@article{ProttengeierKoutsilieriScheller2014,
  author    = {Prottengeier, Johannes and Koutsilieri, Eleni and Scheller, Carsten},
  title     = {The effects of opioids on HIV reactivation in latently-infected T-lymphoblasts},
  series = {AIDS Research and Therapy},
  volume    = {11},
  journal   = {AIDS Research and Therapy},
  number    = {17},
  issn      = {1742-6405},
  doi       = {10.1186/1742-6405-11-17},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-115860},
  year      = {2014},
  abstract  = {Background: Opioids may have effects on susceptibility to HIV-infection, viral replication and disease progression. Injecting drug users (IDU), as well as anyone receiving opioids for anesthesia and analgesia may suffer the clinical consequences of such interactions. There is conflicting data between in vitro experiments showing an enhancing effect of opioids on HIV replication and clinical data, mostly showing no such effect. For clarification we studied the effects of the opioids heroin and morphine on HIV replication in cultured CD4-positive T cells at several concentrations and we related the observed effects with the relevant reached plasma concentrations found in IDUs. Methods: Latently-infected ACH-2 T lymphoblasts were incubated with different concentrations of morphine and heroine. Reactivation of HIV was assessed by intracellular staining of viral Gag p24 protein and subsequent flow cytometric quantification of p24-positive cells. The influence of the opioid antagonist naloxone and the antioxidants N-acetyl-cysteine (NAC) and glutathione (GSH) on HIV reactivation was determined. Cell viability was investigated by 7-AAD staining and flow cytometric quantification. Results: Morphine and heroine triggered reactivation of HIV replication in ACH-2 cells in a dose-dependent manner at concentrations above 1 mM (EC50 morphine 2.82 mM; EC50 morphine 1.96 mM). Naloxone did not interfere with heroine-mediated HIV reactivation, even at high concentrations (1 mM). Opioids also triggered necrotic cell death at similar concentrations at which HIV reactivation was observed. Both opioid-mediated reactivation of HIV and opioid-triggered cell death could be inhibited by the antioxidants GSH and NAC. Conclusions: Opioids reactivate HIV in vitro but at concentrations that are far above the plasma levels of analgesic regimes or drug concentrations found in IDUs. HIV reactivation was mediated by effects unrelated to opioid-receptor activation and was tightly linked to the cytotoxic activity of the substances at millimolar concentrations, suggesting that opioid-mediated reactivation of HIV was due to accompanying effects of cellular necrosis such as activation of reactive oxygen species and NF-kB.},
  language  = {en}
}
@article{BuedelVivasLange2013,
  author    = {B{\"u}del, Burkhard and Vivas, Mercedes and Lange, Otto L.},
  title     = {Lichen species dominance and the resulting photosynthetic behavior of sonoran desert soil crust types (Baja California, Mexico)},
  series = {Ecological Processes},
  volume    = {2},
  journal   = {Ecological Processes},
  number    = {6},
  doi       = {http://dx.doi.org/10.1186/2192-1709-2-6},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-131878},
  year      = {2013},
  abstract  = {Introduction: Lichen dominated biological soil crusts (BSCs) occur over large areas in the Sonoran Desert of the southwestern USA and northwest Mexico. In Baja California BSCs show a distinct patchiness and several types can be distinguished. Two chlorolichen- and two cyanolichen-dominated BSCs were selected. We hypothesize that patchiness and the resulting domination of certain functional lichen groups will result in patchiness of photosynthetic CO2-uptake related to environmental factors as well. Methods: Four different soil crust samples were placed in cuvettes and their CO2 exchange was recorded in an open system with an infrared gas analyzer. Air blown over the BSCs had a controlled CO2 content of 350 ppm. Four cuvettes were operated in parallel. Photosynthetic CO2 exchange was continually recorded throughout the experiment. Results: Besides the dominating chlorolichens Psora decipiens and Placidium squamulosum and the cyanolichens Peltula patellata and P. richardsii, several other lichen species and 12 cyanobacterial species were found in the biological soil crusts sampled. The chlorolichen BSCs already gained positive net photosynthesis with high air humidity alone, while the cyanolichen types did not, but showed smaller CO2-uptake depression after water suprasaturation. Such specific net photosynthesis responses to mode of hydration and to crust water content seem to correlate with precipitation characteristics of their habitat. Conclusions: Species specific photosynthetic performance related to activation of respiration and net photosynthesis as well as to crust water content help to explain niche occupation and species composition of BSCs. Different functional types have to be considered when they have a patchy distribution.},
  language  = {en}
}