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Browsing by Issue Date, starting with "2007-10"

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  • Implications of partial immunity on the prospects for tuberculosis control by post-exposure interventions
    Publication . Gomes, M. G. M.; Rodrigues, P.; Hilker, F. M.; Mantilla-Beniers, N. B.; Muehlen, M.; Paulo, A. C.; Medley, G. F.
    One-third of the world population (approximately 2 billion individuals) is currently infected with Mycobacterium tuberculosis, the vast majority harboring a latent infection. As the risk of reactivation is around 10% in a lifetime, it follows that 200 million of these will eventually develop active pulmonary disease. Only therapeutic or post-exposure interventions can tame this vast reservoir of infection. Treatment of latent infections can reduce the risk of reactivation, and there is accumulating evidence that combination with post-exposure vaccines can reduce the risk of reinfection. Here we develop mathematical models to explore the potential of these post-exposure interventions to control tuberculosis on a global scale. Intensive programs targeting recent infections appear generally effective, but the benefit is potentially greater in intermediate prevalence scenarios. Extending these strategies to longer-term persistent infections appears more beneficial where prevalence is low. Finally, we consider that susceptibility to reinfection is altered by therapy, and explore its epidemiological consequences. When we assume that therapy reduces susceptibility to subsequent reinfection, catastrophic dynamics are observed. Thus, a bipolar outcome is obtained, where either small or large reductions in prevalence levels result, depending on the rate of detection and treatment of latent infections. By contrast, increased susceptibility after therapy may induce an increase in disease prevalence and does not lead to catastrophic dynamics. These potential outcomes are silent unless a widespread intervention is implemented
    2007-10Journal article Open access Show more
  • Genetic subtraction profiling identifies genes essential for Arabidopsis reproduction and reveals interaction between the female ganetophyte and the maternal sporophyte
    Publication . Johnston, A.J.; Meier, P.; Gheyselinck, J.; Federer, M.; Wuest, A.E.J.; Schlagenhauf, E.; Becker, J.D.; Grossnikalus, U.
    The embryo sac contains the haploid maternal cell types necessary for double fertilization and subsequent seed development in plants. Large-scale identification of genes expressed in the embryo sac remains cumbersome because of its inherent microscopic and inaccessible nature. We used genetic subtraction and comparative profiling by microarray between the Arabidopsis thaliana wild-type and a sporophytic mutant lacking an embryo sac in order to identify embryo sac expressed genes in this model organism. The influences of the embryo sac on the surrounding sporophytic tissues were previously thought to be negligible or nonexistent; we investigated the extent of these interactions by transcriptome analysis.
    2007-10-03Journal article Open access Show more