Perspective evaluation of the post-graduate courses of the Nursing Department at UFRN (1980-1992)

Superantigens have been used to study peripheral tolerance in CD4+ T cells. The superantigen SEB induces T cell anergy by promoting the differentiation of SEB-activated virgin T cells into anergic memory T cells. Memory T cells from SEB or antigen-primed mice do not proliferate when they are cultured with SEB. The present studies were performed to determine whether memory T cells fail to interact with SEB antigen-presenting cells or whether SEB promotes incomplete or negative signals in memory T cells. When murine virgin and memory T cells were separated on the basis of CD45RB expression and cultured with SEB-pulsed B cells, SEB induced the expression of CD25, which then mediated proliferation when IL-2 was added to the cultures. In addition, SEB promoted the expression of the CD40L, which is required for T helper cell function. Finally, PMA induced a costimulatory signal leading to the proliferation of these cells. Surprisingly, the agents, i.e., IL-2 and PMA, which induced TM cell proliferation in conjunction with SEB failed to induce lymphokine secretion. However, in the presence of IL-4 plus IL-5, the T memory cells induced the SEB-pulsed B cells to secrete IgM and IgG. These results suggest that memory T cells are not simply unresponsive to SEB but are actively anergized.     

Metabolic activation of 2-aminofluorene by isolated rat liver cells through different pathways leading to hepatocellular DNA-repair and bacterial mutagenesis

The aromatic amine 2-aminofluorene (2-AF) is metabolised by isolated rat liver cells to reactive species, thereby causing mutagenic effects in Salmonella typhimurium TA 1538 and evoking DNA-excision repair within the liver cells. The pathway leading to the production of metabolites mutagenic in Salmonella is likely to proceed via direct N-hydroxylation of 2-AF to N-hydroxy-2-aminofluorene (N-OH-2-AF). On the other hand, the formation of intermediates giving rise to hepatocellular DNA-repair is shown to depend upon N-acetylation of 2-AF to 2-acetylaminofluorene(2-AAF), whereas a subsequent conjugation reaction, most likely to be sulfate ester formation, is also essentially involved.     

Poly(glycolic acid) sutures in canine vascular anastomoses

Poly(glycolic acid) (Dexon; Davis and Geck Company) canine vascular anastomoses between aorta and synthetic grafts and between severed femoral vessels were compared with comparable anastomoses made with Teflon-coated Dacron (Tevdek; The Deknatel Company) with respect to clinical performance, morphologic characteristics, and tensile strength. While the Dexon anastomoses performed well and were morphologically superior to Tevdek, their tensile strength was significantly lower. Implications of these findings for vascular wound healing are discussed.