Stress situations induce cyanide-resistant respiration in spoilage yeasts

AIMS: To investigate the conditions that promote the expression of cyanide-resistant respiration (CRR) in the spoilage yeasts Pichia membranifaciens and Debaryomyces hansenii. METHODS AND RESULTS: CRR was detected by sensitivity of oxygen consumption to salicylhydroxamic acid. It was absent in both yeasts in the early exponential phase, but was triggered by several stress situations. Starvation under aerobic conditions, decreasing pH or incubation of the culture in a narrow temperature range below the maximum temperature for growth promoted the emergence of CRR in both yeasts. In D. hansenii, CRR was also induced by 1.5-2 mol l(-1) NaCl. Although the presence of H2O2 and menadione induced CRR, radical scavengers had no effect on the emergence of CRR. Also, the level of reactive oxygen species did not vary with the CRR activity. CONCLUSIONS: Under aerobic conditions, a respiratory pathway alternative to the cytochrome chain is triggered by stress conditions in P. membranifaciens and D. hansenii. SIGNIFICANCE AND IMPACT OF THE STUDY: The relationship between stress situations and CRR must be taken into account in studies on the performance of spoilage yeasts in the food processing environments where several forms of stress are common.     

Neutralization of enteric coronaviruses with Escherichia coli cells expressing single-chain Fv-autotransporter fusions

We report here that fusions of single-chain antibodies (scFvs) to the autotransporter beta domain of the IgA protease of Neisseria gonorrhoeae are instrumental in locating virus-neutralizing activity on the cell surface of Escherichia coli. E. coli cells displaying scFvs against the transmissible gastroenteritis coronavirus on their surface blocked in vivo the access of the infectious agent to cultured epithelial cells. This result raises prospects for antiviral strategies aimed at hindering the entry into target cells by bacteria that naturally colonize the same intestinal niches.     

Cytokine-mediated inflammatory hyperalgesia limited by interleukin-13

The effect of interleukin-13 (IL-13) on hyperalgesic responses to intraplantar (i.pl.) injection of carrageenin, E. coli endotoxin (LPS), bradykinin, tumour necrosis factor a (TNF-alpha), interleukin-1 beta (IL-1 beta), interleukin-8 (IL-8) and prostaglandin E(2) (PGE(2)) was investigated in a model of mechanical hyperalgesia in rats. Also, the cellular source of the IL-13 was investigated. IL-13, administered 30 min before the stimulus, inhibited responses to carrageenin, LPS, bradykinin, and TNF-alpha, but not responses to IL-1 beta, IL-8 and PGE2. IL-13, administered 2 hours before the injection of IL-1b, did not affect the response to IL-1b, whereas IL-13, administered 12 hours or 12 + 2 hours before the IL-1 beta, inhibited the hyperalgesia (- 35%, - 77%, respectively). In murine peritoneal macrophages, IL-13 administered 2 hours before stimulation with LPS, inhibited the production of IL-1 beta (- 67%) and PGE(2) (- 56%). IL-13 administered 12 hours before stimulation with LPS inhibited LPS-stimulated PGE(2) but not IL-1 beta. An anti-IL-13 serum potentiated responses to carrageenin, LPS, bradykinin and TNF-alpha (but not IL-1 beta and IL-8), as well as responses to bradykinin in rats depleted of mast cells with compound 40/80, but not in athymic rats. These data suggest that IL-13, released by lymphocytes, limits inflammatory hyperalgesia by the inhibition of the production TNF-alpha, IL-1 beta, IL-8 and PGs.     

The Role of <Emphasis Type="SmallCaps">l</Emphasis>-arginine in Inclusion Complexes of Omeprazole with Cyclodextrins

In this study, we investigate how the effect of l-arginine (ARG) and cyclodextrins upon omeprazole (OME) stability and solubility. The effect of the presence of ARG on the apparent stability constants (K_1:1) of the inclusion complexes formed between OME and each cyclodextrin, β-cyclodextrin (βCD), and methyl-β-cyclodextrin (MβCD) is studied by phase solubility diagrams and nuclear magnetic resonance (NMR) spectroscopy. The interaction of OME with those cyclodextrins, in the presence of ARG, is characterized using NMR spectroscopy and molecular dynamics simulations. ARG significantly increases the drug solubility and complex stability, in comparison to inclusion complexes formed in its absence. The effect is more pronounced for the OME:βCD complex. ARG also contributes to a larger stability of OME when free in aqueous solution. The combination of ARG with cyclodextrins can represent an important tool to develop stable drug formulations.     

Exposure of human leukemic cells to direct electric current

Treatment with direct electric current (DC) influences the growth of several cancer cells. In this work, we evaluated the effects of DC treatment on the human leukemic cell line HL60. Human cells were separately treated in the presence of the cathode or the anode or without contact with the electrodes. In all systems, DC-treated cells presented an impaired ability to proliferate. Growth inhibition was dependent on the generation of soluble products of electrolysis. Cathodic treatment of HL60 cells predominantly induced lysis, whereas treatment without contact with electrodes did not induce alterations in cell viability. In contrast, cell stimulation by the anode resulted in irreversible membrane damage, as demonstrated by trypan blue and 7-aminoactinomycin staining. Analysis of these cells by transmission electron microscopy indicated that necrosis is a major mechanism inducing cell death. In addition, apoptotic-like cells were observed under light microscopy after anodic treatment. Accordingly, DNA from anodic-treated cells presented a typical pattern of apoptosis. Apoptotic cell death was only generated after the treatment of HL60 cells in conditions in which the generation of chloride-derived compounds was favored. These results indicate that the nature of the products from cathodic or anodic reactions differently influences the mechanisms of cell death induced by DC-derived toxic compounds.