No abstract

Background:The role of mitochondrial DNA (mtDNA) mutations in the development of breast cancer is largely unknown. In this study, we investigated the frequency and pattern of mutations in the D310 region, the most commonly mutated region in mtDNA, in a series of breast lesions.Methods:Using capillary electrophoresis, we genotyped the D310 sequence of neoplastic epithelial cells from 23 patients with synchronous ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC), 26 patients with IDC only and 29 patients with DCIS only.Results:A majority of DCIS (68.4%) and IDC (71.4%) lesions harbour different D310 sequences compared with their matched normal control. Specific D310 sequences were more frequently identified in tumour samples (77.1% of DCIS and 75.5% of IDC) compared with normal tissues (35.3% of normal; P<0.0001). No difference was identified between DCIS lesions with synchronous IDC and those from pure DCIS cases. In five cases, histologically normal tissue adjacent to tumour was found to share D310 sequences with the tumour, while normal tissue taken further away did not.Conclusion:Although D310 alterations do not seem to be related to DCIS progression, they were found in histologically normal cells adjacent to tumour. This suggests a field of genetically altered cells, thus D310 mutations could represent a potential marker for the clonal expansion of premalignant breast cancer cells.

SUMMARYA thermodynamic study indicates that the hypothetical modification of gas-turbine engines to include two heat additions rather than one may result in significant efficiency improvements of over 4% compared with conventional engines. Specifically, the usual constant pressure heat addition would be constrained to a given temperature and then further heat addition carried out in a manner approaching an isothermal process. Owing to the limited peak combustion temperature of the overall heat addition process, the emissions of NO V may be reduced by as much as 50%, thus offering an environmental benefit as well as an efficiency advantage. This paper details the analysis of a proposed combustion chamber in which an isothermal heat addition is approximated. The combustion chamber would consist of a converging duct featuring discrete combustion sites positioned along the streamwise direction. A numerical analysis developed to assess the deviation from isothermal flow in the combustion chamber shows that a reasonable approximation of such a heat addition may be possible with two or more combustion sites. Moreover, a simplified treatment of the combustion process implies that flame stabilization at these sites is feasible.