ABSTRACT
Egg is a regularly consumed food item. Currently, chlorinated water washing is the most common practice used to disinfect eggs, but this process has a negative environmental impact. A new physical technique, plasma-activated water (PAW), has been demonstrated to possess effective antibacterial activities without long-term chemical residue. In this study, air PAW was used to inactivate Salmonella enterica serovar Enteritidis on shell eggs. Different combinations of activation parameters, including water sources (reverse osmotic (RO) water, tap water), power (40 W, 50 W, 60 W) and activation time (10 min, 20 min, 30 min), were evaluated. The oxidation-reduction potential (ORP) and pH values of each combination were measured, and their antibacterial activity was tested in a bacterial suspension. Higher antibacterial activities, higher ORP values, and lower pH values were obtained with higher power, longer activation time, and lower water hardness. The antibacterial activities of PAW decreased rapidly by increasing the storage time both at room and refrigeration temperatures. Afterwards, RO water was pre-activated for 20 min at 60 W, and then the eggs inoculated with S. enteritidis were placed into PAW for 30 s, 60 s, 90 s, or 120 s with a plasma on-site treatment in the water. More than a 4 log reduction was obtained with 60-s and 120-s treatments. The results showed that the freshness indexes of the eggs treated with PAW were similar to those of the untreated controls and better than those of the eggs treated with commercial processes. In addition, observation under a scanning electron microscope also showed less surface damage of the cuticle on the PAW-treated eggs than on the commercially treated eggs. The results of this study indicate that PAW could be an effective antibacterial agent with less damage to the freshness of shell eggs than commercial methods.
ABSTRACT
Background: Pulsed radiofrequency (PRF) treatment offers pain relief for patients suffering from chronic pain who do not respond well to conventional treatments. We tested whether PRF treatment attenuated complete Freund's adjuvant (CFA)-induced inflammatory pain. Epigenetic modification of potassium-chloride cotransporter 2 (KCC2) gene expression was examined to elucidate the potential contributing mechanism. Methods: Male Sprague-Dawley rats were injected with CFA into the plantar surface of the left hind paw to induce inflammation. PRF (20 minutes of 500-kHz RF pulses, delivered at a rate of 2 Hz, maximum temperature 42ºC) was delivered to the L5 and L6 anterior primary ramus just distal to the intervertebral foramen of adult CFA or saline rats. The hind paw withdrawal threshold to von Frey filament stimuli and withdrawal latency to radiant heat were determined before and after CFA. Acetyl-histone H3 and H4 was determined by chromatin immunoprecipitation in spinal dorsal horn. KCC2 expression was determined by Western blot. Inhibitory synaptic function was evaluated by patch clamp in lamina II neurons. Results: KCC2 gene expression was suppressed through histone hypoacetylation, resulting in decreased efficacy of GABAergic signaling in CFA rats. PRF increased histone acetylation and KCC2 expression, partially restored the GABA synaptic function, and relieved sensitized pain behavior. Conclusion: These findings suggest that PRF might be an alternative therapy for inflammatory pain. One of the underlying mechanisms is through modification of KCC2, which is an important determinant for the efficacy of inhibitory neurotransmission in the spinal cord, and its expression levels are regulated by histone acetylation epigenetically following inflammation.