A strong correlation between chronic periodontitis and systemic diseases (e.g., cardiovascular disease, metabolic disorders) has been suggested for several decades. However, the evidence supporting this correlation is restricted primarily to epidemiologic studies, with only a few experimental outcomes confirming such a correlation and providing information about the underlying molecular mechanisms. To reveal a correlation between periodontitis and systemic diseases as well as a relevant molecular pathway, we investigated the effects of Porphyromonas gingivalis and Fusobacterium nucleatum, which play roles in chronic periodontitis progression, on Raw264.7 and THP-1 macrophages. Infection with P. gingivalis or F. nucleatum significantly induced the expression of fatty acid binding protein 4 (FABP4), one of the most important adipokines that play a role in the progression of systemic diseases such as atherosclerosis and type 2 diabetes. Periodontal pathogen–induced FABP4 expression in macrophages promoted lipid uptake by these cells, as demonstrated by the diminished lipid accumulation in cells treated with an FABP4 inhibitor, BMS309403, or with knockdown of FABP4 expression. This periodontal pathogen–induced FABP4 expression was dependent on the JNK pathway, and JNK inhibition reduced lipid uptake by reducing FABP4 expression. Serum levels of antibodies against P. gingivalis correlated with serum FABP4 levels in humans, whereas no association occurred between F. nucleatum antibody titers and FABP4 levels. To our knowledge, this report is the first to experimentally demonstrate that periodontal pathogens stimulate lipid uptake in macrophages by modulating FABP4 expression. These findings strongly support the hypothesis that periodontitis may affect the progression of various systemic diseases.

In the present study, a numerical study and an experimental study on the break-up process of a hollow-cone fuel spray were performed. This was done to develop a new hybrid break-up model and to validate this model under various ambient pressure conditions. The new hybrid break-up model was composed of the linearized instability sheet atomization (LISA) model for the primary break-up and the aerodynamically progressed Taylor analogy break-up (APTAB) model, with consideration for the deformed droplet shape, for the secondary break-up. The APTAB model was used instead of the Taylor analogy break-up (TAB) model used in the previous hybrid break-up model (the LISA-TAB model). The hybrid break-up models were implemented in modified KIVA code. The calculated results of the spray characteristics, such as the spray tip penetration, spray width, Sauter mean diameter, and droplet velocity, by means of the LISA-APTAB model were compared with the calculated results via the LISA-TAB model and the experimental results found with the laser-induced exciplex fluorescence technique and the phase Doppler anemometry (PDA) system. The calculations and the experiment were performed under ambient pressures of 0.1 MPa and 0.5 MPa and an ambient temperature of 293 K. It was found that the calculated results from the LISA-APTAB model showed good agreement with the experimental results. The discrepancies between the calculated results and the experimental results in spray characteristics were reduced by a considerable margin by adopting the APTAB model instead of the TAB model for the secondary break-up process.