No abstract

Results show that PuO(2+x), a high-composition (x

Intestinal commensals are potential important contributors to the etiology of sporadic colorectal cancer but mechanisms by which bacteria can initiate tumors remain uncertain. Herein we describe mechanisms that link Enterococcus faecalis, a bacterium known to produce extracellular superoxide, to the acute induction of chromosomal instability. Immortalized human and non-transformed murine colonic epithelial cells, along with a mouse colonic ligation model, were used to assess the effect of E. faecalis on genomic DNA stability and damage. We found that this human intestinal commensal generated aneuploidy, tetraploidy, and γH2AX foci in HCT116, RKO, and YAMC cells. In addition, direct exposure of E. faecalis to these cells induced a G2 cell cycle arrest. Similar observations were noted by exposuring cells to E. faecalis-infected macrophages in a dual-chamber co-culture system for detecting bystander effects. Manganese superoxide dismutase, catalase, and tocopherols attenuated, caffeine and inhibitor of glutathione synthase exacerbated, aneugenic and cyclomodulatory effects and linked the redox-active phenotype of this intestinal commensal to potentially transforming events. These findings provide novel insights into mechanisms by which E. faecalis and intestinal commensals can contribute to cellular transformation and tumorigenesis.

The thermal conductivity of SiO2 and TiO2 optical coatings are measured in the temperature range 80–400 K. For SiO2, the thermal conductivity of sputtered and evaporated films are 77% and 55% of the bulk value, respectively, independent of temperature. Similarly, the thermal conductivity of evaporated TiO2 is 63% of the conductivity of sputtered TiO2.