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In this study, we examined the invasive capacity of Staphylococcus aureus and Salmonella typhi in human keratinocytes and monitored the number of viable intracellular bacteria at different post-infection times. The strains tested entered keratinocytes; both S. typhi and S. aureus were internalized within 30 min to 2 h after infection. No intracellular multiplication was observed, but S. typhi and S. aureus remained viable 72 h after infection. We also demonstrated that keratinocyte death following S. typhi and S. aureus invasion occurs by apoptosis as shown by DNA fragmentation. After 24 h of infection with S. typhi, the number of cells undergoing apoptosis were higher compared to infection with S. aureus. For prolonged infection times (48 h, 72 h) with both bacteria, there was no significant change in the number of cells undergoing apoptosis. The results demonstrated that viable intracellular S. typhi and S. aureus induced apoptosis in keratinocyte cells.

A new antiplaque agent was tested on nine subjects. The antiplaque agent, a 5% aqueous solution (p/v) of sodium polystyrene sulfonate, applied on the tooth surfaces by daily topical application for two weeks, caused a statistically significant 30% reduction of plaque index (PI), with corresponding reduction of total bacteria and qualitative modifications of plaque formation with reduction of Gram-negative bacteria.

In this study we provide evidence that structural and soluble components of periodontopathogenic bacteria, such as Prevotella melaninogenica and Fusobacterium nucleatum, induce the release of cytokines in vitro known to cause in vivo necrotic inflammatory phenomena and bone resorption (tumor necrosis factor-alpha, interleukin-1 alpha and interleukin-6). Human monocytes and gingival fibroblasts were cultivated in vitro in the presence of both particulate and soluble bacterial fractions. A dose-dependent production of tumor necrosis factor-alpha by monocytes and gingival fibroblasts was observed in the presence of fractions of P. melaninogenica and F. nucleatum. Interleukin-1 alpha was produced in approximately the same quantities in the presence of soluble fractions of either P. melaninogenica or F. nucleatum, but in greater quantities in response to particulate fractions of P. melaninogenica. Monocytes released larger amounts of interleukin-1 alpha (about 3000 pg/ml) than gingival fibroblasts (about 1500 pg/ml). Interleukin-6 was released in greater quantities by monocytes in the presence of the pellet fraction of P. melaninogenica (about 5.5 ng/ml), but gingival fibroblasts released larger amounts of interleukin-6, especially in the presence of particulate and soluble components of F. nucleatum (about 12 ng/ml). The ability to induce the release of these cytokines notably increases the pathogenic potential of the bacteria involved in the damage of periodontal tissue.

Our study was focused on the functional characteristics of neutrophil leukocytes (PMN) and the subgingival microflora in two different forms of periodontal disease: 1) adult periodontitis (AP); 2) rapidly progressive periodontitis (RPP). Our study dealt with the functional characteristics of neutrophil leukocytes in the gingival fluid and in the peripheral blood. These were found markedly reduced in the RPP group, while, in the AP group, they were comparable to those of a healthy control group. No difference between local and systemic values was detected. Moreover, some samples of subgingival plaque were taken from two groups of patients, affected by AP and RPP respectively. The above samples showed a predominance of Gram-negative flora over Gram-positive flora, and of anaerobic flora over the aerobic one, and the predominance of specific pathogens in each of the two forms of periodontal disease. The subgingival plaque samples taken at the end of the periodontal treatment from five out of ten patients affected by RPP showed inverse ratios, as well as the absence of the previously detected pathogens. The findings underline the relevance of tests of leukocytes functionality and that of microbiological analysis to allow correct diagnosis of dubious forms of periodontal disease and the checking of the posttreatment results.

The Authors studies effects of chlorexidine gel 1% on subgingival microbial flora in a group of periodontal patients. Microbial findings appear to demonstrate some activity of chlorexidine gel 1%.

Some antiviral properties of amniotic fluid (AF) were studied. A close relationship between maternal blood and AF antiviral antibodies was seen. Substances other than antibodies which could have an effect on viruses were assumed to be present in AF. Using HSV2 as a model, we found a virus-neutralizing activity in 6 out of 7 specimens studied which does not appear to be related to antibodies.