Showing papers by "Margaret Bell published in 2007"

Runx2 disruption promotes immortalization and confers resistance to oncogene-induced senescence in primary murine fibroblasts.

Abstract: The Runx genes play paradoxical roles in cancer where they can function either as dominant oncogenes or tumor suppressors according to context. We now show that the ability to induce premature senescence in primary murine embryonic fibroblasts (MEF) is a common feature of all three Runx genes. However, ectopic Runx–induced senescence contrasts with Ras oncogene–induced senescence, as it occurs directly and lacks the hallmarks of proliferative stress. Moreover, a fundamental role for Runx function in the senescence program is indicated by the effects of Runx2 disruption, which renders MEFs prone to spontaneous immortalization and confers an early growth advantage that is resistant to stress-induced growth arrest. Runx2−/− cells are refractory to H-RasV12–induced premature senescence, despite the activation of a cascade of growth inhibitors and senescence markers, and are permissive for oncogenic transformation. The aberrant behavior of Runx2−/− cells is associated with signaling defects and elevated expression of S-G2-M cyclins and their associated cyclin dependent kinase activities that may override the effects of growth inhibitory signals. Coupling of stress responses to the cell cycle represents a novel facet of Runx tumor suppressor function and provides a rationale for the lineage-specific effects of loss of Runx function in cancer. [Cancer Res 2007;67(23):11263–71]

Analysis of Driving Parameters and Emissions for Real World Urban Driving Cycles using an on-board Measurement Method for a EURO 2 SI car

Abstract: A FTIR in-vehicle on-road emission measurement system was installed in a EURO 2 emissions compliant SI car to investigate exhaust emissions under different urban traffic conditions. The real time fuel consumption and vehicle traveling speed was measured and logged. The temperatures were measured along the exhaust pipe so as to monitor the thermal characteristics and efficiency of the catalyst. Two real world driving cycles were developed with different traffic conditions. One (WP cycle) was located in a quiet area with few trafficinterference and the other one (HPL cycle) was in a busy area with more traffic variations. The test car was pre-warmed before each test to eliminate cold start effect. The driving parameters were analyzed for two real world cycles. The WP cycle had higher acceleration rate, longer acceleration mode and shorter steady speed driving mode and thus harsher than the HPL cycle. The CO, THC, NOx CO2, benzene and other hydrocarbon emissions were higher for the WP cycle. The comparison with EU legislation shows that the CO and THC emissions from both real world cycles could meet the legislated limit but the NOx emissions from both cycle exceeded the legislated emissions when the engine was hot. The research analyzed the elements that affect urban traffic emissions and will be useful for a better traffic management to reduce emissions. The data of this research can be used for the prediction of emissions in cities.