RESUMEN
Human T cell leukemia virus type I (HTLV-I) has been linked to the development of an aggressive lymphoproliferative disorder (adult T cell leukemia), a chronic neurodegenerative presentation (HTLV-I-associated myelopathy/tropical spastic paraparesis) and numerous less well-defined inflammatory conditions. The viral regulatory protein Tax has been implicated in cellular transformation events leading to the onset of adult T cell leukemia. Details on the stepwise processes through which Tax induces morphological changes in cells are poorly understood. We show here that Tax can bind to a class of intermediate filaments, the cytokeratins (Ker). Tax interacts with the 1B helical coil of keratin 8, a domain critical for higher-order intermediate filament matrix formation. Expression of Tax in epithelial cells visibly altered the structural pattern of the Ker network. In a T lymphocyte cell line, induction of Tax expression resulted in increased cellular adherence/invasion of Matrigel filters. We propose that one aspect of Tax function is the induction of morphological changes in cellular cytoskeletal structures. This finding for Tax-expressing cells might be one factor contributing directly to the pathogenesis of HTLV-I disease(s). Copyright 1997 S. Karger AG, Basel
RESUMEN
The authors have been interested over the last year in the detection of pneumocystis carinii in patients with immune deficiencies, whether natural or artificial. After a brief historical and general introduction, they discuss their procedures, the pathological substances available, the staining techniques and the examination of autopsy specimens. They undertook experimental work on this micro-organism, e.g. the development of the germ in immuno-depressed rats and, from this material, numerous varied trials of culture and inoculation in new-born animals, chick embryos and cell cultures. Microphotographs illustrate this work which is still in progress.