Photodynamic Inactivation of Foodborne Bacteria: Screening of 32 Potential Photosensitizers.

The development of novel antimicrobial technologies for the food industry represents an important strategy to improve food safety. Antimicrobial photodynamic disinfection (aPDD) is a method that can inactivate microbes without the use of harsh chemicals. aPDD involves the administration of a non-toxic, light-sensitive substance, known as a photosensitizer, followed by exposure to visible light at a specific wavelength. The objective of this study was to screen the antimicrobial photodynamic efficacy of 32 food-safe pigments tested as candidate photosensitizers (PSs) against pathogenic and food-spoilage bacterial suspensions as well as biofilms grown on relevant food contact surfaces. This screening evaluated the minimum bactericidal concentration (MBC), minimum biofilm eradication concentration (MBEC), and colony forming unit (CFU) reduction against Salmonella enterica, methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas fragi, and Brochothrix thermosphacta. Based on multiple characteristics, including solubility and the ability to reduce the biofilms by at least 3 log10 CFU/sample, 4 out of the 32 PSs were selected for further optimization against S. enterica and MRSA, including sunset yellow, curcumin, riboflavin-5'-phosphate (R-5-P), and erythrosin B. Optimized factors included the PS concentration, irradiance, and time of light exposure. Finally, 0.1% w/v R-5-P, irradiated with a 445 nm LED at 55.5 J/cm2, yielded a "max kill" (upwards of 3 to 7 log10 CFU/sample) against S. enterica and MRSA biofilms grown on metallic food contact surfaces, proving its potential for industrial applications. Overall, the aPDD method shows substantial promise as an alternative to existing disinfection technologies used in the food processing industry.

Changing Arctic Ocean freshwater pathways.

Freshening in the Canada basin of the Arctic Ocean began in the 1990s and continued to at least the end of 2008. By then, the Arctic Ocean might have gained four times as much fresh water as comprised the Great Salinity Anomaly of the 1970s, raising the spectre of slowing global ocean circulation. Freshening has been attributed to increased sea ice melting and contributions from runoff, but a leading explanation has been a strengthening of the Beaufort High--a characteristic peak in sea level atmospheric pressure--which tends to accelerate an anticyclonic (clockwise) wind pattern causing convergence of fresh surface water. Limited observations have made this explanation difficult to verify, and observations of increasing freshwater content under a weakened Beaufort High suggest that other factors must be affecting freshwater content. Here we use observations to show that during a time of record reductions in ice extent from 2005 to 2008, the dominant freshwater content changes were an increase in the Canada basin balanced by a decrease in the Eurasian basin. Observations are drawn from satellite data (sea surface height and ocean-bottom pressure) and in situ data. The freshwater changes were due to a cyclonic (anticlockwise) shift in the ocean pathway of Eurasian runoff forced by strengthening of the west-to-east Northern Hemisphere atmospheric circulation characterized by an increased Arctic Oscillation index. Our results confirm that runoff is an important influence on the Arctic Ocean and establish that the spatial and temporal manifestations of the runoff pathways are modulated by the Arctic Oscillation, rather than the strength of the wind-driven Beaufort Gyre circulation.

Treatment of periodontal disease by photodisinfection compared to scaling and root planing.

OBJECTIVE: The aim of the present study was to compare the effectiveness of a photodisinfection process to that of scaling and root planing (SRP) for non-surgical periodontal treatment. METHODOLOGY: Thirty-three subjects with moderate to advanced periodontal disease were randomly treated in one of three study arms with either photodisinfection (PD) alone (Group 1) using a diode laser and photosensitizer combination, with SRP alone (Group 2), or with SRP and PD combined (Group 3). Clinical assessments of bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment level (CAL) were made at baseline, three weeks, six weeks, and 12 weeks following therapy. RESULTS: No difference in any of the investigated parameters was observed at baseline between the three groups. The mean value of BOP decreased in the PD group (Group 1) from baseline by 71% at six weeks and 73% at 12 weeks, and in the SRP alone group (Group 2) from baseline by 43% at six weeks and 56% at 12 weeks. The BOP in the combined SRP + PD group (Group 3) decreased from baseline by 65% at six and 59% at 12 weeks. The sites treated with PD alone demonstrated mean CAL gains of 0.09 +/- 0.38 mm and 0.14 +/- 0.65 mm at six and 12 weeks, respectively. Those sites treated with SRP alone demonstrated mean CAL gains of 0.37 +/- 0.34 mm and of 0.36 +/- 0.35 mm at six and 12 weeks, respectively. The final group of SRP + PD demonstrated mean CAL gains of 0.92 +/- 0.62 mm and 0.86 +/- 0.61 mm at six and 12 weeks, respectively (p < 0.01 for six weeks and p < 0.02 for 12 weeks when compared to SRP alone). The sites treated with PD alone demonstrated mean PPD reductions of 0.69 +/- 0.33 mm and of 0.67 +/- 0.44 mm at six and 12 weeks, respectively. Those sites treated with SRP alone demonstrated mean PPD reductions of 0.78 +/- 0.47 mm and 0.74 +/- 0.43 mm at six and 12 weeks, respectively. The final group of SRP + PD demonstrated mean PPD reductions of 1.16 +/- 0.39 mm and 1.11 +/- 0.53 at six and 12 weeks, respectively (p < 0.06 for six weeks and p < 0.05 for 12 weeks when compared to SRP alone). CONCLUSION: Within the limits of the present study, it can be concluded that SRP combined with photodisinfection leads to significant improvements of the investigated parameters over the use of SRP alone.

Long-term follow-up comparison of durasphere and contigen in the treatment of stress urinary incontinence.

OBJECTIVES.: This study evaluates the long-term clinical success of Durasphere (Carbon Metal Technologies, St. Paul, MN) compared with Contigen (C. R. Bard, Covington, GA) in the treatment of stress urinary incontinence caused by intrinsic sphincter deficiency (ISD). METHODS.: Fifty-two women diagnosed with stress urinary incontinence caused by ISD were treated between March and November of 1998 in a randomized, double-blinded trial comparing Durasphere and Contigen. Pad testing, Stamey Continence Grading, and urodynamics, including abdominal leak point pressures, were performed during the initial evaluation. All patients were diagnosed with ISD and displayed abdominal leak point pressures of /=1 continence grade at this follow-up. Of these patients, 10/25 (40%) Durasphere patients and 3/21 (14%) Contigen patients are dry. CONCLUSIONS.: Long-term follow-up demonstrated that Durasphere had greater success than Contigen in providing improved continence grades.