architecture. Thymus fragments were stored in liquid nitrogen at -196°C for 30 days or one year. The tissue architecture of the fragments was preserved, including the distinction between medullary thymic epithelial cells (TECs), cortical TECs, and Hassall bodies. Moreover, depleted thymus fragments cryopreserved for one year were recolonized by intrathymic injections of 3×106 thymocytes per mL, demonstrating the capability of these fragments to support T cell development. Thus, this technique opens up the possibility of freezing and storing large volumes of thymus tissue for immediate transplantation into patients with DiGeorge syndrome or atypical (Omenn-like) phenotype.

Anurofauna of an Atlantic Rainforest fragment and its surroundings in Northern Rio de Janeiro State, Brazil

We carried out a study on the anurofaunal community from an Atlantic Forest fragment (Monte Verde mountains) and the surrounding area in Cambuci municipality, Rio de Janeiro State, Brazil, which constitutes one of the largest fragments remaining in the largely deforested landscape of the northern portion of the State. We combined three sampling methods: plot sampling, transects and pit-fall traps. We recorded twenty species of amphibians, of which only eleven were found within the forest fragment (and five of these also occurred in the surrounding matrix). Two of the species recorded in the present study (Crossodactylus sp. and Ischnocnema cf. parva) may represent undescribed taxa. Our records expand the distribution range of one species (Scinax trapicheiroi) to the north, and fill a geographic distribution gap for another one (Ischnocnema oea). The estimated overall density of frogs living in the leaf litter of the fragment (based on results of plot sampling) was 3.1 individuals/100 m², with Haddadus binotatus being the most abundant species (2.4 individuals/100 m²). Comparisons of our data with those of other studies suggest that anuran communities in forest fragments ca. 1,000 ha or smaller may be severely limited in their richness, and often include a large proportion of species tolerant to open areas, such as many hylids. Our results show the importance of increasing knowledge about the anurofaunal community of the northern portion of the State of Rio de Janeiro and preserve the forest remnants that still exist in the region.

Conduzimos um estudo de curta duração sobre a comunidade de anurofauna de um fragmento de Mata Atlântica (Serra do Monte Verde) localizado no município de Cambuci, Estado do Rio de Janeiro, Brasil, o qual constitui um dos maiores fragmentos remanescentes ainda existentes na paisagem amplamente desflorestada da porção norte do Estado. Utilizamos três métodos de amostragem combinados: parcelas, transectos e armadilhas de queda. Registramos vinte espécies de anfíbios, das quais apenas onze foram encontradas dentro do fragmento florestal (e dessas, cinco também ocorreram no seu entorno). Duas das espécies registradas no presente trabalho (Crossodactylus sp. e Ischnocnema cf. parva) podem representar táxons ainda não descritos. Nossos registros expandem a distribuição geográfica de uma espécie (Scinax trapicheiroi) para o norte e preenchem uma lacuna na distribuição de outra (Ischnocnema oea). A densidade total estimada de anfíbios anuros vivendo na camada de folhiço do fragmento (baseada nos resultados do método de plots) foi de 3,1 indivíduos/100 m², sendo Haddadus binotatus a espécie mais abundante (2,4 indivíduos/100 m²). Comparações de nossos dados com os de outros estudos sugerem que comunidades de anuros em fragmentos florestais com cerca de 1.000 ha ou menos podem ser severamente limitados em sua riqueza e frequentemente incluem uma grande proporção de espécies tolerantes a ambientes abertos, como é o caso de vários hilídeos. Nossos resultados demonstram a importância de ampliar o conhecimento sobre a anurofauna da região norte do Estado do Rio de Janeiro e de conservar os poucos remanescentes florestais ainda existentes na região.