Pseudo-first-order reaction of chemically and biologically formed green rusts with HgII and C15H15N3O2: effects of pH and stabilizing agents (phosphate, silicate, polyacrylic acid, and bacterial cells).

The kinetics of Hg(II) and methyl red (MR) reduction by hydroxycarbonate green rust (GR1) and by hydroxysulfate green rust (GR2) were studied in the presence of naturally occurring organic and inorganic ligands (phosphate, polyacrylic acid, bacterial cells, silicate). The reducing ability of biogenic hydroxycarbonate green rust (GR1bio), obtained after microbial reduction of lepidocrocite by Shewanella putrefaciens, was also investigated and compared to those of chemically synthesized GR1 and GR2 (GR1ab and GR2ab). Pseudo first-order rate constants (kobs) of Hg(II) reduction (at pH 7.0, 8.2, and 9.5) and MR reduction (at pH 7.0) were determined and were normalized to the structural Fe(II) content of GRs (kFeII) and to the estimated concentration of surface Fe(II) sites (kS). The kS values ranged from 0.3 L mmol(-1) min(-1) to 43 L mmol(-1) min(-1) for the Hg reduction, and from 0.007 L mmol(-1) min(-1) to 3.4 L mmol(-1) min(-1) for the MR reduction. No significant discrepancy between GRab and GRbio was observed in term of reactivity. However, the reduction kinetics of MR was generally slower than the Hg(II) reduction kinetics for all tested GRs. While a slight difference in Hg(II) reduction rate was noted whatever the pH values (7.0, 8.2, or 9.5), the reduction of MR was significantly affected in the presence of ligands. A decrease by a factor of 2-200, depending on the type of ligand used, was observed. These data give new insights into the reactivity of GRs in the presence of co-occurring organic and inorganic ligands, and have major implications in the characterization of contaminated systems as well as water treatment processes.

[Need of risk reevaluation in morphine dependence in pain patients]. / Nécessité de réévaluation du risque de dépendance avec les analgésiques morphiniques chez le malade douloureux.

It is commonly recognized than opioids analgesics have an major place in the treatment of pain. In spite of guidelines, opioids drugs remain underutilized in chronic cancer pain and acute severe pain. Among the possible factors, involved in the insufficient use of opioids drugs, is the fear (opiophoby) of physicians, nurses, patients and family to induce or to maintain an addiction. This review examines the potential of iatrogenic addiction. We will examined the place of morphine-like drugs in the treatment of severe acute pain and chronic cancer pain, the definition of dependency in pain patients, the assessment of the dependency potential in patients treated for pain. Available studies indicate that iatrogenic addiction is quite scarce and that the risk for a major tolerance is very small. Further studies will be necessary, since opioids analgesics may also be useful in some non-cancer chronic pain.