Gastrointestinal Hyperplasia with Altered Expression of DNA Polymerase β

Background: Altered expression of DNA polymerase β (Pol β) has been documented in a large percentage of human tumors. However, tumor prevalence or predisposition resulting from Pol β over-expression has not yet been evaluated in a mouse model. Methodology/Principal Findings: We have recently developed a novel transgenic mouse model that over-expresses Pol β. These mice present with an elevated incidence of spontaneous histologic lesions, including cataracts, hyperplasia of Brunner's gland and mucosal hyperplasia in the duodenum. In addition, osteogenic tumors in mice tails, such as osteoma and osteosarcoma were detected. This is the first report of elevated tumor incidence in a mouse model of Pol β over-expression. These findings prompted an evaluation of human gastrointestinal tumors with regard to Pol β expression. We observed elevated expression of Pol β in stomach adenomas and thyroid follicular carcinomas, but reduced Pol β expression in esophageal adenocarcinomas and squamous carcinomas. Conclusions/Significance: These data support the hypothesis that balanced and proficient base excision repair protein expression and base excision repair capacity is required for genome stability and protection from hyperplasia and tumor formation

Doppler beam sharpening in passive bistatic radar with spaceborne illuminators of opportunity

The applicability of Doppler beam sharpening (DBS) is assessed for the use in a passive bistatic system using a spaceborne transmitter in the Inmarsat constellation (Alphasat) as the illuminator of opportunity, for potential application in low cost maritime early warning systems in vessels. The effect of sharpening for both stationary and moving targets is discussed in theory, with models to show the effects for stationary targets that predicted a large improvement in angular resolution through the use of DBS. Experimental results show the effect in action, with three distinguishable targets found within 10 degrees using an antenna with a full beamwidth of 30 degrees, for a receiver moving at a mean of 11.6m/s over a coherent integration time of 1s, a carrier wave wavelength of 0.193m, a target range of 2.5-3km, and target look angle of 20-30 degrees. The results from the experiment are shown to agree with a simulation of a similar system, and a visual demonstration of the results overlaid on a satellite map is also displayed.</p