Mineralization and Preservation of an extremotolerant Bacterium Isolated from an Early Mars Analog Environment.

The artificial mineralization of a polyresistant bacterial strain isolated from an acidic, oligotrophic lake was carried out to better understand microbial (i) early mineralization and (ii) potential for further fossilisation. Mineralization was conducted in mineral matrixes commonly found on Mars and Early-Earth, silica and gypsum, for 6 months. Samples were analyzed using microbiological (survival rates), morphological (electron microscopy), biochemical (GC-MS, Microarray immunoassay, Rock-Eval) and spectroscopic (EDX, FTIR, RAMAN spectroscopy) methods. We also investigated the impact of physiological status on mineralization and long-term fossilisation by exposing cells or not to Mars-related stresses (desiccation and radiation). Bacterial populations remained viable after 6 months although the kinetics of mineralization and cell-mineral interactions depended on the nature of minerals. Detection of biosignatures strongly depended on analytical methods, successful with FTIR and EDX but not with RAMAN and immunoassays. Neither influence of stress exposure, nor qualitative and quantitative changes of detected molecules were observed as a function of mineralization time and matrix. Rock-Eval analysis suggests that potential for preservation on geological times may be possible only with moderate diagenetic and metamorphic conditions. The implications of our results for microfossil preservation in the geological record of Earth as well as on Mars are discussed.

[Modulation of the tumoral progression by anti-idiotypic antibodies of angiogenesis factors]. / Modulation de la progression tumorale par des anticorps anti-idiotypiques de facteurs angiogéniques.

We took advantage of the anti-idiotypic strategy to design circulating probes mimicking the biological effects of VEGF (vascular endothelial growth factor) or FGF2 (fibroblast growth factor 2). The activation of the VEGF receptor KDR/flk-1 induced endothelial cell proliferation but not their migration, whereas that of the FGF receptor FGF-R1 gave opposite results. The long lasting delivery of KDR/flk-1 agonists, but not that of FGF-R1, in nude mice grafted with tumor fragments enhanced the tumor volume. Microscopic examination showed an increase in both the vascularization and the proliferation of cancer cells. In contrast, no difference in cell proliferation was observed within normal tissues.

Deep infection of the hand with Mycobacterium avium-intracellulare: two case reports.

Two case reports of deep hand infections with Mycobacterium avium-intracellulare are presented. Both occurred in elderly men. Aggressive surgical débridement combined with antitubercular chemotherapy resulted in an excellent outcome in both cases. Atypical mycobacterial infections should be considered in the differential diagnosis of any patient with prolonged and progressive tenosynovitis. A complete history, including temporally remote inoculation injuries or immunocompromised host status, should be elicited. Acid-fast staining and mycobacterial cultures, including reduced-temperature cultures, must be included in the diagnostic evaluation. Therapy should include immediate and aggressive surgical débridement, as well as appropriate chemotherapy.