The aim of the present study was to investigate the effects of Porphyromonas gingivalis (P. gingivalis) on inflammatory cytokine and nitic oxide (NO) production in lung epithelial cells infected with H1N1, and the underlying mechanisms. Lung epithelial cells were co-infected with P. gingivalis and H1N1. The concentrations of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6 were detected via an ELISA, and the concentration of NO was detected by the nitrate reductive enzymatic method at 4, 8, 12 and 24 h following infection. The expression levels of inducible NO synthase (iNOS) was detected by western blotting. The apoptotic rate of lung epithelial cells was detected by flow cytometry. The relative protein expression levels of B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax) and caspase-3 in lung epithelial cells were detected by western blotting. Compared with the control group, the concentration of the inflammatory cytokines TNF-α, IL-1β and IL-6 exhibited a significant increase (P<0.05) in the viral-infected, bacterial-infected and co-infected groups. The concentration of NO also increased significantly (P<0.05), along with the rise in the expression levels of iNOS (P<0.05) and the increase in the apoptosis rate of lung epithelial cells (P<0.05). The relative expression levels of caspase-3 and Bax proteins were increased significantly in the viral- and bacterial-infected groups when compared with the control. The relative expression levels of Bcl-2 protein exhibited a significant decrease in lung epithelial cells following the co-infection with P. gingivalis and H1N1 compared with the control (P<0.05). The results of the present study revealed that the combination of P. gingivalis and H1N1 infection in lung epithelial cells may promote the production of inflammatory cytokines and increase NO production, leading to increased levels of apoptosis in lung epithelial cells via the Bcl-2/Bax/caspase-3 signaling pathway.

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We demonstrate the significant role of long quantum orbits in strong-field atomic processes by investigating experimentally and theoretically the above-threshold ionization spectra of noble gases in intense elliptically polarized laser pulses. With increasing laser ellipticity, the yields of different energy regions of the measured electron spectrum in high-order above-threshold ionization drop at different rates. The experimental features can be reproduced by a theoretical simulation based on quantum-orbit theory, revealing that increasing ellipticity favors the contributions of the long quantum orbits in the high-order above-threshold ionization process.

A novel and universal interference structure is found in the photoelectron momentum distribution of atoms in intense infrared laser field. Theoretical analysis shows that this structure can be attributed to a new form of Coulomb-field-driven backward-scattering of photoelectrons in the direction perpendicular to the laser field, in contrast to the conventional rescattering along the laser polarization direction. This transverse backward-scattering process is closely related to a family of photoelectrons initially ionized within a time interval of less than 200 attosecond around the crest of the laser electric field. Those electrons, acquiring near-zero return energy in the laser field, will be pulled back solely by the ionic Coulomb field and backscattered in the transverse direction. Moreover, this rescattering process mainly occurs at the first or the second return times, giving rise to different phases of the photoelectrons. The interference between these photoelectrons leads to unique curved interference fringes which are observable for most current intense field experiments, opening a new way to record the electron dynamics in atoms and molecules on a time scale much shorter than an optical cycle.PACS numbers: 32.80. Wr, 33.60.+q, 61.05.jp In the ionization process of atoms in intense laser field, the electron wave packet (EWP) may follow different paths from its bound state to the continuum in the combined laser and Coulomb fields. The interference between the EWPs might create richly structured patterns in the final photoelectron distribution, which inherently encode the temporal and spatial information of the ions and electrons. For example, a holographic interference structure was recently observed in the photoelectron momentum distribution (PMD) of metastable xenon atom ionized by a 7 µm free-electron laser pulse [1]. This interference structure was explained as interference between the direct and the laser-driven forward-scattered EWPs generated within the same quarter-cycle of the laser pulse, providing an efficient way in exploring the structure and the dynamics of the atoms and molecules with attosecond temporal and angstrom spatial resolution. Thereafter, the photoelectron interference structure has been extensively investigated for a broad range of laser parameters covering tunneling to multiphoton ionization regimes, however, a full understanding of its underlying physics has not yet been achieved [2][3][4][5][6][7][8].Note that for the formation of this specific holographic interference structure, the reference wave, i.e., the direct electron, upon ionization, was assumed to be very weakly affected by the ionic Coulomb field, while the rescattered one, experienced strong Coulomb focusing and passed close to the ion, was considered as the signal wave. Moreover, previous studies have suggested that the Coulomb field plays a negligible role in the holographic interference patterns [1,2,4]. On the other hand, it has been generally accepted that the ionic Coulomb field plays a pivotal role in the ...

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