Cold atmospheric plasma for surface disinfection: a promising weapon against deleterious meticillin-resistant Staphylococcus aureus biofilms.

BACKGROUND: Bacteria are becoming increasingly resistant to classical antimicrobial agents, so new approaches need to be explored. AIM: To assess the potential of cold atmospheric plasma for the management of meticillin-resistant Staphylococcus aureus (MRSA). METHODS: The 24, 48, and 72 h resistant and susceptible S. aureus biofilms were exposed to 60, 120, and 180 s treatment with plasma. FINDINGS: Increasing the treatment time results in higher cell reduction for both susceptible and resistant strains of S. aureus (P < 0.05). Up to log10 reduction factor of 5.24 cfu/cm2 can be achieved in 180 s of plasma treatment. Furthermore, plasma can substantially alter the cell's metabolisms and impact cell membrane integrity. However, it has not been shown that plasma can reduce biofilm biomass in the case of 24 h and 48 h biofilms, although the 72 h biofilm was more susceptible, and its biomass was decreased (P < 0.05). The accumulation of intrabacterial reactive oxygen species was also observed, which confirms the plasma's induction of oxidative stress. Finally, it was shown that continuous plasma exposure of bacterial cells does not cause resistance to plasma, nor is resistance developed to cefoxitin. CONCLUSION: Cold atmospheric plasma is a good candidate for S. aureus and MRSA biofilm treatment and may therefore be of value in the bacterial resistance crisis.

Plasma chemical and chemical functionalization of polystyrene colloidal crystals.

Self-assembling systems of colloidal spheres are widely used as templates for the structured deposition of metals and semiconductors. Multilayer samples of ordered polystyrene spheres are prepared by a flow induced process. The subsequent surface activation by a dielectric barrier discharge in oxygen is followed by the fabrication of protecting polysiloxane layers. Electrochemical deposition of copper is used to test the stability of the pre-treated colloidal crystal. The arrangement of the spheres is preserved during the deposition process, due to the polysiloxane layer. The results of the consecutive preparation steps are investigated concerning topographical and chemical changes by atomic force microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy.

Effects of an external nasal dilator strip (ENDS) compared to xylometazolin nasal spray.

Nasal blockage is a common complaint in Family Practice. Decongestive nosedrops are frequently employed therapeutic measures. Due to a considerable risk of abuse and side effects, alternatives are wanted. The purpose of this study was to elucidate to what extent ENDS might represent an alternative to decongestive nose sprays (DNS). The effects of DNS (xylometazolin) and ENDS (BreatheRight) on subjective and objective nasal blockage were compared in 89 patients. Main outcome measures were recordings of nasal symptom scores on visual analogue scales (VAS), minimal cross-sectional areas (MCA) and nasal cavity volumes (NCV) as measured by acoustic rhinometry (AR), and peak nasal inspiratory flow (PNIF). ENDS significantly increased the MCA and the NCV in the anterior 0.0-3.0 cm of the nose compared to DNS, but had no effect on MCA from 3.0 to 5.4 cm behind the nostrils. In contrast to DNS, ENDS had no effect on the posterior NCV. ENDS and DNS gave comparable increase in nasal inspiratory flow as measured by PNIF, and in the subject's own experience of nasal obstruction. ENDS may represent an alternative to DNS as a measure against nasal blockage.

Snow and ice concentrations of selected persistent pollutants in the Ob-Yenisey river watershed.

As one of the largest river systems attached to the Arctic Basin, the Ob-Yenisey watershed has the potential to be a major supply route of persistent organic pollutants into marine ecosystems of the Arctic Ocean. Snowfall and ice formation taking place in the Ob-Yenisey river basin and shelf are key components of the system of processes responsible for the transfer of pollutants from this high latitude river to the adjacent Kara and Barents Seas. Here we examine a large data set on persistent organic pollutants in snow and ice determined for areas within the Ob (interior and coastal), Yenisey and adjacent shelf. Data on the levels of total oil hydrocarbons, as well as individual components for groups (PAHs, HCHs, CBs, DDTs, PCBs) were examined in this investigation for two time periods: winter (1992)-spring (1993) and winter (1993)-spring (1994). Spatial averaging of each data set for individual years was performed in order to identify large-scale geographical trends in contaminant distributions within the four regions. The analysis indicates that mean pollutant concentrations in snow are consistent throughout the watershed. Comparing data from 1992/1993 and 1993/1994, in all cases, concentrations do not vary appreciatively among the different regions. A similar finding was observed for concentrations of pollutants in ice. Persistent organic pollutants for the Ob-Yenisey watershed are in most cases not dissimilar to measurements carried out in the far north of Canada. The exception is summation operator DDT. Concentrations of this pollutant are an order of magnitude higher in the Ob-Yenisey watershed as compared to the Canadian Arctic (0.09 ng/l).

Congener specific PCB and polychlorinated camphene (toxaphene) levels in Svalbard ringed seals (Phoca hispida) in relation to sex, age, condition and cytochrome P450 enzyme activity.

Congener specific PCB and toxaphene (polychlorinated camphene, PCC) analyses were performed in seal blubber, collected in Svalbard, Norway. The concentration, body burden and metabolic index (PCB congener concentration in seal relative to their prey) were calculated. Multiple regression analyses were carried out to evaluate the influence of age, sex, blubber (as a percentage of total body weight) and cytochrome P450 activities on PCB and PCC levels. Levels of total PCBs found were five times higher than in ringed seals from the Canadian Arctic, corresponding with the relatively high contaminant levels in the European Arctic. The dominant PCB congeners (> 70% of the total PCBs measured) were 153, 138, 99, 180 and 101. The observed PCB and PCC accumulation patterns were very similar to patterns in seals from other studies, suggesting a large resemblance in contaminant metabolism. A decrease in the relative abundance of the lower chlorinated PCBs, was associated with higher concentrations of PCB 153. Since there was no indication for selective PCB excretion by lactating females, this suggests metabolism of these PCBs in ringed seals due to xenobiotic metabolising enzymes. The metabolic index confirmed the model of persistency of the different PCBs except for congener 128 and 138. These congeners, considered persistent in seals, could to some extent be metabolised in ringed seals. However, co-elution of PCB 138 with PCB 163 and of PCB 128 with TOX 50 possibly has resulted in an underestimation of the metabolic index for these congeners. Multiple regression analyses revealed a significant positive effect of age and a negative effect of the blubber content on the PCB concentrations. Since large fluctuations of body lipids occur between seasons in pinnipeds, PCB measurements should account for the total blubber content to avoid biased results. PCBs with vicinal H-atoms in the o, m or the m, p positions showed in addition a relation with cytochrome P450 enzyme activities. Surprisingly, no effect of sex on the PCB concentrations was observed, probably because female ringed seals, unlike other pinnipeds, continue feeding during lactation. This results in only small amounts of lipid and lipid-associated contaminants being mobilised from the blubber. Consequently, contaminant excretion with the milk will be low. Toxaphene concentrations found were low compared to levels found in the Canadian Arctic. Two congeners, TOX 26 and TOX 50 were predominant (15 and 18%, respectively of total toxaphene). There was no effect of sex, age, total blubber, or cytochrome P450 activities on the toxaphene levels. There was also no correlation between toxaphene and PCB levels, which may indicate differences in exposure and metabolism between these contaminants. Toxaphenes did not bioaccumulate to any substantial extent in ringed seals.