Genotoxic effects of X-rays on keratinized mucosa cells during panoramic dental radiography.

OBJECTIVES: The aim of this study was to evaluate the genotoxic effects of X-rays on epithelial gingival cells during panoramic dental radiography using a differentiated protocol for the micronucleus test. METHODS: 40 healthy individuals who underwent this procedure for diagnostic purposes on request from their dentists agreed to participate in this study. All of them answered a questionnaire before the examination. Epithelial gingival cells were obtained from the keratinized mucosa of the upper dental arcade by gentle scraping with a cervical brush immediately before exposure and 10 days later. Cytological preparations were stained according to the Feulgen-Rossenbeck reaction, counterstained with fast green 1% for 1 min and analysed under a light microscope. Micronuclei, nuclear projections (broken eggs) and degenerative nuclear alterations (pyknosis, karyolysis, karyorrhexis and condensed chromatin) were scored. RESULTS: The frequency of micronuclei was significantly higher after exposure (P < 0.05), as were the frequencies of nuclear alterations indicative of apoptosis (P < 0.001). CONCLUSIONS: These results indicate that X-ray radiation emitted during panoramic dental radiography induces a genotoxic effect on epithelial gingival cells that increases the frequency of chromosomal damage and nuclear alterations indicative of apoptosis.

Acute effects of inhalable particles on the frog palate mucociliary epithelium.

This work was designed to evaluate the toxicity of inhalable particles [less than/equal to] 10 microm in aerodynamic diameter (PM(10)) collected from the urban air in São Paulo, Brazil, to the mucociliary apparatus using the frog palate preparation. Seven groups of frog palates were immersed in different concentrations of PM(10) diluted in Ringer's solution during 120 min: 0 (control, n = 31); 50 (n = 10); 100 (n = 9); 500 (n = 28); 1,000 (n = 10); 5,000 (n = 11); and 10,000 microg/m(3) (n = 10). Mucociliary transport and transepithelial potential difference were determined at 0, 30, 60, and 120 min exposure. Additional groups (control and 500 microg/m(3)) were studied by means of morphometric analyses (quantification of the amount of intraepithelial and surface mucins), measurement of cilia beat frequency, and quantification of total glutathione. Mucociliary transport and transepithelial potential difference were significantly decreased at higher concentrations of PM(10) (p = 0.03 and p = 0.02, respectively). Exposure to PM(10) also elicited a significant decrease of total glutathione (p = 0. 003) and depletion of neutral intraepithelial mucins (p = 0.0461). These results show that PM(10) can promote significant alterations in ciliated epithelium in vitro.

Alicyclobacillus in orange juice: occurrence and heat resistance of spores.

Spore suspensions of a pure culture of Alicyclobacillus acidoterrestris DSM 2498 were submitted to different heat treatments (60 degrees C for 60 min, 60 degrees C for 30 min, 70 degrees C for 20 min, 80 degrees C for 5 min, 80 degrees C for 10 min, 80 degrees C for 30 min, and boiling for 5 min) to determine the best activation conditions in orange juice. The best treatment for spore activation was shown to be 70 degrees C/20 min. Seventy-five samples of concentrated orange juice from 11 different suppliers were examined for the presence of thermophilic acid-tolerant spore formers by the most probable number technique using Bacillus acidocaldarius medium (BAM broth) and incubation at 44 degrees C for 5 days after a prior spore activation. After incubation, isolation was carried out using BAM agar medium incubating at 44 degrees C for 5 days. Typical colonies were submitted to a microscopic examination, evaluation for the presence of spores, and various biochemical tests. Of the orange juice samples examined, 14.7% were found to be positive for Alicyclobacillus. The thermal death time open tube method was used to determine the heat resistance of the spores of strains confirmed as being Alicyclobacillus. The D-values determined were in the range from 60.8 to 94.5 min at 85 degrees C, 10.0 to 20.6 min at 90 degrees C, and 2.5 to 8.7 min at 95 degrees C. The z-values were between 7.2 degrees C and 11.3 degrees C. The results demonstrated the occurrence of Alicyclobacillus in orange juice and the high heat resistance of the spores that could survive the heat treatments normally applied in the processing of orange juice.