Longitudinal Attachment Research Articles

Behavior ofPseudomonas fluorescens within the hydrodynamic boundary layers of surface microenvironments

Phase, darkfield, and computer-enhanced microscopy were used to observe the surface microenvironment of flow cells during bacterial colonization. Microbial behavior was consistent with the assumptions used previously to derive surface colonization kinetics and to calculate surface growth and attachment rates from cell number and distribution. Surface microcolonies consisted of closely packed cells. Each colony contained 2(n) cells, where n is the number of cell divisions following attachment. Initially, cells were freely motile while attached, performing circular looping movements within the plane of the solid-liquid interface. Subsequently, cells attached apically, maintained a fixed position on the surface, and rotated. This type of attachment was reversible and did not necessarily lead to the formation of microcolonies. Cells became irreversibly attached by progressing from apical to longitudinal attachment. Longitudinally attached cells increased in length, then divided, separated, moved apart laterally, and slid next to one another. This resulted in tight cell packing and permitted simultaneous growth and adherence. After approximately 4 generations, individual cells emigrated from developing microcolonies to recolonize the surface at new locations. Surface colonization byPseudomonas fluorescens can thus be subdivided into the following sequential colonization phases: motile attachment phase, reversible attachment phase, irreversible attachment phase, growth phase, and recolonization phase.

Crevicular fluid prostaglandin E levels as a measure of the periodontal disease status of adult and juvenile periodontitis patients

The measurement of crevicular fluid PGE (CF‐PGE) as an indicator of periodontal disease status was investigated. The association between CF‐PGE levels and the PGE content of the adjacent periodontal tissues was found to be highly significant (P=5.3 × 10−6). The high correlation (r=0.925) between the log CF‐PGE level and the tissue PGE concentration indicates that CF levels can be used to reliably predict tissue levels. The CF‐PGE measurements at each periodontal site were found to be highly reproducible. Samples from adult and juvenile periodontitis patients demonstrated that the mean CF‐PGE levels were correlated with disease severity, as determined by mean attachment loss. The mean CF‐PGE level in juvenile periodontitis patients was almost three‐fold higher than that present in adult periodontitis (144.0 ± 28.0 ng/ml vs 57.5 ± 8.7 ng/ml, mean ± S.E., significant at P = 0.002). The use of CF‐PGE concentrations as an indicator of disease activity (i.e. longitudinal attachment loss) cannot be demonstrated by this cross‐sectional study. However, the CF‐PGE measurement has been demonstrated to be a non‐invasive, sensitive, reproducible, and reliable reflection of tissue levels of PGE2. The association of increasing levels of CF‐PGE with increased severity and aggressiveness of disease is consistent with PGE as an inflammatory mediator of tissue destruction.