Analysis of cell death in Bacillus subtilis caused by sesquiterpenes from Chrysopogon zizanioides (L.) Roberty.

Recently, the antibacterial effects of essential oils have been investigated in addition to their therapeutic purposes. Owing to their hydrophobic nature, they are thought to perturb the integrity of the bacterial cell membrane, leading to cell death. Against such antibiotic challenges, bacteria develop mechanisms for cell envelope stress responses (CESR). In Bacillus subtilis, a gram-positive sporulating soil bacterium, the extracytoplasmic function (ECF) sigma factor-mediated response system plays a pivotal role in CESR. Among them, σM is strongly involved in response to cell envelope stress, including a shortage of available bactoprenol. Vetiver essential oil, a product of Chrysopogon zizanioides (L.) Roberty root, is also known to possess bactericidal activity. σM was exclusively and strongly induced when the cells were exposed to Vetiver extract, and depletion of multi-ECF sigma factors (ΔsigM, ΔsigW, ΔsigX, and ΔsigV) enhanced sensitivity to it. From this quadruple mutant strain, the suppressor strains, which restored resistance to the bactericidal activity of Vetiver extract, emerged, although attempts to obtain resistant strains from the wild type did not succeed. Whole-genome resequencing of the suppressor strains and genetic analysis revealed inactivation of xseB or pnpA, which code for exodeoxyribonuclease or polynucleotide phosphorylase, respectively. This allowed the quadruple mutant strain to escape from cell death caused by Vetiver extract. Composition analysis suggested that the sesquiterpene, khusimol, might contribute to the bactericidal activity of the Vetiver extract.

Effect of arthrocentesis on TMJ disturbance of mouth closure with loud clicking: a preliminary study.

The objective of this study was to evaluate the short-term effect of arthrocentesis on temporomandibular joint disturbance of mouth closure with loud clicking compared to the effect of one-time pumping into the joint space previous to arthrography. Twenty-one consecutive patients (22 joints) with loud clicking during mouth closure were enrolled. All were unable to smoothly close the mouth without effort. Eleven patients (12 joints) were examined using magnetic resonance imaging (MRI) to determine disk position. They then underwent arthrocentesis. Ten patients (10 joints) underwent arthrography alone as controls. Six months later, changes in clicking and temporomandibular joint movement were analyzed and the disk position was re-examined. There was improvement of mouth closing and clicking occurred in nine joints from the arthrocentesis group and two joints from the control group, with a significant difference between the two groups. Arthrocentesis may be indicated for patients with temporomandibular joint dysfunction and loud clicking when mouth closing.