The inhibitory effects of oolong tea extract (OTE) on the caries–inducing properties of mutans streptococci were examined in vitro. OTE reduced the rate of acid production by mutans streptococci accompanied with the retardation of growth rate of mutans streptococci, while the action by chromatographically isolated oolong tea polyphenol (OTF6) was weak. On the other hand, both oolong tea products decreased cell surface hydrophobicity of almost all the oral streptococci examined in the present study, and also induced cellular aggregation of Streptococcus mutans, Streptococcus oralis, Streptococcus sanguis or Streptococcus gordonii. In these reactions, OTF6 showed a more pronounced activity than OTE. Furthermore, the oolong tea products inhibited the adherence of mutans streptococci to saliva–coated hydroxyapatite. These results suggest that OTF6 may inhibit bacterial adherence to the tooth surfaces by reducing the hydrophobicity of mutans streptococci, and OTE may inhibit caries–inducing activity of mutans streptococci by reducing the rate of acid production.
The latest heavy ion therapy tends to require information about the spatial distribution of the quality of radiation in a patient's body in order to make the best use of any potential advantage of swift heavy ions for the therapeutic treatment of a tumour. The deflection of incident particles is described well by Molière's multiple-scattering theory of primary particles; however, the deflection of projectile fragments is not yet thoroughly understood. This paper reports on our investigation of the spatial distribution of fragments produced from a therapeutic carbon beam through nuclear reactions in thick water. A DeltaE-E counter telescope system, composed of a plastic scintillator, a gas-flow proportional counter and a BGO scintillator, was rotated around a water target in order to measure the spatial distribution of the radiation quality. The results revealed that the observed deflection of fragment particles exceeded the multiple scattering effect estimated by Molière's theory. However, the difference can be sufficiently accounted for by considering one term involved in the multiple-scattering formula; this term corresponds to a lateral 'kick' at the point of production of the fragment. This kick is successfully explained as a transfer of the intra-nucleus Fermi momentum of a projectile to the fragment; the extent of the kick obeys the expectation derived from the Goldhaber model.
Cacao bean husk extract (CBH) has been shown to possess antibacterial and antiglucosyltransferase activities through its unsaturated fatty acids and epicatechin polymers, respectively. In the present study, the antiplaque activities of CBH were examined in vitro and in vivo. The extract inhibited the adherence of Streptococcus mutans MT8148 to saliva-coated hydroxyapatite and reduced the accumulation of artificial dental plaque by S. mutans MT8148 on orthodontic wire. The number of mutans streptococci in dental plaque was also significantly reduced when human dental plaque was exposed to CBH from 21 children at 37 degrees C for 1 h. For the in vivo study, 28 volunteers aged 19-29 yr old rinsed their mouth with CBH, before and after each intake of food and before sleeping at night for 4 d without using other oral hygiene procedures. Plaque depositions and the numbers of mutans streptococci were reduced in the subjects, compared with rinsing with 1% ethanol alone. These results indicate that CBH possesses significant antiplaque activity in vitro and in vivo.
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