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The binding of the chemotactic complement fragment, C5a, to peripheral blood neutrophils of Localized Juvenile Periodontitis (LJP) patients and normal controls was quantitated using iodinated human C5a and a rapid centrifugation assay. There was a significant reduction in the number of binding sites per cell on neutrophils from the patient group, whereas the binding affinity remained the same as control values. [ABSTRACT FROM AUTHOR]

Porphyromonas gingivalis (P. gingivalis) is an important pathogenic bacterium in periodontal Fimbriae have been proposed as important in the adherence of P. gingivalis to a variety of such surfaces as buccal epithelial cells, experimental pellicles and other oral bacteria. However, no strong direct evidence has supported the role of fimbriae in P. gingivalis is adherence. The article presents a study that shows direct evidence that binding of P. gingivalis to saliva-coated hydroxyapatite beads is mediated by fimbriae via specific interactions between salivary components adsorbed to hydroxyapatite and fimbrillin the monomeric structural subunit of fimbria.

Numerous investigations in the past five years have provided considerable support for the concept that the neutrophil plays an important protective role in the pathogenesis of periodontal disease. The importance of the neutrophil in the pathogenesis of this disease provides an excellent model to elucidate the molecular basis of neutrophil dysfunction. Neutrophil dysfunction may be considered to be of two basic causes either exogenous inhibitors in the extracellular environment block normal leukocyte function, or the neutrophil itself is intrinsically defective.

The article presents a study which examined whether a subgingival microflora associated with periodontal disease dominated by Gram-negative anaerobic organisms could be changed to a microflora dominated by Gram-positive organisms as found with a healthy periodontium. Two kinds of periodontal treatment were examined, conventional treatment with periodontal scaling and root planing, and conventional treatment plus a superimposed systemic tetracycline therapy. Three studies with different therapeutic regimes were initiated, which showed that the effect of systemic tetracycline therapy on the amount of supragingival plaque is of short-term duration.

Presents abstracts of articles on dentistry in Great Britain. Periodontics; Dental pathology; Prosthodontics.

The article presents a study which determines whether the host's immunologic response reflected stimulation by the appropriate organisms. Human cellular immunity, assessed by lymphocyte blastogenesis, was measured to a large and representative battery of oral microorganisms. The pattern of lymphocyte reactivity to these organisms correlated with their presence in the flora adjacent to the periodontal tissues. For example, cellular immunity to oral spirochetes, as measured by the lymphoproliferative response was observed in subjects with gingivitis, adult periodontitis and juvenile periodontitis, conditions in which large numbers of spirochetes are present.

In this article, the concept that phagocytic cells protect the host against attack by micro-organisms has been clearly established. This idea is supported by the increased prevalence and severity of infection associated with severe neutropenia or agranulocytosis. What has become apparent in recent years is that the phagocytic cell, particularly the neutrophil or polymorphonuclear leukocyte, may be present in the bloodstream in normal numbers and yet exhibit derangement of one or more of its functions, resulting in reduced resistance to infection. In this article the pathologic sequela of reduced neutrophil function have been reviewed. Special emphasis has been placed upon the pathologic changes in the oral cavity as a result of neutrophil dysfunction.

Evidence for complement utilization in middle ear fluids (MEF) from patients with otitis media with effusion was sought. It was found that cleavage products of C3, C4 and Factor B could be demonstrated immunochemically in MEF, and that native C3 was present in much lower concentrations than other proteins, relative to their serum concentrations. Haemolytic assays for C1-C5 showed that early complement components are inactivated in MEF. Potential mechanisms for complement utilization in MEF are discussed. [ABSTRACT FROM AUTHOR]

Abstract The preservation of historical buildings mainly depends on our capacity to monitor their ageing and quickly detect potential damage. We show how the dynamic characteristics of a building (i.e., frequency, shapes mode and seismic wave velocity) can be automatically identified and tracked in real-time by combining modal analysis with seismic interferometry. The assessment of these characteristics is performed on Giotto's bell tower in Firenze, Italy, by installing a temporary network of seismic sensors. The natural frequencies and modal shapes of the structure are calculated by enhanced frequency domain decomposition (EFDD). The impulse response functions estimated by following a waveform deconvolution approach are analysed to investigate the seismic wave dispersion in Giotto's bell tower. We show that Giotto's bell tower is a dispersive structure affected by a bending deformation, with a weak contribution from soil-system interaction. Combining the results of operational modal analysis (OMA) and seismic interferometry from the same ambient noise recording provides a unique and complete dynamic response of important monuments such as Giotto's bell tower. [ABSTRACT FROM AUTHOR]

