42 research outputs found

    Selective Mycobacterium avium-induced production of nitric oxide by human monocyte-derived macrophages.

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    International audienceInfection with a virulent strain of Mycobacterium avium, but not with virulent Mycobacterium tuberculosis or avirulent Mycobacterium smegmatis, induced the formation of nitric oxide by human monocyte-derived macrophages. This process was not affected by lipopolysaccharide or cytokines such as interferon-gamma or tumor necrosis factor alpha. M. avium-induced nitric oxide production was significantly decreased by NG-monomethyl-L-arginine, a potent inhibitor of nitric oxide synthase activity, without any significant enhancement of intramacrophagic mycobacterial growth. Infection with all the three mycobacterial species induced a significant activation of phospholipase A2 activity of macrophages as evidenced by the increased release of thromboxane A2. Finally, nitric oxide production by human monocyte-derived macrophages required infection with live M. avium, as neither gamma-irradiated M. avium nor the subcellular fractions of this microorganism (cell wall, cytosol) were able to trigger nitric oxide synthesis

    Growth-behavior of human pancreatic-carcinoma xenograft correlates with nuclear features

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    Two human pancreatic ductal adenocarcinomas with different growth rates were serially transplanted into nude mice. Feulgen-stained 4-mu-m sections and imprints from the xenografts were studied with a VICOM automated image analysis system. After pooling the results from two passages, with three mice in each passage, it was shown that of 23 nuclear parameters measured the following were correlated with a fast tumor growth rate: in sections, a decrease in heterogeneity of the chromatin and an increase in perimeter and nuclear area; in imprints, an increase in lesser diameter, in mean grey level difference between second neighboring pixels, and in total integrated optical density (DNA content). Several parameters differed significantly between passages, and between animals in the same passage. These findings suggest that the growth speed of pancreatic tumors may be predicted by nuclear parameters
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