Hydrogen sulfide caused apoptosis and DNA damage in human gingival fibroblasts. An increased level of reactive oxygen species stimulated by hydrogen sulfide may induce apoptosis and DNA strand breaks.

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The purpose of this study was to determine the usefulness of salivary biochemical markers for the screening of periodontal disease and examine the agreement between the results of saliva enzyme tests and those of probing depth. The present study included a total of 187 subjects who underwent annual medical check-ups at the Comprehensive Health Care Center, Honjo, Saitama Prefecture, Japan. Periodontal pocket probing was performed with a WHO probe, and various enzymes and biochemical parameters in saliva were measured. For lactate dehydrogenase (LDH), the proportions of the five isoenzymes were calculated. To decide the cut-off point for each enzymatic activity, receiver operating characteristic curves (ROC curves) were constructed and the points of minimum difference between sensitivity and specificity were decided. Among the biochemical markers tested, salivary LDH level had the highest sensitivity and specificity (sensitivity 0.66, specificity 0.67), while salivary levels of aspartate aminotransferase (AST) and blood urea nitrogen (BUN) also had sensitivity and specificity above 0.60. Among the LDH isoenzymes, LDH4 and LDH5 dominated in whole saliva samples. Salivary LDH may be a feasible and useful parameter for the screening of periodontal disease, while salivary AST and BUN also appear to be potentially useful for this purpose. (J. Oral Sci. 48, [177][178][179][180][181][182][183] 2006)

Here, we report a real-time THz near-field microscope with a high dynamic range that can capture images of a 370 x 740 µm 2 area at 35 frames per second. We achieve high spatial resolution on a large area by combining two novel techniques: THz pulse generation by tilted-pulse-front excitation 7 and electrooptic (EO) balanced imaging detection using a thin crystal. To demonstrate the microscope capability, we reveal the field enhancement at the gap position of a dipole antenna after the irradiation of a THz pulse.Our results are the first demonstration of a direct quantification of a 2-dimensional subwavelength THz electric field taken in real-time.The very first demonstration of THz imaging 8 clarified that microscopic resolution is required for applications ranging from semiconductors inspections 9 to biomedical imaging 3,4 . For a corresponding wavelength at 1 THz, however, the far-field spatial resolution of an image is restricted to the Rayleigh criterion that corresponds to ∼180 µm in vacuum. To overcome this limit, we must work in the near-field region of a sample. In this case, the THz wave has to be captured very close to the sample surface in a region before light diffraction occurs 10 . Many schemes have been proposed since the first demonstration of THz near-field imaging 11 , most of which involve a subwavelength probe or a aperture placed very near the sample 9,11-17 .

Summary Many food products are claimed to be effective in controlling halitosis. Halitosis is caused mainly by volatile sulfur compounds (VSCs) such as H 2 S and CH 3 SH produced in the oral cavity. Oral microorganisms degrade proteinaceous substrates to cysteine and methionine, which are then converted to VSCs. Most treatments for halitosis focus on controlling the number of microorganisms in the oral cavity. Since tea polyphenols have been shown to have antimicrobial and deodorant effects, we have investigated whether green tea powder reduces VSCs in mouth air, and compared its effectiveness with that of other foods which are claimed to control halitosis. Immediately after administrating the products, green tea showed the largest reduction in concentration of both H 2 S and CH 3 SH gases, especially CH 3 SH which also demonstrated a better correlation with odor strength than H 2 S; however, no reduction was observed at 1, 2 and 3 h after administration. Chewing gum, mints and parsley-seed oil product did not reduce the concentration of VSCs in mouth air at any time. Toothpaste, mints and green tea strongly inhibited VSCs production in a saliva-putrefaction system, but chewing gum and parsley-seed oil product could not inhibit saliva putrefaction. Toothpaste and green tea also demonstrated strong deodorant activities in vitro, but no significant deodorant activity of mints, chewing gum or parsley-seed oil product were observed. We concluded that green tea was very effective in reducing oral malodor temporarily because of its disinfectant and deodorant activities, whereas other foods were not effective.