Background The aim of this study was to determine the role of ascending aortic length and diameter in type A aortic dissection. Methods and Results Computed tomography scans from patients with acute type A dissections (n=51), patients with proximal thoracic aortic aneurysms (n=121), and controls with normal aortas (n=200) were analyzed from aortic annulus to the innominate artery using multiplanar reconstruction. In the control group, ascending aortic length correlated with diameter ( r 2 =0.35, P <0.001), age ( r 2 =0.17, P <0.001), and sex ( P <0.001). As a result of immediate changes in aortic morphology at the time of acute dissection, predissection lengths and diameters were estimated based on models from published literature. Ascending aortic length was longer in patients immediately following acute dissection (median, 109.7 mm; interquartile range [IQR], 101.0–115.1 mm), patients in the estimated predissection group (median, 104.2 mm; IQR, 96.0–109.3 mm), and patients in the aneurysm group (median, 107.0 mm; IQR, 99.6–118.7 mm) in comparison to controls (median, 83.2 mm; IQR, 74.5–90.7 mm) ( P <0.001 all comparisons). The diameter of the ascending aorta was largest in the aneurysm group (median, 52.0 mm; IQR, 45.9–58.0 mm), followed by the dissection group (median, 50.3 mm; IQR, 46.6–57.5 mm), and not significantly different between controls and the estimated predissection group (median, 33.4 mm [IQR, 30.7–36.7 mm] versus 35.2 mm [IQR, 32.6–40.3 mm], P =0.09). After adjustment for diameter, age, and sex, the estimated predissection aortic lengths were 16 mm longer than those in the controls and 12 mm longer than in patients with nondissected thoracic aneurysms. Conclusions The length of the ascending aorta, after adjustment for age, sex, and aortic diameter, may be useful in discriminating patients with type A dissection from normal controls and patients with nondissected thoracic aneurysms.

To isolate and karyotype the progeny of erythroid progenitors, we applied colony erythroblasts derived from plasma clot marrow cultures from two healthy adults and two patients with newly diagnosed Ph1+ chronic myelogenous leukaemia (CML) to discontinuous Stractan density gradients. Erythroid colony proliferation by patient cells was increased relative to that of normal donor cells (P less than 0.01). 'Endogenous' colonies appeared in patient but not in normal donor marrow cultures. Greater than 95% of nucleated cells equilibrating at rho greater than or equal to 1.071 were basophilic proerythroblasts. While analysis of chromosome spreads of normal donor cells in this fraction showed normal karyotypes, cells from patient marrow cultures were Ph1+, whether cultured in the presence or absence of added erythropoietin. These findings suggest that chromosome abnormalities of erythroid progenitors may be expressed by their progeny in tissue culture, and that Stractan may be a useful supporting medium for separating colony erythroblasts for chromosome analysis.