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    ABSTRACT: Control of dental plaque-related diseases has traditionally relied on non-specific removal of plaque by mechanical means. As our knowledge of oral disease mechanisms increases, future treatment is likely to be more targeted, for example at small groups of organisms, single species or at key virulence factors they produce. The aim of this review is to consider the current status as regards novel treatment approaches. Maintenance of oral hygiene often includes use of chemical agents; however, increasing problems of resistance to synthetic antimicrobials have encouraged the search for alternative natural products. Plants are the source of more than 25% of prescription and over-the-counter preparations, and the potential of natural agents for oral prophylaxis will therefore be considered. Targeted approaches may be directed at the black-pigmented anaerobes associated with periodontitis. Such pigments provide an opportunity for targeted phototherapy with high-intensity monochromatic light. Studies to date have demonstrated selective killing of Porphyromonas gingivalis and Prevotella intermedia in biofilms. Functional inhibition approaches, including the use of protease inhibitors, are also being explored to control periodontitis. Replacement therapy by which a resident pathogen is replaced with a non-pathogenic bacteriocin-producing variant is currently under development with respect to Streptococcus mutans and dental caries.
    No preview · Article · Oct 2008 · International Journal of Antimicrobial Agents
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    ABSTRACT: In a CO2-limited algal culture, grown in a tubular loop photobioreactor, the maximum rate of CO2 absorption increased about 1.5-fold when the culture pH value was increased from 6.5 to 7.5 with a fixed initial PCO2. The mean volumetric CO2 transfer coefficient (KLa) increased about 1.8-fold. The bicarbonate ion concentration would be increased 10-fold by the pH increase. The effect of pH on the absorption rate is attributed to changes in either the CO2 diffusivity, the gas bubble size, or the CO2 reaction kinetics at the gas/liquid boundary.
    No preview · Article · Mar 2008
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    ABSTRACT: Satisfactory growth of Bacillus macerans and high activities of cyclodextrin glycosyltransferase (CGT) were obtained in media containing potato extract. The appearance of CGT in culture supernatant fluids during the stationary phase of growth was not due to autolysis, since intracellular levels of the enzyme were very low throughout the cultivation. When cell growth was limited by the starch concentration in the medium, CGT activity remained low during the logarithmic phase of growth but high activities appeared suddenly in the supernatant fluid when growth ceased. Negligible activities were produced by cultures growing in a nitrogen-deficient medium in which starch was present in excess. CGT therefore appears to be a true extracellular enzyme, produced in response to exhaustion of the starch from the medium. A simple fractionaltion procedure was developed for concentrating the CGT from culture supernatant fluids. This enzyme preparation was used to convert 20% (w/v) starch solutions to cyclodextrins in 24 h and the cyclodextrins recovered were equivalent to 55% of the original starch.
    No preview · Article · Nov 2007 · Journal of Applied Chemistry and Biotechnology
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