Collagen content dating
However, because collagen I is the main constituent of CAs and because we generally excised and analyzed ≥2/3 of the aneurysm dome, the birth dating measurements are likely to reflect the majority of the aneurysmal mass. In addition, we can only estimate relative collagen turnover using radiocarbon birth dating as an indicator because the total collagen content in human CA samples cannot be monitored over time.C results have been compared with the archaeological evidence, showing some relationship between measured C/N atomic ratios and collagen quality. In particular, when grouping the measured samples according to their C/N ratio, the agreement between C dates and archaeological evidence is good or inconsistent when the C/N ratio clearly falls inside or outside the “recommended” range, respectively, with a still reasonable agreement also when it is slightly above the upper limit of that range. Importantly, we could not compare the age and turnover of collagen type I in CAs with that in cerebral arteries because CAs and normal arteries of the circle of Willis did not share a representative and exclusive structural protein, such as collagen type I. The age of collagen in CAs is independent of CA clinical presentation (ruptured versus incidental) and, moreover, of factors that may be associated with CA formation or rupture (ie, patient age, aneurysm size, and morphology).
Bone samples recently C dated at INFN-LABEC have confirmed that the measurement of C/N atomic ratios can give some indications of the collagen quality. M.); and Department of Surgery, University of Toronto, Toronto, Ontario, Canada (R. Aside from our preliminary birth dating study in a small patient cohort, data to support or challenge this concept are mainly derived from animal studies or mathematical models and observational studies of human CAs. The prevailing concept remains that there are different populations of small CAs, including those that grow and reach a stable size, those that continue to enlarge and either reach a stable larger size or rupture over the long term, and those that form, enlarge, and then rupture over a relatively short period of time. This is consistent with serial imaging data, showing that some unruptured CAs do undergo growth, including selected smaller aneurysms and a substantial proportion of larger aneurysms especially in patients who smoke. Interestingly, this remodeling seems to be significantly accelerated in patients with risk factors associated with atherosclerosis and potentially aneurysm growth and rupture (hypertension, cigarette smoking, or cocaine use), possibly because of increased hemodynamic stress.
The latter shows more variability in all quality parameters than the former.