16 research outputs found

    Short-time dynamic patterns of bioaerosol generation and displacement in an indoor environment

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    Short-time dynamics and distribution of airborne biological and total particles were assessed in a large university hallway by particle counting using laser particle counters and impaction air samplers. Particle numbers of four different size ranges were determined every 2 minutes over several hours. Bioaerosols (culturable bacteria and fungi determined as colony-forming units) were directly collected every 5 minutes on Petri dishes containing the corresponding growth medium. Results clearly show distinct shorttime dynamics of particulate aerosols, both of biological and non-biological origin. These reproducible periodic patterns are closely related to periods when lectures are held in lecture rooms and the intermissions in between where students are present in the hallway. Peaks of airborne culturable bacteria were observed with a periodicity of 1 hour. Bioaerosol concentrations follow synchronously the variation in total number of particles. These highly reproducible temporal dynamics have to be considered when monitoring indoor environments with respect to air quality

    Cyanobacterial lipopolysaccharides and human health – a review

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    Cyanobacterial lipopolysaccharide/s (LPS) are frequently cited in the cyanobacteria literature as toxins responsible for a variety of heath effects in humans, from skin rashes to gastrointestinal, respiratory and allergic reactions. The attribution of toxic properties to cyanobacterial LPS dates from the 1970s, when it was thought that lipid A, the toxic moiety of LPS, was structurally and functionally conserved across all Gram-negative bacteria. However, more recent research has shown that this is not the case, and lipid A structures are now known to be very different, expressing properties ranging from LPS agonists, through weak endotoxicity to LPS antagonists. Although cyanobacterial LPS is widely cited as a putative toxin, most of the small number of formal research reports describe cyanobacterial LPS as weakly toxic compared to LPS from the Enterobacteriaceae. We systematically reviewed the literature on cyanobacterial LPS, and also examined the much lager body of literature relating to heterotrophic bacterial LPS and the atypical lipid A structures of some photosynthetic bacteria. While the literature on the biological activity of heterotrophic bacterial LPS is overwhelmingly large and therefore difficult to review for the purposes of exclusion, we were unable to find a convincing body of evidence to suggest that heterotrophic bacterial LPS, in the absence of other virulence factors, is responsible for acute gastrointestinal, dermatological or allergic reactions via natural exposure routes in humans. There is a danger that initial speculation about cyanobacterial LPS may evolve into orthodoxy without basis in research findings. No cyanobacterial lipid A structures have been described and published to date, so a recommendation is made that cyanobacteriologists should not continue to attribute such a diverse range of clinical symptoms to cyanobacterial LPS without research confirmation
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