Metabolic effects of static magnetic fields on Streptococcus pyogenes.

School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales, Australia.
Bioelectromagnetics (Impact Factor: 2.02). 10/2007; 28(6):439-45. DOI: 10.1002/bem.20332
Source: PubMed

ABSTRACT This study aimed to develop a simple experimental system utilising bacterial cells to investigate the dose responses resulting from exposures to static magnetic flux densities ranging from 0.05 to 0.5 T on viability, bacterial metabolism and levels of DNA damage in Streptococcus pyogenes. Exposure of S. pyogenes to a field of 0.3 T at 24 degrees C under anaerobic conditions resulted in a significant (P < 0.05) decrease in growth rate, with an increased mean generation time of 199 +/- 6 min compared to the control cells at 165 +/- 6 min (P < 0.05). Conversely, exposure to magnetic fields of 0.5 T significantly accelerated the growth rate at 24 degrees C compared to control cells, with a decreased mean generation time of 147 +/- 4 min (P < 0.05). The patterns of metabolite release from cells incubated in phosphate buffered saline (PBS) at 24 degrees C and exposed to different magnetic flux densities (0.05-0.5 T) were significantly (P < 0.05) altered, compared to non-exposed controls. Concentrations of metabolites, with the exception of aspartic acid (r = 0.44), were not linearly correlated with magnetic flux density, with all other r < 0.20. Instead, "window" effects were observed, with 0.25-0.3 T eliciting the maximal release of the majority of metabolites, suggesting that magnetic fields of these strengths had significant impacts on metabolic homeostasis in S. pyogenes. The exposure of cells to 0.3 T was also found to significantly reduce the yield of 8-hydroxyguanine in extracted DNA compared to controls, suggesting some possible anti-oxidant protection to S. pyogenes at this field strength.

  • [Show abstract] [Hide abstract]
    ABSTRACT: The optimal approach to cytomegalovirus (CMV) prevention after lung transplantation is controversial. We recently completed a prospective, randomized, placebo-controlled study of CMV prevention in lung transplantation that demonstrated the short-term efficacy and safety of extending valganciclovir prophylaxis to 12 months vs 3 months of therapy. In the current analysis, we monitored a single-center subset of patients enrolled in the CMV prevention trial to determine if extended prophylaxis conferred a sustained long-term benefit and to assess its hematologic safety. The sub-analysis included 38 randomized patients from Duke University Medical Center. All patients underwent consistent serial serum CMV monitoring and surveillance bronchoscopies. CMV was defined by viremia (≥ 500 CMV DNA copies/ml) or pneumonitis. The safety assessment included a review of all complete blood counts obtained from transplant onward. During a mean follow-up of 3.9 years in each group, extended-course compared with short-course prophylaxis provided a sustained protective benefit with a lifetime CMV incidence of 12% vs 55%, respectively (hazard ratio, 0.13; 95% confidence interval, 0.03-0.61; p = 0.009), an effect that persisted after adjustment for clinical risk factors. Patients in each group underwent a comparable number of peripheral blood draws and bronchoscopies. Post-transplant white blood cell, neutrophil, and platelet counts were similar between each treatment group during the course of follow-up. Extending valganciclovir prophylaxis to 12 months provides a durable long-term CMV protective benefit compared with short-course therapy, without increasing adverse hematologic effects.
    The Journal of heart and lung transplantation: the official publication of the International Society for Heart Transplantation 04/2011; 30(9):990-6. · 3.54 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study is to investigate the effect of low-intensity static magnetic fields (SMFs) on invertase activity and growth on different newly identified molds. The most positive effect of SMFs on invertase activity and growth was observed for Aspergillus niger OZ-3. The submerged production of invertase was performed with the spores obtained at the different exposure times (120, 144, 168, and 196 hr) and magnetic field intensities (0.45, 3, 5, 7, and 9 mT). The normal magnetic field of the laboratory was assayed as 0.45 mT (control). Optimization of magnetic field intensity and exposure time significantly increased biomass production and invertase activity compared to 0.45 mT. The maximum invertase activity (51.14 U/mL) and biomass concentration (4.36 g/L) were achieved with the spores obtained at the 144 hr exposure time and 5 mT magnetic field intensity. The effect of low-intensity static magnetic fields (SMFs) on invertase activities of molds was investigated for the first time in the present study. As an additional contribution, a new hyper-invertase-producing mold strain was isolated. Supplemental materials are available for this article. Go to the publisher's online edition of Preparative Biochemistry and Biotechnology to view the supplemental file.
    Preparative Biochemistry &amp Biotechnology 01/2013; 43(2):177-88. · 0.41 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this study, the evidence of electron-dense magnetic inclusions with polyhedral shape in the cytoplasm of Harveyi clade Vibrio strain PS1, a bioluminescent bacterium living in symbiosis with marine organisms, led us to investigate the behavior of this bacterium under exposure to static magnetic fields ranging between 20 and 2000 Gauss. When compared to sham-exposed, the light emission of magnetic field-exposed bacteria growing on solid medium at 18°C ±0.1°C was increased up to two-fold as a function of dose and growth phase. Stimulation of bioluminescence by magnetic field was more pronounced during the post-exponential growth and stationary phase, and was lost when bacteria were grown in the presence of the iron chelator deferoxamine, which caused disassembly of the magnetic inclusions suggesting their involvement in magnetic response. As in luminescent Vibrio spp. bioluminescence is regulated by quorum sensing, possible effects of magnetic field exposure on quorum sensing were investigated. Measurement of mRNA levels by reverse transcriptase real time-PCR demonstrated that luxR regulatory gene and luxCDABE operon coding for luciferase and fatty acid reductase complex were significantly up-regulated in magnetic field-exposed bacteria. In contrast, genes coding for a type III secretion system, whose expression was negatively affected by LuxR, were down-regulated. Up-regulation of luxR paralleled with down-regulation of small RNAs that mediate destabilization of luxR mRNA in quorum sensing signaling pathways. The results of experiments with the well-studied Vibrio campbellii strain BB120 (originally classified as Vibrio harveyi) and derivative mutants unable to synthesize autoinducers suggest that the effects of magnetic fields on quorum sensing may be mediated by AI-2, the interspecies quorum sensing signal molecule.
    PLoS ONE 06/2014; 9(6):e100825. · 3.73 Impact Factor