Interleukin 1β and Prostaglandin E2 Affect Expression of DNA Methylating and Demethylating Enzymes in Human Gingival Fibroblasts

Periodontitis is a common chronic inflammatory condition that results in increased levels of inflammatory cytokines and inflammatory mediators. In addition to oral disease and tooth loss, it also causes low-grade systemic inflammation that contributes to development of systemic conditions including cardiovascular disease, pre-term birth, diabetes and cancer. Chronic inflammation is associated with epigenetic change, and it has been suggested that such changes can alter cell phenotypes in ways that contribute to both ongoing inflammation and development of associated pathologies. Here we show that exposure of human gingival fibroblasts to IL-1β increases expression of maintenance methyltransferase DNMT1 but decreases expression of de novo methyltransferase DNMT3a and the demethylating enzyme TET1, while exposure to PGE2 decreases expression of all three enzymes. IL-1β and PGE2 both affect global levels of DNA methylation and hydroxymethylation, as well as methylation of some specific CpG in inflammation-associated genes. The effects of IL-1β are independent of its ability to induce production of PGE2, and the effects of PGE2 on DNMT3a expression are mediated by the EP4 receptor. The finding that exposure of fibroblasts to IL-1β and PGE2 can result in altered expression of DNA methylating/demethylating enzymes and in changing patterns of DNA methylation suggests a mechanism through which inflammatory mediators might contribute to the increased risk of carcinogenesis associated with inflammation

Understanding of sub-band gap absorption of femtosecond-laser sulfur hyperdoped silicon using synchrotron-based techniques

[[abstract]]The correlation between sub-band gap absorption and the chemical states and electronic and atomic structures of S-hyperdoped Si have been extensively studied, using synchrotron-based x-ray photoelectron spectroscopy (XPS), x-ray absorption near-edge spectroscopy (XANES), extended x-ray absorption fine structure (EXAFS), valence-band photoemission spectroscopy (VB-PES) and first-principles calculation. S 2p XPS spectra reveal that the S-hyperdoped Si with the greatest (~87%) sub-band gap absorption contains the highest concentration of S2− (monosulfide) species. Annealing S-hyperdoped Si reduces the sub-band gap absorptance and the concentration of S2− species, but significantly increases the concentration of larger S clusters [polysulfides (Sn2−, n > 2)]. The Si K-edge XANES spectra show that S hyperdoping in Si increases (decreased) the occupied (unoccupied) electronic density of states at/above the conduction-band-minimum. VB-PES spectra evidently reveal that the S-dopants not only form an impurity band deep within the band gap, giving rise to the sub-band gap absorption, but also cause the insulator-to-metal transition in S-hyperdoped Si samples. Based on the experimental results and the calculations by density functional theory, the chemical state of the S species and the formation of the S-dopant states in the band gap of Si are critical in determining the sub-band gap absorptance of hyperdoped Si samples.[[notice]]補正完畢[[journaltype]]國外[[incitationindex]]SCI[[ispeerreviewed]]Y[[booktype]]電子版[[countrycodes]]GB

MEASUREMENT OF RELATIVE INTENSITIES OF MICROWAVE ABSORPTION LINES∗LINES^{*}

$^{*}$The research was made possible by support extended Harvard University by the Office of Naval Research under ONR Contract Nonr 1866, Task Order XIV.Author Institution: Mallinckrodt Chemical Laboratory, Harvard UniversityA technique has been developed which allows a conventional Stark-modulated spectrometer to be utilized for the measurement of the relative intensities of absorption lines. It has long been known that reflections from various waveguide components set up standing waves within the absorption cell resulting in effective path lengths that are functions of frequency. This effect is largely responsible for the errors of 20\% or more usually encountered in measuring intensity ratios. By careful choice and design of various waveguide elements and by the use of ferrite isolators, particularly ahead of the crystal holder, which was found to reflect very strongly, the problem of reflections has been satisfactorily eliminated. Also, non-linearities in the detection system were neutralized by the use of a calibrated attenuator inserted between the preamplifier and the detector. Finally, a number of other phenomena including power saturation, interference of nearby lines and lobes, and the presence of stray signals at the modulation frequency (pickup) have been investigated. Measurements of the relative intensities of lines due to different isotopes, to various quadrupole components, and to molecules in different vibrational states have been made. The deviation between the values obtained and those predicted by other means has been between 1 and 2\% for 7 such measurements