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Down syndrome (trisomy 21) is the most common cause of mental retardation in children and leads to marked deficits in contextual learning and memory. In rodents, these tasks require the hippocampus and are mediated by several inputs, particularly those originating in the locus coeruleus. These afferents mainly use norepinephrine as a transmitter. To explore(More)
Melanins are implicated in the pathogenesis of several human diseases, including some microbial infections. In this study, we analyzed whether the conidia and the yeasts of the thermally dimorphic fungal pathogen Paracoccidioides brasiliensis produce melanin or melanin-like compounds in vitro and during infection. Growth of P. brasiliensis mycelia on water(More)
Melanin synthesis is associated with virulence for the pathogenic fungus Cryptococcus neoformans. Exposure of nonmelanized C. neoformans 4067 cells to 4 M guanidinium isothiocyanate followed by 6 M HCl at 100 degrees C resulted in complete solubilization of cellular structures. However, exposure of melanized C. neoformans 24067 to the same conditions(More)
Black melanin-like pigments are produced by several neurotropic fungi, including Cryptococcus neoformans. Pigment production is associated with virulence. In media containing phenolic substrates such as L-dopa, C. neoformans cells become black as a result of pigment accumulation. Pigmented and nonpigmented C. neoformans cells were studied with transmission(More)
Neisseria are obligate human pathogens causing bacterial meningitis, septicaemia and gonorrhoea. Neisseria require iron for survival and can extract it directly from human transferrin for transport across the outer membrane. The transport system consists of TbpA, an integral outer membrane protein, and TbpB, a co-receptor attached to the cell surface; both(More)
The ability of Friend erythroleukemic cells to bind transferrin and take up its iron increases substantially as a result of dimethyl sulfoxide-stimulated differentiation. Although transferrin-binding activity is also demonstrable in another mouse cell line of hematopoietic origin, the lymphoma cell, it does not increase on exposure to dimethyl sulfoxide.(More)
Melanin has been implicated in the pathogenesis of several important human fungal pathogens. Existing data suggest that the conidia of the dimorphic fungal pathogen Sporothrix schenckii produce melanin or melanin-like compounds; in this study we aimed to confirm this suggestion and to demonstrate in vitro and in vivo production of melanin by yeast cells. S.(More)
A macromolecular complex of transferrin and a membrane component was isolated by gel filtration chromatography from Triton X-100-solubilized ghosts of reticulocytes previously incubated with 125I-labeled transferrin. This complex is believed to be transferrin specifically associated with its primary receptors. Following the procedures of Clark [14], the(More)
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