Photodegradation of veterinary ionophore antibiotics under UV and solar irradiation.

The veterinary ionophore antibiotics (IPAs) are extensively used as coccidiostats and growth promoters and are released to the environment via land application of animal waste. Due to their propensity to be transported with runoff, IPAs likely end up in surface waters where they are subject to photodegradation. This study is among the first to investigate the photodegradation of three commonly used IPAs, monensin (MON), salinomycin (SAL) and narasin (NAR), under UV and solar irradiation. Results showed that MON was persistent in a deionized (DI) water matrix when exposed to UV and sunlight, whereas SAL and NAR could undergo direct photolysis with a high quantum yield. Water components including nitrate and dissolved organic matter had a great impact on the photodegradation of IPAs. A pseudosteady state kinetic model was successfully applied to predict IPAs' photodegradation rates in real water matrices. Applying LC/MS/MS, multiple photolytic transformation products of IPAs were observed and their structures were proposed. The direct photolysis of SAL and NAR occurred via cleavage on the ketone moiety and self-sensitized photolysis. With the presence of nitrate, MON was primarily degraded by hydroxyl radicals, whereas SAL showed reactivity toward both hydroxyl and nitrogen-dioxide radicals. Additionally, toxicity tests showed that photodegradation of SAL eliminated its antibiotic properties against Bacillus subtilis.

[Modulated extremely high frequency electromagnetic radiation of low intensity activates or inhibits respiratory burst in neutrophils depending on modulation frequency]. / Modulirovannoe élektromagnitnoe izluchenie kraine vysokikh chastot nizkoi intensivnosti aktiviruet ili ingibiruet respiratornyi vzryv v zavisimosti ot chastoty moduliatsii.

The influence of low-intensity modulated electromagnetic radiation of extremely high frequencies (EHF EMR) on synergistic reaction of calcium ionophore A23187 and phorbol ester PMA in activation of the respiratory burst of the peritoneal neutrophils of mice line NMRI was investigated. The production of reactive oxygen species by the neutrophils was estimated by luminol-dependent chemiluminescence technique. The cells were irradiated in the far field zone of the channel radiator for 20 min in the presence of A23187 and then were activated by PMA after switching off the irradiation. It was shown, that continuous EHF EMR (50 microW/cm2) inhibited quasi-resonantly the synergistic reaction. The maximum effect was about 25% at carrier frequency of 41.95 GHz. Modulated radiation with carrier frequency of 41.95 GHz and modulation frequency of 1 Hz activated the synergistic reaction, but at modulation frequencies of 0.1, 16 and 50 Hz inhibited one. At fixed modulation frequency of 1 Hz the nonlinear dependence of the effect on the carrier frequency was found. The synergistic reaction was activated in the frequency range of 41.95-42.05 GHz and was inhibited at the frequencies of 41.8-41.9 GHz. The effect was observed only at raised intracellular free calcium concentration and at calcium fluxes through plasma membrane. The obtained results prove the possibility of control over cell functioning by low-intensity modulated EHF EMR, presumably, manipulating by connected systems of enzyme reactions.