Using normal canine embryonic fibroblasts (CaEF) that were shown to be senescent at passages 7th-9th, we established two spontaneously immortalized CaEF cell lines (designated CGFR-Ca-1 and -2) from normal senescent CaEF cells, and an immortal CaEF cell line by exogenous introduction of a catalytic telomerase subunit (designated CGFR-Ca-3). Immortal CGFR- Ca-1, -2 and -3 cell lines grew faster than primary CaEF counterpart in the presence of either 0.1% or 10% FBS. Cell cycle analysis demonstrated that all three immortal CaEF cell lines contained a significantly high proportion of S-phase cells compared to primary CaEF cells. CGFR-Ca-1 and -3 cell lines showed a loss of p53 mRNA and protein expression leading to inactivation of p53 regulatory function, while the CGFR-Ca-2 cell line was found to have the inactive mutant p53. Unlike the CGFR-Ca-3 cell line that down-regulated p16INK4a mRNA due to its promoter methylation but had an intact p16INK4a regulatory function, CGFR-Ca-1 and -2 cell lines expressed p16INK4a mRNA but had a functionally inactive p16INK4a regulatory pathway as judged by the lack of obvious differences in cell growth and phenotype when reconstituted with wild-type p16INK4a. All CGFR-Ca-1, -2 and -3 cell lines were shown to be untransformed but immortal as determined by anchorage-dependent assay, while these cell lines were fully transformed when overexpressed oncogenic H-rasG12V. Taken together, similar to the nature of murine embryo fibroblasts, the present study suggests that normal primary CaEF cells have relatively short in vitro lifespans and should be spontaneously immortalized at high frequency.
Animals ; Catalytic Domain/genetics ; *Cell Aging/genetics ; Cell Line, Transformed ; Cell Transformation, Neoplastic ; Dogs ; Embryo/cytology ; Fibroblasts/*cytology/metabolism ; Gene Expression ; Protein p16/genetics ; Protein p53/genetics ; RNA, Messenger/analysis/metabolism ; Research Support, Non-U.S. Gov't ; Telomerase/genetics/metabolism ; ras Proteins/genetics/metabolism

To evaluate the safety and efficacy of the computed tomography coronary angiography (CTCA) for evaluation of acute chest pain in real world population, we prospectively enrolled 296 patients with acute chest pain at emergency department (ED) from November 2005 to February 2007. The patients were grouped based on the clinical information and CTCA result. The patients with a low risk profile and no significant coronary stenosis (>50%) in CTCA were discharged immediately (Group 1, n=103). On the other hand, the patients with an intermediate risk profile without significant stenosis were observed in ED for 24 hr (Group 2, n=104). The patients with significant stenosis underwent further coronary evaluation and management accordingly (Group 3, n=89). While no false negative case was found in Group 1, seven cases (6.73%) were found in Group 2, mostly during the observation period. In Group 3, there were 54 (60.67%) cases of acute coronary syndrome including 10 myocardial infarctions. The overall accuracy of CTCA for acute coronary syndrome was 88.5% (sensitivity), 85.1% (specificity), 60.7% (positive predictive value) and 96.6% (negative predictive value). In conclusion, clinical decision based on CTCA is safe and effective for low risk patients. Further validation is needed in patients with intermediate risk profile.
Adult ; Aged ; *Chest Pain/diagnosis/etiology/radiography ; Coronary Angiography/*methods ; Coronary Stenosis/radiography ; Decision Making ; Emergency Service, Hospital ; Female ; Follow-Up Studies ; Humans ; Male ; Middle Aged ; Prospective Studies ; Risk Factors ; Sensitivity and Specificity ; Tomography, X-Ray Computed/*methods