Explosive volcanic eruptions can eject large amounts of ash into the atmosphere, posing a serious threat to populations living near the volcano. The abrupt occurrence of such events requires a rapid response and proper volcanic hazard evaluation. Current monitoring procedures still require human intervention, which often results in significant delays between the occurrence of an eruption and notifications being dispatched. We show how dedicated infrasound array processing can be used to detect and notify the authorities, automatically and in real time, of the onset of explosive eruptions. Conceptually, our method relies on the strong coupling between infrasound and the explosive process, and it is not based on probabilistic considerations but on the ability infrasound has to detect the early stage of the explosive phase. This procedure has been tested for the last 8 years, and it is currently applied to issue early warnings for explosive eruptions at Etna Volcano. We show that the system is able to provide a prealert ~1 hr before the eruption, and it has a 96.6% success rate, with only 1.7% false positive alerts and no false negative alerts. This is, to our knowledge, the first example of an operational early warning system totally based on an unsupervised algorithm that provides automatic notifications of eruptions to a government agency. We show that the same early warning concept might be applicable to arrays at large distances (>500 km), suggesting that infrasound could be successfully used to issue automatic notifications of ongoing eruptions at regional to global scales. Plain Language Summary: Most of the volcanic eruptions are rapidly evolving phenomena, strongly limiting the possibility to prompt activate emergency plans. We still lack the possibility to notify volcanic eruptions automatically, making our society highly exposed to the effects of large explosive eruptions. We present the first early‐warning system based on the acoustic waves generated by volcanic eruptions. Our approach relies on the strong coupling between sound and explosive process, and, as for the earthquake, it is not based on probabilistic consideration but on a quasi‐deterministic approach. In the last 8 years, the system was providing a prealert notification ~1 hr before the eruptive onset with 96.6% rate of success, 1.7% positive false alerts, and no negative false alerts. This is, in our knowledge, the first example of an operational early‐warning system totally based on automatic and unmanned algorithm that provides automatic notification of eruption to government agency automatically and without man supervision. Early warnings can be applied even at regional distances (˃500 km), and notification of ongoing volcanic eruptions would be of valuable importance for aviation safety especially for the many active volcanoes worldwide that are still lacking of geophysical monitoring systems. Key Points: We present the first example of operational early warning for volcanic eruptions based on automatic and unsupervised algorithmThe infrasound array processing detects in real‐time explosive eruptions with a 96.6% of success and no false negative alertsThe early‐warning algorithm automatically delivers prealert notification ~1 hr before the occurrence of the eruptive onset [ABSTRACT FROM AUTHOR]

The periodontal pathogen Tannerella forsythia has the unique ability to produce methylglyoxal (MGO), an electrophilic compound which can covalently modify amino acid side chains and generate inflammatory adducts known as advanced glycation endproducts (AGEs). In periodontitis, concentrations of MGO in gingival-crevicular fluid are increased and are correlated with the T. forsythia load. However, the source of MGO and the extent to which MGO may contribute to periodontal inflammation has not been fully explored. In this study we identified a functional homolog of the enzyme methylglyoxal synthase (MgsA) involved in the production of MGO in T. forsythia. While wild-type T.forsythia produced a significant amount of MGO in the medium, a mutant lacking this homolog produced little to no MGO. Furthermore, compared with the spent medium of the T. forsythia parental strain, the spent medium of the T. forsythia mgsA-deletion strain induced significantly lower nuclear factor-kappa B activity as well as proinflammogenic and pro-osteoclastogenic cytokines from THP-1 monocytes. The ability of T. forsythia to induce protein glycation endproducts via MGO was confirmed by an electrophoresis-based collagen chain mobility shift assay. Together these data demonstrated that T. forsythia produces MGO, which may contribute to inflammation via the generation of AGEs and thus act as a potential virulence factor of the bacterium. [ABSTRACT FROM AUTHOR]